FDA Approval

FDA Approval :
On 27 th March, 1998 , The Food and Drug Administration (FDA) approved Viagra® ( sildenafil citrate ) , an oral medication to treat erectile dysfunction (ED, or impotence) in men.

Viagra is the first oral pill to treat impotence, a dysfunction that affects millions of men.

Manufacturer:
Viagra is manufactured by Pfizer Pharmaceuticals, New York , NY .

Mode of Action :
Viagra acts by relaxing muscles in the penis and blood vessels, allowing increased blood flow into the penis, which produces an erection.

Clinical Trials:
Viagra was evaluated in numerous randomized, placebo controlled trials involving more than 3000 men with varying degrees of impotence associated with diabetes, spinal cord injury, history of prostate surgery, and no identifiable organic cause of impotence. Patients also had a wide range of other concomitant illnesses including hypertension and coronary artery disease.

The drug's effectiveness was assessed primarily using a sexual function questionnaire. Patients were asked to report at the beginning, and periodically throughout the studies, how often they were able to achieve an erection adequate for intercourse, and how often that erection was maintained after penetration. In addition, patients kept diaries of their sexual histories. In all trials, men on Viagra reported success more often than did men on placebo, and rates of success increased with dose. The findings were consistent in men representing a wide range of severity and etiology of their erectile dysfunction (impotence). Men with diabetes or radical prostate surgery had somewhat less improvement than did other groups.

Recommended Dose :

• Viagra should not be used more than once per day.
• The recommended starting dose for most patients is 50 mg taken one hour prior to anticipated sexual activity.
• A higher dose of 100 mg is prescribed for patients whose response to the 50 mg dose is not adequate.
• A lower dose (25 mg) recommended for patients taking other medicines or having medical conditions that may decrease the body's ability to metabolize sildenafil citrate .

Precautions:

It should not be taken with

• Nitrates (such as nitroglycerin tablets or patches)
• Alpha blockers: alpha blockers are medicines used to treat benign prostatic hyperplasia and high blood pressure because the combination may significantly lower blood pressure and lead to fainting or even death in some men.
• If you are taking a protease inhibitor, your dose may be adjusted by your doctor.
• It should not be used with any other medical treatments that cause erections.
• Viagra should not be taken by men in whom sexual activity is inadvisable because of their underlying cardiovascular status (heart condition).
• Viagra is not recommended in patients who have suffered a heart attack or stroke within the last six months, or patients who have significantly low blood pressure, uncontrolled high blood pressure, unstable angina, severe liver impairment, or retinitis pigmentosa (an eye disorder).

Side Effects :
The most common side effects of Viagra are headache, flushing of the face, and upset stomach. Less common side effects that may occur are temporary changes in color vision (such as trouble telling the difference between blue and green objects or having a blue color tinge to them), eyes being more sensitive to light, or blurred vision.

In rare instances, men have reported an erection that lasts many hours. You should call a doctor immediately if you ever have an erection that lasts more than 4 hours. If you develop any other side effects, call your doctor immediately

Viagra does not protect from AIDS or other sexually transmitted diseases.