Mirabegron is a novel β3-adrenergic receptor agonist developed for the treatment of overactive bladder (OAB) syndrome. It offers an alternative therapeutic approach by relaxing the detrusor muscle, thereby increasing bladder storage capacity and reducing symptoms such as urinary urgency, frequency, and incontinence. It was first approved in Japan in July 2011, followed by regulatory approvals in the United States (FDA) in June 2012, the European Union (EMA) in December 2012, and subsequently in several other countries worldwide.
BRAND NAMES
Myrbetriq: Myrbetriq (Mirabegron) prescribed for overactive bladder. It works by relaxing the bladder muscle and is typically taken once daily, starting at 25 mg and can be increased to 50 mg if needed.
Betanis: Betanis (Mirabegron) used in Japan to treat overactive bladder by relaxing the bladder muscle. It’s taken once daily, starting at 25 mg, and can be increased to 50 mg based on response.
Miragron: Miragron is an Indian brand of mirabegron used to treat overactive bladder. It is taken once daily as a 25 mg extended-release tablet, which can be increased to 50 mg based on patient response.
MECHANISM OF ACTION
PHARMACOKINETICS
Absorption
Mirabegron is well absorbed orally, with a bioavailability of approximately 29% to 35% due to first-pass metabolism.
Distribution
It exhibits a large volume of distribution of approximately 1670 liters, reflecting extensive distribution throughout body tissues. Approximately 71% to 72% bound to plasma proteins.
Metabolism
Mainly metabolized in the liver via multiple pathways including CYP3A4, CYP2D6, and other non-CYP enzymes
Elimination
Ranges from 50 to 60 hours, allowing once-daily dosing. The drug is mainly eliminated as metabolites, with about 55% excreted through urine and 34% through feces.
DOSAGE AND ADMINISTRATION
Mirabegron is administered orally, starting at 25 mg once daily, with the possibility of increasing to 50 mg once daily based on clinical response and tolerability; it can be taken with or without food, and dose modifications are recommended for patients with moderate to severe renal or hepatic impairment to minimize the risk of adverse effects, with treatment duration tailored according to symptom control.
DRUG INTERACTIONS
CONTRAINDICATIONS
SIDE EFFECTS
TOXICITY