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What is Viagra used for? Viagra is used to treat impotence in men. Viagra increases the body’s ability to achieve and maintain an erection during sexual stimulation. Viagra does not protect you from getting sexually transmitted diseases, including HIV. take Viagra? Men who are currently using medicines that contain nitrates, such as nitroglycerin should not use Viagra because taken together they can lower the blood pressure too much. Viagra should not be used by women or children. In patients taking Viagra, several heart-related side effects have been reported, including heart attack, sudden death, irregular heart rhythm, stroke, chest pain, and increased blood pressure. It is not possible to determine whether these events are directly related to Viagra, to sexual activity, to the patient’s heart condition, to a combination of these factors, or to other factors. taking certain medications at the same time (e.g., ketoconazole, itraconazole, erythromycin and saquinavir). In these patients, the recommended starting dose of Viagra is 25 mg. Heart attack, stroke, or life-threatening irregular heart rhythm within the last 6 months Because Viagra lowers blood pressure, your doctor will evaluate your overall medical condition to determine if Viagra, in combination with sexual activity, could adversely affect you. Viagra can cause a rare but serious condition of prolonged erection (priapism). It is important to contact your health care provider immediately if your erection lasts longer than 4 hours. Men for whom sexual activity is inadvisable may not be good candidates for Viagra. Tell your doctor if you are taking protease inhibitors for the treatment of HIV. You should have a complete medical history and exam to determine the cause of your impotence before taking Viagra. Men who have medical conditions that may cause a sustained erection such as sickle cell anemia, leukemia or multiple myeloma or who have an abnormally shaped penis may not be able to take Viagra. There are several medications that are known to interact with Viagra, so be sure to tell your doctor about all medications you are taking including those you can get without a prescription. Viagra has not been studied with other treatments for impotence, so use in combination with other treatments is not recommended. What are some possible side effects of Viagra? a complete list of side effects reported with Viagra. Your health care provider can discuss with you a more complete list of side effects.) ). The following is a listing of the most common side effects Visual changes such as mild and temporary changes in blue/green colors or increased sensitivity to light. For more detailed information about Viagra, ask your health care provider.

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What is Viagra used for? Viagra is used to treat impotence in men. Viagra increases the body’s ability to achieve and maintain an erection during sexual stimulation. Viagra does not protect you from getting sexually transmitted diseases, including HIV. take Viagra? Men who are currently using medicines that contain nitrates, such as nitroglycerin should not use Viagra because taken together they can lower the blood pressure too much. Viagra should not be used by women or children. You should have a complete medical history and exam to determine the cause of your impotence before taking Viagra. Men who have medical conditions that may cause a sustained erection such as sickle cell anemia, leukemia or multiple myeloma or who have an abnormally shaped penis may not be able to take Viagra. There are several medications that are known to interact with Viagra, so be sure to tell your doctor about all medications you are taking including those you can get without a prescription. Viagra has not been studied with other treatments for impotence, so use in combination with other treatments is not recommended. How should I take Viagra? Your healthcare provider may prescribe Viagra as one tablet once a day, about 1 hour before sexual activity. However, Viagra may be taken anywhere from 30 minutes to 4 hours before sexual activity. What are some possible side effects of Viagra? a complete list of side effects reported with Viagra. Your healthcare provider can discuss with you a more complete list of side effects. Viagra is generally well tolerated. If any side effects are experienced, they are usually mild and temporary. The following is a listing of the most common side effects: Visual changes such as mild and temporary changes in blue/green colors or increased sensitivity to light. For more detailed information on Viagra, ask your healthcare provider. More Articles... If you have any questions or comments on senior health nutrition, fitness, etc., go to the is for educational / reference use only.  cheapest viagra substitute sildenafil Impotence and erectile dysfunction affect many men, and in recent years, have become more widely discussed. Various treatments have been developed to cure such problems, the most popular and widely available being Viagra. There are more and more alternatives to Viagra appearing on the market, some of which are more reliable and trustworthy than others! Read on to discover a legitimate and safe alternatives to Viagra. Firstly, some men experience side effects from using Viagra. Although this isn't widespread amongst users, Viagra alternatives don't involve any risk of side effects. Side effects such as dizziness, loss of vision, headaches, flushing and low blood pressure can occur. In more extreme cases some men have experienced priapism( a painful condition when a man's penis fails to return to its natural flaccid state. The Viagra alternative extracts such side effects as the non- chemical remedies consist of natural herbal ingredients. Such alternatives are widely available and their increased use by male consumers on the rise. Secondly, such herbal alternatives are available over the counter or on the internet (as are Viagra however), without a prescription, and are relatively cheap, ranging from $1- 1.50 a pill. Generic Viagra treatments however are also available without a prescription, and although are slightly more expensive they still appear to be the most popular choice amongst consumers. Thirdly, an alternative Viagra treatment takes 30- 45 minutes to work, however the length of its effect varies widely. Certain herbal ingredients work effectively such as Epicedium (commonly known as the horny goat weed), which is a great sex drive booster. Viagra however, whilst taking about the same time to have an effect on a man's penis normally lasts for around 1-2 hours (sometimes more) from the time of ingestion, and so guarantees a man sexual pleasure. It is important for each individual male to weigh up the pro's and cons to his preferred treatment of erectile dysfunction, taking into account all the available information.

The most widely used remedy for erectile dysfunction; research has indicated that Viagra has an effect on the condition of the human heart as well as a male's penis. The hormonal stress normally exerted on the human heart has been noted to be decreased in men who take Viagra. When conducted with mice, the testing was more noticeable, Viagra having the tendency to avert harmful and long term effects of chronic hypertension on their heart. The study, lead by the John Hopkins research team, found that there is potential benefits for the treatment of pulmonary hypertension, linked in with how Viagra dilates genital blood vessels. Viagra works by dulling the heart beat, which is increased during stress. It works to decrease the force which is needed to pump blood from the heart to the rest of the body. The research conducted by David Kass, cardiologist and senior researcher of the John Hopkins study noticed Viagra can be effective in blocking short- term consequences of hormonal stresses in the heart. Further evidence on the testing of mice (although further research is needed until this is applicable to humans), indicated that negative effects of heart failure and cardiac hypertrophy on weakened heart muscles can be reversed. Further research is need in this area on humans however. Thirty five men and women were tested and injected with Dobutamine (a synthetic derivative of dopamine that increases heart rate and contractions), which resulted in increased rate of 150%. The men and women were then separated into two groups, one of which were given sildenafil (Viagra) and the other given a placebo (fake) pill. Results showed that the first group's heart rate decreased by 50%, whilst the latter group's further increased. This has led to widespread scientific interest in the effects of sildenafil (Viagra) on the human heart condition. HE is only two, but Oliver Sherwood regularly takes Viagra - to keep him alive. The toddler has a rare condition that causes chronic high blood pressure. Something as simple a chest infection could kill him. The pulmonary hypertension, as it is known, can be controlled with four doses of Viagra a day. The drug improves blood flow, which in adults can boost erectile function but in rare cases such as Oliver's can open the veins and capillaries to aid circulation. His mother Sarah, a part-time nurse, said: "We joke when we pick up his drugs that it would be Christmas come early for most people. Obviously the dose isn't high enough to have the effect it would on adults. "Viagra is an expensive drug but it's actually one of the cheapest to treat pulmonary hypertension. "We're just hoping it'll continue to work as he grows a bit older." But Oliver's future could be in doubt because other drugs he could use as he gets older might no longer be funded by the Health Service. Pulmonary hypertension causes the blood pressure in the arteries in the lungs to rise, straining the heart and reducing blood oxygen levels, causing breathlessness and exhaustion. Symptoms include severe coughing and breathing problems as blood fills the lungs, constant nose bleeds, dizziness and chest pains. The condition, which affects 4,000 in Britain, often leads to heart failure. It is so rare that only five children a year are diagnosed with it in the UK. The survival rate is around five years, even with medication such as Oliver, who cannot walk more than a few steps without getting out of breath, takes one tablet of Sildenafil crushed into four 5ml doses a day. Doctors can increase the dose when his condition worsens, but there is no way of telling how much longer the drugs will be effective. As he grows up he will need to switch to more expensive treatments called Epoprostenol and Iloprost to control his condition. But the Government's drug rationing agency, the National Institute for Health and Clinical Excellence, is considering whether to continue prescribing them. Oliver's mother has started a petition calling for the Health Service to keep funding the treatments. Mrs Sherwood, 34, of Hucclecote, Gloucestershire, said: "The only hope we had was that he would be maintained through medication but if anything-happens in the future that hope may be taken away." The Pulmonary Hypertension Association said: "The clinical evidence for this is unfounded and it must be assumed it is based on cost alone." A spokesman for NICE added: "Our review of the evidence suggests that Sildenafil is both clinically effective and cost-effective in treating pulmonary arterial hypertension." citrate generic sildenafil viagra Should I Confront My Wife About Affair? TEN years ago I fell in love with a girl. She was 22 years younger than me and I was married. But the love I felt for her then - and still do - was overwhelming. So I left my wife for her. It was messy and my two grown-up children made it clear they wanted nothing to do with me after what I had done to their mum. I felt guilty but the dust settled and after the divorce I married my second wife. It was the happiest day of my life. We now have an eight-year-old and I've managed to patch things up with the older ones. My wife is 37 and I'll be 60 this year. The problem is I have been having trouble sustaining an erection. I'm taking Viagra which helps, but I don't have the same energy I used to have. I'm almost certain my wife is having an affair. We had a young guy, in his twenties, help get the garden in our new house into shape and I could see he was attracted to her. She's still an amazing-looking woman and doesn't look a year older than when I first saw her. She's been getting texts which she deletes immediately and I know for a fact when she told me she was round at her mum's that it was a lie. So I'm worried sick. I know I should tackle her about what's going on but I can't. I can't live without her and I don't like the thought of my ex-wife, most of my friends and my relatives pointing out that they all told me the age gap was too big and we wouldn't last. OF course you could carry on as you are with your head buried in the sand. There is the possibility your wife isn't having an affair or even if she is, it isn't serious and will soon blow itself out. Your problem keeping an erection could be affecting self-confidence and putting your imagination into overdrive. In some ways, sitting tight might be the sensible thing to do, especially as you have a young child but no intention of ending the marriage. But I don't think you can live with the uncertainty forever. Maybe you should give yourself a deadline of a few months. If you remain suspicious or get more solid evidence, I don't believe you can go on ignoring the issue. If she wants to save the marriage, counselling through Relate Scotland or Scottish Marriage Care is the next step. But if things can't be fixed, there's no point trying to glue it together just because you don't want those who warned you against marrying a younger woman crowing. If you have a problem, write to: Just Joan, Daily Record, One Central Quay, Glasgow G3 8DA or email j.burnie@dailyrecord.co.uk. I cannot reply personally. citrate consult no sildenafil What is Viagra used for? Viagra is used to treat impotence in men. Viagra increases the body’s ability to achieve and maintain an erection during sexual stimulation. Viagra does not protect you from getting sexually transmitted diseases, including HIV. take Viagra? Men who are currently using medicines that contain nitrates, such as nitroglycerin should not use Viagra because taken together they can lower the blood pressure too much. Viagra should not be used by women or children. You should have a complete medical history and exam to determine the cause of your impotence before taking Viagra. Men who have medical conditions that may cause a sustained erection such as sickle cell anemia, leukemia or multiple myeloma or who have an abnormally shaped penis may not be able to take Viagra. There are several medications that are known to interact with Viagra, so be sure to tell your doctor about all medications you are taking including those you can get without a prescription. Viagra has not been studied with other treatments for impotence, so use in combination with other treatments is not recommended. How should I take Viagra? Your healthcare provider may prescribe Viagra as one tablet once a day, about 1 hour before sexual activity. However, Viagra may be taken anywhere from 30 minutes to 4 hours before sexual activity. What are some possible side effects of Viagra? a complete list of side effects reported with Viagra. Your healthcare provider can discuss with you a more complete list of side effects. Viagra is generally well tolerated. If any side effects are experienced, they are usually mild and temporary. The following is a listing of the most common side effects: Visual changes such as mild and temporary changes in blue/green colors or increased sensitivity to light. For more detailed information on Viagra, ask your healthcare provider. More Articles... If you have any questions or comments on senior health nutrition, fitness, etc., go to the is for educational / reference use only.

