What are the first-line medications for treating overactive bladder?

First-Line and Second-Line Medications for Overactive Bladder

Behavioral therapies should be offered as first-line treatment for all patients with overactive bladder, followed by antimuscarinic medications or beta-3 adrenergic agonists as second-line therapy when behavioral interventions are insufficient. 1, 2

First-Line Treatment: Behavioral Therapies

• Bladder training, bladder control strategies, and pelvic floor muscle training should be offered to all patients with OAB as initial management 1
• Fluid management with reduction in fluid intake can reduce frequency and urgency 1
• Weight loss in obese patients can reduce incontinence episodes by up to 47% 1
• Behavioral treatments are as effective as antimuscarinic medications in reducing symptom levels 1

Second-Line Treatment: Pharmacologic Options

Antimuscarinic Medications (alphabetical order)

• Darifenacin - selective M3 receptor antagonist with lower risk of cognitive effects 1, 3
• Fesoterodine - non-selective muscarinic receptor antagonist 1
• Oxybutynin - available in oral and transdermal formulations; highest risk of discontinuation due to adverse effects 1, 2
• Solifenacin - indicated for OAB with symptoms of urge urinary incontinence, urgency, and frequency; better tolerability profile 4, 5
• Tolterodine - similar efficacy to oxybutynin but with lower incidence of dry mouth 6, 3
• Trospium - quaternary amine structure limits CNS penetration 3, 5

Beta-3 Adrenergic Agonists

• Mirabegron - indicated for OAB in adults with symptoms of urge urinary incontinence, urgency, and urinary frequency 7
• Starting dose is 25 mg once daily, may increase to 50 mg once daily after 4-8 weeks if needed 7
• Better tolerated than antimuscarinics with lower incidence of dry mouth and constipation 1

Special Considerations

Antimuscarinic Side Effects and Precautions

• Dry mouth is the most common side effect of antimuscarinic medications 1, 6
• Antimuscarinics should be used with extreme caution in patients with:
  • Narrow-angle glaucoma 1
  • Impaired gastric emptying 1
  • History of urinary retention 1
• Potential risk for developing dementia and cognitive impairment with antimuscarinic medications, which may be cumulative and dose-dependent 1
• Beta-3 agonists are typically preferred before antimuscarinic medications due to cognitive risk concerns 1

Dosage Adjustments

• For patients with renal impairment (eGFR 15-29 mL/min/1.73m²), mirabegron should be limited to 25 mg once daily 7
• For patients with moderate hepatic impairment (Child-Pugh Class B), mirabegron should be limited to 25 mg once daily 7

Treatment Algorithm

1. Start with behavioral therapies for all patients with OAB 1, 2

   • Bladder training
   • Pelvic floor muscle training
   • Fluid management
   • Weight loss (if applicable)

2. If behavioral therapies are insufficient, add pharmacotherapy 1

   • For patients without cognitive concerns: Either antimuscarinic or beta-3 agonist
   • For patients with cognitive concerns or elderly: Beta-3 agonist preferred (mirabegron) 1
   • For patients with dry mouth concerns: Consider transdermal oxybutynin or beta-3 agonist 1

3. If first medication is ineffective or causes intolerable side effects 1

   • Try dose modification
   • Switch to a different antimuscarinic medication
   • Switch to a beta-3 agonist
   • Consider combination therapy with an antimuscarinic and beta-3 agonist for refractory cases 1

4. For patients who fail pharmacotherapy or have intolerable side effects 1

   • Consider minimally invasive procedures:
     • Sacral neuromodulation
     • Tibial nerve stimulation
     • Intradetrusor botulinum toxin injection

Common Pitfalls

• Failing to optimize behavioral therapies before starting medications 1, 2
• Not considering cognitive risks when prescribing antimuscarinics, especially in elderly patients 1
• Abandoning antimuscarinic therapy after failure of one medication instead of trying another agent or a beta-3 agonist 1
• Not adjusting medication doses for patients with renal or hepatic impairment 7
• Using antimuscarinics in patients with contraindications such as narrow-angle glaucoma, impaired gastric emptying, or history of urinary retention 1