Labetalol is unique among beta-blockers used for hypertensive emergencies because it:

• A Selectively blocks cardiac beta-1 receptors without any alpha-blocking activity
• B Acts centrally to reduce sympathetic outflow from the vasomotor center
• C Combines alpha-1 and beta (beta-1 + beta-2) blockade, lowering BP without reflex tachycardia ✓
• D Has intrinsic sympathomimetic activity preventing excessive bradycardia

Explanation

Labetalol blocks alpha-1 adrenoceptors (reducing peripheral vascular resistance) as well as beta-1 and beta-2 receptors (reducing cardiac output and preventing reflex tachycardia triggered by vasodilatation). The oral ratio of alpha:beta blockade is approximately 1:3; IV ratio is 1:7. This combined blockade makes it especially useful in hypertensive emergencies including hypertension of pregnancy and aortic dissection.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.