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. It relaxes muscles and increases blood flow to particular areas of the body.
Discontinue sildenafil if you are using nitrate drug for chest pain or heart problems. Taking sildenafil with nitrate medicine can cause a serious decrease in blood pressure, leading to fainting, stroke, or heart attack. If you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw during sexual activity, stop and call your doctor right away.
Do not take sildenafil more than once a day. Allow 24 hours to pass between doses. If your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis.
A small number of patients have had a sudden loss of eyesight after taking sildenafil. This type of vision loss is caused by decreased blood flow to the optic nerve of the eye. It is not clear whether sildenafil is the actual cause of such vision loss. Sudden vision loss with sildenafil use has occurred most often in people with 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.
You must tell to your doctor if you have the following conditions such as: heart disease or heart rhythm problems; a recent history (in the past 6 months) of a heart attack, stroke, or heart rhythm disorder; a recent history (in the past 6 months) of a heart attack, stroke, or heart rhythm disorder; high or low blood pressure; liver and kidney disease; a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia; bleeding disorder such as hemophilia; a stomach ulcer; retinitis pigmentosa (an inherited condition of the eye); a physical deformity of the penis (such as Peyronie's disease); or if you have been told you should not have sexual intercourse for health reasons.
The revation is usually taken three times each day, about 4 to 6 hours apart. It 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. It 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.
Things to avoid while taking sildenafil are drinking alcohol which can increase some of the side effects of sildenafil. The side effects of these drug are dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw during sexual activity. Avoid using other medicines to treat impotence, such as alprostadil (Caverject, Muse, Edex) or yohimbine (Yocon, Yodoxin, others), without first talking to your doctor.
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.
Sildenafil has the following structural formula: