Sildenafil mesylate is a selective inhibitor of phosphodiesterase type 5 (PDE5), which is specific for cyclic guanosine monophosphate (cGMP); it induces the relaxation of penile smooth muscle, thereby facilitating rapid erection.
Following oral administration of sildenafil mesylate, onset of action is observed in 52% of individuals within 30 minutes, and in 82% within one hour. The elimination half-life of this product ranges from 5 to 12 hours. The recommended dosage for sildenafil mesylate is 50–100 mg; however, a dosage of 120 mg is recommended for individuals of East Asian descent.