Buenos Aires, Argentina—The onset of action may be very rapid within 10 minutes in some men who take vardenafil (Levitra) to treat erectile dysfunction, according to the results of a multinational study.
Designed to identify the earliest time to onset of action leading to successful sexual intercourse after vardenafil dosing, the "Onset of vardenafil in men with erectile dysfunction" (ONTIME) trial—overseen by Luc Valiquette, MD, professor of urology at the Hospital Saint-Luc du CHUM in Montreal—randomized 732 patients to treatment with vardenafil, 10 mg; vardenafil, 20 mg; or placebo. The study participants had a baseline International Index of Erectile Function score of 13.4 (moderate severity), and all had demonstrated a response to vardenafil.
The study results, based on an intention-to-treat population of 708 men, showed the SEP3 responder rate was significantly higher among men taking vardenafil, 10 mg, than among placebo recipients beginning at 10 minutes (21% vs. 14%, p<.025), and this difference was maintained at all later time points tested for statistical significance (15, 20, 25, and 30 minutes).
In men taking vardenafil, 20 mg, SEP3 responder rates were statistically higher than those of placebo at 11 minutes (23% vs. 15%, p<.025) and at all time points beyond, according to the researchers, whose data were presented at the International Society for Sexual and Impotence Research world congress and published in the Journal of Sexual Medicine (2004; 1:168-78).
"In the clinical trials leading to vardenafil approval, men were instructed to initiate sexual activity about 1 hour after taking their study medication. That protocol represented a best-case scenario, taking into account pharmacokinetic studies showing that the peak serum concentration of vardenafil is achieved after 50 to 60 minutes," said Randall B. Meacham, MD, associate professor of urology, University of Colorado Health Sciences Center, Denver.
Dr. Meacham noted that the findings of this study provide important information for counseling patients who are being prescribed the drug.
"I tell my patients that, for the most reliable results when first starting the medication, they should wait 50 to 60 minutes before attempting intercourse," Dr. Meacham said. "However, as they find they are responding to the treatment, they can identify whether they fit into a group of earlier responders and then adjust the time of administration depending on their personal experience."
75% complete intercourse
Between 15 and 30 minutes after dosing, 75% to 77% of all attempts with an erection sufficient for penetration led to intercourse completion among men who took vardenafil, either dosage, compared with only 45% to 47% of all attempts for the men in the control group.