Intravesical Prostatic Protrusion does not compromise therapeutic effects of Mirabegron in male patients with overactive bladder.

AIMS: Intravesical prostatic protrusion (IPP) is associated with degree of benign prostatic obstruction (BPO). We evaluated the effects of Mirabegron, a selective β3 adrenoceptor agonist, on overactive bladder (OAB) in male patients with different degrees of IPP. METHODS: 185 male patients ≥ 40 years with lower urinary tract symptoms (LUTS) were recruited from a tertiary referral center. OAB was defined by OAB symptom score urgency score of ≥2 and sum score of ≥3. IPP was measured in the mid sagittal section using transrectal ultrasound and patients were divided into IPP≤5mm and IPP>5mm groups. Outcomes were assessed at baseline, four, and twelve weeks. RESULTS: 104 patients (56.2%) were diagnosed with OAB and received Mirabegron (50mg) daily use. Both IPP groups (≤5mm and >5mm) had similar baseline OAB Symptom Scores and International Prostate Symptom Scores (IPSS). Four-week Mirabegron usage was associated with significant decreases in both symptom score measurements, OABSS: IPP≤5mm -27.4% and IPP>5mm -19.7% (p=0.419) and IPSS: -32% and -22.5% (p=0.202), respectively. Urgency, urge incontinence and nocturia sub-scores were decreased in both groups, -26.3% and -27.4% (p=0.690), 53.3% and 46.2% (p= 0.916), and 20.8% and 15.4% (p=0.958). Effects were maintained at twelve weeks. We found no significant improvement in the frequency sub-score in either group. One patient stopped medication due to intolerable hypertension. Most frequent adverse event was increased residual urine (≥ 50 ml higher than baseline), IPP≤5mm 9.2% and IPP>5mm 5.1% (p= 0.707), but no case had acute urinary retention. CONCLUSIONS: Mirabegron is an effective drug to treat male OAB regardless of IPP grade.