[Drug of the month. Sildenafil (Viagra)].

Sildenafil (Viagra) from Pfizer (UK-92,480) is a competitive and selective inhibitor of cyclic GMP specific type 5 phosphodiesterase. Male erectile dysfunction is defined as "the inability to attain and/or maintain penile erection sufficient for satisfactory sexual performance". Sildenafil (Viagra) is effective in a significant proportion of patients with erectile dysfunction. Patients should be instructed to take a dose from 25 to 100 mgrs approximately 30 to 60 minutes before sexual activity, but no more than once daily. Sexual stimulation is necessary to produce erectile reaction. The safety and tolerance of sildenafil have been demonstrated. However, prior to initiating treatment with sildenafil, physicians should consider the cardiovascular status of their patients, particularly for patients with unstable coronary heart disease or concomitant treatment with nitrates.