[Medication of the month. Vardenafil (Levitra)]

Vardenafil (Levitra), recently launched in Belgium by Bayer and Glaxo-SmithKline, is a new drug that potently and selectively inhibits phosphodiesterase type 5 (PDE5) in the cavernosum tissue of the penis. Inhibition of PDE5 blocks the hydrolysis of cyclic guanosine monophosphate (GMPc) and results in increased arterial blood flow leading to enlargement of the corpus cavernosum and resulting in erection. In controlled clinical trials, vardenafil at least doubled the rate of successful erections as compared to placebo, whatever the evaluation parameter considered and the subgroup of patients studied. Vardenafil is thus indicated in the treatment of patients with erectile dysfunction. It is presented as 5, 10 and 20 mg tablets and the usual dose is 10 mg to be ingested 25 to 60 minutes before sexual activity. Vardenafil has a more potent inhibitory activity of PDE5 in vitro than sildenafil or tadalafil while its pharmacokinetics in vivo is somewhat more rapid than that of the two other compounds. The dosage of vardenafil may be reduced to 5 mg (especially in older individuals) to improve tolerance or be increased up to 20 mg (especially in the presence of organic diseases aggravating erectile dysfunction) to improve efficacy. Contra-indications (co-administration with drugs increasing nitric oxide) and side-effects (headache and flushing due to vasodilatation) of vardenafil are similar to those of other PDE5 inhibitors.