Clinical efficacy and safety of imidafenacin as add-on treatment for persistent overactive bladder symptoms despite α-blocker treatment in patients with BPH: the ADDITION study.

To evaluate the effects of add-on treatment with an anticholinergic (imidafenacin) on persistent overactive bladder (OAB) symptoms despite α-blocker (tamsulosin) treatment in patients with benign prostatic hyperplasia (BPH). Patients with BPH ≥50 years old, with urinary urgency at least once per week and total OAB symptom score (OABSS) ≥3 points after ≥8-week treatment with tamsulosin were enrolled in a multicenter, open-label study (not double-blinded). Patients were randomized to receive tamsulosin (0.2 mg/day) alone or tamsulosin (0.2 mg/day) + imidafenacin (0.1 mg 2 times a day). Primary endpoint was 12-week change in OABSS; secondary endpoints were changes in OABSS, International Prostate Symptom Score (IPSS), micturition time chart (MTC), hours of undisturbed sleep (HUS), and quality of life (IPSS-QOL and BPH impact index [BII]). For statistical analysis, a mixed-effects model and t test were used. In total, 308 men were enrolled. The change from baseline to 12 weeks in total OABSS was significantly greater with add-on imidafenacin than tamsulosin alone (2.11, 95% confidence interval [CI] 1.47-2.74, P <.0001). Improvements in frequencies of daytime urination, nighttime urination, urinary urgency, urgency incontinence, IPSS, HUS, IPSS-QOL, and BII, were significantly greater from 4 weeks through 12 weeks in the imidafenacin group. Between-group difference in postvoid residual volume at 12 weeks was not significant (-1.74 mL, 95% CI -8.19 to 4.72), and no events of urinary retention were reported. Combined tamsulosin and imidafenacin treatment is effective and safe in patients with BPH with persistent OAB symptoms after tamsulosin monotherapy. Furthermore the combination treatment improved the QOL in BPH patients with OAB.