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Looking at the psychology of impotence is comparable to taking a trip down the Amazon during the rainy season. It is a topic fraught with hidden currents, treacherous shallows and wide meanderings. Viagra, the little blue pill has given a new life to the treatment of impotence and has a significant bearing on men who are suffering from erectile dysfunction. It is worth noting that just finding a "quick fix" for impotence does not overcome other issues that may have been the cause of the dysfunction before treatment began. Overcoming impotence often gives men unrealistic expectations about their ability to instantly come over their emotional as well as physical problems. For most men, their ability to get an erection and have sex is considered as a important part of their masculinity and potency. It is no surprise that the onset of impotence, even when due to underlying physical condition, can lead to psychological issues that increase the problem of impotence. Generally speaking, performance anxiety is a very real problem for many men. In other words, the fear of not being able to perform, dissatisfaction with penis size and self-consciousness about body appearance can all lead to the thing that most men do not want even in their dreams: failure to get an erection. Most men have an occasional episode of impotence due to anxiety. If erectile dysfunction has been there for considerable amount of time, this anxiety is multiplied. From a physiological point of view, anxiety can effectively prevent a man from becoming aroused and maintaining an erection. All the psychological issues seem to disappear with the help of Viagra, which is why it is the most effective and most prescribed erectile dysfunction treatment on the market. There is no reason to feel awkward if you are having issues getting an erection. Just remember that erectile dysfunction is a common problem and can happen to anyone of any age. When you take Viagra for the first time it provides harder erections and plays a prominent role in maintaining the erection for a longer period of time during sex. As Viagra has been proven safe to use in men who are suffering from heart problems, high cholesterol, diabetes, high blood pressure, prostate problems as well as spinal injury you feel at ease when using it. The best part about Viagra is that it works when you want it to. Studies have shown that it works for most men in as little as fourteen minutes, on average within half an hour, and makes it’s presence felt for at least four hours. is there a generic for viagra A consistent inability to sustain an erection sufficient for sexual intercourse. Also commonly known as impotence. Medically, the term erectile dysfunction is used to differentiate impotence from other problems that interfere with sexual intercourse The following drugs and medications are in some way related to, or used in the treatment of Impotence. This service should be used as a supplement to, and NOT a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners..
Wsj's health blog offers news and analysis on health and the business of health. the lead writer is jacob goldstein. he came to the wall street journal from the miami herald, where he was a medical writer. scott hensley, who covered the drug industry as a reporter for the journal for seven years, is the editor and also a contributor. the blog also includes contributions from other staffers at the journal, wsj.com and dow jones newswires. write to us at . Male impotence a problem that virtually every man fears, but at sometime or other in life every man has to confront Erectile Dysfunction (ED). A man’s psychology plays a prominent part in his sexual relationship. If he is depressed, stressed or tense, there is bound to be some impact on his sexual relationship. Anxiety about a man’s sexual routine makes him more stressed and causes his ability to perform to decrease. Erectile Dysfunction can be defined as the inability to have or maintain an erection long enough to have satisfactory sexual intercourse. According to research, ED afflicts nearly 30 million men in America alone and is a cause of great tension. The ideal solution to male sexual impotence issues lies in the little blue pill known as Viagra. Viagra has been quite a handy tool to men who have ED or may be suffering from any degree of male sexual dysfunction. Since the advent of Viagra there has been a great deal of confidence in the patients of erectile dysfunction whether suffering because of the physical or psychological issues. Viagra revives the feeling of self-esteem and manliness, which seems to be lost if you are suffering from ED. Viagra works by enhancing the flow of blood in the penile region and causing a firm erection. The sexual lives of many men have improved because they have the option of Viagra. Viagra can proudly claim to be the first anti-impotence oral pill. The basic chemical base in Viagra is sildenafil citrate. This chemical that treats erectile dysfunction by enabling the man to have an erection long enough to satisfactorily complete sexual intercourse. Many people think that Viagra will enhance their libido or improve their sexual prowess, but this is totally baseless. Viagra can surely be termed as a sex pill, but it is not a libido enhancer drug at all. As a matter of fact, Viagra just acts on the chemicals and enzymes present in your body causing an increased flow of blood in the penis to cause an erection.

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Viagra receives much cynicism about its effects and usefulness, despite the facts that all the evidence suggests otherwise, and there are thousands of satisfied users world wide. Most generally acknowledged as a cure for male erectile dysfunction, it has been documented that Viagra does more than just aid a man's erection. Various reports from numerous areas of health research worldwide point to other possible health benefits of Viagra. For instance, Saarland discovered that Viagra can reduce symptoms of Raynaud's phenomenon, a circulatory disorder. The hormonal stress normally exerted on the human heart has been noted to be decreased in men who take Viagra. When conducted with mice, the testing was more noticeable, Viagra having the tendency to avert harmful and long term effects of chronic hypertension on their heart. The study, lead by the John Hopkins research team, found that there is potential benefits for the treatment of pulmonary hypertension, linked in with how viagra dilates genital blood vessels. After testing on humans, abnormally high heart rates appeared to reduce by 50% after taking sildenafil (Viagra). Current evidence indicates health benefits of Viagra, in addition to the most commonly associated benefit of curing erectile dysfunction. buy xenical viagra propecia com Viagra has made a significant difference in the quality of life of millions of men and their partners. When the FDA approved the first oral medication for the treatment of erectile dysfunction in 1998, it gave rise to a new world of possibilities that would restore men to healthy sex routine. For plenty of these individuals, the ability to have reliable erections has brought them and their partners’ sexual satisfaction and a tremendous sense of emotional comfort in their lives. Many times, the return to sexual potency greatly enriches overall relationship satisfaction. Thanks to the advantages of Viagra, many men have come to the conclusion that they enjoy sex and had sex more frequently. While Viagra is not an aphrodisiac, men have reported an enhancement in sexual desire and arousal. Some are of the opinion that their orgasms felt more intense and enjoyable. Rather than being directly attached to Viagra, these sorts of opinions are most likely because of an increase in the man's general interest in sex, which is due to their Viagra-assisted reliable erections. Even with the sexual success that having a good erection allows, there are a wide array of psychological and relationship aspects involved in a couple's sexual routine. The continued quality of a couple's sexual routine will still be dependent on past, present and future relationship factors. To illustrate this point, consider The following factors: the sort of changes that occurred in the relationship when, thanks to Viagra, erectile problems were no longer a factor Some couples may enjoy renewed sexual routine, but others might feel that sex will now be required on demand. This can place unnecessary pressure on either partner to perform. If the erectile issues were due to problems between the partners, they need to be addressed. It is not unusual for men to be of the view that everything is in order once modern medicine has restored his erections. This is where work must be done to avoid future problems involving intimacy and communication about sex. Even with the restoration of a man's erections, the same sort of sexual turn-offs and difficulties surrounding sex, (timing, frequency, life-style, routines and methods) can still be crucial issues in judging overall sexual satisfaction.

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Is Viagra the Answer for you ? Viagra is not simply a sex pill ...learn its various properties is a pill that not only helps cure erectile dysnfunction but also makes the act of sex more fulfilling. now and know personally how it can help you. Viagra is perhaps one of the most notorious medicines in the market. Considering how integral it is for men's health, psychologically and socially, its funny to note that social and cultural hang-ups still survive in the 21st Century making Viagra, a simple medicine, seem to be a 'drug' that is not mentioned in polite circles. Viagra, is a drug or impotence. Sildenafil is available by prescription only. Viagra can only stimulate if a man is sexually excited. The question is when isn't he sexually excited? Viagra is a medicine, much like Asprin and Panadol that people take to treat their health problems. Erectile Dysfunction is a health problem faced by men. It is prescribed by doctors to help men with erectile problems which can be caused due to age, stress, social pressures or other physiological and psychological reasons. Viagra is not, contrary to popular perception, a sex pill that will help you get bigger erections, act as a love enhancer or protect you against sexually transmitted disease. Viagra is a pill that contains Sildenafil Citrate a chemical that helps treat impotence. Sildenafil Citrate is available under several brand names that vary from Viagra to Revatio and may also be found under its generic name. Commercially speaking Sildenafil citrate's, main competitor is tadalafil [Cialis] and vardenafil [Levitra]. While there maybe many medicines out there that are considered to be alternatives to Viagra, it is that has taken the world by storm and remains the top best seller.

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When we speak of sex drive problems, or dysfunction, we automatically think of males and erectile dysfunction, and omit women from the equation. However, many women experience problems with their �libido' or sexual energy, and this phenomena deserves attention too. Viagra is the most common treatment for erectile dysfunction in males, and has traditionally been recommended for men only, women being advised not to use it. So the main reason for this is lack of empirical research stating otherwise, which is due to the absence of definitive studies on women. Viagra however can work for women, as it increases the blood flow to a woman's genitals (much the same way as with a man's), which boosts their libido. There are important considerations however, which shall be listed below. As Viagra is aimed at men's erectile dysfunction, women are unable to obtain a prescription and buy Viagra from a pharmaceutical store. However generic versions are available on the internet, but as so many are on the market, if in doubt contact the supplier as to whether a product is available. When buying from online pharmacies, it is possible to check their pharmacy ID if concerned about legitimacy. It is important for women to take into consideration possible side effects of Viagra, although not widespread there is still a possibility of them occurring. For instance, some Viagra users have reported dizziness, flushing, loss of vision, and so on. Check all possible side effects before commencing use. Furthermore, Viagra should not be taken alongside any nitrate medicines as this can cause abnormally low blood pressure, so always check! Women, who suffer with a low sex drive often, should seek a long term cure other then Viagra in order to increase their libido and have a permanent effect. Long term Viagra use can result in expense, so if the problem continues regularly, even after Viagra use, women should aim to seek other remedial methods..
