Add-on effects of tadalafil in tamsulosin-treated patients with small benign prostatic enlargement: A randomized, placebo-controlled, double-blind, crossover study

Aim To assess the add-on effects of tadalafil in patients with a relatively small benign prostatic enlargement (BPE) treated with tamsulosin. Methods From September 2014 to July 2018, we prospectively studied patients (aged 50 years or more) attending our hospital who had received tamsulosin for small BPE (20-40 mL) for 4 weeks at least and still had residual lower urinary tract symptoms (LUTS) with total International Prostate Symptom Scores (IPSS) of at least 8 and IPSS-quality of life scores at least 3. We randomized eligible patients into two groups: one of which received tadalafil 5 mg once daily for 6 weeks, followed by placebo for 6 weeks, and the other of which received placebo followed by tadalafil in the same manner. The patients were reviewed at our outpatient clinic after 2, 6, 8, and 12 weeks. Results There were 13 patients in the tadalafil-placebo and 13 in the placebo-tadalafil group. Their median ages (range) were 70 (65-85) and 73 (50-80) years, prostatic volumes (median) 30.0 (22.0-39.7) and 32.0 (20.1-39.5) mL, and total IPSS (median) 17 (10-27) and 16 (10-24), respectively. The primary endpoints, namely mean changes of total IPSS from baseline, were 1.85 on placebo and -3.42 on tadalafil; this difference is statistically significant (difference: -1.57; 95% confidence interval: -3.00, -0.69; P = .032). We encountered no adverse effects. Conclusions Add-on of tadalafil for symptomatic patients with small BPE treated with tamsulosin appears to be effective and safe.