Viagra structural formula:

What is Viagra (sildenafil)?

• Sildenafil 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.
• Sildenafil may also be used for purposes other than those listed here.

What should I discuss with my doctor before taking Viagra (sildenafil)?

• Do not take sildenafil 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 sildenafil with a nitrate medicine can cause a serious decrease in blood pressure, leading to fainting, stroke, or heart attack.
• 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.
• Before taking sildenafil, tell your doctor if you have:
  • heart disease or heart rhythm problems;
  • a recent history (in the past 6 months) of a heart attack, stroke, or heart rhythm disorder;
  • congestive heart failure;
  • high or low blood pressure;
  • coronary artery disease;
  • liver disease;
  • kidney disease;
  • a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia;
  • a 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.
• If you have any of these conditions, you may not be able to use sildenafil or you may need a dosage adjustment or special tests during treatment.
• FDA pregnancy category B: This medication is not expected to be harmful to an unborn baby. Do not use sildenafil without telling your doctor if you are pregnant or plan to become pregnant during treatment.
• It is not known if sildenafil 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 (sildenafil)?

• Take each dose with a full glass of water.
• Avoid taking High-fat food before taking Viagra as it may cause the medicine to take more time to start working.
• Sildenafil is usually taken only when needed, 30 - 90 minutes before sexual activity. The medication can help achieve an erection when sexual stimulation occurs. An erection will not occur just by taking a pill.
• Do not take sildenafil more than once a day. Allow 24 hours to pass between doses.
• Store this medication at room temperature away from moisture and heat.

What is the shelf life of the pills?

• The expiry date is mentioned on each blister. It is different for different batches. The shelf life is 2 years from the date of manufacture and would differ from batch to batch depending on when they were manufactured.