A proof-of-concept study: Mirabegron, a new therapy for overactive bladder
Chapple CR, Amarenco G, López Aramburu MA, Everaert K, Liehne J, Lucas M, Vik V, Ridder A, Snijder R, Yamaguchi O; on behalf of the BLOSSOM Investigator Group. Neurourol Urodyn. 2013 Feb 19. doi: 10.1002/nau.22373. [Epub ahead of print]


Department of Urology, Royal Hallamshire Hospital, Sheffield Teaching Hospitals, Sheffield, UK. c.r.chapple@sheffield.ac.uk.



To evaluate the potential of mirabegron, a selective β3-adrenoceptor agonist, for treatment of overactive bladder (OAB) symptoms.


A multicenter, randomized, double-blind, double-dummy, parallel group, placebo and active-controlled, Phase 2, proof-of-concept study was conducted. Eligible patients (n = 314) were enrolled into a single-blind, 2-week placebo run-in period followed by a randomized, double-blind, placebo-controlled treatment period. Patients received mirabegron 100 or 150 mg twice-daily (BID), placebo or tolterodine 4 mg extended release (ER) once-daily for 4 weeks. Primary endpoint was change from baseline to end-of-treatment in mean number of micturition episodes per 24 hr. Secondary endpoints included changes in mean volume voided per micturition; mean number of urinary incontinence, urgency urinary incontinence, and urgency episodes per 24 hr; severity of urgency; nocturia, and quality of life measures. Safety parameters included adverse events, laboratory tests, electrocardiogram parameters and post-void residual volume.


Mirabegron 100 and 150 mg BID resulted in a statistically significant improvement versus placebo in mean change from baseline to end-of-treatment in the primary endpoint of micturition frequency (2.2 micturitions/24 hr vs. 1.2 micturitions/24 hr for both doses, adjusted P ≤ 0.01 for both comparisons). Mirabegron had a statistically significant effect versus placebo for most secondary endpoints, including quality of life variables. Despite a small increase in pulse rate, mirabegron demonstrated good safety and tolerability.


Mirabegron was efficacious and well tolerated in patients with OAB symptoms and heralds the first of a new class of oral pharmacological therapy for OAB for more than 30 years.