Introduction:
Urinary frequency urgency and urgency urinary incontinence (UUI) are commonly encountered in
patients after transurethral prostatectomy (TURP) or transurethral incision of the prostate
(TUIP). [1] Patients usually bother by these overactive bladder (OAB) symptoms. The causes of
postprostatectomy OAB might be detrusor overactivity (DO) before TURP, increase afferent
input due to acute inflammation after TURP, or a weak urethral sphincter which cannot hold
urine at the bladder capacity. Antimuscarinics and beta-3 adrenoceptor agonist are two
different classes of medication for OAB. [2] Antimuscarinics has been widely used to treat
OAB and around 70% of patients can improve symptoms after treatment. Beta-3 adrenoceptor
agonist (mirabegron) can also decrease DO and improve OAB symptoms. Combination treatment of
solifenacin 5mg plus mirabegron 25 or 50mg was more effective than mirabegron 50mg alone, but
with more anticholinergic side effects. [3] However, antimuscarnics might decrease detrusor
contractility and result in increase of postvoid residual (PVR) volume. Current clinical
studies reveal that mirabegron does not impair detrusor contractility or increase PVR. [4]
Under this consideration, mirabegron has been widely used to treat male lower urinary tract
symptoms (LUTS) due to benign prostate hyperplasia (BPH). [5] However, there has been no
clinical trial to compare which drug provides more benefit to decrease the OAB symptom
severity immediately after TURP. This study tries to compare the safety and therapeutic
efficacy between solifenacin and mirabegron in men with BPH and having OAB symptoms
immediately after TURP.
Material and methods:
Objectives and Endpoints: This study was designed as a prospective, randomized trial to
compare the safety and efficacy of OAB medication on the decrease of overactive bladder
symptoms score (OABSS) and urgency severity score (USS) between solifenacin 5mg QD and
mirabegron 50mg QD in men with BPH undergoing TURP.
Randomization: Permuted block randomization method will be applied to generate randomization
codes. Each randomization number will be assigned to individual patient according to the
time-sequence for screened patient become eligible.
Expected Results:
Patients receiving solifenacin and mirabegron might have similar therapeutic effects on
decrease of USS, but patients who received mirabegron might have less adverse events such as
dry mouth or difficulty in urination.