Which of the following drug may cause hypertensive crisis in a patient on MAO inhibitor therapy ?
**Core Concept**
The question is testing the student's knowledge of drug interactions, specifically the potential for hypertensive crisis in a patient taking monoamine oxidase inhibitors (MAOIs) and another drug. MAOIs inhibit the enzyme monoamine oxidase, which breaks down certain neurotransmitters, including norepinephrine, serotonin, and dopamine.
**Why the Correct Answer is Right**
When a patient on MAOI therapy takes a drug that releases or inhibits the same neurotransmitters, it can lead to a sudden and dangerous increase in blood pressure. The correct answer is a drug that contains tyramine, a naturally occurring amino acid that is a potent stimulator of the sympathetic nervous system. When tyramine is ingested in large amounts, it can cause a massive release of norepinephrine, leading to a hypertensive crisis. This is because the MAOI has inhibited the breakdown of norepinephrine, allowing it to accumulate and cause a severe increase in blood pressure.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not contain tyramine. A drug that does not contain tyramine would not cause a hypertensive crisis in a patient on MAOI therapy.
* **Option B:** This option is incorrect because it is a beta-blocker, which would actually lower blood pressure, not cause a hypertensive crisis.
* **Option D:** This option is incorrect because it is an ACE inhibitor, which would also lower blood pressure and is not associated with a hypertensive crisis in patients on MAOI therapy.
**Clinical Pearl / High-Yield Fact**
A classic exam trap is to remember that MAOIs can interact with foods that contain tyramine, such as aged cheese, red wine, and certain types of fish. These foods should be avoided by patients on MAOI therapy to prevent a hypertensive crisis.
**Correct Answer:** C.