Viagra is a prescription medication developed, manufactured and marketed by Pfizer. It is indicated for the treatment of erectile dysfunction. The U.S. Food and Drug Administration approved Viagra in 1998, making it the first in a new class of drugs called phosphodiesterase inhibitors. Viagra works by increasing levels of nitric oxide in the penis that in turn relax the smooth muscle, enabling more blood inflow to cause and sustain an erection.
Erectile Dysfunction
According to the National Institute of Diabetes and Digestive and Kidney Diseases, erectile dysfunction is the repeated inability to get or sustain an erection hard enough for sexual intercourse. Men with erectile dysfunction suffer from loss of confidence and low self esteem, according to 2005 research published in "Actas Urologicas Espanolas." The NIDDKD estimates that erectile dysfunction affects between 15 and 30 million men in the United States, about 5 percent of 40-year-old men and 10 to 15 percent of 65-year-old men.
Dosage
Viagra is supplied in 25, 50 and 100 mg blue rounded-diamond-shaped tablets. The recommended dose for most people is 50 mg per day, taken one hour before sexual activity, although it may still be effective if taken 30 minutes to four hours before sex. Physicians can decrease or increase the dosage to 25 mg or 100 mg, respectively, based on the effectiveness of the drug and toleration by the patient.
Benefits
Viagra was evaluated in 21 randomized, double-blind placebo-controlled clinical trials in more than 3,000 patients ages 19 to 87 with erectile dysfunction, according to the product label. In every study, Viagra demonstrated improvements in sexual intercourse compared with placebo. Research published in "Current Medical Research and Opinion" demonstrates that Viagra improves erectile function, self esteem and sexual relationships, plus it increases sexual intercourse success rate. According to research in "Drug Safety," Viagra can be prescribed to a very large group of patients with erectile dysfunction because of its acceptable risk-benefit ratio.
Side Effects
Viagra has many side effects according to its product label. The most common side effects are headache, redness of skin on the face and body, indigestion, nasal congestion, urinary tract infection, abnormal vision such as blurriness and blue color tinge on objects, diarrhea, dizziness and rash. Sudden loss of hearing and seizures can also occur.
Warnings
According to the product label, Viagra should not be used by men with preexisting cardiovascular disease that have a potential risk for a heart attack during sexual activity. This is because the heart works harder during sexual activity. People with cardiovascular disease that have obstruction of blood, high or low blood pressure, a prior heart attack, stroke or irregular heartbeat are particularly vulnerable to a heart attack when taking Viagra and engaging in sexual activity. A 2000 study published in "Circulation" reports that sudden death can occur to patients with cardiovascular disease who take Viagra. Viagra can cause prolonged erection for four hours or longer in some people. Viagra can also cause visual disturbances, particularly among patients also taking Norvir, a drug that treats HIV infection and AIDS.
References
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health Erectile Dysfunction
- "Actas Urologicas Espanolas"; Psychological Impact of Erectile Dysfunction; Martin-Morales, A.; May 2005
- "Current Medical Research and Opinion"; Correlation of Improved Erectile Function; Steidle, C.P.; May 2006
- "Drug Safety"; A Risk-Benefit Assessment of Sildenafil in the Treatment of Erectile Dysfunction; Vitezic, D.; 2001
- "Circulation"; Sildenafil (Viagra) Prolongs Cardiac Repolarization; Geelen, P.; Jul 18 2000
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