Viagra treatment
Viagra is the first oral medication designed specifically to treat impotence. Known generically as sildenafil citrate, Viagra works by blocking an enzyme (PDE5), found in the penis, that breaks down a chemical (cyclic GMP), which is produced during sexual stimulation. The longer GMP remains available, the greater the chance of achieving and maintaining an erection. Unlike other drugs commonly used to treat impotence, which are addressed later in this chapter, Viagra does not cause an erection unless the man is sexually stimulated.
Viagra was tested on several thousand men with mild, moderate, or complete erectile dysfunction. These men had a broad range of conditions associated with ED, including high blood pressure, high cholesterol, diabetes, and prostate surgery. Viagra was effective in 50% to 80% of the men who participated in 21 clinical trials. Men with diabetes and those with a history of radical prostate surgery showed less improvement than other groups. No evidence suggests that Viagra enhances the sexual performance of healthy men.