Myrbetriq (Mirabegron) Uses and Indications
Myrbetriq (mirabegron) is a beta-3 adrenergic agonist primarily indicated for the treatment of overactive bladder (OAB) in adults with symptoms of urge urinary incontinence, urgency, and urinary frequency, and for neurogenic detrusor overactivity (NDO) in pediatric patients aged 3 years and older weighing 35 kg or more. 1
Primary Indications
- Mirabegron is approved for treating overactive bladder syndrome in adults who experience symptoms including urinary urgency, increased micturition frequency, and/or urgency incontinence 1
- It is also indicated for neurogenic detrusor overactivity in pediatric patients aged 3 years and older who weigh at least 35 kg 1
- Mirabegron works as a selective beta-3 adrenoceptor agonist that enhances storage function and relaxes the urinary bladder, improving OAB symptoms 2
Treatment Algorithm for OAB
- First-line therapy should include behavioral interventions such as bladder training, pelvic floor exercises, and fluid management 3, 4
- For pharmacological treatment, mirabegron 25 mg is recommended as the starting dose, which may be increased to 50 mg after 4-8 weeks if needed 1
- Mirabegron offers an alternative to antimuscarinic medications, particularly for patients who experience inadequate response or intolerable side effects from antimuscarinic agents 4, 2
- Combination therapy with mirabegron 50 mg plus solifenacin 5 mg has demonstrated superior efficacy compared to either monotherapy alone for reducing urinary incontinence episodes and micturitions 3, 4
Efficacy Profile
- Clinical trials have shown that mirabegron doses of 25-200 mg result in dose-dependent reductions in micturition frequency compared to placebo 5
- Mirabegron has demonstrated improvements in multiple OAB parameters including mean number of incontinence episodes, urgency episodes, and volume voided per micturition 6
- Efficacy has been observed in patients who previously discontinued antimuscarinic therapy due to lack of efficacy or poor tolerability 7
Special Populations and Dosing Considerations
- In older patients with OAB and multiple comorbidities, mirabegron 25 mg has demonstrated safety and therapeutic efficacy 3, 4
- For patients with severe renal impairment (eGFR 15-29 mL/min/1.73 m²), the daily dose should not exceed 25 mg 1
- For patients with moderate hepatic impairment (Child-Pugh Class B), the daily dose should not exceed 25 mg 1
- Mirabegron is not recommended for patients with severe hepatic impairment (Child-Pugh Class C) or end-stage renal disease 1
Safety Considerations and Monitoring
- The most common adverse events include hypertension, nasopharyngitis, urinary tract infections, and headache 8, 6
- Mirabegron is contraindicated in patients with severe uncontrolled hypertension 8, 1
- Regular blood pressure monitoring is recommended, especially during the initial treatment period 8
- In men with lower urinary tract symptoms, regular re-evaluation of symptoms and post-void residual volume is advised 8
- Caution is advised when prescribing mirabegron to frail elderly patients who may have a lower therapeutic index and higher adverse event profile 8