A 68-year-old man with hypertension presents to the emergency department with acute onset chest pain, diaphoresis, and dyspnea. Vital signs are BP 210/135 mmHg, HR 125/min, RR 24/min, O2 saturation 94% on room air. Physical examination reveals an anxious, diaphoretic patient with clear lungs. ECG shows sinus tachycardia without ischemic changes. Troponin is negative. The patient is administered intravenous labetalol for hypertensive emergency. Which of the following best explains the pharmacologic advantage of labetalol over a pure beta-blocker in this clinical scenario?
- A)Beta-1 selectivity prevents bronchospasm and allows unopposed alpha-2 receptor activation
- B)Combined alpha and beta-adrenergic blockade produces vasodilation while preventing reflex tachycardiaGABARITO
- C)Intrinsic sympathomimetic activity maintains cardiac output and prevents hypotension
- D)Selective beta-2 blockade in coronary vessels improves myocardial perfusion
- E)Dual inhibition of ACE and renin-angiotensin system reduces afterload
Explicação
Labetalol is a combined alpha-1 and non-selective beta-adrenergic antagonist with approximately 4-7 times greater beta-blocking potency than alpha-blocking potency. In hypertensive emergency, pure beta-blockers can paradoxically worsen hypertension by allowing... Ver explicação completa e trilha adaptativa →