Question
Chloroquine
Answer
Chloroquine is a 4-aminoquinoline blood schizonticide.
MOA: chloroquine → accumulates in the parasite’s acidic food vacuole (ion-trapped as a weak base) → inhibits haem polymerase → blocks conversion of toxic free haem (released during hemoglobin digestion) into inert haemozoin → toxic free haem accumulates and kills the parasite.
Uses: treatment of P. vivax malaria (still largely effective), chemoprophylaxis, rheumatoid arthritis/lupus (immunomodulatory property, distinct from its antimalarial mechanism).
Adverse effects: retinopathy (irreversible, dose/duration-related — periodic ophthalmologic monitoring with long-term use), pruritus (notably common in patients of West African descent), QT prolongation at high doses. Widespread resistance (via the PfCRT transporter pumping the drug out of the food vacuole) has substantially limited its use against P. falciparum.

