Currently, the midurethral sling (MUS) is widely used as a standard treatment in patients with stress urinary incontinence (SUI). Several studies have reported the failure rate of MUS to be approximately 5%–20%. In general, sling failure can be defined as persistent SUI after surgery or a temporary improvement in incontinence followed by recurrence. Failure is also often considered to include cases requiring secondary surgery due to mesh exposure, postoperative voiding difficulty, de novo urgency/urge incontinence, and severe postoperative pain. Because of the lack of large-scale, high-quality research on this topic, no clear guidelines exist for second-line management. To date, transurethral bulking agent injections, tape shortening, repeat MUS, pubovaginal sling (PVS) using autologous fascia, and Burch colposuspension are available options for second-line surgery. Repeat MUS is the most widely used second-line surgical method at present. Bulking agent injections have lower durability and efficacy than other treatments. Tape shortening demonstrates a relatively low success rate, but comparable outcomes if the period from first treatment to relapse is short. In patients with intrinsic sphincter deficiency, PVS and retropubic (RP) MUS can be considered first as second-line management because of their higher success rate than other treatments. When revision or reoperation is required due to prior mesh-related complications, PVS or colposuspension, which is performed without a synthetic mesh, is appropriate for second-line surgery. For patients with detrusor underactivity, a readjustable sling can be a better option because of the high risk of postoperative voiding dysfunction in PVS or RP slings.

Currently, the midurethral sling (MUS) is widely used as a standard treatment in patients with stress urinary incontinence (SUI). Several studies have reported the failure rate of MUS to be approximately 5%–20%. In general, sling failure can be defined as persistent SUI after surgery or a temporary improvement in incontinence followed by recurrence. Failure is also often considered to include cases requiring secondary surgery due to mesh exposure, postoperative voiding difficulty, de novo urgency/urge incontinence, and severe postoperative pain. Because of the lack of large-scale, high-quality research on this topic, no clear guidelines exist for second-line management. To date, transurethral bulking agent injections, tape shortening, repeat MUS, pubovaginal sling (PVS) using autologous fascia, and Burch colposuspension are available options for second-line surgery. Repeat MUS is the most widely used second-line surgical method at present. Bulking agent injections have lower durability and efficacy than other treatments. Tape shortening demonstrates a relatively low success rate, but comparable outcomes if the period from first treatment to relapse is short. In patients with intrinsic sphincter deficiency, PVS and retropubic (RP) MUS can be considered first as second-line management because of their higher success rate than other treatments. When revision or reoperation is required due to prior mesh-related complications, PVS or colposuspension, which is performed without a synthetic mesh, is appropriate for second-line surgery. For patients with detrusor underactivity, a readjustable sling can be a better option because of the high risk of postoperative voiding dysfunction in PVS or RP slings.

Overactive bladder (OAB) is a symptom-based syndrome defined by urinary urgency, frequency, and nocturia with or without urge incontinence. The causative pathology is diverse; including bladder outlet obstruction (BOO), bladder ischemia, aging, metabolic syndrome, psychological stress, affective disorder, urinary microbiome, localized and systemic inflammatory responses, etc. Several hypotheses have been suggested as mechanisms of OAB generation; among them, neurogenic, myogenic, and urothelial mechanisms are well-known hypotheses. Also, a series of local signals called autonomous myogenic contraction, micromotion, or afferent noises, which can occur during bladder filling, may be induced by the leak of acetylcholine (ACh) or urothelial release of adenosine triphosphate (ATP). They can be transmitted to the central nervous system through afferent fibers to trigger coordinated urgency-related detrusor contractions. Antimuscarinics, commonly known to induce smooth muscle relaxation by competitive blockage of muscarinic receptors in the parasympathetic postganglionic nerve, have a minimal effect on detrusor contraction within therapeutic doses. In fact, they have a predominant role in preventing signals in the afferent nerve transmission process. β3-adrenergic receptor (AR) agonists inhibit afferent signals by predominant inhibition of mechanosensitive Aδ-fibers in the normal bladder. However, in pathologic conditions such as spinal cord injury, it seems to inhibit capsaicin-sensitive C-fibers. Particularly, mirabegron, a β3-agonist, prevents ACh release in the BOO-induced detrusor overactivity model by parasympathetic prejunctional mechanisms. A recent study also revealed that vibegron may have 2 mechanisms of action: inhibition of ACh from cholinergic efferent nerves in the detrusor and afferent inhibition via urothelial β3-AR.

Purpose: Vibegron, a novel, potent β3 agonist, has been approved for clinical use in overactive bladder (OAB) treatment in Japan and the Unites States. We performed a bridging study to investigate the efficacy and safety of a daily 50-mg vibegron (code name JLP-2002) dose in Korean patients with OAB. Methods: A multicenter, randomized, double-blind, placebo-controlled study was conducted from September 2020 to August 2021. Adult patients with OAB with a symptom duration of more than 6 months entered a 2-week placebo run-in phase. Eligibility was assessed at the end of this phase and selected patients entered a double-blind treatment phase after 1:1 randomization to either the placebo or vibegron (50 mg) group. The study drug was administered once daily for 12 weeks and follow-up visits were scheduled at weeks 4, 8, and 12. The primary endpoint was the change in mean daily micturition at the end of treatment. The secondary endpoints included changes in OAB symptoms (daily micturition, nocturia, urgency, urgency incontinence, and incontinence episodes, and mean voided volume per micturition) and safety. A constrained longitudinal data model was used for statistical analysis. Results: Patients who took daily vibegron had significant improvements over the placebo group in both primary and secondary endpoints, except for daily nocturia episodes. The proportions of patients with normalized micturition and resolution of urgency incontinence and incontinence episodes were significantly higher in vibegron group than in the placebo. Vibegron also improved the patients’ quality of life with higher satisfaction rates. The incidence of adverse events in the vibegron and placebo groups was similar with no serious, unexpected adverse drug reactions. No abnormality in electrocardiographs was observed as well as no significant increase in postvoid residual volume. Conclusions Once daily vibegron (50 mg) for 12 weeks was effective, safe, and well-tolerated in Korean patients with OAB.