Sildenafil is often a strong and selective inhibitor of cGMP certain phosphodiesterase form 5 (PDE5) in the corpus cavernosum, exactly where PDE5 is to blame for degradation of cGMP. Sildenafil provides a peripheral site of action on erections. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum but potently boosts the rela