Which of the following drugs is used in severe hypertensive emergencies, is very short acting and must be given by i.v. infusion ?
**Core Concept**
The management of severe hypertensive emergencies requires the use of potent, rapidly acting antihypertensive agents that can be administered intravenously to achieve a rapid reduction in blood pressure. This concept is crucial in preventing target organ damage and improving patient outcomes.
**Why the Correct Answer is Right**
Nitroglycerin is a potent vasodilator that works by releasing nitric oxide, which relaxes vascular smooth muscle, leading to a decrease in peripheral resistance and a subsequent decrease in blood pressure. Its very short duration of action necessitates continuous intravenous infusion to maintain its effects. Nitroglycerin is particularly useful in the management of severe hypertensive emergencies, such as in the setting of aortic dissection or acute heart failure.
**Why Each Wrong Option is Incorrect**
**Option A:** Sodium nitroprusside is another potent vasodilator, but it is not typically used for severe hypertensive emergencies due to its potential for cyanide toxicity and the need for continuous monitoring of methemoglobin levels. It is often used in the management of malignant hypertension or acute heart failure.
**Option B:** Fenoldopam is a dopamine D1 receptor agonist that causes vasodilation and has a rapid onset of action. However, it is not typically used for severe hypertensive emergencies and is often used in the management of hypertensive crises in patients with renal insufficiency.
**Option C:** Enalaprilat is the active metabolite of the ACE inhibitor enalapril and is used to treat hypertension. However, it is not typically used in severe hypertensive emergencies due to its slower onset of action and the need for oral administration.
**Clinical Pearl / High-Yield Fact**
In the management of severe hypertensive emergencies, the goal is to rapidly reduce blood pressure to prevent target organ damage, such as cardiac, cerebral, or renal injury. Continuous monitoring of blood pressure and the use of potent, rapidly acting antihypertensive agents, such as nitroglycerin, are essential in achieving this goal.
**Correct Answer:** C. Enalaprilat is incorrect as per the explanation.