Sildenafil, commonly known as Viagra, is used to treat erectile dysfunction in men. Viagra is a drug classified as a phosphodiesterase-5 enzyme inhibitor. The medication causes relaxation of the muscles in the penis and allows the inflow of blood to produce an erection.
Dosing
Viagra is available in tablet form in doses of 25mg, 50mg and 100mg. The dose may need to be reduced in patients over 65 and in those with liver or kidney impairment, according to the "Drug Information Handbook."
Administration
The patient should take Viagra about one hour before sexual activity. It should be taken on an empty stomach, at least two hours before meals for the quickest response. "Pharmacotherapy: A Pathophysiologic Approach" explains that Viagra does not cause an erection; patients must engage in sexual stimulation.
Side Effects
The most common side effects of Viagra are headache, abdominal pain, flushing, dizziness and diarrhea. Increased sensitivity to light, blurred vision and loss of blue-green color discrimination may also occur but reverse when the medication is stopped, reports "Pharmacotherapy."
Warnings
Viagra may cause a decrease in blood pressure and should be used with caution in patients with low blood pressure, fluid depletion and heart valve obstruction or in patients on other antihypertensive drugs. Viagra should not be used in combination with other medications that treat erectile dysfunction, explains Viagra.com.
References
- "Drug Information Handbook"; Charles F. Lacy, Lora L. Armstrong, et al.; 2009
- "Pharmacotherapy: A Pathophysiologic Approach"; Joseph T. Dipiro, Robert L. Talbert, et al.; 2008
- Viagra: Safety of Viagra Including Viagra Side Effects
