Effect of tadalafil add-on therapy in patients with persistant storage symptoms refractory to α1-adrenoceptor antagonist monotherapy for benign prostatic hyperplasia: A randomized pilot trial comparing tadalafil and solifenacin

Objective The aim of this study was to investigate the efficacy and safety of tadalafil add-on therapy with alpha(1)-adrenoceptor antagonists. Methods Patients with persistent storage symptoms refractory to alpha(1)-adrenoceptor antagonists for benign prostatic hyperplasia were enrolled in the study. Patients were randomly assigned to either a 5 mg tadalafil or 5 mg solifenacin treatment group for 12 weeks. International Prostate Symptom Score, Overactive Bladder Symptom Score, urinary flow rates, residual urine volume, and blood pressure were measured prospectively before treatment and after 4 and 12 weeks of treatment. Changes from baseline were compared between groups. The rate of treatment discontinuation due to adverse effects was evaluated. Results Of the 75 patients recruited to the study, 38 and 37 were assigned to the tadalafil and solifenacin groups, respectively. There were no significant difference in baseline characteristics between the two groups. The change in the amount of residual urine volume was significantly larger in the solifenacin- than tadalafil-treated group; other parameters, including lower urinary tract symptoms and uroflowmetry measures, did not differ significantly between the two groups. Seven (18%) and 12 (32%) patients in the tadalafil and solifenacin groups, respectively, discontinued treatment because of adverse events. The main reasons for discontinuation in the tadalafil group were stomach discomfort or nausea and dizziness or vertigo; voiding difficulty and constipation were the main reasons for discontinuation in the solifenacin group. There was no significant difference in blood pressure fluctuations from baseline between the two groups. Conclusions Tadalafil add-on therapy was not inferior to solifenacin add-on therapy in terms of effect and safety. Therefore, tadalafil could be an alternative add-on drug for patients with persistent lower urinary tract symptoms refractory to alpha(1)-adrenoceptor antagonists.