Mirabegron Safety and Use in Elderly Patients with Impaired Renal Function
Mirabegron is generally safe and effective for elderly patients with impaired renal function, but dose adjustments are required for severe renal impairment (eGFR 15-29 mL/min/1.73m²), where the daily dose should not exceed 25 mg. 1
Safety Profile in Elderly Patients
- Mirabegron has been extensively studied in elderly populations with no overall differences in safety or effectiveness observed between patients younger than 65 years of age and those 65 years of age or older 1
- The most common adverse events in geriatric patients include hypertension, urinary tract infections, headache, and nasopharyngitis 2
- Mirabegron does not significantly affect voiding urodynamic parameters, and the overall change in post-void residual volume is small in elderly patients 2
- In very elderly patients (>80 years), mirabegron has demonstrated effectiveness in treating overactive bladder symptoms with a favorable safety profile 3
Renal Considerations
- For patients with mild to moderate renal impairment (eGFR 30-89 mL/min/1.73m²), no dose adjustment is necessary 1
- In patients with severe renal impairment (eGFR 15-29 mL/min/1.73m²), the daily dose should not exceed 25 mg 1
- Mirabegron has not been studied in patients with End-Stage Renal Disease (eGFR <15 mL/min/1.73m²) or patients requiring hemodialysis and is therefore not recommended for these populations 1
- Excretion of unchanged mirabegron in urine increases with dose, from approximately 7% at 25 mg to 18% at 300 mg once daily 4
Cardiovascular Considerations
- Regular blood pressure monitoring is recommended, especially during the initial treatment period 2
- Mirabegron is contraindicated in patients with severe uncontrolled hypertension 2
- A systematic review of the cardiovascular safety profile of mirabegron has not identified any clinically significant effects on blood pressure or pulse rate at therapeutic doses among patients aged ≥65 years 5
Advantages Over Antimuscarinic Agents in Elderly
- Mirabegron has a significantly lower incidence of dry mouth compared to antimuscarinic agents (six-fold lower incidence than tolterodine ER in patients ≥65 years) 5
- Constipation, a common issue in elderly patients, occurs less frequently with mirabegron than with antimuscarinic agents 5
- Mirabegron does not contribute to anticholinergic burden, making it particularly suitable for elderly patients who are often on multiple medications with anticholinergic properties 5
- Mirabegron has a low incidence of central nervous system effects, an important consideration in elderly patients 5
Monitoring Recommendations
- Regular monitoring of blood pressure is essential, especially in patients with pre-existing hypertension 2
- In men with lower urinary tract symptoms, regular re-evaluation of symptoms and post-void residual volume is advised 2
- Patients should be instructed to discontinue medication if worsening voiding symptoms or urinary stream is noted after initiation of therapy 2
Dosing Considerations
- For elderly patients with normal renal function, standard dosing (25-50 mg daily) is appropriate 1
- In elderly patients with moderate hepatic impairment (Child-Pugh Class B), the daily dose should not exceed 25 mg 1
- Mirabegron has not been studied in patients with severe hepatic impairment (Child-Pugh Class C) and is therefore not recommended for this population 1
Common Pitfalls to Avoid
- Avoid using mirabegron in patients with severe uncontrolled hypertension 2
- Be aware that steady state is achieved within 7 days of once-daily administration, with an accumulation ratio of approximately 2 4
- Consider potential drug interactions, particularly in elderly patients who are often on multiple medications 2
- Remember that sex affects mirabegron exposure (women exhibit approximately 40% higher mirabegron concentrations than men), which may require consideration in frail elderly women 4