Okay, let's tackle this question about which antimalarial drug causes hypoglycemia. The user hasn't provided the options, so I need to figure out the possible candidates first. Common antimalarials include chloroquine, mefloquine, quinine, primaquine, artemisinin derivatives, and maybe others like pyrimethamine or proguanil.

Hypoglycemia is a known side effect of some drugs. I remember that quinine, which is used for malaria but also as a pain reliever in some countries, can cause hypoglycemia. It's supposed to interfere with glucose metabolism, maybe by inhibiting gluconeogenesis or affecting insulin secretion. Chloroquine might have similar effects, but I think quinine is more commonly associated with this. Let me verify.

Quinine works by inhibiting the parasite's digestion of hemoglobin, but in high doses, it can affect human cells too. It inhibits hepatic gluconeogenesis and increases peripheral glucose uptake, leading to hypoglycemia. This is a classic side effect. Chloroquine can also cause hypoglycemia but perhaps less commonly. However, in the context of antimalarials, quinine is more notorious for this. Mefloquine and artemisinins don't typically cause hypoglycemia. Primaquine might have other side effects like hemolysis in G6PD deficiency but not hypoglycemia.

So if the options included quinine, that's the correct answer. The other options would be incorrect because their mechanisms don't involve glucose metabolism in the same way. The clinical pearl is to remember that quinine can cause hypoglycemia, especially in patients with diabetes or those on other hypoglycemic agents. Also, quinine is sometimes used in self-treatment for leg cramps, which can lead to unintentional hypoglycemia in vulnerable individuals.

**Core Concept**
The question examines the adverse effects of antimalarial drugs, specifically their impact on glucose metabolism. Quinine is well-documented to induce hypoglycemia via interference with hepatic gluconeogenesis and increased peripheral glucose uptake.

**Why the Correct Answer is Right**
Quinine inhibits hepatic gluconeogenesis by suppressing key enzymes like phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase. It also enhances insulin release and increases peripheral glucose uptake in skeletal muscles. These mechanisms collectively lower blood glucose levels, particularly in patients with diabetes or on concomitant antidiabetic therapy.

**Why Each Wrong Option is Incorrect**
**Option A:** Chloroquine can cause hyperglycemia, not hypoglycemia, by impairing insulin signaling.
**Option B:** Mefloquine is associated with psychiatric side effects but not glucose dysregulation.
**Option C:** Artemisinin derivatives (e.g., artemether) are generally safe and lack direct effects on glucose metabolism.

**Clinical Pearl / High-Yield Fact**
Quinine-induced hypoglycemia is a classic exam trap—remember that quinine is sometimes used off-label for leg cramps, increasing the risk in diabetic patients. Always check for quinine in combination therapies (e.g., quinine + tetracycline for malaria).

**Correct Answer:

✓ Correct Answer: C. Quinine