Revatio, viagra what is viagra? viagra relaxes muscles and increases blood flow to particular areas of the body. sildenafil under the name viagra is used to treat erectile dysfunction (impotence) in men. another brand of sildenafil is revatio, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women. viagra may also be used for other purposes not listed in this medication guide. do not take viagra if you are also using a nitrate drug for chest pain or heart problems. this includes nitroglycerin (nitrostat, nitrolingual, nitro-dur, nitro-bid, and others), isosorbide dinitrate (dilatrate-sr, isordil, sorbitrate), and isosorbide mononitrate (imdur, ismo, monoket). nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). taking viagra with a nitrate medicine can cause a serious decrease in blood pressure, leading to fainting, stroke, or heart attack. during sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. you could be having a serious side effect of viagra. do not take viagra more than once a day. allow 24 hours to pass between doses. contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. a prolonged erection (priapism) can damage the penis. viagra can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. this has occurred in a small number of people taking viagra, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoke or are over 50 years old. it is not clear whether viagra is the actual cause of vision loss. stop using viagra and get emergency medical help if you have sudden vision loss. do not take viagra if you are also using a nitrate drug for chest pain or heart problems. this includes nitroglycerin (nitrostat, nitrolingual, nitro-dur, nitro-bid, and others), isosorbide dinitrate (dilatrate-sr, isordil, sorbitrate), and isosorbide mononitrate (imdur, ismo, monoket). nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). taking viagra with a nitrate medicine can cause a serious decrease in blood pressure, leading to fainting, stroke, or heart attack. before taking viagra, tell your doctor if you are allergic to any drugs, or if you have: a recent history (in the past 6 months) of a heart attack, stroke, or heart rhythm disorder; a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia; if you have been told you should not have sexual intercourse for health reasons. if you have any of these conditions, you may need a dose adjustment or special tests to safely take viagra. viagra can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. this has occurred in a small number of people taking viagra, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoke or are over 50 years old. it is not clear whether viagra is the actual cause of vision loss. stop using viagra and get emergency medical help if you have sudden vision loss. fda pregnancy category b: this medication is not expected to be harmful to an unborn baby. do not use viagra without telling your doctor if you are pregnant or plan to become pregnant during treatment. it is not known if viagra passes into breast milk or if it could harm a nursing baby. do not use this medication without telling your doctor if you are breast-feeding a baby. how should i take viagra? take viagra exactly as it was prescribed for you. do not take it in larger doses or for longer than recommended by your doctor. follow the directions on your prescription label. revatio is usually taken three times each day, about 4 to 6 hours apart. viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. you may take it up to 4 hours before sexual activity. do not take viagra more than once per day. viagra can help you have an erection when sexual stimulation occurs. an erection will not occur just by taking a pill. follow your doctor's instructions. during sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. you could be having a serious side effect of viagra. store this medication at room temperature away from moisture and heat. what happens if i miss a dose? viagra is used as needed, so you are not likely to be on a dosing schedule. if you miss a dose of revatio, take the missed dose as soon as you remember. if it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. do not take extra medicine to make up the missed dose. what happens if i overdose? seek emergency medical attention if you think you have used too much of this medicine. overdose symptoms may include chest pain, nausea, irregular heartbeat, and feeling light-headed or fainting. what should i avoid while taking viagra? avoid drinking alcohol, which can increase some of the side effects of viagra. avoid using other medicines to treat impotence, such as alprostadil (caverject, muse, edex) or yohimbine (yocon, yodoxin, others), without first talking to your doctor. get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. during sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. you could be having a serious side effect of viagra. ringing in your ears, or sudden hearing loss; chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling; swelling in your hands, ankles, or feet; feeling light-headed, fainting; or penis erection that is painful or lasts 4 hours or longer. warmth or redness in your face, neck, or chest; back pain. this is not a complete list of side effects and others may occur. tell your doctor about any unusual or bothersome side effect. what other drugs will affect viagra? do not take viagra if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin (nitrostat, nitrolingual, nitro-dur, nitro-bid, minitran, deponit, transderm-nitro), isosorbide dinitrate (dilatrate-sr, isordil, sorbitrate), and isosorbide mononitrate (imdur, ismo, monoket), or recreational drugs such as amyl nitrate or nitrite ("poppers"). before taking viagra, tell your doctor about all other medications you use for erectile dysfunction, or if you are using any of the following medications: cimetidine (tagamet, tagamet hb); an antibiotic such as erythromycin (e-mycin, eryc, ery-tab) or clarithromycin (biaxin); doxazosin (cardura), prazosin (minipress), terazosin (hytrin); hiv medicines such as amprenavir (agenerase), tipranavir (aptivus), darunavir (prezista), efavirenz (sustiva), nevirapine (viramune), indinavir (crixivan), saquinavir (invirase, fortovase), lopinavir/ritonavir (kaletra), fosamprenavir (lexiva), ritonavir (norvir), atazanavir (reyataz), or nelfinavir (viracept); carbamazepine (tegretol), phenobarbital (luminal), or phenytoin (dilantin); or rifampin (rifadin, rimactane) or rifabutin (mycobutin). this list is not complete and there may be other drugs that can interact with viagra. tell your doctor about all the prescription and over-the-counter medications you use. this includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. do not start using a new medication without telling your doctor. where can i get more information? your pharmacist can provide more information about viagra. what does my medication look like? sildenafil is available with a prescription under the brand names viagra and revatio. other brand or generic formulations may also be available. ask your pharmacist any questions you have about this medication, especially if it is new to you. revatio 20 mg - white, film-coated round tablets viagra 25 mg - blue, film-coated tablets with a rounded-diamond shape viagra 50 mg - blue, film-coated tablets with a rounded-diamond shape viagra 100 mg - blue, film-coated tablets with a rounded-diamond shape remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed. every effort has been made to ensure that the information provided by cerner multum, inc. ('multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. drug information contained herein may be time sensitive. multum information has been compiled for use by healthcare practitioners and consumers in the united states and therefore multum does not warrant that uses outside of the united states are appropriate, unless specifically indicated otherwise. multum's drug information does not endorse drugs, diagnose patients or recommend therapy. multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. the absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. multum does not assume any responsibility for any aspect of healthcare administered with the aid of information multum provides. the information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. if you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist. My girlfriend and I are very sexually active. I am very healthy sexually but when we have relations two or three times in a day, I'm a better lover if I take a Viagra. Is this healthy? Every relationship is different in terms of the frequency of intimacy. Some couples have sexual relations every 10 days, and others may crave intimacy daily or even several times a day. The key here is that both individuals need to feel that their lovemaking frequency is just right. The definition of erectile dysfunction is the inability to achieve or maintain a satisfactory erection for sexual relations. While apparently that is not a problem for your first round of lovemaking, it sounds as though you are improving your performance with Viagra when you and your girlfriend enjoy subsequent intimate relations in a short time period. There is nothing wrong with this approach medically. The important point to realize is that intimacy is physical and psychological. Just be certain that while you are fine-tuning your physical sexual abilities, that you and your girlfriend continue to fine-tune the elements that contribute to your emotional and psychological intimacy. Those elements may be as simple as sharing books, discussing lifelong secrets or becoming wine enthusiasts together.  free online order viagra Life is, of course, all about managing death. Or rather, it's all about managing pain and pollution and disease and gravity and germs and bacteria and poison and Dick Cheney and those little shards of glass in your burrito; it's all about, in short, how you sort through the sundry and ever-increasing laundry list of things in your immediate world that want to torment and toxify and destroy you because oh my God they are legion and they are ready and they are . . Did you know? It shouldn't come as much of a surprise, really, given how many millions of drug-blasted Americans inhale prescription meds by the fistful and then hit the bathroom and the water flows and the treatment plant churns and pumps it all back into municipal water pipes, still brimming with trace amounts of Xanax and Zoloft and Medrol and Norvasc, asthma drugs and cholesterol drugs and birth control pills, cancer drugs and painkillers and diuretics and who the hell knows what else. Hell, who needs Vitamin Water when there's Lipitor in your ice cubes? This is the wacky fun reminder: Living in the city is deadly and toxic a million ways from Sunday. in every breath, electromagnetic waves in every gizmo, plastic off-gassing and high-VOC paints and chemicals in the carpet and toxins in your very clothing and every modern home so packed with thriving bacteria and synthetic substances and venomous Glade air fresheners it's a wonder we manage to stay upright at all. Hell, they just discovered that even our national parks, the fish and trees and lakes and the snow itself, are hugely polluted, . Go ahead, hug that tree. But be sure to wear a body condom. This is what we have to accept: You do not avoid poison. You do not escape toxin or chemical or gravity or modern synthetic residue even if you move to the woods and build a humble off-grid shack made only of fresh pine needles and bird dung and make your own jam out of river moss and beetle larvae because, hey look, up there in the sky, it's the very air itself, full of chemicals and pollutants drifting over from China and India and, um, Marin County, and you're breathing it in and it's coating the very trees and raining down upon your organic tomatoes right now. Sorry. Please enjoy your salad. No, you do not escape. You cannot completely block. You merely minimize. You recognize the most dire sources and most abhorrent problems and you choose your battles wisely, as you acknowledge just how complicit you are in all of it, how much you contribute to the problem, and adjust and recalibrate your life accordingly. This is the first, mandatory, all-important step. But more important than that, you learn to shun the paranoia. You gotta mock the relentless direness and shrug off the gods of death, every single day, even as they seem to be multiplying like rabid evangelicals at a Colorado megachurch. You gotta keep perspective, recall how man has been under deadly pressure from himself since the dawn of time. Otherwise, well, life is merely an army of demons and sins lined up and ready to take a bite out of your sweet, innocent flesh as you stroll by like a virgin at a porn convention. You know? Wait, did I mention sin? Good thing. Because apparently they've . Did you hear? Indeed, a dour red-robed figure just slithered out of the shadows of the Vatican and proclaimed some new additions to the master list of Thou Shalt Nots, adding juicy tidbits like pedophilia and pollution and the taking/dealing of drugs (then you'd best not drink the water, father) and questions of bioethics (stem cell research, cloning, whatnot) to the massive catalog of things that make God scowl and angels whine and for which we are all surely going to Hell like, a billion times over. Is this not delightful, in a deeply pathetic and insulting sort of way? Is it not amusing that, after 2,000 years, they're finally saying, hey gosh, trashing the planet and abusing creation itself is sort of wrong? Or that they — the Catholic Church! — dared to add pedophilia to the list, which is a bit like McDonald's announcing that beef is bad for you? Yo, preacher: Heal thyself, OK? As for bioethics, well, of course they worry that we'll try to "play God," which is just sort of cute and ridiculous given how most of us, you know, , every single day, by defying death and tormenting our bodies and launching brutal unwinnable wars (in the name of God, natch), choosing whether or not to eat meat and destroy plants and get pregnant or fall in love or hate gay people or buy an Escalade or enjoy Adam Sandler movies. Playing God? Who the hell is playing? God, that's where the real action is. And now, the bad news: They didn't remove a single damnable thing. They did not say, OK, we've added some vile and obvious new sins, so just for the sake of balance and just so you