USMLE Step 2 Review 18 05 Drugs of Choice Hypertensive Crisis

USMLE Step 2 Review 18 05 Drugs of Choice Hypertensive Crisis

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Let’s start our USMLE Review with Drugs of Choice from the Gold Standard USMLE Step 2 Audio Review program.

Play USMLE Audio MP3 18 05 Drugs of Choice Hypertensive Crisis Below

 

Begin 18 05 Drugs of Choice Hypertensive Crisis Transcription

Until recently, what has been the drug of choice in the emergency room for almost all types of hypertensive crises, with the notable exception of pregnancy-induced hypertension, and is safe for children?

  • Nitroprusside.

And the trade name for Nitroprusside?

  • Nipride.

What 2 toxins may accumulate with long-term IV administration of Nitroprusside/Nipride that has caused some emergency departments to look for alternatives?

  • Thiocyanate and Cyanide.

Are these 2 toxins usually a problem with short-term use of Nitroprusside/Nipride?

  • No.

Despite this worry about toxicity, what sort of patient is Nitroprusside/Nipride especially beneficial for?

  • It’s especially beneficial for hypertensive patients who have heart failure.

And why is this?

  • Because Nitroprusside/Nipride produces venous dilation as well as arteriolar dilation.

And what is the benefit of dilating both the venous and arterial sides of the vasculature?

  • Both preload and afterload are reduced.

And this is especially helpful in what particular heart condition?

  • CHF- Congestive Heart Failure.

And what does Nitroprusside/Nipride first react with in the body, and what compound is formed?

  • It reacts with cysteine, and forms nitrocysteine.

And what does nitrocysteine then activate?

  • Guanylate cyclase.

What does guanylate cyclase cause the formation of?

  • Cyclic GMP.

And finally, what therapeutic action does cyclic GMP have?

  • In this case, it causes smooth muscle relaxation.

What vessels are relaxed and dilated, and what is the result in terms of cardiac burden?

  • Both arteries and veins are relaxed, resulting in reduced reload and afterload. The heart rate increases slightly which may be a problem in coronary artery insufficiency, but does not significantly elevate the blood pressure.

What causes the rise in heart rate due to Nitroprusside/Nipride?

  • Baroreceptor-mediated reflex.

What is the commonly accepted alternative to Nitroprusside/Nipride in the emergency department, which is used when Nitroprusside/Nipride fails, or is used as the first line agent in hypertensive crises involving coronary artery disease, cerebral artery disease, excessive catecholamine syndromes, MAO Inhibitor induced emergencies, and abrupt clonidine withdrawal?

  • Lebatalol.

What are 2 trade names for labetalol?

  • Normodyne, Trandate.

What class of drug is Lebatalol/Normodyne/Trandate?

  • A cardioselective alpha-1 blocker and a nonselective beta blocker. In both cases, a competitive inhibitor.

What type of tumor is most commonly associated with excessive catecholamine release?

  • Pheochromocytoma.

Now, where are pheochromocytomas usually found and from what cells?

  • In the adrenal medulla, arising from chromaffin cells.

Pheochromocytomas may also arise in other locations. What is the embryological origin of the type of tissue they arise from, no matter the location?

  • Tissue from neural crest cells.

What 2 drugs are used together as drugs of choice in treating hypertensive crisis due to pregnancy induced hypertension?

  • Magnesium sulfate and hydralazine.

****END OF TRANSCRIPTION****

 

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