Emma Hitt, PhD

June 01, 2012

June 1, 2012 (Atlanta) — Avanafil (Stendra, Vivus) is well tolerated and effective in the treatment of erectile dysfunction (ED) in postprostatectomy patients who are diabetic, 65 years and older, and who have severe or long-term ED.

John P. Mulhall, MD, director of the male sexual and reproductive medicine program at Memorial Sloan-Kettering Cancer Center in New York City, and colleagues presented these findings in a late-breaking session here at the American Urological Association 2012 Annual Scientific Meeting.

Avanafil was approved by the US Food and Drug Administration (FDA) for the treatment of erectile dysfunction in April. According to study author Irwin Goldstein, MD, director of sexual medicine at the Alvarado Hospital in San Diego, California, its metabolism is distinctly different from that of sildenafil, tadalafil, and vardenafil, and it has a time from drug administration to peak concentration of approximately 30 minutes.

"A subgroup of men with erectile dysfunction had successful erection function improvement within 10 minutes of avanafil administration," Dr. Goldstein told Medscape Medical News.

According to the researchers, the effectiveness of avanafil has been demonstrated in an integrated analysis of randomized double-blind placebo-controlled phase 2 and 3 trials of men with mild, moderate, or severe ED, and of men who have undergone bilateral nerve-sparing radical prostatectomy.

In difficult-to-treat patients, the researchers assessed improvement in erectile function using change in successful sexual intercourse (SEP3) score and International Index of Erectile Function (IIEF) erectile function domain score.

The analysis involved men with severe or long-term ED (n = 995). Of those, 279 were at least 65 years of age, 379 had type 1 or type 2 diabetes, and 286 had undergone prostatectomy. Patients were treated with either 100 mg or 200 mg of avanafil, and results were compared with baseline.

Significant Improvements From Baseline

There were dose-related improvements in SEP3 and IIEF erectile function scores from baseline for all high-risk subgroups with the 2 doses (< .01 for both).

Although more research is needed, Dr. Goldstein said, avanafil might be the first ever "on-demand" drug for the treatment of ED. "A future focused clinical research study using a stopwatch, started at the time of drug administration, will be needed" to address whether this is the case, he added.

According to Dr. Goldstein, "the man with erectile dysfunction wishing to realize improvement in function, who does not wish to take a drug unless it is needed, would only take avanafil as the sexual event is developing," he said. "Should the sexual event be delayed, avanafil acts to improve function for several hours after administration."

Differences in Avanafil

Serap Gur, MD, from Tulane University in New Orleans, Louisiana, noted that avanafil gives men with ED more options.

"Avanafil acts more quickly than other phosphodiesterase type 5 [PDE5] inhibitors, with 72% of participants being able to have successful intercourse in less than 15 minutes after administration," he told Medscape Medical News.

"This agent also has better selectivity, which translates into fewer side effects," Dr. Gur said. "Postmarketing studies will need to confirm these phase 3 results," he added.

Potential Adverse-Effect Benefit

Gregory Lowe, MD, from the Department of Urology, Wexner Medical Center, Ohio State University, in Columbus, noted that improvements in erectile function seen with avanafil in available studies are "very promising."

"In clinical practice, I expect physicians to use avanafil for patients desiring rapidity of onset," he told Medscape Medical News. "Some physicians will likely use this medication in patients with coronary risk because of the decreased half-life, decreasing risk if a patient were to have a vascular episode," he explained.

"For patients having difficulty with visual disturbance from other agents, avanafil appears to have less risk of this side effect. Avanafil also has less risk of back pain, which is occasionally seen with tadalafil," he said. "Other side effects appear to be similar."

Dr. Lowe added that even with the more rapid onset of activity and decreased half-life, it remains to be seen if there is a significant difference for patients who have had success with other PDE5 inhibitors. "Early results suggest that avanafil will be useful in patients with any severity or etiology of erectile dysfunction, and that it has the potential for improved tolerability," he said.

The study was funded by Vivus Inc. Dr. Gur and Dr. Lowe have disclosed no relevant financial relationships.

American Urological Association (AUA) 2012 Annual Scientific Meeting: Abstract LBA8. Presented May 22, 2012.

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