What medications are used to treat bladder spasms?

Medications for Bladder Spasms

Oral antimuscarinic agents are the first-line pharmacological treatment for bladder spasms, with solifenacin having the lowest discontinuation rate due to adverse effects, while beta-3 agonists like mirabegron serve as an effective alternative, particularly in elderly patients or those intolerant to antimuscarinics. 1, 2

First-Line Antimuscarinic Agents

The following antimuscarinic medications are recommended as first-line therapy for bladder spasms:

• Oxybutynin (immediate-release 5 mg 2-3 times daily, extended-release, or transdermal formulations) is effective but has the highest discontinuation rate due to adverse effects (NNTH 14) 2, 3
• Tolterodine (immediate or extended-release) provides significant clinical improvement at 12 weeks with discontinuation rates similar to placebo 2, 4
• Solifenacin (5-10 mg daily) is associated with the lowest risk for discontinuation due to adverse effects among all antimuscarinics and demonstrates significant efficacy (mean reduction of 2.3-2.9 micturitions per 24 hours with 10 mg dose) 2, 5
• Darifenacin has discontinuation rates similar to placebo and may be preferred in patients with cardiac concerns or cognitive dysfunction 2, 4
• Fesoterodine is effective but has higher discontinuation rates than tolterodine (NNTH 58) 2
• Trospium (immediate or extended-release) is appropriate for patients with pre-existing cognitive impairment or those taking CYP450 inhibitors, as it does not cross the blood-brain barrier significantly 6, 4

Beta-3 Adrenergic Agonist Alternative

• Mirabegron should be prescribed as an alternative first-line agent, particularly in elderly patients where antimuscarinics pose cognitive risks 1, 2
• Mirabegron has a relatively lower adverse effect profile compared to antimuscarinics while maintaining similar efficacy 2

Medication Selection Algorithm

Choose antimuscarinics based on the following patient-specific factors:

• Elderly patients or cognitive impairment: Use mirabegron, trospium, solifenacin, or darifenacin to minimize CNS effects 1, 4
• Narrow-angle glaucoma, impaired gastric emptying, or urinary retention history: Avoid antimuscarinics entirely; use mirabegron 1, 3
• Post-void residual >150 mL: Do not use antimuscarinics; consider mirabegron or address obstruction first 2
• Dry mouth intolerance: Switch to transdermal oxybutynin or extended-release formulations 3, 4
• Concurrent CYP450 inhibitor use: Use trospium (not metabolized by CYP450) 4
• Cost-sensitive patients: Immediate-release oxybutynin has superior cost-effectiveness despite higher side effects 4

Combination Therapy Considerations

• Alpha-blockers (tamsulosin, alfuzosin) combined with antimuscarinics may be used in men with bladder outlet obstruction and overactive bladder symptoms, but only if post-void residual is <150 mL 2, 1
• Alpha-blockers combined with mirabegron result in mild improvement of urinary frequency and urgency episodes compared to alpha-blockers alone, with 1.7% incidence of acute urinary retention 2
• Combination therapy should be assembled methodically, adding one therapy at a time 3

Common Adverse Effects and Management

Antimuscarinic side effects include:

• Dry mouth (RR 3.50 compared to placebo), constipation, blurred vision, and urinary retention (RR 3.52) 7, 2
• Cognitive effects, particularly in elderly patients 2, 4

Management strategies:

• Switch to lower doses, extended-release formulations, or transdermal delivery systems to reduce side effects 3, 4
• Consider switching between antimuscarinic agents if one is not tolerated, as individual responses vary 2
• Monitor post-void residual in patients at risk for urinary retention 2, 3

Critical Contraindications

Absolute contraindications for antimuscarinics:

• Narrow-angle glaucoma 1, 3
• Impaired gastric emptying 1, 3
• History of urinary retention 1, 3
• Post-void residual >250-300 mL 3

Treatment Duration and Expectations

• Adequate trial periods of 8-12 weeks should be given before determining treatment failure 2, 3
• Treatment effects are maintained only as long as therapy is continued 3
• Patient education on realistic expectations and length of treatment is essential, as continuation rates for antimuscarinic therapy are low 4

Third-Line Options for Refractory Cases

If behavioral therapy and at least one antimuscarinic trial (4-8 weeks) fail:

• Intradetrusor onabotulinumtoxinA (100 U) for carefully selected patients who can perform self-catheterization if needed 2, 3
• Sacral neuromodulation or peripheral tibial nerve stimulation for severe refractory bladder spasms 3