Chloroquine
Chloroquine is an antimalarial medication that has been in use for several decades. It's primarily used for the treatment and prophylaxis of malaria. Besides its antimalarial effects, chloroquine has been utilized in the treatment of autoimmune diseases like rheumatoid arthritis and lupus erythematosus. Its mechanism of action involves inhibiting the growth of parasites in the red blood cells for malaria, and for autoimmune diseases, its exact mechanism is less understood, but it's believed to modulate the immune response.