Which of the following antimalarial agents is most commonly associated with acute hemolytic reaction in patients with glucose-6- phosphate dehydrogenase deficiency?
First, the core concept here is understanding which antimalarial drugs cause hemolysis in G6PD-deficient individuals. G6PD is an enzyme that protects red blood cells from oxidative stress. When someone with a deficiency takes a drug that induces oxidative stress, hemolysis occurs.
Primaquine is a well-known culprit here. It's a 8-aminoquinoline, and it's used for both the radical cure of P. vivax malaria and as a prophylactic. The mechanism involves generating reactive oxygen species, which red blood cells with G6PD deficiency can't handle, leading to hemolysis.
Now, the wrong options. Chloroquine is a 4-aminoquinoline, and while it's effective against P. falciparum, it doesn't cause hemolysis in G6PD deficiency. Artemisinin derivatives like artemether are safe in G6PD deficiency and are part of artemisinin-based combination therapies (ACTs). Mefloquine is another antimalarial used for prophylaxis and treatment, but it's not associated with hemolysis in this context.
Clinical pearls: Remember that 8-aminoquinolines (Primaquine) are the big ones. Also, check G6PD status before prescribing Primaquine. A mnemonic could be "8-ox" for the 8-aminoquinolines causing issues.
Need to make sure each section is concise, uses the right terms, and fits within the character limit. Let me structure the explanation with the required sections and check each part for accuracy and clarity.
**Core Concept**
Acute hemolytic anemia in glucose-6-phosphate dehydrogenase (G6PD) deficiency is triggered by oxidative stress. Antimalarials like **primaquine**, an 8-aminoquinoline, induce oxidative damage to red blood cells lacking sufficient G6PD activity, leading to hemolysis.
**Why the Correct Answer is Right**
Primaquine generates reactive oxygen species (ROS) during its metabolism, which G6PD-deficient red blood cells cannot detoxify due to impaired NADPH production. This ROS accumulation causes hemoglobin oxidation and membrane damage, resulting in acute hemolysis. Primaquine is specifically used for radical cure of *Plasmodium vivax* hypnozoites but is contraindicated in G6PD deficiency.
**Why Each Wrong Option is Incorrect**
**Option A:** Chloroquine (4-aminoquinoline) does not induce oxidative stress and is safe in G6PD deficiency.
**Option B:** Artemether (a sesquiterpene lactone) is metabolized to artemisinin, which does not cause hemolysis in G6PD deficiency.
**Option D:** Mefloquine (a quinoline methanol derivative) lacks oxidative properties and is not linked to hemolysis in this context.
**Clinical Pearl / High-Yield Fact**
Remember the "8-ox" rule: 8-aminoquinolines (e.g., primaquine) and oxidant agents (e