Lipid-lowering drugs: nicotinic acid: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Lipid-lowering drugs: nicotinic acid

Sample item

A man with raised triglycerides and low HDL cholesterol is started on nicotinic acid and has facial flushing. Which mechanism explains its triglyceride-lowering effect?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Activation of the GPR109A receptor in adipocytes, which inhibits hormone-sensitive lipase and reduces free fatty acid flux to the liver

Nicotinic acid (niacin) activates GPR109A on adipocytes, lowering cAMP and inhibiting hormone-sensitive lipase. Less free fatty acid reaches the liver, so VLDL synthesis falls and triglycerides and LDL decrease, while HDL rises. Flushing is mediated by prostaglandin D2 and is blunted by aspirin.

Option by option

  • A. Inhibition of intestinal NPC1L1 cholesterol uptake

    NPC1L1 inhibition is the action of ezetimibe.

  • B. Binding of bile acids in the intestinal lumen

    Bile acid binding is the action of resins such as cholestyramine.

  • C. Activation of PPAR-alpha, which increases lipoprotein lipase expression

    PPAR-alpha activation is the mechanism of fibrates, not niacin.

  • D. Activation of the GPR109A receptor in adipocytes, which inhibits hormone-sensitive lipase and reduces free fatty acid flux to the liver (correct)

    Reduced adipocyte lipolysis means less substrate for hepatic VLDL production.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Activation of the GPR109A receptor in adipocytes, which inhibits hormone-sensitive lipase and reduces free fatty acid flux to the liver. Nicotinic acid (niacin) activates GPR109A on adipocytes, lowering cAMP and inhibiting hormone-sensitive lipase.

Why is "Inhibition of intestinal NPC1L1 cholesterol uptake" not the answer?

NPC1L1 inhibition is the action of ezetimibe.

Why is "Binding of bile acids in the intestinal lumen" not the answer?

Bile acid binding is the action of resins such as cholestyramine.

Why is "Activation of PPAR-alpha, which increases lipoprotein lipase expressi…" not the answer?

PPAR-alpha activation is the mechanism of fibrates, not niacin.

What concept does this question test?

It tests Lipid-lowering drugs: nicotinic acid in Biochemistry. Less free fatty acid reaches the liver, so VLDL synthesis falls and triglycerides and LDL decrease, while HDL rises. Flushing is mediated by prostaglandin D2 and is blunted by aspirin.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Lipid-lowering drugs: nicotinic acid?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.