What is the best medication for relaxing the bladder?

Best Medications for Relaxing the Bladder

For patients with urgency urinary incontinence (overactive bladder), mirabegron is the recommended first-choice medication for relaxing the bladder due to its efficacy comparable to antimuscarinics but with significantly fewer anticholinergic side effects, which is particularly important in elderly patients. 1

First-Line Non-Pharmacological Approaches

• Bladder training is recommended as first-line treatment for urgency urinary incontinence 2
• Pelvic floor muscle training (PFMT) is recommended for stress urinary incontinence 2
• For mixed urinary incontinence, PFMT combined with bladder training is recommended 2
• Weight loss and exercise are recommended for obese women with urinary incontinence 2

Pharmacological Treatment Algorithm

First-Line Medication (if bladder training is unsuccessful):

• Mirabegron (β3-adrenergic agonist) is the preferred first-choice medication because:
  • It has comparable efficacy to antimuscarinics 1
  • It has significantly lower incidence of anticholinergic side effects 1
  • It has lower risk of cognitive effects, particularly important in elderly patients 1, 3
  • It relaxes detrusor smooth muscle during the storage phase by activating β3-adrenergic receptors 3

Second-Line Medications (Antimuscarinics):

If mirabegron is ineffective or contraindicated, consider these antimuscarinics in order of preference:

1. Solifenacin:

   • Has the lowest risk for discontinuation due to adverse effects among antimuscarinics 2, 1
   • Achieves continence more effectively than placebo (NNTB of 9) 1, 4

2. Darifenacin:

   • Has risks for discontinuation due to adverse effects similar to placebo 2, 1
   • Effective in improving urinary incontinence in older women 5

3. Tolterodine:

   • Causes fewer adverse effects than oxybutynin 2
   • Fesoterodine (related medication) achieves continence more effectively than tolterodine 1

4. Trospium:

   • Good option for patients with pre-existing cognitive impairment 5, 1
   • Effective in improving urinary incontinence and quality of life in older women 5

5. Oxybutynin (least preferred):

   • Effective but has higher rates of adverse effects 5, 6, 7
   • Associated with the highest risk of discontinuation due to side effects 2
   • Available in immediate release, extended release, and transdermal formulations 8, 9

Comparative Efficacy and Safety

• All antimuscarinics have similar objective efficacy for treating overactive bladder 8
• Solifenacin achieves continence more often than placebo regardless of age 5, 1
• Tolterodine and oxybutynin have similar benefits, but tolterodine causes fewer adverse effects 2
• Age does not significantly modify clinical outcomes associated with pharmacologic treatment 5, 1, 4

Common Side Effects to Monitor

• Antimuscarinics: dry mouth, constipation, blurred vision 2, 1
• Mirabegron: potential increases in blood pressure and heart rate (dose-dependent) 3
• Risk of cognitive impairment with antimuscarinics, especially in elderly patients 1
• Patients taking multiple medications (7 or more) have increased risk of adverse effects with antimuscarinic agents 5, 1

Special Considerations

• For patients with stress urinary incontinence, pharmacologic therapy is not recommended 2
• For patients with mixed urinary incontinence, combine PFMT with bladder training 2
• In women with urogenital symptoms, consider adding vaginal estrogen to antimuscarinic therapy 1
• Evaluate treatment efficacy after 4-8 weeks 1, 4
• Monitor for urinary retention, particularly with antimuscarinic medications 1, 4

Pitfalls and Caveats

• Poor adherence to antimuscarinic medications is common due to side effects 8
• To decrease side effects, consider extended-release formulations or transdermal delivery systems 8
• Antimuscarinic medications may be associated with development of dementia with cumulative and dose-dependent effects 1
• Pharmacologic treatment should only be initiated after non-pharmacologic approaches have been tried 2