What is the use of Mirabegron (Beta-3 adrenergic agonist)?

From the Guidelines

Mirabegron is a recommended treatment for overactive bladder (OAB) symptoms, including urinary urgency, frequency, and incontinence, as evidenced by the most recent guideline from 2024 1.

Key Points

• The standard starting dose of mirabegron is 25 mg once daily, which can be increased to 50 mg daily if needed and tolerated.
• Mirabegron works by activating beta-3 adrenergic receptors in the bladder, increasing bladder capacity without affecting contraction strength during voiding.
• Common side effects include headache, increased blood pressure, urinary tract infections, and nasal congestion.
• It is essential to monitor blood pressure while taking this medication, especially in patients with hypertension.
• Mirabegron is contraindicated in patients with severe uncontrolled hypertension and should be used cautiously in those with bladder outlet obstruction or taking medications metabolized by CYP2D6.

Clinical Considerations

• Full therapeutic effects may take 8-12 weeks to develop, so patients should continue treatment even if immediate benefits aren't apparent.
• Clinicians should offer antimuscarinic medications or beta-3 agonists, such as mirabegron, to patients with OAB to improve urinary urgency, frequency, and/or urgency urinary incontinence, as recommended by the AUA/SUFU guideline 1.
• For patients with benign prostatic hyperplasia (BPH) and OAB, monotherapy with antimuscarinic medications or beta-3 agonists, or combination therapy with an alpha blocker and an antimuscarinic medication or beta-3 agonist, may be considered 1.

Evidence Summary

• The BESIDE trial (2016) evaluated the efficacy and safety of combination therapy with solifenacin and mirabegron, showing that the combination was superior to monotherapy in reducing incontinence episodes and micturitions per 24 hours 1.
• The SYNERGY II trial (2018) demonstrated the safety and efficacy of combination therapy with solifenacin and mirabegron over 12 months, with statistically significant improvements in incontinence episodes and micturitions per 24 hours compared to monotherapy 1.

From the FDA Drug Label

Mirabegron extended-release tablets are a beta-3 adrenergic agonist indicated for the treatment of: Overactive bladder (OAB) in adult patients with symptoms of urge urinary incontinence, urgency, and urinary frequency. The recommended starting dose of mirabegron extended-release tablets is 25 mg orally once daily. After 4 to 8 weeks, the mirabegron extended-release tablets dose may be increased to 50 mg orally once daily.

Mirabegron is used to treat Overactive Bladder (OAB) in adults and Neurogenic Detrusor Overactivity (NDO) in pediatric patients.

• The recommended starting dose is 25 mg orally once daily.
• The dose may be increased to 50 mg orally once daily after 4 to 8 weeks. 2

From the Research

Mirabegron Overview

• Mirabegron is a β3-adrenoceptor agonist used to treat overactive bladder (OAB) symptoms 3, 4, 5, 6, 7
• It has a different mechanism of action compared to antimuscarinic agents, which are traditionally used to treat OAB 4, 6

Efficacy

• Mirabegron has been shown to be effective in treating OAB symptoms, including micturition frequency, urgency incontinence, and urgency 3, 4, 5, 6, 7
• It has been compared to antimuscarinic agents, such as tolterodine and solifenacin, and has been found to have similar efficacy 3, 6
• Mirabegron has also been shown to be effective in combination with solifenacin, with improved efficacy compared to mirabegron alone 3

Safety and Tolerability

• Mirabegron has been found to be well-tolerated, with a lower incidence of dry mouth compared to antimuscarinic agents 3, 4, 6, 7
• It has also been found to have a lower incidence of constipation and urinary retention compared to some antimuscarinic agents 3
• The most common adverse events associated with mirabegron are hypertension, nasopharyngitis, and urinary tract infection 4

Special Populations

• Mirabegron has been found to be effective and well-tolerated in elderly patients and those with poor tolerability to antimuscarinics 5
• It has also been found to be effective in male patients and those from different geographic areas, including Asia 5

Comparison to Antimuscarinics

• Mirabegron has been found to have similar efficacy to antimuscarinic agents, but with a more favorable safety and tolerability profile 3, 6
• It has been found to have a lower incidence of dry mouth and other anticholinergic side effects compared to antimuscarinic agents 3, 6