What is the recommended dosing for Mirbetriq (mirabegron)?

Mirbetriq (Mirabegron) Dosing Recommendations

The recommended starting dose of Mirbetriq (mirabegron) for adults with overactive bladder is 25 mg orally once daily, which can be increased to 50 mg once daily after 4-8 weeks if needed for better symptom control. 1

Adult Dosing for Overactive Bladder

Standard Dosing

• Starting dose: 25 mg orally once daily
• Maximum dose: 50 mg orally once daily (after 4-8 weeks if needed)
• Administration: Take with or without food; swallow tablets whole

Dosing in Special Populations

Renal Impairment 1

• eGFR 30-89 mL/min/1.73 m²:
  • Starting dose: 25 mg once daily
  • Maximum dose: 50 mg once daily
• eGFR 15-29 mL/min/1.73 m²:
  • Starting dose: 25 mg once daily
  • Maximum dose: 25 mg once daily (do not increase)
• eGFR <15 mL/min/1.73 m² or requiring dialysis:
  • Not recommended

Hepatic Impairment 1

• Child-Pugh Class A (Mild):
  • Starting dose: 25 mg once daily
  • Maximum dose: 50 mg once daily
• Child-Pugh Class B (Moderate):
  • Starting dose: 25 mg once daily
  • Maximum dose: 25 mg once daily (do not increase)
• Child-Pugh Class C (Severe):
  • Not recommended

Pediatric Dosing for Neurogenic Detrusor Overactivity

For pediatric patients ≥3 years weighing ≥35 kg: 1

• Starting dose: 25 mg once daily
• Maximum dose: 50 mg once daily (after 4-8 weeks if needed)

Clinical Considerations

Efficacy

• Mirabegron demonstrates significant improvements in key OAB symptoms including: 2
  • Micturition frequency
  • Urgency incontinence
  • Urinary frequency
• Improvements are typically seen as early as 4 weeks after treatment initiation 3

Advantages Over Antimuscarinic Medications

• Similar efficacy to antimuscarinic medications but with significantly better side effect profile 2
• Particularly beneficial for patients who cannot tolerate antimuscarinic side effects 2
• Incidence of dry mouth similar to placebo (3-5 times lower than with antimuscarinic agents) 3

Monitoring Requirements

• Regular blood pressure monitoring is recommended, especially in patients with pre-existing hypertension 2
• Monitor for urinary retention and constipation 2

Common Side Effects

• Hypertension
• Nasopharyngitis
• Urinary tract infection 2, 3

Special Considerations for Elderly Patients

• Efficacy and safety are not substantially different in older patients 2
• Preferred over antimuscarinic agents in elderly patients due to lower risk of cognitive side effects 2
• Use caution in frail patients (those with mobility deficits, weight loss, weakness) 2

Treatment Algorithm

1. Start with behavioral therapies as first-line treatment for OAB
2. Consider mirabegron as second-line therapy, particularly for patients who cannot tolerate antimuscarinic side effects
3. Start at 25 mg once daily
4. Assess response after 4-8 weeks
5. If inadequate response and no significant side effects, increase to 50 mg once daily
6. For patients with inadequate response to mirabegron monotherapy, consider combination therapy with mirabegron plus an antimuscarinic (preferably solifenacin 5 mg) 2

Common Pitfalls to Avoid

• Failure to monitor blood pressure, especially in hypertensive patients
• Prescribing maximum dose in patients with moderate renal or hepatic impairment
• Not allowing sufficient time (4-8 weeks) to assess treatment response before dose adjustment
• Using in patients with severe uncontrolled hypertension, severe hepatic impairment, or end-stage renal disease 1