Can mirabegron be added to a patient's regimen who is already on Vesicare (solifenacin)?

Mirabegron Can Be Added to Solifenacin (Vesicare) for Enhanced Efficacy in Overactive Bladder

Yes, mirabegron can be safely added to solifenacin (Vesicare) therapy, and this combination provides superior efficacy compared to either medication alone for patients with overactive bladder symptoms. 1, 2

Efficacy of Combination Therapy

• Combination therapy with solifenacin 5mg plus mirabegron 50mg provides consistent improvements in efficacy compared to respective monotherapies across most outcome parameters 3
• Adding mirabegron 50mg to solifenacin 5mg further improves overactive bladder symptoms versus solifenacin 5mg or 10mg alone in patients who remain incontinent after initial solifenacin 5mg treatment 1
• The combination therapy demonstrates superior efficacy for reducing:
  • Incontinence episodes per day 1, 4
  • Micturition frequency 3, 4
  • Urgency episodes 3
  • Nocturia episodes 3

Safety and Pharmacokinetic Considerations

• The FDA label specifically addresses this combination, stating: "Although no dose adjustment is recommended with solifenacin succinate based on the lack of pharmacokinetic interaction, mirabegron should be administered with caution to patients taking muscarinic antagonist medications for the treatment of OAB" 2
• The combination is generally well-tolerated over 12 months of treatment 4
• Slightly higher frequencies of dry mouth, constipation, and dyspepsia may occur with combination therapy compared to monotherapy 3
• There is no clinically significant pharmacokinetic interaction between mirabegron and solifenacin that would necessitate dose adjustment 2

Clinical Approach to Combination Therapy

• According to AUA/SUFU guidelines, if a patient experiences inadequate symptom control with one medication (such as solifenacin), adding another medication with a different mechanism of action (like mirabegron) is appropriate 5
• The guidelines specifically mention that β3-adrenoceptor agonists (mirabegron) can be added when patients don't experience adequate efficacy from antimuscarinic medications (solifenacin) 5
• Combination therapy should be considered when:
  • The patient has inadequate symptom control with solifenacin alone 5
  • The patient cannot tolerate dose escalation of solifenacin due to side effects 5

Monitoring and Precautions

• Regular blood pressure monitoring is recommended when initiating mirabegron, especially during the initial treatment period 6
• Mirabegron is contraindicated in patients with severe uncontrolled hypertension 6
• Use caution when prescribing this combination to frail elderly patients, as they may have a lower therapeutic index and higher adverse event profile 5, 6
• Monitor for potential urinary retention, especially in patients with bladder outlet obstruction 2
• For patients who cannot tolerate pharmacologic management, behavioral strategies including prompted voiding and fluid management may be helpful 5

Benefits of Combination Therapy vs. Monotherapy

• The combination provides additive effects on symptom improvement 3
• Patients are more likely to achieve zero incontinence episodes and micturition frequency normalization with combination therapy 3
• The combination approach allows for lower doses of each medication, potentially reducing side effects while maintaining efficacy 1
• Mirabegron has a distinct mechanism of action (β3-adrenoceptor agonist) compared to solifenacin (antimuscarinic), allowing for complementary effects on bladder function 7