Is Gemtesa (vibegron) a suitable treatment option for a patient with continuous bladder leakage due to a vesicovaginal fistula, currently taking Myrbetriq (mirabegron) and experiencing hypertension?

Gemtesa (Vibegron) is Not Appropriate for Vesicovaginal Fistula-Related Leakage

Gemtesa should not be certified for this patient because vesicovaginal fistula causes anatomic, continuous urinary leakage—not overactive bladder—and neither vibegron nor any β3-adrenergic agonist is indicated for, or effective in, treating structural urinary tract defects. 1

Fundamental Mismatch Between Diagnosis and Drug Indication

• Gemtesa (vibegron) is FDA-approved exclusively for overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and urinary frequency 1
• The patient's continuous bladder leakage results from a documented 1.0 cm vesicovaginal fistula—a structural defect causing constant urine drainage through an abnormal connection between bladder and vagina 1
• OAB medications (antimuscarinics or β3-agonists) work by modulating detrusor muscle activity; they cannot address anatomic leakage from a fistula tract 2
• The AUA/SUFU guidelines define OAB as urgency-predominant symptoms with or without urge incontinence, not continuous anatomic leakage 2

Clinical Evidence Does Not Support Use in Fistula

• The pivotal EMPOWUR trial specifically enrolled patients with ≥8 micturitions per day and urge incontinence episodes—not patients with structural urinary tract abnormalities 3
• Vibegron demonstrated efficacy by reducing urge incontinence episodes by 2.0 per day versus 1.4 for placebo, but this mechanism is irrelevant to continuous fistula drainage 3
• Long-term data from the 52-week extension study maintained improvements in urgency and urge incontinence, but no data exist for anatomic leakage 4
• Rectovaginal and vesicovaginal fistulas in Crohn's disease require surgical repair or immunosuppressive therapy (infliximab, azathioprine), not bladder antispasmodics 2

The Provider's Rationale Contains Critical Flaws

Regarding Previous Myrbetriq Failure

• The provider states Myrbetriq (mirabegron, also a β3-agonist) "did not provide adequate therapeutic benefit"—this is expected because the underlying problem is anatomic, not functional OAB 1
• Both mirabegron and vibegron are β3-adrenergic receptor agonists with similar mechanisms of action; switching between them for a non-OAB indication is not evidence-based 5, 6
• If a β3-agonist failed to control leakage from a fistula, another β3-agonist will similarly fail 2

Regarding Hypertension Concerns

• The provider suggests vibegron is preferable to mirabegron due to the patient's hypertension, but ambulatory blood pressure monitoring studies show vibegron has no clinically meaningful effect on BP (LSMD 0.8 mmHg for daytime SBP) 7
• The incidence of hypertension as an adverse event was comparable between vibegron (4.7%) and placebo (3.7%) in controlled trials 7
• In the EMPOWUR extension study, hypertension occurred in 8.8% of vibegron patients versus 8.6% of tolterodine patients—essentially identical rates 4
• Both mirabegron and vibegron have favorable cardiovascular profiles; the distinction for hypertension management is not clinically significant 5, 7

Regarding Anticholinergic Side Effects

• The provider correctly notes anticholinergics cause dry eyes, constipation, and dizziness 2
• However, this argument is irrelevant because neither anticholinergics nor β3-agonists treat vesicovaginal fistula 2, 1
• The AUA/SUFU guidelines recommend β3-agonists as alternatives to antimuscarinics for OAB, not for anatomic urinary leakage 2

What This Patient Actually Needs

• Vesicovaginal fistulas require surgical repair with advancement flap procedures when there is no active inflammation, or fecal diversion/proctectomy as last resort 2
• The patient underwent bladder repair surgery in the documented timeline, with stent removal and subsequent catheter removal 2
• Persistent leakage after surgical repair suggests either incomplete healing, recurrent fistula, or new fistula formation—not OAB requiring pharmacotherapy 2
• Appropriate next steps include cystoscopy to reassess fistula status, consideration of repeat surgical repair, or evaluation for urinary diversion 2

Common Pitfall: Misattributing All Incontinence to OAB

• Clinicians must distinguish between urge incontinence (detrusor overactivity), stress incontinence (sphincter weakness), overflow incontinence (retention), and continuous leakage (fistula or ectopic ureter) 2
• The patient's description of "insensible loss" requiring 5-6 pad changes daily, without mention of urgency episodes or specific triggers, is classic for fistula rather than OAB 2, 3
• The documented 1.0 cm posterior bladder wall defect on cystoscopy definitively establishes the anatomic cause 2

Final Disposition

Non-certification is appropriate. The patient requires urologic re-evaluation for persistent vesicovaginal fistula, not escalation of OAB pharmacotherapy. Gemtesa has no role in managing structural urinary tract defects. 2, 1