Question

Which of the following is a Partial Fatty acid oxidation (pFox) inhibitor:

• A. \( \text{Trimetazidine} \)
• B. \( \text{Atosiban} \)
• C. \( \text{Verapamil} \)
• D. \( \text{Nicardipine} \)

Hint:

pFox inhibitors like Trimetazidine are beneficial in chronic stable angina by improving myocardial energy efficiency. They are often used as adjunct therapy when standard treatments are insufficient.

Answer 1

The Correct Option is A

Step 1: Understanding pFox inhibitors. Partial Fatty acid oxidation (pFox) inhibitors, such as Trimetazidine, work by shifting myocardial energy metabolism from fatty acid oxidation to glucose oxidation. This is more oxygen-efficient and helps improve cardiac efficiency, especially in conditions like ischemic heart disease. 

Step 2: Explanation of Trimetazidine. Trimetazidine is the prototype pFox inhibitor. It selectively inhibits long-chain 3-ketoacyl-CoA thiolase (an enzyme involved in fatty acid oxidation), thereby enhancing glucose oxidation and reducing myocardial oxygen demand. 

Step 3: Comparison with other options. - Option \( (B) \): Atosiban is an oxytocin receptor antagonist used in preterm labor, not a pFox inhibitor. 
- Option \( (C) \): Verapamil is a calcium channel blocker used for angina and arrhythmias, not a pFox inhibitor. 
- Option \( (D) \): Nicardipine is also a calcium channel blocker and not related to fatty acid oxidation. 

Conclusion: Trimetazidine is the correct answer as a pFox inhibitor.

Answer 2

This question asks which drug acts as a partial fatty acid oxidation (pFox) inhibitor, a class of anti-anginal drugs that work by changing which fuel the heart muscle burns. A good way to answer is to sort each drug by its known pharmacological class and check whether that class fits the pFox mechanism.

1. Trimetazidine: This drug blocks long chain 3-ketoacyl CoA thiolase, an enzyme the heart muscle needs to burn fatty acids. With fatty acid burning reduced, the heart shifts to burning glucose instead, which needs less oxygen for the same amount of energy. This is exactly the pFox mechanism, so this drug fits.
2. Atosiban: This drug blocks oxytocin receptors in the uterus and is given to stop preterm labor. It has no effect on how heart muscle chooses its fuel, so it is not a pFox inhibitor.
3. Verapamil: This is a calcium channel blocker. It lowers heart rate and blood pressure by limiting calcium entry into muscle cells, helping angina through a completely different route than fuel switching.
4. Nicardipine: This is also a calcium channel blocker, closely related to verapamil in its action of relaxing blood vessels. Like verapamil, it works on calcium channels, not on fatty acid metabolism.

Only one of the four drugs actually changes the heart's fuel preference from fat to glucose, which is the defining feature of a pFox inhibitor.

Therefore, the correct answer is Trimetazidine.