What is the drug of choice to treat malignant hypertension?

AIIMS Delhi NO-2016

Pharmacology

Easy

Appeared in: AIIMS Delhi NO-2016

Explanation

Malignant hypertension is a hypertensive emergency requiring immediate parenteral drug therapy to prevent target organ damage.
Sodium nitroprusside is a potent, direct-acting vasodilator that works on both arterial and venous smooth muscle.
Its key advantages are an almost instantaneous onset of action and a very short duration (1-10 minutes), allowing for precise, titratable control of blood pressure via IV infusion.
This rapid titratability is crucial to lower blood pressure in a controlled manner, avoiding the danger of excessive or precipitous drops that could compromise organ perfusion.

Option B: Atenolol is a beta-blocker used for long-term, chronic management of hypertension. Its onset is too slow and it lacks the potency required for an emergency.
Option C: Amlodipine is a long-acting oral calcium channel blocker. It is used for maintenance therapy and is completely unsuitable for a hypertensive emergency requiring rapid IV intervention.
Option D: While Nitroglycerin is an IV vasodilator, it primarily acts on veins (venodilator). It is less potent in reducing arterial pressure compared to sodium nitroprusside.

Clinical Relevance

Nursing practice connection: Knowing Pharmacological management of hypertensive emergencies helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must protect sodium nitroprusside infusions from light by wrapping the IV bag and tubing in the supplied opaque cover, as the drug is photosensitive and degrades upon exposure.
Continuous intra-arterial blood pressure monitoring is the standard of care during nitroprusside administration due to its potency. This allows for immediate feedback to titrate the dose accurately and prevent dangerous hypotension.
Monitor for signs of cyanide toxicity (e.g., metabolic acidosis, altered mental status, seizures) with prolonged use, especially in patients with renal impairment, as the drug is metabolized to cyanide and then thiocyanate.

How to Approach the Question

First, identify the clinical condition in the stem: 'Malignant hypertension' is a critical term for a hypertensive emergency.
Next, understand the question's requirement: It asks for the 'drug of choice,' which implies the most standard, effective, and often first-line agent for this acute condition.
Evaluate the options based on their drug class, route of administration, and primary use. Differentiate between drugs for acute emergencies (IV, rapid-acting) and those for chronic management (oral, long-acting).
Eliminate Atenolol and Amlodipine as they are oral medications for chronic hypertension.
Compare the remaining IV options, Sodium Nitroprusside and Nitroglycerin. Recall that Sodium Nitroprusside is a balanced and highly potent arterial and venous vasodilator, making it a standard choice for rapid BP control. Nitroglycerin is more specific for conditions involving myocardial ischemia.
Conclude that Sodium Nitroprusside is the most appropriate general 'drug of choice' among the given options for a hypertensive emergency.

Concept Tested & Keywords

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E6 Pharmacology Katzung 16e pp. 290-292, 278-280

E6 Pharmacology KD Tripathi Essentials 9e Part 2 p. 245-247