**Question:** Drug useful in chloroquine resistant malaria is

A. Artemisinin
B. Quinine
C. Mefloquine
D. Primaquine

**Correct Answer:** A. Artemisinin

**Core Concept:** Malaria is a mosquito-borne infectious disease caused primarily by Plasmodium species, particularly Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. Chloroquine-resistant malaria has emerged as a significant global health concern due to the widespread use of chloroquine as the primary treatment option.

**Why the Correct Answer is Right:** Artemisinin is a class of antimalarial drugs derived from the Chinese traditional herb, Artemisia annua (sweet wormwood). Artemisinin and its derivatives, such as artemether, artesunate, dihydroartemisinin, and artelinic acid, are highly effective against chloroquine-resistant Plasmodium species. These drugs are considered first-line treatment for uncomplicated Plasmodium falciparum malaria in many countries.

**Why Each Wrong Option is Incorrect:**

B. Quinine: Quinine is an older antimalarial drug primarily used for severe malaria cases and not the first-line treatment for uncomplicated malaria due to its limited efficacy in treating chloroquine-resistant Plasmodium species.

C. Mefloquine: Mefloquine is an antimalarial drug with a relatively low success rate against chloroquine-resistant Plasmodium species. It is mainly used for chemoprophylaxis (preventive therapy) rather than for treating malaria cases.

D. Primaquine: Primaquine is an antimalarial drug that targets the dormant parasite forms (e.g., hypnozoites) in the liver, preventing relapses of Plasmodium vivax and Plasmodium ovale malaria. However, it is not effective against Plasmodium falciparum and chloroquine-resistant Plasmodium species.

**Clinical Pearl:** Artemisinin-based combination therapies (ACTs) are recommended as first-line treatment for uncomplicated Plasmodium falciparum malaria due to their high efficacy against chloroquine-resistant Plasmodium species. These drugs are effective against both asexual and sexual stages of the Plasmodium life cycle, making them a superior choice to single-agent antimalarial drugs.