Half of sildenafil users stay on prescription 5 years post-radical prostatectomy

San Antonio-Five years after radical prostatectomy, fewer than half of the men with erectile dysfunction who responded initially to sildenafil citrate (Viagra) continued to respond to the drug, which works best in patients who have had bilateral nerve-sparing surgery, according to a report presented at the AUA annual meeting here.

Among patients who initially responded to sildenafil after prostatectomy, 45.6% continued to respond at 5 years. The remaining 54.4% of patients discontinued therapy, switched to another ED therapy, or used sildenafil in combination therapy.

"About 30% of patients who discontinued therapy did so because of comorbidities, primarily cardiovascular conditions," said Rupesh Raina, MD, currently a resident at MetroHealth Medical Center in Cleveland. "Another 30% discontinued because of loss of interest in sex. Other reasons were loss of partner, side effects, and loss of libido due to hormonal therapy."

"The patient is sexually active, and return of potency is important," said Dr. Raina, formerly a research fellow at The Cleveland Clinic working with Craig Zippe, MD. "In the era of sexual longevity, we are looking at 10 to 15 years of quality of life."

Pursuing other options

Today, patients have more options than ever for maintaining sexual longevity, he said. They can choose from three different oral medications, combination therapy, intraurethral alprostadil (MUSE), intracavernosal injection, vacuum constriction device, and penile prosthesis.

The vacuum constriction device has initial efficacy of 55% to 79% and is associated with a discontinuation rate of 40% to 45% at 1 year (J Urol 1993; 149:290-94; Curr Urol Rep 2001; 2:495-03). Intracavernosal injection has a success rate of 75% to 85% and a dropout rate of 31% to 40% at 1 to 3 years (J Urol 1996; 155:639; J Urol 1999; 162:1291-94). Intraurethral alprostadil has an initial success rate of 32% to 40% and is associated with a dropout rate of 57% to 74% at 2 years (J Urol 1998; 160:1325-28; Curr Urol Rep 2001; 2:495-03).

An initial study from the Cleveland group showed that 12 of 15 patients who had bilateral nerve-sparing prostatectomies responded to sildenafil treatment, compared with none of 13 patients who had either unilateral nerve-sparing procedures or non-nerve-sparing procedures (Urology 1998; 52:963-66). A subsequent study showed that 31 of 43 (71%) initial responders to sildenafil maintained their response at 3 years of follow-up (Urology 2003; 62:110-5).

Dr. Raina reported findings from a study involving 68 patients who underwent radical prostatectomy during 1998-99 and who were initial responders to sildenafil after surgery. Sildenafil therapy was started at a dose of 50 mg and increased to 100 mg as needed. Each patient was surveyed 1 and 5 years after surgery to determine response and efficacy, compliance with therapy, and side effects. Data were collected by means of the International Index of Erectile Function (IIEF) or the Sexual Health Inventory for Men (SHIM), an abridged version of the IIEF.

Five years after surgery, 31 of the 68 men (45.6%) were still responding to sildenafil. Of the remaining 37 patients, six switched to another therapy because of suboptimal response, 12 had suboptimal responses and used sildenafil in combination therapy, and 17 discontinued sildenafil because of comorbid conditions (30%), loss of interest in sex (30%), change in personal circumstances (23%), side effects (11%), and loss of libido (6%).

Among sildenafil responders, the average cumulative SHIM score (based on answers to five questions rated on a scale of 0 to 5) was 20.1 prior to surgery and 6.7 after surgery. The mean SHIM score among responders increased to 19 at 1 year and was 18 at 5 years.

The most common side effects associated with sildenafil were headache (9%), flushing (4.7%), and blurred vision (4.7%).