Objectives: To evaluate the effect of two doses of vardenafil hydrochloride on penile rigidity and tumescence while determining the pharmacokinetics.
Methods: Twenty-one patients with erectile dysfunction completed three oral single-dose regimens (placebo, 20 and 40 mg vardenafil) in a randomized, placebo-controlled, 3-way cross-over study. Penile rigidity and tumescence were measured at the base and tip with a Rigiscan for up to 2 h after dosing. The period included three 20-min repeated episodes of visual sexual stimulation. Blood samples were taken periodically up to 24 h after dosing.
Results: After 20 and 40 mg vardenafil, the mean duration of >60% rigidity of the base of the penis was greater than after placebo by 42.9 min (95% Cl 29.3-56.4) and by 49.3 min (95% Cl 35.7-62.9), respectively (p<0.001), and greater than after placebo by 34.6 min (95% Cl 22.1-47.1) for both doses at the tip. Additionally, significantly greater rigidity activity units and tumescence activity units were found for both doses compared with placebo (p<0.001). The plasma concentrations of vardenafil increased rapidly, with a median t(max) of about 40 min and a mean t1/2 of 4.4-4.8 h. Relative bioavailability was slightly higher for the 40-mg dose than for the 20-mg dose. The treatments were well tolerated, although slightly more adverse events, primarily headache, flushing and nasal congestion, were seen with the 40-mg dose compared with placebo.
Conclusion: The findings confirm that vardenafil was able to generate stronger erections of longer duration than placebo under conditions of visual sexual stimulation in patients with erectile dysfunction. The pharmacokinetic, pharmacodynamic and tolerability profiles support vardenafil hydrochloride as a strong candidate for further testing as a treatment for erectile dysfunction.