The high selectivity of the alpha-blocker silodosin (Rapaflo) may be the reason for its success in treating CP/CPPS in a recent trial.
Still, it shouldn't be used as a monotherapy, emphasized J. Curtis Nickel, MD, who presented the silodosin multicenter trial results at the AUA annual meeting in Washington as well as results of the earlier alpha-blocker trials at previous meetings. This trial showed statistically significant improvements in quality of life and urinary symptoms but not in pain.
The dose-ranging trial included 153 men with CPPS who had NIH Chronic Prostatitis Symptom Index (CPSI) scores of at least 15 and pain scores of at least 8 at 32 North American centers. There was "an emphasis on trying to get patients with a urinary phenotype involved in this particular study," explained Dr. Nickel, professor of urology at Queen's University, Kingston, Ontario.
CPSI total scores, quality of life impact, and urinary component scores improved significantly compared with placebo-both statistically and clinically-for the men receiving silodosin, 4 mg/day, but not for those taking the 8-mg/day dosage.
The mean improvement was also significant compared with placebo for the 4-mg/day group on the physical component score in the Medical Outcomes Study Short Form 12 questionnaire.
"This is the first time I've ever seen the SF12 QoL difference between a treatment and a placebo or sham therapy [in CP/CPPS trials]," said Dr. Nickel.
In the 4-mg/day group, significantly more (55.8%) of the men considered their condition to be moderately or markedly improved on the 7-point global response assessment, compared with only 33.3% of the 8-mg/day group and 29.4% of the placebo group.
"I noticed there wasn't a dose response here," remarked session moderator John Krieger, MD, professor of urology at the University of Washington, Seattle. "Why do you suppose there wasn't?"
Dr. Nickel explained that, although 8 mg/day is superior in treating BPH-related lower urinary tract symptoms, LUTS associated with CP/CPPS likely has a different pathophysiology. The younger patient population in this CP/CPPS trial might also experience different efficacy and less tolerance for higher doses than that experienced by the typically older BPH patient.