Newer alpha-blocker efficacious against BPH symptoms

September 1, 2010

A newer selective alpha-1 blocker provided statistically significant reductions in BPH symptom scores compared with placebo and was well tolerated in a study from several European institutions.

Key Points

Silodosin (Rapaflo) received FDA approval in 2008 for symptoms of BPH following clinical trials that showed a rapid increase in urine flow and relief of BPH symptoms, as well as a low incidence of adverse events.

"Silodosin has undergone an extensive drug development program, with a number of trials being carried out in North America and Europe," said first author Christopher Chapple, MD, professor of urology and consultant urologic surgeon at the Royal Hallamshire Hospital, University of Sheffield, England.

Patients taking silodosin experienced a 7-point reduction in IPSS from baseline compared with a reduction of 6.7 points for tamsulosin and 4.7 points for placebo. These findings indicate that silodosin is statistically significantly superior to placebo and offers a "slightly greater efficacy" than tamsulosin that did not reach statistical significance, Dr. Chapple and colleagues wrote.

"Silodosin is a highly selective alpha-1A antagonist and is at least as effective, based on the clinical data, as the other alpha-blockers that are currently marketed for the treatment of symptomatic bladder outlet obstruction due to benign prostatic hyperplasia," Dr. Chapple told Urology Times.

A selective alpha-blocker, silodosin acts specifically to relax muscles in the prostate and bladder neck and has little effect on blood pressure, he noted. In the study, discontinuation rates due to adverse events were similar in all three groups.

CV side effects 'unlikely'

"Because of its high pharmacological selectivity, silodosin is likely to have the additional potential benefit of being unlikely to produce cardiovascular side effects or interact with agents which are active on the cardiovascular system," Dr. Chapple said.

Dr. Chapple is a consultant and researcher for Recordati, Astellas, and Pfizer.