Comparison of Silodosin versus Tadalafil in Patients with Lower Urinary Tract Symptoms Associated with Benign Prostatic Hyperplasia.

OBJECTIVES: To compare the efficacy and safety of silodosin versus tadalafil for treating lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH).

METHODS: After informed consent, patients with LUTS/BPH were randomized in a 1:1 ratio to receive silodosin 8 mg/day or tadalafil 5 mg/day for 8 weeks (Period 1). Patients treated with tadalafil entered an exploratory phase and received silodosin or tadalafil for another 8 weeks. The primary efficacy endpoint was the change in the total International Prostate Symptom Score (IPSS) with Period 1 treatment.

RESULTS: Both silodosin and tadalafil demonstrated statistically significant improvement in IPSS total symptom score, with a mean ± standard deviation change of -10.1 ± 6.4 (P < 0.0001) and -8.0 ± 6.3 (P < 0.0001), respectively. The former reduction was significantly greater than the latter (P = 0.0277). Adverse drug reactions occurred at a rate of 23.4% with silodosin and 8.4% with tadalafil. No serious adverse drug reactions were documented, suggesting that both drugs were well tolerated. Moreover, results of Period 2 showed that switching to silodosin from tadalafil achieved a faster onset of improvements in IPSS Quality of Life Index score and total Overactive Bladder Symptom Score.

CONCLUSIONS: Silodosin achieved significantly greater improvement than tadalafil, with a higher incidence of adverse drug reactions. The risk-benefit profiles obtained in this study will provide useful information for optimal pharmacological treatment of LUTS/BPH. Our results suggest that silodosin can be one of the first-line therapies for rapid and efficient relief in patients with LUTS/BPH.