Generic name: sildenafil (sil-DEN-a-fil)

Brand name: Viagra

The active ingredient in Viagra is sildenafil, which is a PDE5 inhibitor. Sildenafil inhibits the production of cGMP, which is responsible for relaxing the smooth muscles in the penis and increasing blood flow.

Viagra is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. Its active ingredient is sildenafil, which is a PDE5 inhibitor. Viagra was originally developed by Pfizer as a treatment for angina, but the drug was found to be more effective at treating erectile dysfunction. Viagra was approved for use in the United States in 1998, and has since become one of the most popular medications for ED.

Viagra works by relaxing the blood vessels in the penis, which allows more blood to flow into the penis during sexual arousal. The increased blood flow results in an erection. Viagra generally starts working within 30-60 minutes after taking the drug, and its effects last for about 4 hours. Viagra can be taken with or without food, but you may find that the medication works better if you take it on an empty stomach.

To make sure Viagra is safe for you, tell your doctor about your other medical conditions, especially if you have or ever had:

  • heart disease or heart rhythm problems
  • a heart attack, stroke, or congestive heart failure
  • high or low blood pressure
  • liver disease
  • kidney disease (or if you are on dialysis)
  • 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)
  • if you have been told you should not have sexual intercourse for health reasons

Viagra should be taken with water and can be taken with or without food. It typically begins to work within 30 minutes, although it may take up to two hours for the full effect to kick in. Viagra usually remains effective for four to five hours. If you take it more than once a day, you may be more likely to experience side effects. Viagra should not be taken more than once a day.

Pharmacokinetics

The pharmacokinetics of sildenafil are dose-proportional over the recommended dose range. The mean maximum concentration (Cmax) is reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When sildenafil is taken with a high fat meal, the rate of absorption is reduced, with a mean delay in Tmax of 60 minutes and a mean reduction in Cmax of 29%. The mean steady state volume of distribution (Vss) for sildenafil is 105 L, indicating distribution into the tissues.

Side Effects

Viagra (sildenafil) is a medication used to treat erectile dysfunction. Although Viagra is generally considered safe, it can cause some potentially serious side effects.

Common side effects of Viagra include headaches, flushing, upset stomach, stuffy or runny nose and abnormal vision.

These side effects are usually mild and go away on their own. If they persist or become bothersome, talk to your doctor.

The most serious side effect of Viagra is a rare but potentially life-threatening condition called priapism. Priapism is a prolonged erection that can cause permanent damage to the penis if not treated promptly.

More rare side effects include sudden hearing loss, and an increased risk of skin cancer.

Viagra can also interact with other medications, so be sure to tell your doctor about all the medications you’re taking before taking Viagra. Request an appointment with a men’s health specialist to discuss your erectile dysfunction and whether Viagra is right for you.

Dosage and Administration

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 30 minutes to 4 hours before sexual activity. The maximum recommended dose is 100 mg.

Patients should take Viagra on an empty stomach or at least 3 hours after a meal.

Overdose

A Viagra overdose can be serious. If you think you have taken too much of this medicine, contact a poison control center or emergency room at once.

The signs of an overdose may include:

  • feeling light-headed or fainting
  • vision changes or sudden vision loss
  • chest pain or irregular heartbeat
  • shortness of breath
  • swelling in your hands, ankles, or feet
  • seizure (convulsions)

Call your doctor at once if you have any of these serious side effects.

Storage

Viagra should be stored at room temperature, away from heat and light. The expiration date is usually printed on the Viagra bottle, and it is typically good for one year after that date. Viagra pills may be split in half if they are not too difficult to chew, but they should not be crushed or dissolved. Doing so could result in too much of the medication being absorbed into the body at once, which could be dangerous.

If you miss a dose of Viagra, you may take it when you remember but do not take more than one dose per day.