What are the treatment options for overactive bladder?

Treatment Options for Overactive Bladder

Beta-3 adrenoceptor agonists such as mirabegron are the preferred first-line pharmacological treatment for overactive bladder (OAB), followed by antimuscarinic medications if needed, due to their efficacy and lower risk of cognitive side effects. 1

Treatment Algorithm

First-Line Approaches

1. Behavioral Modifications

   • Establish timed voiding schedule based on bladder diary (starting with 1-2 hour intervals) 1
   • Reduce fluid intake by approximately 25% 1
   • Eliminate or significantly reduce caffeine intake 1
   • Weight loss (even 8% can reduce incontinence episodes by up to 47% in overweight patients) 1
   • Avoid bladder irritants through elimination diet to identify trigger foods 1
   • Implement pelvic floor muscle relaxation techniques 1

2. First-Line Pharmacotherapy

   • Beta-3 adrenoceptor agonists (preferred):
     • Mirabegron starting dose: 25 mg orally once daily 2
     • May increase to 50 mg after 4-8 weeks if needed 2
     • Assess effectiveness at 3 months 1
     • Dosage adjustments required for renal and hepatic impairment 1, 2

Second-Line Approaches

1. Antimuscarinic Medications:

   • Options include oxybutynin, tolterodine, trospium, solifenacin, and darifenacin 1
   • Tolterodine is indicated for OAB with symptoms of urge urinary incontinence, urgency, and frequency 3
   • Assess effectiveness at 2-4 weeks 1
   • Use with caution in elderly patients, those with narrow-angle glaucoma, impaired gastric emptying, or history of urinary retention 1
   • For elderly patients (>65 years), start with lower doses (e.g., oxybutynin 2.5mg twice daily) 1

2. Combination Therapy:

   • Consider combining antimuscarinic with beta-3 agonist for refractory cases
   • Best evidence supports solifenacin (5 mg) with mirabegron (25 or 50 mg) 1

Third-Line Approaches

1. Minimally Invasive Options:

   • Intradetrusor onabotulinumtoxinA (100 U) 1
   • Sacral neuromodulation (SNS) 1
   • Peripheral tibial nerve stimulation (PTNS) 1

2. Other Options:

   • Tricyclic antidepressants (TCAs) - reserved for patients who have failed first and second-line therapies 1

Management of Common Adverse Effects

• Dry mouth: Switch to extended-release oxybutynin or transdermal formulation 1
• Constipation: Increase fluid and fiber intake, consider stool softeners 1
• Urinary retention: Check post-void residual, consider dose reduction or discontinuation if >200 mL 1

Special Considerations

Renal Impairment (for Mirabegron) 1, 2

• eGFR 30-89 mL/min/1.73 m²: Start 25 mg, max 50 mg
• eGFR 15-29 mL/min/1.73 m²: Start 25 mg, max 25 mg
• eGFR <15 mL/min/1.73 m²: Not recommended

Hepatic Impairment (for Mirabegron) 1, 2

• Child-Pugh Class A (mild): Start 25 mg, max 50 mg
• Child-Pugh Class B (moderate): Start 25 mg, max 25 mg
• Child-Pugh Class C (severe): Not recommended

Treatment Monitoring and Follow-up

• Assess treatment success at 2-4 weeks for antimuscarinics and 3 months for beta-3 agonists 1
• Annual follow-up for successful treatment to detect any changes in symptoms 1
• Consider alternative or advanced therapies if treatment fails and patient is not satisfied 1

Common Pitfalls to Avoid

• Antimuscarinic use in elderly patients: High risk of cognitive side effects; consider mirabegron as a safer alternative 1
• Inadequate trial duration: Ensure proper assessment timeframes before declaring treatment failure 1
• Overlooking behavioral therapies: These are as effective as antimuscarinic medications with no risk of adverse effects 1
• Failure to adjust dosages: Patients with renal or hepatic impairment require specific dosage adjustments 1, 2