don't think we're authoritarian cretins, let's remove a few of the outdated, insulting ones, shall we? Condoms? Birth control? Go for it (they should've said). Pre-marital sex? Have at it, children. In fact, it's now highly recommended. Especially if you do it right. And often. And develop some mad skills so if you ever get married you can keep surprising each other with delightful new ways to enjoy various kitchen tools and yoga straps and Viagra chewing gum. Praise Jesus. Better yet, they should take it a step further, and for every new sin they add, they should remove . This way, eventually we'll whittle it down to just one grand sin, one terrifically all-encompassing God-mocking insult. Which is, of course, the idea of sin itself. Believe in sin? Believe that we're all, at our core, corrupt and evil and mortally flawed and that life is basically a grueling slog against disease and pain and pollution and 10,000 household poisons until you eventually whimper and sigh and lay yourself in a chemical-soaked pine box and sink it six feet under? Baby, that's the biggest sin of all. And you are hereby absolved. Thoughts about this column? . Generic Viagra is a drug used for erectile dysfunctions, or male impotence, and it represents the name for a substance known as sildenafil citrate. The substance is the same, while the market name of the drug may vary and so may its price. Generic versions for many types of drugs have been around for quite some time, but Generic Viagra is a fairly new drug on the market, and it gives men a chance at treating their erectile dysfunctions in an affordable way. Generic Viagra can be expected to have the same effects that the brand name Viagra does, because both drugs have the same active ingredient. Therefore, if your doctor has decided that Viagra is safe for you, it means that you can also use Generic Viagra. How does Generic Viagra work? It increases your ability to have and sustain an erection by inhibiting the enzymes that degrade the cyclic guanosine monophosphate, a substance that facilitates the influx of blood into the penis, by relaxing its spongy tissue. In other words, Viagra dilates blood vessels in the penis, and allows the necessary inflow of blood that an erection requires. Viagra can cause erections only when a man is sexually excited. This is the reason why this drug is not for regular use. It should be taken about one hour before sexual activity, and once the sexual intercourse is over the erection goes away. The efficacy of Generic Viagra has been evaluated based on self-assessment questionnaires, and this evaluation has shown that this drug is responsible for the sexual function improvement of almost ninety percent of those who have used it to treat their erectile dysfunctions. The evaluation included firmness, frequency, and ability to maintain an erection; level and frequency of desire; frequency of orgasm; sexual intercourse satisfaction; and relationship satisfaction. When it comes to the side effects that Generic Viagra can have, it is difficult to anticipate them. Your doctor should be informed shortly after the development of a side effect has occurred, or it has changed its intensity. Some of the side effects of Generic Viagra that are more likely to be experienced by those who use it as treatment include headache, abnormal vision, diarrhea, indigestion, urinary tract infection, and nasal congestion. There are other possible side effects, but these have been experienced at a considerably lower frequency. Remember that it is hard to predict how your body will react to this drug. Chances are that you’ll be just fine, if you don’t have a preexisting condition, such as a heart problem. However, you should inform your doctor about any modification that may occur, and he/she will tell you whether or not you should keep taking Generic Viagra. It is the doctor once again that will give you the most detailed information about the food and drugs Generic Viagra interacts with. It is a well-known fact that erectile dysfunction drugs should not be used simultaneously unless prescribed by a doctor. However, Generic Viagra may interact with other drugs as well, which is why you have to consult with your doctor before taking this medicine. He or she will also inform you about the special warnings that come with this medication, and what conditions do not allow the use of Generic Viagra. sildenafil generic viagra You have to be cautious. There are literally thousands of internet operations ready to sell you unregulated versions of Pfizer's Viagra. Often the sites claim to be selling the real thing, and it can be a daunting task to identify a safe resource for genuine, Pfizer Viagra. Ukmedix has had to compete with these fakes (which often are cheaper) and has even had to assist in identifying illegal operations (fakes are a threat to your safety, and ultimately Pfizer). In order to stand out from the crowd and reassure our customers Ukmedix produces useful customer tools e.g. a forum dedicated to viagra and makes sure that with every order sent batch numbers and manufacturer;s hall marks are always maintained. Dispatch pharmacists* are always available on receipt of your order for any further queries of authenticity. This means you can trace the product all the way back to Pfizer's manufacturing facility and even know the date your viagra was produced. *A UK pharmacist will always be able to assist you and any licensed pharmacy should be able to verify the viagra batch number. Apart from being unsafe and more then likely to be completely ineffective, fake viagra (wherever it has been produced) has passed no tests, is unregulated and for all you know may have been produced in a garden shed. In some instances dangerous substances have been found in this copied viagra, which would completely defeat the purpose of your seeking help with impotence in the first place! Ukmedix is obviously a business, but we care about our reputation and we care about our customers. We support Pfizer's Safe Drug Initiative which has been created to specifically find and close any illegal sellers of the unsubstantiated, fake viagra being sold on and offline. To this extent we want to know if you have been sold viagra that you think may be fake or viagra that doesn't look like it should. Contact ukmedix and we will gladly assist you and qualify your findings to Pfizer on your behalf. The fact is that fake viagra could have any substances in it and it is not to be trusted as a suitable replacement for the real thing. Impotence is a health condition that may be complex in its causes. Unnecessary e-mail spam on viagra or ludicrous claims that viagra will fix everything in your life are not what we are about. We never send out unsolicited e-mail and try to encourage you to research as much as you can yourself/ through your doctor and local pharmacists. Viagra has truly revolutionized many millions of lives, but viagra (that is Pfizer's viagra) is not suitable for everybody, and fake viagra is suitable for NO-ONE generic viagra online pharmacy This is a summary of the most important information about Viagra. For details, talk to your healthcare professional. FDA ALERT [7/2005]: A small number of men have lost eyesight in one eye some time after taking Viagra, Cialis, or Levitra. This type of vision loss is called non-arteritic anterior ischemic optic neuropathy (NAION). NAION causes a sudden loss of eyesight because blood flow is blocked to the optic nerve. We do not know at this time if Viagra, Cialis, or Levitra causes NAION. NAION also happens in men who do not take these medicines. People who have a higher chance for NAION include those who: FDA has approved new labels for Viagra, Cialis, and Levitra to include information on possible eyesight loss (NAION). Stop using Viagra, Cialis, or Levitra if you have a loss in your eyesight. Get medical help right away. This information reflects FDA's current analysis of data available to FDA concerning this drug. FDA intends to update this sheet when additional information or analyses become available. What is Viagra? Viagra is a prescription medicine taken by mouth for the treatment of erectile dysfunction (ED) in men. ED is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. Viagra may help a man with ED get and keep an erection when he is sexually excited. Viagra must be used only under a doctor's care. protect a man or his partner from sexually transmitted diseases, including HIV. Speak to your healthcare professional about ways to guard against sexually transmitted diseases. Viagra is only for men with ED. Viagra is not for women or children. Viagra must be used only under a healthcare professional's care. Who Should Not Take Viagra? What are The Risks? The following are the major possible risks and side effects of Viagra therapy. This list is not complete. Viagra can cause your blood pressure to drop suddenly to an unsafe level if it is taken with certain other medicines such as nitrates and alpha-blockers, and recreational drugs that contain nitrates called "poppers". A sudden drop in your blood pressure could cause you to become dizzy, faint, or have a heart attack or stroke. Tell all your healthcare professionals that you take Viagra. If you need emergency medical care for a heart problem, it will be important for your healthcare professionals to know when you last took Viagra. vision changes, such as seeing a blue tinge to objects or having difficulty telling the difference between the colors blue and green What Should I Tell My Healthcare Professional? have retinitis pigmentosa, a rare genetic (runs in families) eye disease have blood cell problems such as sickle cell anemia, multiple myeloma, or leukemia Can Other Medicines or Food Affect Viagra? Viagra and certain other medicines can interact with each other. Tell your healthcare professional about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Know the medicines you take. Keep a list of them with you to show your healthcare professional. Date created: July 8, 2005, updated October 2, 2007 5 sildenafil citrate lithium 2 Responses to “Viagra a miracle drug?” Why pay £12-£15 per tablet via your Doctor’s Prescription? You can now get 4 x Genuine 100mg (DOUBLE STRENGTH!) Viagra Tablets DIRECT at these LOW LOW PRICES! Genuine 100mg (DOUBLE STRENGTH!) Viagra Tablets give YOU rock hard erections every time! You just take HALF A TABLET 30-60 minutes before any sexual activity. (THIS GIVES YOU 8 TOTAL DOSES!) We have this product in stock sealed, hologrammed boxes of 4 x Viagra 100mg. Regain your sex life! Thousands of men have regained their sex life with the use of this product. Viagra works in as little as 60 minutes and its effects last up to six hours. You don’t have to wait anymore to get back in the swing of life.You have a choice. Viagra improves erections for men from ages 18-90 and is 98% effective We guarantee it! Money Back Guarantee if not 100% Satisfied. All orders received before 2pm GMT will be dispatched same day from the UK. Postage is free. Why pay £20 per tablet via your Doctor’s Prescription? You can now get 4 x Genuine 20mg (DOUBLE STRENGTH!) Cialis Tablets DIRECT at these LOW LOW PRICES! Genuine 20mg (DOUBLE STRENGTH!) Cialis Tablets give YOU rock hard erections every time! You just take HALF A TABLET 30-60 minutes before any sexual activity. (THIS GIVES YOU 8 TOTAL DOSES!) We have this product in stock sealed, hologrammed boxes of 4 x Cialis 20mg. Expiry date is December 2010. Regain your sex life! Cialis 20mg is the first tablet for erectile dysfunction (ED) that gives you up to 36 hours to choose the moment that’s right for you and your partner. Cialis works fast - within 30 minutes in some patients - and can work up to 36 hours. That means you and your partner can be spontaneous, responding to each other sexually when the moment is right. Of course results may vary. We guarantee it! Money Back Guarantee if not 100% Satisfied. All orders received before 2pm GMT will be dispatched same day from the UK. Postage is free. sales genuine viagra Why pay £20 per tablet via your Doctor’s Prescription? You can now get 4 x Genuine 20mg (DOUBLE STRENGTH!) Cialis Tablets DIRECT at these LOW LOW PRICES! Genuine 20mg (DOUBLE STRENGTH!) Cialis Tablets give YOU rock hard erections every time! You just take HALF A TABLET 30-60 minutes before any sexual activity. (THIS GIVES YOU 8 TOTAL DOSES!) We have this product in stock sealed, hologrammed boxes of 4 x Cialis 20mg. Expiry date is December 2010. Yes, i like viagra, cialis and Sex When we speak of sex drive problems, or dysfunction, we automatically think of males and erectile dysfunction, and omit women from the equation. However, many women experience problems with their â€?libido' or sexual energy, and this phenomena deserves attention too. Viagra is the most common treatment for erectile dysfunction in males, and has traditionally been recommended for men only, women being advised not to use it. So the main reason for this is lack of empirical research stating otherwise, which is due to the absence of definitive studies on women. Viagra however can work for women, as it increases the blood flow to a woman's genitals (much the same way as with a man's), which boosts their libido. There are important considerations however, which shall be listed below. As Viagra is aimed at men's erectile dysfunction, women are unable to obtain a prescription and buy Viagra from a pharmaceutical store. However generic versions are available on the internet, but as so many are on the market, if in doubt contact the supplier as to whether a product is available. When buying from online pharmacies, it is possible to check their pharmacy ID if concerned about legitimacy. It is important for women to take into consideration possible side effects of Viagra, although not widespread there is still a possibility of them occurring. For instance, some Viagra users have reported dizziness, flushing, loss of vision, and so on. Check all possible side effects before commencing use. Furthermore, Viagra should not be taken alongside any nitrate medicines as this can cause abnormally low blood pressure, so always check! Women, who suffer with a low sex drive often, should seek a long term cure other then Viagra in order to increase their libido and have a permanent effect. Long term Viagra use can result in expense, so if the problem continues regularly, even after Viagra use, women should aim to seek other remedial methods.

