Long-term Nightly Sildenafil Promotes Normal Erectile Function

Paula Moyer, MA

May 12, 2004

May 12, 2004 (San Francisco) -- Use of sildenafil (Viagra) every night, rather than on an as-needed basis, may do more to restore erectile function by promoting more nocturnal erections, according to findings presented here at the 99th annual meeting of the American Urological Association.

"Nightly sildenafil may help promote erectile function as the result of its beneficial effect on endothelial cells," Frank Sommer, MD, said in a press briefing. "Nocturnal erections promote adequate oxygenation of the penis and reduce collagen levels, and nightly sildenafil facilitates nocturnal erections." Dr. Sommer is the chief of andrology in the department of urology at the University of Cologne in Germany. The current research is part of a larger German study project, the Men's Health Study Group.

Dr. Sommer and colleagues enrolled 76 patients who had experienced erectile dysfunction (ED) for at least six months in a prospective, randomized controlled trial to determine whether sildenafil taken every night affected erectile function after one year. These patients were assigned to two groups. Group 1 took 50 mg of sildenafil nightly at bedtime. Group 2 took 50 to 100 mg of sildenafil on demand. The investigators also followed a third group that consisted of patients with ED who chose not to receive any medical therapy. The patients were an average of 47.1 years old.

The two treatment groups received sildenafil for 12 months; the treatment phase was followed by two wash-out phases with no treatment, consisting of one month and then an additional six months for treatment responders. The investigators measured response with the International Index of Erectile Function (IIEF) questionnaire and peak systolic velocity (PSV) of penile arteries after 12 and 13 months of treatment.

The investigators defined patients with an IIEF domain score of more than 26 as having normal erectile function. After the one-month wash-out phase, 58.8% of group 1 and 9.7% of group 2 had an IIEF domain score exceeding 26. The PSV of the cavernous arteries improved in group 1 from 29.4 ± 9.8 cm/sec to 38.9 ± 10.3 cm/sec ( P < .05). In group 2, the investigators documented a small, statistically insignificant improvement in PSV, averaging 3.0 cm/sec. In group 3, the PSV declined slightly.

Of the 34 patients in group 1, 20 had an IIEF domain score exceeding 26. These 20 patients with normal erectile function were followed for an additional six months while not receiving any medication. Of these 20 patients, all but one (95%) still had normal erectile function at the end of the final wash-out period.

"This is the only study we know of that has investigated the long-term effects of taking [erectogenic therapy] on a daily basis," Dr. Sommer told presenters. "After only one year, sildenafil taken regularly at bedtime may be able to bring about regression of ED, or may be a useful tool for curing ED."

"We know that sildenafil protects the endothelium, which is the primary regulator of blood flow in many organs, particularly organs like the penis," John P. Mulhall, MD, told Medscape in an interview seeking independent comment. "However, change in blood flow as an end point may pose difficulties, because you can have considerable intra-individual variation." Dr. Mulhall is an associate professor of urology at Weill Medical College of Cornell in New York, where he is also director of sexual medicine in the departments of urology at both Weill and at Memorial Sloan-Kettering Cancer Center.

"Also, we don't know how frequently the on-demand group used sildenafil," he said. "Did they use it once a week, three times a week, or once a month? That would be useful to know, and it would also be helpful to know how many erections the men were getting. A study like this would be helped not only by a sildenafil diary, but also by an erection diary, including nocturnal erections."

The concept of nightly sildenafil deserves thought, Dr. Mulhall said, noting that some urologists are advising nightly sildenafil as a way to restore erectile function. "We need a large, well-done study to define the use of medications to preserve or improve erectile function," he said. "We should also be profiling responders [to erectogenic treatment]. We should start identifying who they are, how long they've had ED, and what other comorbidities they have." Such information will help physicians know who will respond to treatment and therefore when to prescribe erectogenic therapy, he said.

AUA 99th Annual Meeting: Abstract 903. Presented May 10, 2004.

Reviewed by Gary D. Vogin, MD

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