Can you take Myrbetriq (mirabegron) and Oxybutynin simultaneously for overactive bladder treatment?

Combination Therapy with Mirabegron and Oxybutynin for Overactive Bladder

Yes, mirabegron (Myrbetriq) and oxybutynin can be used together for overactive bladder treatment, particularly in patients who have inadequate symptom control with monotherapy. 1

Treatment Algorithm for Overactive Bladder

First-Line Treatment

• Behavioral therapies should be offered to all patients with OAB as first-line treatment, including bladder training, pelvic floor muscle training, and fluid management 1
• These therapies are risk-free and can be as effective as antimuscarinic medications in reducing symptoms 1

Second-Line Treatment

• When behavioral therapies alone are insufficient, pharmacologic management is recommended:
  • Antimuscarinic medications (like oxybutynin) or beta-3 adrenergic agonists (like mirabegron) can be offered as monotherapy 1
  • Each medication class works through different mechanisms of action:
    • Oxybutynin blocks muscarinic receptors to reduce bladder contractions 2
    • Mirabegron activates beta-3 adrenergic receptors to enhance bladder storage function and relax the urinary bladder 3, 4

Combination Therapy

• For patients who don't adequately respond to monotherapy, combination therapy with an antimuscarinic (oxybutynin) and a beta-3 adrenergic agonist (mirabegron) may be considered 1
• The 2019 AUA/SUFU guideline amendment specifically supports combination therapy for patients refractory to monotherapy (Evidence Strength Grade B) 1
• Clinical trials have demonstrated improved efficacy with combination therapy without significant worsening of the safety profile compared to monotherapy 1, 5

Benefits of Combination Therapy

• Combination therapy shows superior efficacy compared to monotherapy for:
  • Reduction in urinary incontinence episodes 1
  • Decrease in urgency episodes 1
  • Improvement in nocturia 1
• The effect sizes appear to be additive, suggesting complementary mechanisms of action 1
• Mirabegron has a favorable safety profile compared to antimuscarinic agents, particularly regarding dry mouth, constipation, and CNS effects 6

Important Considerations and Precautions

Side Effect Profile

• When combining medications, monitor for:
  • Slightly increased incidence of dry mouth, constipation, and dyspepsia 1
  • Potential increased risk of urinary retention 1
  • Cognitive effects, particularly with antimuscarinic medications 1

Contraindications and Cautions

• Use antimuscarinic medications with extreme caution in patients with:
  • Narrow-angle glaucoma (unless approved by ophthalmologist) 1
  • Impaired gastric emptying 1
  • History of urinary retention 1
• Consider potential cognitive risks with antimuscarinic medications, especially in older adults 1
• For frail patients, use caution with both medication classes due to potentially higher adverse event profiles 1

Monitoring Recommendations

• When combining therapies, carefully monitor improvement of OAB symptoms 1
• If no improvement is noted, one or both therapies should be discontinued and other treatments pursued 1
• Proceed in a stepwise fashion when combining therapies to determine the individual impact of each therapy on symptoms 1

Treatment Approach

• Start with behavioral therapies as first-line treatment 1
• If inadequate response, add either mirabegron or oxybutynin as monotherapy 1
• If monotherapy provides partial but insufficient relief, consider adding the second agent 1
• For patients who fail combination therapy, consider third-line treatments such as intradetrusor onabotulinumtoxinA, peripheral tibial nerve stimulation, or sacral neuromodulation 1

The combination of mirabegron and oxybutynin represents a viable treatment strategy for patients with OAB who do not achieve optimal outcomes with monotherapy, leveraging their complementary mechanisms of action to improve bladder control and quality of life.