Tamsulosin plus mirabegron proven safe, effective in men with overactive bladder

Mirabegron add-on therapy is both safe and effective in the treatment of men with overactive bladder symptoms receiving tamsulosin for benign prostatic hyperplasia, according to the results of a randomized, phase IV study.

The investigators conducted a 4-week tamsulosin 0.4 mg run-in period followed by a 12-week randomized, double-blind, treatment period where patients initially received mirabegron 25 mg or placebo add-on therapy. Doses were titrated to 50 mg mirabegron or placebo equivalent at 4 weeks. A total of 676 men were included, of which 380 (56.2 percent) were aged ≥65 years.

The primary efficacy endpoints were changes from baseline to end of treatment in mean number of micturitions per day, while secondary ones included mean volume voided per micturition, number of urgency episodes per day, total urgency and frequency score, and total International Prostate Symptom Score. Safety assessments included treatment-emergent adverse events (TEAEs), postvoid residual volume and maximum urinary flow measurements.

Tamsulosin plus mirabegron showed superiority to tamsulosin plus placebo in reducing the mean number of micturitions per day (–2.00 vs –1.62; adjusted difference, –0.39, 95 percent confidence interval, –0.76 to –0.02). Tamsulosin plus mirabegron was also statistically superior in mean volume voided per micturition, urgency episodes per day, and total urgency and frequency score, but not in the International Prostate Symptom Score.

Tamsulosin plus placebo had higher TEAEs overall, but tamsulosin plus mirabegron had higher rates of drug-related TEAEs. The latter also led to higher urinary retention rates. On the other hand, postvoid residual volume and maximum urinary flow results were not clinically meaningful.