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If you become dizzy or nauseated, have pain, numbness or tingling in your chest, arms, neck, or jaw during sex, it is of the utmost importance that you stop and call your doctor immediately. You could be having a serious side effect from taking Cialis. Stop using Cialis and get emergency medical assistance from your health provider if you have sudden vision loss. It is also advisable that you get immediate medical assistance if you have any of these signs of an allergic reaction: hives, difficulty breathing, or swelling of your face, lips, tongue, or throat. Chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling Swelling in your hands, ankles, or feet Erection that is painful and lasts for around 4 hours. Warmth or redness in your face, neck, or chest Headache, upset stomach and back pain Tadalafil was administered to over 5,700 men (mean age 59, ranging from 19 - 87 years old) during clinical trials all round the world. In this trial, over 1000 patients were treated for 1 year whereas over 1,300 patients were treated for 6 months or more. In placebo controlled, Phase 3 clinical trials, the discontinuation rate because of adverse events in patients treated with tadalafil 10 or 20 mg was 3.1%, which was significantly less than placebo treated patients. In tadalafil clinical pharmacology trials, back pain normally occurred 12 - 24 hours after dosing and often resolved within a mater of two days. Across all research with any tadalafil dose, findings of changes in color vision were rare. Serious cardiovascular issues, including myocardial infarction and sudden cardiac death have been reported post marketing with the use of tadalafil. Many, but not all, of these patients had pre-existing cardiovascular risk issues. Most of these events were reported to occur during or shortly after sexual routine, and some were reported to occur shortly after the use of Cialis. Other adverse events suffer from a lack of clear alternative causation because these reactions were reported voluntarily from a population of uncertain size. This makes it tough to reliably judge their frequency or come up with a causal relationship to drug exposure citrate quickly to link search sildenafil Message copied & clipped from an e-mail we recieved from a more than happy customer. Wow what can I say… an amazing experience. In August a couple of my friends and I had planned to go on a short break to Amsterdam to unwind from stress and worries of our normal lives. We already had lots of things planned to do while we were there but once we arrived we were suprised to see one of our mates had brought along ). I personally hadn’t tried this stuff before, but I was always anxious when joining a female in the ‘bedroom department’ just incase I under performed so the thought of buying viagra or a viagra alternative had always crossed my mind but I just simply didn’t get around to it. This made me quite excited to use it. On the second night of being there, our mate suggested for us to go to a strip bar and as you can imagine we hit bar after bar and ended up in you know where. My mate pulled out the strip of kamagra jellys and we got down to business! My friend who brought the kamagra originally gave me your website address so I could buy some more at a later date. So I decided to e-mail you guys with a short story of my experience of generic viagra. Oh and yes, the sex was amazing! comparison of cialis levitra and viagra This medicine is a phosphodiesterase inhibitor used to treat sexual function problems such as impotence or erectile dysfunction. In combination with sexual stimulation, this medicine works by helping the blood flow into the penis to achieve and maintain an erection. This medicine is not intended for use in women or children. This medicine will not protect against sexually transmitted diseases including HIV infection. Use "safe sex" practices such as latex condoms. Contact your doctor or pharmacist for more details. Some medicines or medical conditions may interact with this medicine. INFORM YOUR DOCTOR OR PHARMACIST of all prescription and over-the-counter medicine that you are taking. DO NOT TAKE THIS MEDICINE if you are taking any form of nitroglycerin, (such as tablet, patch, or ointment dose forms) or other nitrates (such as isosorbide), nitroprusside (or any "nitric oxide donor" medicine), or recreational drugs called "poppers" containing amyl or butyl nitrate because very serious interactions may occur. If you are not sure whether a certain medicine is a nitrate, contact your doctor or pharmacist. If you are currently using any of these medicines, tell your doctor or pharmacist before using sildenafil. ADDITIONAL MONITORING OF YOUR DOSE OR CONDITION may be needed if you are taking other medicines for impotence, antifungals (such as itraconazole or ketoconazole), cimetidine, delavirdine, erythromycin, mibefradil, or rifampin. If you are taking an HIV protease inhibitor (such as ritonavir or saquinavir), do not take more than a 25 mg dose of sildenafil in a 48-hour period. If you are taking more than a 25 mg dose of sildenafil and are also taking an alpha-blocker medicine (such as doxazosin, prazosin, or terazosin) for various conditions (such as enlarged prostate), separate the time between taking these medicines by more than 4 hours. DO NOT START OR STOP any medicine without doctor or pharmacist approval. Inform your doctor of any other medical conditions including penis conditions (such as angulation, fibrosis/scarring, or Peyronie's disease), history of painful/prolonged erection (priapism), sickle cell anemia, blood system cancers (such as leukemia or myeloma), vision problems (such as retina diseases like retinitis pigmentosa) or history of vision loss, kidney or liver disease, bleeding disorders, active stomach ulcers, heart problems (such as recent heart attack or irregular heartbeat within past 6 months, heart failure, coronary artery disease with unstable angina, aortic stenosis or idiopathic hypertrophic subaortic stenosis), recent stroke within past 6 months, very high or low blood pressure, or allergies. Contact your doctor or pharmacist if you have any questions or concerns about taking this medicine. Follow the directions for using this medicine provided by your doctor. An additional patient information leaflet is available with this medicine. Read it carefully. Ask your doctor, nurse, or pharmacist any questions that you may have about this medicine. TAKE THIS MEDICINE by mouth as needed between four hours and one-half hour before sexual activity (about 1 hour before is most effective); or take as directed by your doctor. DO NOT TAKE THIS MEDICINE more often than once daily as needed. A high fat meal may delay the time of onset of this medicine. Your dosage is based on your medical condition, your response to therapy, and other medicines you are taking. Consult your doctor or pharmacist for more information. STORE THIS MEDICINE at room temperature 77 degrees F (25 degrees C) in a tightly-closed container, away from heat, moisture, and light. Brief storage between 59 and 86 degrees F (15 and 30 degrees C) is permitted. DO NOT TAKE THIS MEDICINE if you have had an allergic reaction to it in the past or to any other ingredient that is found in it. THIS MEDICINE MAY CAUSE VISION CHANGES. DO NOT DRIVE, OPERATE MACHINERY, OR DO ANYTHING ELSE THAT COULD BE DANGEROUS until you know how you react to this medicine. Using this medicine alone, with other medicines, or with alcohol may lessen your ability to drive or to perform other potentially dangerous tasks. TO MINIMIZE DIZZINESS OR LIGHTHEADEDNESS, sit up or stand slowly when rising from a seated or lying position. Your dose is based on your medical condition, response to therapy, and the other medicines you are taking. DO NOT EXCEED THE RECOMMENDED DOSE without checking with your doctor. Rarely, this medicine may change heart rhythm, especially if taken with other medicines that can change the heart rhythm. This change in heart rhythm can result in serious, rarely fatal, irregular heartbeats. Ask your doctor for more information and if you should stop taking any of your other medicines to reduce the risk of this side effect. BEFORE YOU BEGIN TAKING ANY NEW MEDICINE, either prescription or over-the-counter, check with your doctor or pharmacist. CAUTION IS ADVISED WHEN USING THIS MEDICINE IN THE ELDERLY because they may be more sensitive to the side effects of this medicine. THIS MEDICINE SHOULD NOT BE USED IN WOMEN OR CHILDREN. SIDE EFFECTS that may occur while taking this medicine include headache, flushing, stomach upset, heartburn, nasal stuffiness, diarrhea, dizziness, or lightheadedness. Vision changes such as increased sensitivity to light, blurred vision, or impaired blue/green color discrimination may also occur. If these continue or are bothersome, check with your doctor or pharmacist. CONTACT YOUR DOCTOR IMMEDIATELY if you experience vision loss in one or both eyes, hearing loss, ringing in the ears, or severe or persistent dizziness. Sexual activity may put extra strain on your heart, especially if you have heart problems. If you have heart problems and experience any serious side effects while having sex, stop having sex and tell your doctor immediately. These side effects include severe dizziness, fainting, chest pain, or nausea. In the unlikely event that you have a painful or prolonged erection (lasting more than 4 hours), stop using this medicine and seek immediate medical attention or permanent problems could occur. AN ALLERGIC REACTION TO THIS MEDICINE is unlikely, but seek immediate medical attention if it occurs. Symptoms of an allergic reaction include rash, itching, unusual swelling, severe dizziness, or trouble breathing. If you notice other effects not listed above, contact your doctor, nurse, or pharmacist. If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include severe dizziness, fainting, or prolonged erection. If your symptoms do not improve or if they become worse, check with your doctor. DO NOT SHARE THIS MEDICINE with others for whom it was not prescribed, since they may have a problem that is not effectively treated with this medicine, or they may have a condition that is complicated by this medicine. DO NOT USE THIS MEDICINE for other health conditions. KEEP THIS MEDICINE out of the reach of children and pets. IF USING THIS MEDICINE FOR AN EXTENDED PERIOD OF TIME, obtain refills before your supply runs out. Copyright 2008 Wolters Kluwer Health, Inc. - This information is not intended to substitute for professional medical advice. Be sure to contact your physician, pharmacist or other health care provider for more information about this medication. By searching these web site pages, you agree to our generic viagra online Both the drugs enhance blood flow to the groin area. The major point of difference is that Cialis remains effective for a 36-hour time period, compared to just four hours with Viagra. In addition, Cialis can take effect slightly faster than Viagra. They each take effect in up to 30 minutes, give or take a few minutes. The best part about Cialis is that it offers the couple more flexibility. You should remember that both of these male impotence drugs have restrictions. First and foremost, men with a high risk of heart attack or stroke should not use them. Also, potential side effects include back pain and muscle aches with Cialis. People interested in using these drugs should read Consumer Reports on Health which indicates that Viagra has a longer track record because it has been on the market since 1998. Both of the drugs need a doctor's prescription and are rather expensive. Many insurance companies cover the cost of Cialis and Viagra, but it is permitted for a limited supply, normally 4 times a week. If you are not sure which treatment to opt for, it is recommended that you take a look at the causes of impotence and the treatments advised. It is also quite important that you check websites that list all the treatments in comparison to each other to decide which is the best treatment for your situation. Since its inception, Viagra has ruled the erectile dysfunction market, but with the release of drugs like Cialis and Levitra, men have many more options to choose from. There is no hiding the fact that all three have been proven very effective, but it is worth pointing out that there are specific attributes to each drug that you may find suit your requirements. These drugs are in a class known as PDE-5 inhibitors. According to one study, they all have been proven to work in 70% of men with various kinds of erectile dysfunction. They all work in the same way; they need sexual stimulation to activate. Viagra, the oldest of this type of drug, has the fastest acting time. It takes only 14 minutes to be absorbed into the body if taken on an empty stomach. Although Viagra has the quickest acting time, its main disadvantage is the decreased absorption with food take. In a normal scenario, it takes around half an hour for the drug to reach its maximum effect. After that it looses half of its maximum effect every 4 hours. Regarding side effects, a person who uses Viagra can expect mild headaches, upset stomach, unusually bright vision and facial flushing. Cialis, on the other hand, has been approved for duration of 36 hours. Some estimates have even stated that it is effective for up to 100 hours, resulting in the nickname, “the weekender”.

