For select patients with benign prostatic hyperplasia (BPH), a combination of the alpha blocker tamsulosin and the antimuscarinic darifenacin improves urinary frequency and incontinence better than tamsulosin alone, a new study suggests. The combination appears relatively safe, although larger trials are needed.
For the study, investigators led by Iqbal Singh, MD, a professor at the University of Delhi in India, randomly assigned 60 symptomatic BPH patients to receive tamsulosin (0.4 mg) and darifenacin (7.5 mg) or the same dose of tamsulosin and a placebo for 8 weeks of treatment. The men had been experiencing 1 or more symptoms of overactive bladder (OAB) daily, such as frequent urination (9 or more episodes), nocturia (3 or more episodes), and urgency (at least 2 episodes). Patients with obstructed BPH, large post-void residual urine volume (PVR), kidney failure, vesical stones, and untreated urinary tract infections were excluded.
Over 8 weeks, symptoms improved more in the combination therapy group than the tamsulosin monotherapy group, based on patients’ voiding diaries and ultrasound reports. The combination therapy group experienced significantly greater reductions in frequency (−4.83 vs. −3.93), incontinence (−1.50 vs. −1.08), nocturia (−2.20 vs. −1.87), and International Prostate Symptom Score (−7.90 vs. −6.27), according to results published online in the Journal of Clinical and Diagnostic Research. The investigators suggested that, in part, darifenacin may increase bladder capacity.
The combination treatment appeared relatively safe and well tolerated. The change in PVR was “marginal,” according to the researchers. Urinary retention occurred in 13% of patients in the combination arm compared with 3% of those on tamsulosin alone. “We assume that in these patients detrusor muscle fibers might be over distended/less responsive to neural mechanisms, therefore these patient may be less responsive to drugs and may have develop[ed] urinary retention,” they reasoned. Catheterization improved urinary retention in these patients.
Larger, adequately powered studies with longer treatment periods are warranted to further establish the efficacy of tamsulosin plus darifenacin and the risk of urinary retention.