TORONTO—Use of an oral phosphodiesterase type-5 inhibitor (PDE5i) significantly reduces urinary incontinence after radical prostatectomy (RP), according to data presented at the joint annual meeting of the International Continence Society and the International Urogynecological Association.

In a study, 58 patients who took a PDE5i had an earlier and larger improvement in pad-free rates at 36 months after surgery compared with the 45 patients who did not take a PDE5i (95% vs. 72%).

“We think PDE5i can improve urinary continence after radical prostatectomy, and that early administration of the agent may be recommended,” lead investigator Yasuhiro Kaiho, MD, PhD, told meeting attendees.

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Previous reports suggest that use of a PDE5i can be effective for treating erectile dysfunction (ED) following RP. The effect of a PDE5i on post-surgical urinary incontinence “has not been well-elucidated,” Dr. Kaiho observed.

Therefore, Dr. Kaiho, of the Department of Urology, Tohoku University School of Medicine, Sendai, Japan, and five colleagues reviewed data from 103 patients who underwent bilateral, nerve-sparing RP between June 2003 and July 2008. A PDE5i had been prescribed to patients requesting pharmacotherapy for post-surgical ED. They were instructed to take it once a week. Although optimal efficacy may be achieved with once daily dosing, the Japanese government’s health insurance does not cover PDE5i’s, Dr. Kaiho noted.

The average time between RP and start of the PDE5i was 91 days (range 1-1,063 days). Patients’ urinary continence had been estimated until March 2006 using the pad-free rate obtained based on a ‘no pads’ response to item 14 of the University of California Los Angeles Prostate Cancer Index and subsequently to item 5 of Extended Prostate Cancer Index Composite questionnaire, which asks how many pads per day the patients need to use. The questionnaire was administered preoperatively and then one, three, six, 12, 18, 24 and 36 months later. Data were collected from 94 of the 103 patients. The average follow-up time was 39.4 months.

The pad-free rates among patients both taking and not taking a PDE5i declined until about one month post-operatively and then gradually improved.

Commenting on Dr. Kaiho’s presentation, Craig Comiter, MD, Associate Professor of Urology at the Stanford University Medical Center, Palo Alto, Calif., said the study results are compelling.

Speculating about the mechanism of action of PDE5i in reducing urinary incontinence, he explained: “It’s probably relaxing the bladder detrusor muscle rather than increasing the blood flow and decreasing scar formation at the anastomosis of the bladder and the urethra.”