Mirabegron
Summary
A beta-3 adrenergic agonist used to treat overactive bladder by relaxing detrusor smooth muscle. Unlike anticholinergics, it does not cause cognitive or urinary retention side effects.
Detail
Mirabegron is a selective beta-3 adrenergic receptor agonist for overactive bladder (OAB) with symptoms of urgency, frequency, and nocturia. Beta-3 receptors on the detrusor muscle trigger relaxation via cAMP-dependent pathways, increasing bladder capacity and reducing involuntary contractions. Mirabegron avoids anticholinergic side effects (dry mouth, constipation, cognitive impairment), making it particularly valuable in elderly patients. However, it can elevate blood pressure and is contraindicated in severe uncontrolled hypertension. Typical dosing is 25-50 mg once daily; efficacy is comparable to anticholinergics.
Sources
- First Aid for the USMLE Step 1
- Katzung Basic & Clinical Pharmacology
- Harrison's Principles of Internal Medicine
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