General Information

Levitra (vardenafil), a phosphodiesterase 5 (PDE5) inhibitor, is an oral medication for the treatment of erectile dysfunction (ED). It helps increase blood flow to the penis and may help men with ED get and keep an erection satisfactory for sexual activity. PDE5 inhibitors are a widely accepted and efficacious therapeutic option for the treatment of erectile dysfunction in men, as a result of extensive clinical experience with sildenafil and others.

It is available in 2.5 mg, 5 mg, 10 mg, and 20 mg tablets no more than once a day.

Clinical Results

FDA approval of Levitra was based on four multi-center, double-blind, randomized, placebo controlled, fixed-dose, parallel design trials. The studies enrolled a total of 2431 men with an average age of 57 years. The doses investigated were 5 mg, 10 mg, and 20 mg. An efficacy assessment was based on the Erectile Function (EF) Domain score of the validated International Index of Erectile Function (IIEF) Questionnaire and two questions from the Sexual Encounter Profile (SEP) corresponding to vaginal penetration achievement (SEP2), and the ability to maintain an erection for intercourse (SEP3).

Results demonstrated clinically meaningful and statistically significant improvements in the EF Domain, SEP2, and SEP3 scores compared to placebo. The mean baseline EF Domain score in these trials was 11.8.

In a major North American fixed dose trial, 762 subjects were evaluated. The mean baseline EF Domain scores were 13, 13, 13, 14 for the Levitra 5 mg, 10 mg, 20 mg and placebo groups, respectively. There was significant improvement at three months with Levitra (EF Domain scores of 18, 21, 21, for the 5 mg, 10 mg and 20 mg dose groups, respectively) compared to the placebo group (EF Domain score of 15). The European trial of 803 subjects confirmed these results. In the North American trial, Levitra significantly improved the rates of achieving an erection sufficient for penetration (SEP2) at doses of 5 mg, 10 mg, and 20 mg compared to placebo (65%, 75%, and 80%, respectively, compared to a 52% response in the placebo at 3 months. The European trial confirmed these results.

Mechanism of Action

Levitra is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5).

Erection of the penis is initiated by the relaxation of smooth muscle in the corpus cavernosum, one of a pair of sponge-like regions in the penis. When aroused, nitric oxide is released from nerve endings and endothelial cells in the corpus cavernosum. Nitric oxide activates the enzyme guanylate cyclase resulting in increased synthesis of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum. The cGMP triggers smooth muscle relaxation, increasing blood flow into the penis, resulting in erection.

Literature References

Brock G, Nehra A, Lipshultz LI, Karlin GS et al.Safety and efficacy of vardenafil for the treatment of men with erectile dysfunction after radical retropubic prostatectomy. J Urol. 2003 Oct; 170 (4 Pt 1): 1278-83.

Porst H, Young JM, Schmidt AC, Buvat J.Efficacy and tolerability of vardenafil for treatment of erectile dysfunction in patient subgroups. Urology. 2003 Sep;62(3):519-23; discussion 523-4.

Kuthe A.Phosphodiesterase 5 inhibitors in male sexual dysfunction. Curr Opin Urol. 2003 Sep;13(5):405-10.

Junemann KP.How effective are PDE-5 inhibitors? Urologe A. 2003 Apr; 42(4): 553-8. Epub 2003 Mar 25.