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An oral therapy for erectile dysfunction, is the citrate salt of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Sildenafil citrate is designated chemically as 1 - [[3 - (6,7 - dihydro - 1 - methyl - 7 - oxo - 3 - propyl - 1H - pyrazolo[4,3 - d]pyrimidin - 5 - yl) - 4 - ethoxyphenyl]sulfonyl] - 4 - methylpiperazine citrate and has the following structural formula: Sildenafil citrate is a white to off-white crystalline powder with a solubility of 3.5 mg/mL in water and a molecular weight of 666.7. Viagra (sildenafil citrate) is formulated as blue, film-coated rounded-diamond-shaped tablets equivalent to 25 mg, 50 mg and 100 mg of sildenafil for oral administration. In addition to the active ingredient, sildenafil citrate, each tablet contains the following inactive ingredients: microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin, and FD & C Blue #2 aluminum lake. The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum, but enhances the effect of nitric oxide (NO) by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP in the corpus cavernosum. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil causes increased levels of cGMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum. Sildenafil at recommended doses has no effect in the absence of sexual stimulation. Studies in vitro have shown that sildenafil is selective for PDE5. Its effect is more potent on PDE5 than on other known phosphodiesterases (10-fold for PDE6, >80-fold for PDE1, >700-fold for PDE2, PDE3, PDE4, PDE7, PDE8, PDE9, PDE10, and PDE11). The approximately 4,000-fold selectivity for PDE5 versus PDE3 is important because PDE3 is involved in control of cardiac contractility. Sildenafil is only about 10-fold as potent for PDE5 compared to PDE6, an enzyme found in the retina which is involved in the phototransduction pathway of the retina. This lower selectivity is thought to be the basis for abnormalities related to color vision observed with higher doses or plasma levels (see ). In addition to human corpus cavernosum smooth muscle, PDE5 is also found in lower concentrations in other tissues including platelets, vascular and visceral smooth muscle, and skeletal muscle. The inhibition of PDE5 in these tissues by sildenafil may be the basis for the enhanced platelet antiaggregatory activity of nitric oxide observed in vitro, an inhibition of platelet thrombus formation in vivo and peripheral arterial-venous dilatation in vivo. Viagra is rapidly absorbed after oral administration, with absolute bioavailability of about 40%. Its pharmacokinetics are dose-proportional over the recommended dose range. It is eliminated predominantly by hepatic metabolism (mainly cytochrome P450 3A4) and is converted to an active metabolite with properties similar to the parent, sildenafil. The concomitant use of potent cytochrome P450 3A4 inhibitors (e.g., erythromycin, ketoconazole, itraconazole) as well as the nonspecific CYP inhibitor, cimetidine, is associated with increased plasma levels of sildenafil (see ). Both sildenafil and the metabolite have terminal half lives of about 4 hours. in Healthy Male Volunteers. Viagra is rapidly absorbed. Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When Viagra is taken with a high fat meal, the rate of absorption is reduced, with a mean delay in T of 29%. The mean steady state volume of distribution (Vss) for sildenafil is 105 L, indicating distribution into the tissues. Sildenafil and its major circulating N-desmethyl metabolite are both approximately 96% bound to plasma proteins. Protein binding is independent of total drug concentrations. Based upon measurements of sildenafil in semen of healthy volunteers 90 minutes after dosing, less than 0.001% of the administered dose may appear in the semen of patients. Sildenafil is cleared predominantly by the CYP3A4 (major route) and CYP2C9 (minor route) hepatic microsomal isoenzymes. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. This metabolite has a PDE selectivity profile similar to sildenafil and an in vitro potency for PDE5 approximately 50% of the parent drug. Plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil, so that the metabolite accounts for about 20% of sildenafil's pharmacologic effects. After either oral or intravenous administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose). Similar values for pharmacokinetic parameters were seen in normal volunteers and in the patient population, using a population pharmacokinetic approach. Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, with free plasma concentrations approximately 40% greater than those seen in healthy younger volunteers (18–45 years). In volunteers with mild (CLcr=50–80 mL/min) and moderate (CLcr=30–49 mL/min) renal impairment, the pharmacokinetics of a single oral dose of Viagra (50 mg) were not altered. In volunteers with severe (CLcr=<30 mL/min) renal impairment, sildenafil clearance was reduced, resulting in approximately doubling of AUC and C compared to age-matched volunteers with no renal impairment. In volunteers with hepatic cirrhosis (Child-Pugh A and B), sildenafil clearance was reduced, resulting in increases in AUC (84%) and C (47%) compared to age-matched volunteers with no hepatic impairment. Therefore, age >65, hepatic impairment and severe renal impairment are associated with increased plasma levels of sildenafil. A starting oral dose of 25 mg should be considered in those patients (see ). In eight double-blind, placebo-controlled crossover studies of patients with either organic or psychogenic erectile dysfunction, sexual stimulation resulted in improved erections, as assessed by an objective measurement of hardness and duration of erections (RigiScan ), after Viagra administration compared with placebo. Most studies assessed the efficacy of Viagra approximately 60 minutes post dose. The erectile response, as assessed by RigiScan , generally increased with increasing sildenafil dose and plasma concentration. The time course of effect was examined in one study, showing an effect for up to 4 hours but the response was diminished compared to 2 hours. Single oral doses of sildenafil (100 mg) administered to healthy volunteers produced decreases in supine blood pressure (mean maximum decrease in systolic/diastolic blood pressure of 8.4/5.5 mmHg). The decrease in blood pressure was most notable approximately 1–2 hours after dosing, and was not different than placebo at 8 hours. Similar effects on blood pressure were noted with 25 mg, 50 mg and 100 mg of Viagra, therefore the effects are not related to dose or plasma levels within this dosage range. Larger effects were recorded among patients receiving concomitant nitrates (see ). Systolic Blood Pressure, Healthy Volunteers. Single oral doses of sildenafil up to 100 mg produced no clinically relevant changes in the ECGs of normal male volunteers. Studies have produced relevant data on the effects of Viagra on cardiac output. In one small, open-label, uncontrolled, pilot study, eight patients with stable ischemic heart disease underwent Swan-Ganz catheterization. A total dose of 40 mg sildenafil was administered by four intravenous infusions. The results from this pilot study are shown in Table 1; the mean resting systolic and diastolic blood pressures decreased by 7% and 10% compared to baseline in these patients. Mean resting values for right atrial pressure, pulmonary artery pressure, pulmonary artery occluded pressure and cardiac output decreased by 28%, 28%, 20% and 7% respectively. Even though this total dosage produced plasma sildenafil concentrations which were approximately 2 to 5 times higher than the mean maximum plasma concentrations following a single oral dose of 100 mg in healthy male volunteers, the hemodynamic response to exercise was preserved in these patients. In a double-blind study, 144 patients with erectile dysfunction and chronic stable angina limited by exercise, not receiving chronic oral nitrates, were randomized to a single dose of placebo or Viagra 100 mg 1 hour prior to exercise testing. The primary endpoint was time to limiting angina in the evaluable cohort. The mean times (adjusted for baseline) to onset of limiting angina were 423.6 and 403.7 seconds for sildenafil (N=70) and placebo, respectively. These results demonstrated that the effect of Viagra on the primary endpoint was statistically non-inferior to placebo. At single oral doses of 100 mg and 200 mg, transient dose-related impairment of color discrimination (blue/green) was detected using the Farnsworth-Munsell 100-hue test, with peak effects near the time of peak plasma levels. This finding is consistent with the inhibition of PDE6, which is involved in phototransduction in the retina. An evaluation of visual function at doses up to twice the maximum recommended dose revealed no effects of Viagra on visual acuity, intraocular pressure, or pupillometry. In clinical studies, Viagra was assessed for its effect on the ability of men with erectile dysfunction (ED) to engage in sexual activity and in many cases specifically on the ability to achieve and maintain an erection sufficient for satisfactory sexual activity. Viagra was evaluated primarily at doses of 25 mg, 50 mg and 100 mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs (fixed dose, titration, parallel, crossover). Viagra was administered to more than 3,000 patients aged 19 to 87 years, with ED of various etiologies (organic, psychogenic, mixed) with a mean duration of 5 years. Viagra demonstrated statistically significant improvement compared to placebo in all 21 studies. The studies that established benefit demonstrated improvements in success rates for sexual intercourse compared with placebo. The effectiveness of Viagra was evaluated in most studies using several assessment instruments. The primary measure in the principal studies was a sexual function questionnaire (the International Index of Erectile Function - IIEF) administered during a 4-week treatment-free run-in period, at baseline, at follow-up visits, and at the end of double-blind, placebo-controlled, at-home treatment. Two of the questions from the IIEF served as primary study endpoints; categorical responses were elicited to questions about (1) the ability to achieve erections sufficient for sexual intercourse and (2) the maintenance of erections after penetration. The patient addressed both questions at the final visit for the last 4 weeks of the study. The possible categorical responses to these questions were (0) no attempted intercourse, (1) never or almost never, (2) a few times, (3) sometimes, (4) most times, and (5) almost always or always. Also collected as part of the IIEF was information about other aspects of sexual function, including information on erectile function, orgasm, desire, satisfaction with intercourse, and overall sexual satisfaction. Sexual function data were also recorded by patients in a daily diary. In addition, patients were asked a global efficacy question and an optional partner questionnaire was administered. The effect on one of the major end points, maintenance of erections after penetration, is shown in Figure 3, for the pooled results of 5 fixed-dose, dose-response studies of greater than one month duration, showing response according to baseline function. Results with all doses have been pooled, but scores showed greater improvement at the 50 and 100 mg doses than at 25 mg. The pattern of responses was similar for the other principal question, the ability to achieve an erection sufficient for intercourse. The titration studies, in which most patients received 100 mg, showed similar results. Figure 3 shows that regardless of the baseline levels of function, subsequent function in patients treated with Viagra was better than that seen in patients treated with placebo. At the same time, on-treatment function was better in treated patients who were less impaired at baseline. Figure 3. Effect of Viagra and Placebo on Maintenance of Erection by Baseline Score. The frequency of patients reporting improvement of erections in response to a global question in four of the randomized, double-blind, parallel, placebo-controlled fixed dose studies (1797 patients) of 12 to 24 weeks duration is shown in Figure 4. These patients had erectile dysfunction at baseline that was characterized by median categorical scores of 2 (a few times) on principal IIEF questions. Erectile dysfunction was attributed to organic (58%; generally not characterized, but including diabetes and excluding spinal cord injury), psychogenic (17%), or mixed (24%) etiologies. Sixty-three percent, 74%, and 82% of the patients on 25 mg, 50 mg and 100 mg of Viagra, respectively, reported an improvement in their erections, compared to 24% on placebo. In the titration studies (n=644) (with most patients eventually receiving 100 mg), results were similar. Figure 4. Percentage of Patients Reporting an Improvement in Erections. The patients in studies had varying degrees of ED. One-third to one-half of the subjects in these studies reported successful intercourse at least once during a 4-week, treatment-free run-in period. In many of the studies, of both fixed dose and titration designs, daily diaries were kept by patients. In these studies, involving about 1600 patients, analyses of patient diaries showed no effect of Viagra on rates of attempted intercourse (about 2 per week), but there was clear treatment-related improvement in sexual function: per patient weekly success rates averaged 1.3 on 50–100 mg of Viagra vs 0.4 on placebo; similarly, group mean success rates (total successes divided by total attempts) were about 66% on Viagra vs about 20% on placebo. During 3 to 6 months of double-blind treatment or longer-term (1 year), open-label studies, few patients withdrew from active treatment for any reason, including lack of effectiveness. At the end of the long-term study, 88% of patients reported that Viagra improved their erections. Men with untreated ED had relatively low baseline scores for all aspects of sexual function measured (again using a 5-point scale) in the IIEF. Viagra improved these aspects of sexual function: frequency, firmness and maintenance of erections; frequency of orgasm; frequency and level of desire; frequency, satisfaction and enjoyment of intercourse; and overall relationship satisfaction. One randomized, double-blind, flexible-dose, placebo-controlled study included only patients with erectile dysfunction attributed to complications of diabetes mellitus (n=268). As in the other titration studies, patients were started on 50 mg and allowed to adjust the dose up to 100 mg or down to 25 mg of Viagra; all patients, however, were receiving 50 mg or 100 mg at the end of the study. There were highly statistically significant improvements on the two principal IIEF questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) on Viagra compared to placebo. On a global improvement question, 57% of Viagra patients reported improved erections versus 10% on placebo. Diary data indicated that on Viagra, 48% of intercourse attempts were successful versus 12% on placebo. One randomized, double-blind, placebo-controlled, crossover, flexible-dose (up to 100 mg) study of patients with erectile dysfunction resulting from spinal cord injury (n=178) was conducted. The changes from baseline in scoring on the two end point questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) were highly statistically significantly in favor of Viagra. On a global improvement question, 83% of patients reported improved erections on Viagra