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Results of a randomized, double-blind, placebo-controlled, phase IV study provide further confirmation that the erectogenic effect of the phosphodiesterase-type-5 inhibitor avanafil (Stendra) has a quick onset.
New Orleans-Results of a randomized, double-blind, placebo-controlled, phase IV study provide further confirmation that the erectogenic effect of the phosphodiesterase-type-5 inhibitor avanafil (Stendra) has a quick onset.
The multicenter study, which was reported at the 2014 AUA annual meeting in Orlando, FL, enrolled 440 men with erectile dysfunction assigned 1:1:1 to treatment with avanafil, 100 mg; avanafil, 200 mg; or placebo. Men were given a stopwatch to record the time between ingestion of study medication and attainment of an erection sufficient for vaginal penetration. The primary endpoint of the study assessed the per-patient proportion of sexual attempts during the 8-week treatment period that resulted in both achievement of an erection enabling vaginal penetration within ~15 minutes of dosing and satisfactory completion of sexual intercourse (Sexual Encounter Profile Question 3 [SEP3]).
The results showed significantly higher rates of successful sexual attempts within ~15 minutes among men using avanafil, 100 or 200 mg, compared to placebo (28.2% and 24.7% vs. 13.8%).
Determination of the earliest onset of erectogenic effect was done using a step-down technique that compared the treatment groups for proportions of men achieving the primary outcome criteria were assessed at 20 minutes and then at each earlier minute (19, 18, etc.) until there was no longer a statistically significant treatment effect. In this analysis, the 100- and 200-mg doses of avanafil were differentiated from placebo at 12 and 10 minutes, respectively.
“Avanafil is a rapidly absorbed, highly specific PDE-5 inhibitor. Its time to maximum blood plasma concentration is 30 to 45 minutes, and in this study we demonstrated the doses of avanafil approved for the treatment of ED had a significant erectogenic effect as early as 10 or 12 minutes post-dosing. These data indicate avanafil is well suited for on-demand treatment of ED,” said co-author Ronny B. Tan, MD, clinical fellow in the section of andrology at Tulane University School of Medicine, New Orleans.
Speaking to Urology Times, lead author Wayne J.G. Hellstrom, MD, noted that the rapid onset of avanafil’s erectogenic effect was observed previously in a phase II study that used RigiScan monitoring to measure penile rigidity while men viewed visual sexual stimulation videos. In that study, the men did not start to watch the videos until 20 minutes post-dosing.
“The phase II study results supported use of avanafil in the setting of on-demand treatment, but the data from the phase IV study quantifies the onset of effect and shows that many men can expect an erectogenic effect within 15 minutes after taking the medication,” said Dr. Hellstrom, professor of urology at Tulane.
Patients were eligible for the study if they had at least four documented attempts at sexual intercourse during a 4-week, non-treatment run-in period with a 50% or greater failure rate in maintaining an erection sufficient for intercourse. An International Index of Erectile Function-Erectile Function (IIEF-EF) domain score between 5 and 25 was also required.
The three study groups were well matched. The study participants had a mean age of about 58 years with long-standing ED that was rated as moderate or severe in about three-fourths of men. The majority of men had also tried other PDE-5 inhibitors.
Other efficacy endpoints analyzed were percentage of men achieving SEP3 irrespective of time, percentage achieving SEP2, and change in IIEF-EF. The outcomes for all of those parameters were consistent with those reported in the premarketing pivotal trials and were consistently statistically significant favoring both doses of avanafil over placebo.
The safety profile of avanafil was also similar to that observed in earlier studies. As expected with any PDE-5 inhibitor, headache and nasal congestion were the most commonly reported adverse events, but they occurred at a rate >2% only in men using avanafil, 200 mg.
Dr. Hellstrom is an investigator, speaker, and advisory board member for Auxilium Pharmaceuticals. One of Dr. Hellstrom’s co-authors is an investigator for Auxilium and VIVUS, and several of his co-authors are investigators or employees of VIVUS.
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