What are the first-line medications for treating urge incontinence?

First-Line Medications for Urge Incontinence

Mirabegron is recommended as the first-choice pharmacologic therapy for urge incontinence due to its superior side effect profile and comparable efficacy to antimuscarinic medications. 1

Treatment Algorithm for Urge Incontinence

Step 1: Non-Pharmacologic Therapies (First-Line)

• Begin with behavioral therapies as recommended by the American Urological Association:
  • Pelvic floor muscle training (PFMT)
  • Bladder training with scheduled voiding
  • Fluid management (25% reduction in fluid intake)
  • Lifestyle modifications

Step 2: Pharmacologic Therapy (When Behavioral Therapies Are Insufficient)

First-Choice Medication:

• Mirabegron (β3-adrenergic agonist)
  • Starting dose: 25 mg once daily 2
  • May increase to 50 mg once daily after 4-8 weeks if needed 2
  • Advantages: Better side effect profile than antimuscarinics 1
  • Dosage adjustments:
    • Renal impairment (eGFR 15-29 mL/min): Maximum 25 mg daily 2
    • Moderate hepatic impairment: Maximum 25 mg daily 2
    • Not recommended in severe hepatic impairment or eGFR <15 mL/min 2

Alternative First-Line Options (Antimuscarinics):

• Solifenacin

  • Lowest risk for discontinuation due to adverse effects among antimuscarinics 1
  • Better tolerated than immediate-release oxybutynin 1

• Tolterodine

  • Better side effect profile than oxybutynin 3
  • Similar efficacy to oxybutynin but with lower rates of dry mouth 1, 3
  • Available in immediate-release (IR) and extended-release (ER) formulations

• Other Antimuscarinics (if above options not suitable):

  • Trospium: Lower incidence of constipation compared to other antimuscarinics 1
  • Darifenacin: Risk for discontinuation due to adverse effects similar to placebo 1
  • Fesoterodine: Higher rates of adverse effects than tolterodine 1
  • Oxybutynin: Effective but has highest side effect burden 4, 5

Monitoring and Follow-up

• Evaluate treatment response at 4-6 weeks to assess technique and compliance 1
• Allow 4-8 weeks for medications to determine efficacy 1
• Monitor for common side effects:
  • Antimuscarinics: Dry mouth, constipation, blurred vision, dizziness
  • Mirabegron: Hypertension, nasopharyngitis, UTI (less common than antimuscarinic side effects)

Important Considerations and Precautions

Drug Interactions

• Mirabegron is a moderate CYP2D6 inhibitor - use caution with CYP2D6 substrates 2
• For patients taking mirabegron and digoxin, start with lowest digoxin dose and monitor levels 2
• Antimuscarinics are contraindicated in narrow-angle glaucoma 1
• Use antimuscarinics with caution in patients with BPH due to increased risk of urinary retention 1

Common Pitfalls to Avoid

1. Misdiagnosis: Ensure correct diagnosis of urge incontinence versus stress or mixed incontinence
2. Inadequate trial of conservative therapy: Allow 8-12 weeks for behavioral therapies before concluding ineffectiveness
3. Overlooking vaginal atrophy: Consider vaginal estrogen in postmenopausal women
4. Premature advancement to surgical options: Exhaust pharmacologic options first
5. Ignoring side effect profiles: Side effects significantly impact medication adherence and treatment success 5

By following this algorithm and selecting mirabegron as first-line pharmacologic therapy when behavioral interventions are insufficient, clinicians can optimize outcomes for patients with urge incontinence while minimizing adverse effects.