versus 12% on placebo. Diary data indicated that on Viagra, 59% of attempts at sexual intercourse were successful compared to 13% on placebo. Across all trials, Viagra improved the erections of 43% of radical prostatectomy patients compared to 15% on placebo. Subgroup analyses of responses to a global improvement question in patients with psychogenic etiology in two fixed-dose studies (total n=179) and two titration studies (total n=149) showed 84% of Viagra patients reported improvement in erections compared with 26% of placebo. The changes from baseline in scoring on the two end point questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) were highly statistically significantly in favor of Viagra. Diary data in two of the studies (n=178) showed rates of successful intercourse per attempt of 70% for Viagra and 29% for placebo. A review of population subgroups demonstrated efficacy regardless of baseline severity, etiology, race and age. Viagra was effective in a broad range of ED patients, including those with a history of coronary artery disease, hypertension, other cardiac disease, peripheral vascular disease, diabetes mellitus, depression, coronary artery bypass graft (CABG), radical prostatectomy, transurethral resection of the prostate (TURP) and spinal cord injury, and in patients taking antidepressants/antipsychotics and antihypertensives/diuretics. Analysis of the safety database showed no apparent difference in the side effect profile in patients taking Viagra with and without antihypertensive medication. This analysis was performed retrospectively, and was not powered to detect any pre-specified difference in adverse reactions. Viagra is indicated for the treatment of erectile dysfunction. ), Viagra was shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using organic nitrates, either regularly and/or intermittently, in any form is therefore contraindicated. After patients have taken Viagra, it is unknown when nitrates, if necessary, can be safely administered. Based on the pharmacokinetic profile of a single 100 mg oral dose given to healthy normal volunteers, the plasma levels of sildenafil at 24 hours post dose are approximately 2 ng/mL (compared to peak plasma levels of approximately 440 ng/mL) (see ). In the following patients: age >65, hepatic impairment (e.g., cirrhosis), severe renal impairment (e.g., creatinine clearance <30 mL/min), and concomitant use of potent cytochrome P450 3A4 inhibitors (erythromycin), plasma levels of sildenafil at 24 hours post dose have been found to be 3 to 8 times higher than those seen in healthy volunteers. Although plasma levels of sildenafil at 24 hours post dose are much lower than at peak concentration, it is unknown whether nitrates can be safely coadministered at this time point. Viagra is contraindicated in patients with a known hypersensitivity to any component of the tablet. There is a potential for cardiac risk of sexual activity in patients with preexisting cardiovascular disease. Therefore, treatments for erectile dysfunction, including Viagra, should not be generally used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status. Viagra has systemic vasodilatory properties that resulted in transient decreases in supine blood pressure in healthy volunteers (mean maximum decrease of 8.4/5.5 mmHg), (see ). While this normally would be expected to be of little consequence in most patients, prior to prescribing Viagra, physicians should carefully consider whether their patients with underlying cardiovascular disease could be affected adversely by such vasodilatory effects, especially in combination with sexual activity. Patients with the following underlying conditions can be particularly sensitive to the actions of vasodilators including Viagra – those with left ventricular outflow obstruction (e.g. aortic stenosis, idiopathic hypertrophic subaortic stenosis) and those with severely impaired autonomic control of blood pressure. There is no controlled clinical data on the safety or efficacy of Viagra in the following groups; if prescribed, this should be done with caution. Patients who have suffered a myocardial infarction, stroke, or life-threatening arrhythmia within the last 6 months; Patients with retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases). Prolonged erection greater than 4 hours and priapism (painful erections greater than 6 hours in duration) have been reported infrequently since market approval of Viagra. In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance. If priapism is not treated immediately, penile tissue damage and permanent loss of potency could result. The concomitant administration of the protease inhibitor ritonavir substantially increases serum concentrations of sildenafil (11-fold increase in AUC). If Viagra is prescribed to patients taking ritonavir, caution should be used. Data from subjects exposed to high systemic levels of sildenafil are limited. Visual disturbances occurred more commonly at higher levels of sildenafil exposure. Decreased blood pressure, syncope, and prolonged erection were reported in some healthy volunteers exposed to high doses of sildenafil (200–800 mg). To decrease the chance of adverse events in patients taking ritonavir, a decrease in sildenafil dosage is recommended (see , ). The evaluation of erectile dysfunction should include a determination of potential underlying causes and the identification of appropriate treatment following a complete medical assessment. Before prescribing Viagra, it is important to note the following: Caution is advised when Phosphodiesterase Type 5 (PDE5) inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including Viagra, and alpha-adrenergic blocking agents are both vasodilators with blood pressure lowering effects. When vasodilators are used in combination, an additive effect on blood pressure may be anticipated. In some patients, concomitant use of these two drug classes can lower blood pressure significantly (see ) leading to symptomatic hypotension (e.g. dizziness, lightheadedness, fainting). Patients should be stable on alpha-blocker therapy prior to initiating a PDE5 inhibitor. Patients who demonstrate hemodynamic instability on alpha-blocker therapy alone are at increased risk of symptomatic hypotension with concomitant use of PDE5 inhibitors. In those patients who are stable on alpha-blocker therapy, PDE5 inhibitors should be initiated at the lowest dose. In those patients already taking an optimized dose of a PDE5 inhibitor, alpha-blocker therapy should be initiated at the lowest dose. Stepwise increase in alpha-blocker dose may be associated with further lowering of blood pressure when taking a PDE5 inhibitor. Safety of combined use of PDE5 inhibitors and alpha-blockers may be affected by other variables, including intravascular volume depletion and other anti-hypertensive drugs. Viagra has systemic vasodilatory properties and may augment the blood pressure lowering effect of other anti-hypertensive medications. Patients on multiple antihypertensive medications were included in the pivotal clinical trials for Viagra. In a separate drug interaction study, when amlodipine, 5 mg or 10 mg, and Viagra, 100 mg were orally administered concomitantly to hypertensive patients mean additional blood pressure reduction of 8 mmHg systolic and 7 mmHg diastolic were noted (see ). The safety of Viagra is unknown in patients with bleeding disorders and patients with active peptic ulceration. Viagra should be used with caution in patients with anatomical deformation of the penis (such as angulation, cavernosal fibrosis or Peyronie's disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell anemia, multiple myeloma, or leukemia). The safety and efficacy of combinations of Viagra with other treatments for erectile dysfunction have not been studied. Therefore, the use of such combinations is not recommended. In humans, Viagra has no effect on bleeding time when taken alone or with aspirin. In vitro studies with human platelets indicate that sildenafil potentiates the antiaggregatory effect of sodium nitroprusside (a nitric oxide donor). The combination of heparin and Viagra had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans. Physicians should discuss with patients the contraindication of Viagra with regular and/or intermittent use of organic nitrates. Physicians should advise patients of the potential for Viagra to augment the blood pressure lowering effect of alpha-blockers and anti-hypertensive medications. Concomitant administration of Viagra and an alpha-blocker may lead to symptomatic hypotension in some patients. Therefore, when Viagra is co-administered with alpha-blockers, patients should be stable on alpha-blocker therapy prior to initiating Viagra treatment and Viagra should be initiated at the lowest dose. Physicians should discuss with patients the potential cardiac risk of sexual activity in patients with preexisting cardiovascular risk factors. Patients who experience symptoms (e.g., angina pectoris, dizziness, nausea) upon initiation of sexual activity should be advised to refrain from further activity and should discuss the episode with their physician. Physicians should advise patients to stop use of all PDE5 inhibitors, including Viagra, and seek medical attention in the event of a sudden loss of vision in one or both eyes. Such an event may be a sign of non-arteritic anterior ischemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision, that has been reported rarely post-marketing in temporal association with the use of all PDE5 inhibitors. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors. Physicians should also discuss with patients the increased risk of NAION in individuals who have already experienced NAION in one eye, including whether such individuals could be adversely affected by use of vasodilators, such as PDE5 inhibitors (see ). Physicians should advise patients to stop taking PDE5 inhibitors, including Viagra, and seek prompt medical attention in the event of sudden decrease or loss of hearing. These events, which may be accompanied by tinnitus and dizziness, have been reported in temporal association to the intake of PDE5 inhibitors, including Viagra. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors (see , ). Physicians should warn patients that prolonged erections greater than 4 hours and priapism (painful erections greater than 6 hours in duration) have been reported infrequently since market approval of Viagra. In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance. If priapism is not treated immediately, penile tissue damage and permanent loss of potency may result. The use of Viagra offers no protection against sexually transmitted diseases. Counseling of patients about the protective measures necessary to guard against sexually transmitted diseases, including the Human Immunodeficiency Virus (HIV), may be considered. Sildenafil metabolism is principally mediated by the cytochrome P450 (CYP) isoforms 3A4 (major route) and 2C9 (minor route). Therefore, inhibitors of these isoenzymes may reduce sildenafil clearance. Cimetidine (800 mg), a nonspecific CYP inhibitor, caused a 56% increase in plasma sildenafil concentrations when coadministered with Viagra (50 mg) to healthy volunteers. When a single 100 mg dose of Viagra was administered with erythromycin, a specific CYP3A4 inhibitor, at steady state (500 mg bid for 5 days), there was a 182% increase in sildenafil systemic exposure (AUC). In addition, in a study performed in healthy male volunteers, coadministration of the HIV protease inhibitor saquinavir, also a CYP3A4 inhibitor, at steady state (1200 mg tid) with Viagra (100 mg single dose) resulted in a 140% increase in sildenafil C and a 210% increase in sildenafil AUC. Viagra had no effect on saquinavir pharmacokinetics. Stronger CYP3A4 inhibitors such as ketoconazole or itraconazole would be expected to have still greater effects, and population data from patients in clinical trials did indicate a reduction in sildenafil clearance when it was coadministered with CYP3A4 inhibitors (such as ketoconazole, erythromycin, or cimetidine) (see ). In another study in healthy male volunteers, coadministration with the HIV protease inhibitor ritonavir, which is a highly potent P450 inhibitor, at steady state (500 mg bid) with Viagra (100 mg single dose) resulted in a 300% (4-fold) increase in sildenafil C and a 1000% (11-fold) increase in sildenafil plasma AUC. At 24 hours the plasma levels of sildenafil were still approximately 200 ng/mL, compared to approximately 5 ng/mL when sildenafil was dosed alone. This is consistent with ritonavir's marked effects on a broad range of P450 substrates. Viagra had no effect on ritonavir pharmacokinetics (see ). Although the interaction between other protease inhibitors and sildenafil has not been studied, their concomitant use is expected to increase sildenafil levels. In a study of healthy male volunteers, co-administration of sildenafil at steady state (80 mg t.i.d.) with endothelin receptor antagonist bosentan (a moderate inducer of CYP3A4, CYP2C9 and possibly of cytochrome P450 2C19) at steady state (125 mg b.i.d.) resulted in a 63% decrease of sildenafil AUC and a 55% decrease in sildenafil C . Concomitant administration of strong CYP3A4 inducers, such as rifampin, is expected to cause greater decreases in plasma levels of sildenafil. Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of Viagra. Pharmacokinetic data from patients in clinical trials showed no effect on sildenafil pharmacokinetics of CYP2C9 inhibitors (such as tolbutamide, warfarin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, ACE inhibitors, and calcium channel blockers. The AUC of the active metabolite, N-desmethyl sildenafil, was increased 62% by loop and potassium-sparing diuretics and 102% by nonspecific beta-blockers. These effects on the metabolite are not expected to be of clinical consequence. Sildenafil is a weak inhibitor of the cytochrome P450 isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 µM). Given sildenafil peak plasma concentrations of approximately 1 µM after recommended doses, it is unlikely that Viagra will alter the clearance of substrates of these isoenzymes. Three double-blind, placebo-controlled, randomized, two-way crossover studies were conducted to assess the interaction of Viagra with doxazosin, an alpha-adrenergic blocking agent. In the first study, a single oral dose of Viagra 100 mg or matching placebo was administered in a 2-period crossover design to 4 generally healthy males with benign prostatic hyperplasia (BPH). Following at least 14 consecutive daily doses of doxazosin, Viagra 100 mg or matching placebo was administered simultaneously with doxazosin. Following a review of the data from these first 4 subjects (details provided below), the Viagra dose was reduced to 25 mg. Thereafter, 17 subjects were treated with Viagra 25 mg or matching placebo in combination with doxazosin 4 mg (15 subjects) or doxazosin 8mg (2 subjects). The mean subject age was 66.5 years. For the 17 subjects who received Viagra 25 mg and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: Blood pressure was measured immediately pre-dose and at 15, 30, 45 minutes, and 1, 1.5, 2, 2.5, 3, 4, 6 and 8 hours after Viagra or matching placebo. Outliers were defined as subjects with a standing systolic blood pressure of <85 mmHg or a decrease from baseline in standing systolic blood pressure of >30 mmHg at one or more timepoints. There were no subjects treated with Viagra 25 mg who had a standing SBP < 85mmHg. There were three subjects with a decrease from baseline in standing systolic BP >30mmHg following Viagra 25 mg, one subject with a decrease from baseline in standing systolic BP > 30 mmHg following placebo and two subjects with a decrease from baseline in standing systolic BP > 30 mmHg following both Viagra and placebo. No severe adverse events potentially related to blood pressure effects were reported in this group. Of the four subjects who received Viagra 100 mg in the first part of this study, a severe adverse event related to blood pressure effect was reported in one patient (postural hypotension that began 35 minutes after dosing with Viagra with symptoms lasting for 8 hours), and mild adverse events potentially related to blood pressure effects were reported in two others (dizziness, headache and fatigue at 1 hour after dosing; and dizziness, lightheadedness and nausea at 4 hours after dosing). There were no reports of syncope among these patients. For these four subjects, the placebo-subtracted mean maximum decreases from baseline in supine and standing systolic blood pressures were 14.8 mmHg and 21.5 mmHg, respectively. Two of these subjects had a standing SBP < 85mmHg. Both of these subjects were protocol violators, one due to a low baseline standing SBP, and the other due to baseline orthostatic hypotension. In the second study, a single oral dose of Viagra 50 mg or matching placebo was administered in a 2-period crossover design to 20 generally healthy males with BPH. Following at least 14 consecutive days of doxazosin, Viagra 50mg or matching placebo was administered simultaneously with doxazosin 4 mg (17 subjects) or with doxazosin 8 mg (3 subjects). The mean subject age in this study was 63.9 years. Twenty subjects received Viagra 50 mg, but only 19 subjects received matching placebo. One patient discontinued the study prematurely due to an adverse event of hypotension following dosing with Viagra 50 mg. This patient had been taking minoxidil, a potent vasodilator, during the study. For the 19 subjects who received both Viagra and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: Blood pressure was measured after administration of Viagra at the same times as those specified for the first doxazosin study. There were two subjects who had a standing SBP of < 85 mmHg. In these two subjects, hypotension was reported as a moderately severe adverse event, beginning at approximately 1 hour after administration of Viagra 50 mg and resolving after approximately 7.5 hours. There was one subject with a decrease from baseline in standing systolic BP >30mmHg following Viagra 50 mg and one subject with a decrease from baseline in standing systolic BP > 30 mmHg following both Viagra 50 mg and placebo. There were no severe adverse events potentially related to blood pressure and no episodes of syncope reported in this study. In the third study, a single oral dose of Viagra 100 mg or matching placebo was administered in a 3-period crossover design to 20 generally healthy males with BPH. In dose period 1, subjects were administered open-label doxazosin and a single dose of Viagra 50 mg simultaneously, after at least 14 consecutive days of doxazosin. If a subject did not successfully complete this first dosing period, he was discontinued from the study. Subjects who had successfully completed the previous doxazosin interaction study (using Viagra 50 mg), including no significant hemodynamic adverse events, were allowed to skip dose period 1. Treatment with doxazosin continued for at least 7 days after dose period 1. Thereafter, Viagra 100mg or matching placebo was administered simultaneously with doxazosin 4 mg (14 subjects) or doxazosin 8 mg (6 subjects) in standard crossover fashion. The mean subject age in this study was 66.4 years. Twenty-five subjects were screened. Two were discontinued after study period 1: one failed to meet pre-dose screening qualifications and the other experienced symptomatic hypotension as a moderately severe adverse event 30 minutes after dosing with open-label Viagra 50 mg. Of the twenty subjects who were ultimately assigned to treatment, a total of 13 subjects successfully completed dose period 1, and seven had successfully completed the previous doxazosin study (using Viagra 50 mg). For the 20 subjects who received Viagra 100 mg and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: Blood pressure was measured after administration of Viagra at the same times as those specified for the previous doxazosin studies. There were three subjects who had a standing SBP of < 85 mmHg. All three were taking Viagra 100 mg, and all three reported mild adverse events at the time of reductions in standing SBP, including vasodilation and lightheadedness. There were four subjects with a decrease from baseline in standing systolic BP >30mmHg following Viagra 100 mg, one subject with a decrease from baseline in standing systolic BP > 30 mmHg following placebo and one subject with a decrease from baseline in standing systolic BP > 30 mmHg following both Viagra and placebo. While there were no severe adverse events potentially related to blood pressure reported in this study, one subject reported moderate vasodilatation after both Viagra 50 mg and 100 mg. There were no episodes of syncope reported in this study. When Viagra 100 mg oral was coadministered with amlodipine, 5 mg or 10 mg oral, to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic. No significant interactions were shown with tolbutamide (250 mg) or warfarin (40 mg), both of which are metabolized by CYP2C9. Viagra (50 mg) did not potentiate the increase in bleeding time caused by aspirin (150 mg). Viagra (50 mg) did not potentiate the hypotensive effect of alcohol in healthy volunteers with mean maximum blood alcohol levels of 0.08%. In a study of healthy male volunteers, sildenafil (100 mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates. Sildenafil at steady state (80 mg t.i.d.) resulted in a 50% increase in AUC and a 42% increase in C of bosentan (125 mg b.i.d.). Carcinogenesis, Mutagenesis, Impairment of Fertility Sildenafil was not carcinogenic when administered to rats for 24 months at a dose resulting in total systemic drug exposure (AUCs) for unbound sildenafil and its major metabolite of 29- and 42-times, for male and female rats, respectively, the exposures observed in human males given the Maximum Recommended Human Dose (MRHD) of 100 mg. Sildenafil was not carcinogenic when administered to mice for 18–21 months at dosages up to the Maximum Tolerated Dose (MTD) of 10 mg/kg/day, approximately 0.6 times the MRHD on a mg/m basis. Sildenafil was negative in in vitro bacterial and Chinese hamster ovary cell assays to detect mutagenicity, and in vitro human lymphocytes and in vivo mouse micronucleus assays to detect clastogenicity. There was no impairment of fertility in rats given sildenafil up to 60 mg/kg/day for 36 days to females and 102 days to males, a dose producing an AUC value of more than 25 times the human male AUC. There was no effect on sperm motility or morphology after single 100 mg oral doses of Viagra in healthy volunteers. Pregnancy, Nursing Mothers and Pediatric Use Viagra is not indicated for use in newborns, children, or women. No evidence of teratogenicity, embryotoxicity or fetotoxicity was observed in rats and rabbits which received up to 200 mg/kg/day during organogenesis. These doses represent, respectively, about 20 and 40 times the MRHD on a mg/m basis in a 50 kg subject. In the rat pre- and postnatal development study, the no observed adverse effect dose was 30 mg/kg/day given for 36 days. In the nonpregnant rat the AUC at this dose was about 20 times human AUC. There are no adequate and well-controlled studies of sildenafil in pregnant women. ). Since higher plasma levels may increase both the efficacy and incidence of adverse events, a starting dose of 25 mg should be considered (see ). Viagra was administered to over 3700 patients (aged 19–87 years) during pre-marketing clinical trials worldwide. Over 550 patients were treated for longer than one year. In placebo-controlled clinical studies, the discontinuation rate due to adverse events for Viagra (2.5%) was not significantly different from placebo (2.3%). The adverse events were generally transient and mild to moderate in nature. In trials of all designs, adverse events reported by patients receiving Viagra were generally similar. In fixed-dose studies, the incidence of some adverse events increased with dose. The nature of the adverse events in flexible-dose studies, which more closely reflect the recommended dosage regimen, was similar to that for fixed-dose studies. When Viagra was taken as recommended (on an as-needed basis) in flexible-dose, placebo-controlled clinical trials, the following adverse events were reported: Other adverse reactions occurred at a rate of >2%, but equally common on placebo: respiratory tract infection, back pain, flu syndrome, and arthralgia. In fixed-dose studies, dyspepsia (17%) and abnormal vision (11%) were more common at 100 mg than at lower doses. At doses above the recommended dose range, adverse events were similar to those detailed above but generally were reported more frequently. The following events occurred in <2% of patients in controlled clinical trials; a causal relationship to Viagra is uncertain. Reported events include those with a plausible relation to drug use; omitted are minor events and reports too imprecise to be meaningful: Body as a whole: face edema, photosensitivity reaction, shock, asthenia, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury. Cardiovascular: angina pectoris, AV block, migraine, syncope, tachycardia, palpitation, hypotension, postural hypotension, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, abnormal electrocardiogram, cardiomyopathy. Digestive: vomiting, glossitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, dry mouth, liver function tests abnormal, rectal hemorrhage, gingivitis. Hemic and Lymphatic: anemia and leukopenia. Metabolic and Nutritional: thirst, edema, gout, unstable diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemic reaction, hypernatremia. Musculoskeletal: arthritis, arthrosis, myalgia, tendon rupture, tenosynovitis, bone pain, myasthenia, synovitis. Nervous: ataxia, hypertonia, neuralgia, neuropathy, paresthesia, tremor, vertigo, depression, insomnia, somnolence, abnormal dreams, reflexes decreased, hypesthesia. Respiratory: asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, sputum increased, cough increased. Skin and Appendages: urticaria, herpes simplex, pruritus, sweating, skin ulcer, contact dermatitis, exfoliative dermatitis. Special Senses: sudden decrease or loss of hearing, mydriasis, conjunctivitis, photophobia, tinnitus, eye pain, ear pain, eye hemorrhage, cataract, dry eyes. Urogenital: cystitis, nocturia, urinary frequency, breast enlargement, urinary incontinence, abnormal ejaculation, genital edema and anorgasmia. Serious cardiovascular, cerebrovascular, and vascular events, including myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, hypertension, subarachnoid and intracerebral hemorrhages, and pulmonary hemorrhage have been reported post-marketing in temporal association with the use of Viagra. Most, but not all, of these patients had preexisting cardiovascular risk factors. Many of these events were reported to occur during or shortly after sexual activity, and a few were reported to occur shortly after the use of Viagra without sexual activity. Others were reported to have occurred hours to days after the use of Viagra and sexual activity. It is not possible to determine whether these events are related directly to Viagra, to sexual activity, to the patient's underlying cardiovascular disease, to a combination of these factors, or to other factors (see for further important cardiovascular information). Cases of sudden decrease or loss of hearing have been reported postmarketing in temporal association with the use of PDE5 inhibitors, including Viagra. In some of the cases, medical conditions and other factors were reported that may have also played a role in the otologic adverse events. In many cases, medical follow-up information was limited. It is not possible to determine whether these reported events are related directly to the use of Viagra, to the patient’s underlying risk factors for hearing loss, a combination of these factors, or to other factors (see ). Nervous: seizure and anxiety. Urogenital: prolonged erection, priapism (see ), and hematuria. Special Senses: diplopia, temporary vision loss/decreased vision, ocular redness or bloodshot appearance, ocular burning, ocular swelling/pressure, increased intraocular pressure, retinal vascular disease or bleeding, vitreous detachment/traction, paramacular edema and epistaxis. Non-arteritic anterior ischemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision, has been reported rarely post-marketing in temporal association with the use of phosphodiesterase type 5 (PDE5) inhibitors, including Viagra. Most, but not all, of these patients had underlying anatomic or vascular risk factors for developing NAION, including but not necessarily limited to: low cup to disc ratio ("crowded disc"), age over 50, diabetes, hypertension, coronary artery disease, hyperlipidemia and smoking. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors, to the patient's underlying vascular risk factors or anatomical defects, to a combination of these factors, or to other factors (see ). In studies with healthy volunteers of single doses up to 800 mg, adverse events were similar to those seen at lower doses but incidence rates were increased. In cases of overdose, standard supportive measures should be adopted as required. Renal dialysis is not expected to accelerate clearance as sildenafil is highly bound to plasma proteins and it is not eliminated in the urine. For most patients, the recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. However, Viagra may be taken anywhere from 4 hours to 0.5 hour before sexual activity. Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. The maximum recommended dosing frequency is once per day. The following factors are associated with increased plasma levels of sildenafil: age >65 (40% increase in AUC), hepatic impairment (e.g., cirrhosis, 80%), severe renal impairment (creatinine clearance <30 mL/min, 100%), and concomitant use of potent cytochrome P450 3A4 inhibitors [ketoconazole, itraconazole, erythromycin (182%), saquinavir (210%)]. Since higher plasma levels may increase both the efficacy and incidence of adverse events, a starting dose of 25 mg should be considered in these patients. Ritonavir greatly increased the systemic level of sildenafil in a study of healthy, non-HIV infected volunteers (11-fold increase in AUC, see .) Based on these pharmacokinetic data, it is recommended not to exceed a maximum single dose of 25 mg of Viagra in a 48 hour period. Viagra was shown to potentiate the hypotensive effects of nitrates and its administration in patients who use nitric oxide donors or nitrates in any form is therefore contraindicated. When Viagra is co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating Viagra treatment and Viagra should be initiated at the lowest dose (see ). Viagra (sildenafil citrate) is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to the nominally indicated amount of sildenafil as follows: Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F) [see USP Controlled Room Temperature]. LAB-0221-8.0 ®. It is not meant to take the place of your doctor's instructions. Read this informa