Mirabegron, used for overactive bladder, acts through which mechanism distinct from traditional anticholinergic agents?
- A Selective beta-3 adrenoceptor agonist causing detrusor relaxation ✓
- B M3 muscarinic antagonist with urothelial selectivity
- C Potassium channel opener reducing afferent nerve firing
- D Alpha-1D adrenoceptor antagonist reducing urethral tone
Correct answer: A. Selective beta-3 adrenoceptor agonist causing detrusor relaxation
Explanation
Mirabegron is a selective beta-3 adrenoceptor agonist. Beta-3 receptors are the predominant adrenoceptor subtype on the bladder detrusor muscle; their activation by mirabegron promotes detrusor relaxation and increases bladder storage capacity. Unlike anticholinergic agents (oxybutynin, solifenacin), mirabegron does not cause dry mouth, constipation, or cognitive impairment, making it preferable in elderly patients. Its main adverse effects are hypertension and tachycardia.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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