Question

Which of the following is a Proliferator-Activated Receptor-Alpha (PPAR-α) agonist?

• A. Sulfonylurea
• B. Metformin
• C. Acarbose
• D. Pioglitazone

Hint:

PPAR-α agonists mainly affect lipid metabolism (fibrates), PPAR-γ agonists improve insulin sensitivity (thiazolidinediones like pioglitazone).

Answer 1

The Correct Option is D

Proliferator-Activated Receptors (PPARs) are nuclear receptor proteins that function as transcription factors regulating the expression of genes. There are three subtypes: PPAR-$α$, PPAR-$γ$, and PPAR-$β/δ$, each with distinct roles in metabolism. - PPAR$α$ agonists mainly regulate lipid metabolism, increasing fatty acid oxidation, and are primarily targeted by fibrates (e.g., fenofibrate). - PPAR-$γ$ agonists regulate glucose metabolism and insulin sensitivity and are the targets of thiazolidinediones (TZDs) such as pioglitazone and rosiglitazone. - Although the question mentions PPAR-$α$, pioglitazone primarily acts as a PPAR-$γ$ agonist; however, pioglitazone also exhibits some affinity for PPAR-$α$, contributing to its beneficial effects on lipid metabolism besides glucose control. - Sulfonylureas stimulate insulin release from pancreatic $β$-cells. - Metformin acts by reducing hepatic glucose production and increasing insulin sensitivity but does not act via PPARs. - Acarbose is an alpha-glucosidase inhibitor delaying carbohydrate absorption in the intestine. Thus, among the given options, pioglitazone is the closest PPAR agonist, specifically PPAR-$γ$, but also with some PPAR $α$ activity, making it the correct answer.

Answer 2

PPARs are nuclear receptors that control gene expression tied to glucose and lipid metabolism, and different diabetes drug classes work through completely different targets. Checking whether each option touches PPAR signaling at all narrows this down fast.

1. Sulfonylurea: Sulfonylureas close ATP-sensitive potassium channels on pancreatic beta cells, which triggers insulin release. This mechanism has nothing to do with nuclear PPAR receptors.
2. Metformin: Metformin lowers blood glucose mainly by reducing hepatic glucose output and activating AMP-activated protein kinase (AMPK). It does not act through PPAR receptors either.
3. Acarbose: Acarbose works locally in the gut, inhibiting alpha-glucosidase enzymes so carbohydrates are absorbed more slowly. This is a purely local, enzyme-based mechanism with no PPAR involvement.
4. Pioglitazone: Pioglitazone belongs to the thiazolidinedione class, and its main action is on PPAR-gamma, improving insulin sensitivity in fat and muscle tissue. Along with this, it also shows measurable agonist activity at PPAR-alpha, which helps explain the improvements in triglyceride and HDL levels often seen with this drug. Among the four options, it is the only one with any PPAR-alpha activity at all.

Since sulfonylureas, metformin, and acarbose act through entirely non-PPAR pathways, pioglitazone is the only drug here with genuine PPAR-alpha agonist activity, alongside its stronger PPAR-gamma effect.

So the correct answer is Pioglitazone.