Oral ED agent has rapid onset of action, study shows
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 u response to vardenafil.
,p> Each participant was instructed to initiate sexual activity immediately after taking the medication and was issued a stopwatch to time the interval between dosing and attainment of erection perceived to be adequate for penetration with subsequent intercourse completion—recorded as a positive response to question 3 in the Sexual Encounter Profile (SEP3).
The study results, based on an intentionto-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 10minutes(2l% vs. l4%, 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<.O25) 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 Randal! B. Meacham, MD, associate professor of urology. University of Colorado Health Sciences Center, Denver.
“However, it is also known that some men respond more rapidly, and this study was specifically designed to identify how early the onset of action of vardenafil might be.”
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. Mea- cham said. “However, as they fmd 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
ONTIME was conducted in 80 centers across eight countries in Europe and North America. The study began witb a 4-week unmedicated run-in period, followed by a 4-week double-blind phase during which men took their assigned treatment on demand. The time to earliest response used in the analyses represented the best time achieved with the first four doses.
Other analyses showed that about half of men taking vardenafil achieved erections adequate for penetration leading to successful intercourse within 25 minutes after ingestion (50% of men taking vardenafil, 10 mg, and 53% of men taking vardenafil, 20 mg). The responder rate after 25 minutes in the placebo group was 26% and was significantly different compared with the vardenafil rates (p<.O001).
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.
The ONTIME study was sponsored by Bayer and GlaxoSmithKline. Dr. Meacham is a speakers bureau member for GlaxoSmithKline and other companies that market products for the treatment of erectile dysfunction.