Myrbetriq (Mirabegron) Dosing for Overactive Bladder
The recommended starting dose of Myrbetriq (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, 2
Standard Dosing Regimen
- 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
Dosage Adjustments for Special Populations
Renal Impairment
- eGFR 30-89 mL/min/1.73 m²: 25 mg starting dose, may increase to 50 mg
- eGFR 15-29 mL/min/1.73 m²: 25 mg maximum dose
- eGFR <15 mL/min/1.73 m² or requiring dialysis: Not recommended 1
Hepatic Impairment
- Child-Pugh Class A (mild): 25 mg starting dose, may increase to 50 mg
- Child-Pugh Class B (moderate): 25 mg maximum dose
- Child-Pugh Class C (severe): Not recommended 1
Elderly Patients
- Standard adult dosing applies
- Efficacy and safety are not substantially different in older patients
- Mirabegron is preferred over antimuscarinics in elderly patients due to lower risk of cognitive side effects 2
Clinical Considerations
Monitoring
- Regular blood pressure monitoring is recommended, especially in patients with pre-existing hypertension
- Monitor for signs of urinary retention and constipation
- Assess treatment response after 4-8 weeks
Adverse Effects
- Most common: hypertension, nasopharyngitis, and urinary tract infection 2, 3
- Notably, mirabegron has a significantly lower incidence of dry mouth (2.8%) compared to antimuscarinic medications like tolterodine ER (8.6%) 3
- Carries a low risk of QT interval prolongation 3
Therapeutic Context
- Mirabegron is recommended as a second-line pharmacological treatment option for OAB
- Has similar efficacy to antimuscarinic medications but with a better side effect profile, particularly regarding cognitive effects and dry mouth 2, 4
- Consider as first-line pharmacological option in patients who cannot tolerate antimuscarinic side effects 2
Important Considerations
- Complete symptom relief is unlikely in patients with severe baseline symptoms
- Improvements in OAB symptoms are typically observed as early as 4 weeks after initiating treatment 5
- For patients who fail mirabegron monotherapy, combination therapy with mirabegron plus solifenacin 5 mg may be considered 2
Contraindications
- Severe uncontrolled hypertension
- Severe hepatic impairment
- End-stage renal disease 1