Vardenafil.

Abstract

Vardenafil selectively inhibits phosphodiesterase type 5 (PDE5), an enzyme which hydrolyses cyclic guanosine monophosphate in the cavernosum tissue of the penis. Inhibition of PDE5 results in increased arterial blood flow leading to enlargement of the corpus cavernosum. Because of the increased tumescence, veins are compressed between the corpus cavernosum and the tunica albuginea, resulting in an erection. Vardenafil has a high bioavailabilty and is rapidly absorbed. An erection of >60% rigidity was maintained for approximately twice as long following visual stimulation in patients treated with vardenafil 10 or 20mg than in recipients of placebo. In a large, placebo-controlled trial in patients with mild to severe erectile dysfunction (ED), vardenafil 5, 10 or 20mg taken as needed over a 12-week period significantly improved the scores in questions 3 and 4 of the International Index of Erectile Function (IIEF). The rate of successful attempts at intercourse with ejaculation was also significantly higher with vardenafil (71 to 75%) than in the placebo group (39.5%), and significantly more patients treated with vardenafil than placebo responded 'yes' to a Global Assessment Question (GAQ) asking if treatment had improved erections. In a 26-week trial in 736 men with ED of varied aetiologies and severity patients receiving vardenafil 5, 10 or 20mg experienced significantly improved erections with 85% of vardenafil 20mg recipients reporting improved erectile function (assessed using the GAQ) compared with 28% of placebo recipients. Treatment with vardenafil also significantly improved scores in response to questions 3 and 4 of the IIEF compared with placebo. A 12-week trial in 452 men with ED associated with diabetes mellitus demonstrated that treatment with vardenafil 20mg compared with placebo significantly improved IIEF erectile function domain scores and the rate of positive responders to the erectile improvement GAQ. Similar results were reported in a placebo-controlled trial of vardenafil 10 to 20mg involving 440 patients with ED after radical prostatectomy. Adverse events associated with vardenafil were those commonly associated with PDE5 inhibitors: headache, flushing, dyspepsia and rhinitis. These were mostly dose-dependent and mild to moderate in intensity.