Viagra (Sildenafil citrate) is an orally active selective inhibitor of cyclic guanosine
monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5) which is used for the treatment
of erectile dysfunction (ED). Objectives:
- To test the efficacy of Viagra 100mg on demand vs. Viagra 100mg daily (taken either at
bedtime or 1 hour prior to sexual intercourse) in restoring erectile function following
- To test the safety and tolerability of Viagra 100 mg on demand vs. Viagra 100 mg daily
after radical prostatectomy.