Urodynamic Efficacy and Safety of Mirabegron Add-on Treatment with Tamsulosin for Japanese Male Patients with Overactive Bladder.
OBJECTIVE
To investigate urodynamic efficacy and safety of mirabegron add-on treatment with tamsulosin for Japanese male patients with overactive bladder (OAB).


METHODS
A prospective study was conducted in 26 consecutive male patients with OAB who had been taking tamsulosin. OAB was diagnosed by overactive bladder symptom score (OABSS). Before and 8 weeks after mirabegron add-on treatment with preceding tamsulosin, we assessed OABSS, International Prostate Symptom Score (IPSS), free uroflowmetry (UFM), filling cystometry and pressure-flow study (PFS).


RESULTS
Mean age and prostate volume of the study patients were 75 ± 7 years and 32 ± 19 mL, respectively. Mirabegron significantly improved OABSS (from 8.5 ± 2.3 to 4.7 ± 2.5, P < 0.001). On free UFM, mirabegron significantly increased voided volume (from 135 ± 47 to 182 ± 102 mL, P = 0.01), maximum (from 10.7 ± 3.7 to 13.5 ± 6.4 mL/sec, P < 0.01) and average flow rate (from 5.5 ± 1.9 to 7.1 ± 3.3 mL/sec, P < 0.01), while postvoid residual urine volume did not change significantly (from 47 ± 38 to 63 ± 61 mL, P = 0.23). Before mirabegron, 24 patients (92%) had detrusor overactivity (DO). After mirabegron add-on, maximum cystometric capacity significantly increased from 170 ± 98 to 212 ± 95 mL (P = 0.01) and DO disappeared in six patients (25%). In the other 18 patients with persistent DO, amplitude of involuntary contraction decreased and bladder volume at first involuntary contraction increased with statistical significance. On PFS, detrusor pressure at maximum flow rate (from 79 ± 31 to 68 ± 19 cmH2 O, P = 0.10) or bladder contractility index (from 126 ± 39 to 120 ± 27, P = 0.45) did not change significantly.


CONCLUSIONS
Mirabegron add-on treatment with tamsulosin has efficacy and safety because it improves storage symptom without impairment of bladder contractility during voiding in male patients with OAB.
Department of Renal and Urologic Surgery, Asahikawa Medical University, Asahikawa, Japan. nwada@asahikawa-med.ac.jp.
Naoki
N
Wada
Department of Urology, Megumino Hospital, Megumino, Japan.
Hiromichi
H
Iuchi
Department of Renal and Urologic Surgery, Asahikawa Medical University, Asahikawa, Japan.
Masafumi
M
Kita
Department of Renal and Urologic Surgery, Asahikawa Medical University, Asahikawa, Japan.
Kazumi
K
Hashizume
Department of Renal and Urologic Surgery, Asahikawa Medical University, Asahikawa, Japan.
Seiji
S
Matsumoto
Department of Renal and Urologic Surgery, Asahikawa Medical University, Asahikawa, Japan.
Hidehiro
H
Kakizaki
D000083:Acetanilides / Q000008:administration & dosage* / Q000009:adverse effects; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage* / Q000009:adverse effects; D000368:Aged; D000369:Aged, 80 and over; D004359:Drug Therapy, Combination; D006801:Humans; D008297:Male; D008875:Middle Aged; D061214:Patient Safety; D011446:Prospective Studies; D013449:Sulfonamides / Q000008:administration & dosage* / Q000009:adverse effects; D000077409:Tamsulosin; D013844:Thiazoles / Q000008:administration & dosage* / Q000009:adverse effects; D016896:Treatment Outcome; D053201:Urinary Bladder, Overactive / Q000188:drug therapy* / Q000503:physiopathology; D014554:Urination / Q000187:drug effects; D014563:Urodynamics / Q000502:physiology; D064804:Urological Agents / Q000008:administration & dosage* / Q000009:adverse effects
D000083:Acetanilides; D000318:Adrenergic beta-Agonists; D013449:Sulfonamides; D013844:Thiazoles; D064804:Urological Agents; D000077409:Tamsulosin; C520025:mirabegron
mirabegron; overactive bladder; urodynamics