Malaria Prophylaxis and Chemotherapy

Chemoprophylaxis for Malaria

• Travelers visiting countries with common malaria are strongly encouraged to undergo chemoprophylaxis using five drugs: chloroquine, malarone, mefloquine, doxycycline, and primaquine.
• These drugs are used depending on the type of malaria and the area of travel.

Chloroquine

• Chloroquine is the oldest antimalarial drug and is commonly used but also misused, leading to high rates of resistance in most countries affected by malaria.
• It is still an effective drug but its use is restricted to areas without resistance.
• Chloroquine is a highly effective blood schizonticide, but it has no effect against other forms of malaria, such as liver stage parasites.
• The mechanism of action involves inhibiting the metabolism of heme groups, which are toxic to malarial parasites.
• Resistance to chloroquine is common among strains of P.falciparum and is increasing for P.vivax.

Resistance to Chloroquine

• Mutations in the PfCRT (P.falciparum chloroquine resistance transporter) are the primary mediators of resistance.
• Chloroquine resistance can be reversed by certain agents, including verapamil, desipramine, and chlorpheniramine.

Pharmacokinetics of Chloroquine

• Chloroquine is rapidly absorbed after oral administration, reaching Tmax in about 3 hours.
• It is rapidly distributed to tissues, including crossing the blood-brain barrier and placenta.
• It concentrates heavily in the spleen, kidneys, lungs, and leukocytes.
• It is excreted into the urine and has an early half-life of 3-5 days and an elimination half-life of 1-2 months.
• It exhibits a very long terminal elimination half-life.

Indications and Clinical Applications of Chloroquine

• Chloroquine is the drug of choice in areas without parasitic resistance and for uncomplicated non-falciparum and sensitive falciparum malaria.
• It is a wide-spectrum drug for parasites but clinical resistance is very high.
• It does not eliminate hypnozoites of P.vivax and ovale, so primaquine must be added to completely eradicate these hypnozoites.
• Chloroquine is safe to use in pregnancy.

This quiz covers the different drugs used for the treatment and prevention of malaria, including chloroquine, malarone, mefloquine, doxycycline, and primaquine.