Intravesical prostatic protrusion does not compromise the therapeutic effects of Mirabegron in male patients with overactive bladder.

Aims: Intravesical prostatic protrusion (IPP) is associated with the degree of benign prostatic obstruction. We evaluated the effects of Mirabegron, a selective β3 adrenoceptor agonist, on overactive bladder (OAB) in male patients with different degrees of IPP.

Methods: About 185 male patients ≥40 years with lower urinary tract symptoms were recruited from a tertiary referral center. OAB was defined by the overactive bladder symptom score (OABSS) urgency score of ≥2 and sum score of ≥3. IPP was measured in the midsagittal section using transrectal ultrasound and patients were divided into IPP ≤5 mm and IPP >5 mm groups. Outcomes were assessed at the baseline, 4, and 12 weeks.

Results: About 104 patients (56.2%) were diagnosed with OAB and received Mirabegron (50 mg) daily use. Both IPP groups (≤5 and >5 mm) had similar baseline OABSS and International Prostate Symptom Scores (IPSS). Four-week Mirabegron usage was associated with significant decreases in both symptom score measurements, OABSS: IPP ≤5 mm -27.4% and IPP >5 mm -19.7% (P = .419) and IPSS: -32% and -22.5% (P = .202), respectively. Urgency, urge incontinence, and nocturia sub-scores were decreased in both groups, -26.3% and -27.4% (P = .690), 53.3% and 46.2% (P = .916), and 20.8% and 15.4% (P = .958). Effects were maintained at 12 weeks. We found no significant improvement in the frequency sub-score in either group. One patient stopped medication because of intolerable hypertension. Most frequent adverse event was increased residual urine (≥50 mL higher than baseline), IPP ≤5 mm 9.2% and IPP >5 mm 5.1% (P = .707), but no case had acute urinary retention.

Conclusions: Mirabegron is an effective drug to treat male OAB regardless of IPP grade.