Chloroquine

Antimalarial — 4-Aminoquinoline

Nigerian brand names:ChloroquinMalareichCamoquin (amodiaquine)Resochin

Reviewed by the PMC Medical Team · Promise Medical Centre

Overview

Chloroquine is one of the oldest and most well-known antimalarial drugs in the world. It works by accumulating in the parasite's digestive vacuole and interfering with haem detoxification, which kills the malaria parasite. Once the first-line treatment for malaria in Nigeria, chloroquine lost this status due to widespread resistance of Plasmodium falciparum — the most dangerous malaria parasite. It is now reserved for areas where malaria remains sensitive to it (mainly Plasmodium vivax and Plasmodium ovale infections, and some specific locations). Chloroquine also has anti-inflammatory properties and is used in rheumatoid arthritis and lupus.

Uses

Chloroquine is used to: - Treat uncomplicated malaria caused by Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae (where these species are confirmed or suspected, and the parasite is still sensitive) - NOT recommended as first-line treatment for Plasmodium falciparum malaria in Nigeria due to near-universal resistance — artemisinin-based combination therapies (ACTs) are used instead - Rheumatoid arthritis (long-term, low-dose treatment) - Systemic lupus erythematosus (SLE) — reduces disease flares and organ damage - Prevention of malaria in areas where Plasmodium vivax remains sensitive (not applicable for most of Nigeria) Note: Hydroxychloroquine (a related, better-tolerated drug) is now preferred over chloroquine for rheumatic conditions.

How to Use

For malaria treatment (adults): Standard regimen: 600 mg base (1000 mg salt) on day 1, then 300 mg base (500 mg salt) at 6, 24, and 48 hours. Total dose: 1500 mg base over 3 days. - Take with or after food to reduce nausea - Swallow tablets whole with plenty of water - Complete the full course even if feeling better - Do not use chloroquine for falciparum malaria in Nigeria — it will not work against resistant parasites For lupus/rheumatoid arthritis: 150–250 mg daily (long-term, as prescribed by a rheumatologist).

Side Effects

Common side effects: - Nausea, vomiting, stomach cramps — usually mild when taken with food - Headache - Dizziness - Itching (pruritus): Chloroquine causes significant itching in dark-skinned individuals — this is very common among Nigerians and can be severe enough to stop treatment; antihistamines may help but are not always effective - Visual disturbances (blurred vision, halos around lights) — usually at high or prolonged doses Serious side effects (with long-term use — eye and heart): - Retinopathy (chloroquine eye disease): Permanent damage to the retina causing vision loss — occurs with prolonged high-dose use; requires annual eye monitoring (Humphrey visual field test, OCT scan) - QT prolongation: Abnormal heart rhythm — potentially life-threatening - Cardiomyopathy with long-term use - Irreversible retinal damage

Warnings & Precautions

Do not take chloroquine if you: - Have known retinal damage or visual field defects from any cause - Have G6PD deficiency — can cause haemolytic anaemia (G6PD deficiency is common in Nigeria; screen before long-term use) - Have epilepsy — chloroquine lowers the seizure threshold and can trigger seizures - Have psoriasis — can trigger or worsen severe psoriasis flares Chloroquine resistance: Plasmodium falciparum (the dominant malaria species in Nigeria) is almost universally resistant to chloroquine. Using chloroquine for falciparum malaria can lead to treatment failure and potentially fatal complications. Always use an ACT (artemether-lumefantrine, artesunate-amodiaquine, etc.) for malaria in Nigeria unless specifically directed otherwise. Pregnancy: Chloroquine can be used in pregnancy for species it remains effective against (vivax, ovale) — but should be used only when benefits outweigh risks. Not for use in falciparum malaria prophylaxis in Nigeria. Overdose is dangerous: Chloroquine overdose is a medical emergency — causes rapid severe hypotension, cardiac arrest, seizures. Keep away from children.

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Drug Interactions

Important interactions: - Mefloquine: Increased risk of seizures and cardiac arrhythmias — avoid combination - Amiodarone and other QT-prolonging drugs: Dangerous additive effect on heart rhythm - Antiepileptics (phenobarbitone, phenytoin): Chloroquine may reduce their effect and lower seizure threshold simultaneously — avoid - Antacids and kaolin: Reduce chloroquine absorption — take 4 hours apart - Cimetidine: Increases chloroquine blood levels — risk of toxicity - Ciclosporin: Chloroquine increases ciclosporin levels — risk of toxicity - Digoxin: Chloroquine can increase digoxin levels - Ampicillin: Reduced absorption if taken together — space doses - Rabies vaccine (intradermal route): Chloroquine reduces immune response to intradermal rabies vaccine — use intramuscular route instead if on chloroquine

Storage

Store at room temperature (below 25°C) in a dry place, away from light. Keep out of reach of children — overdose is rapidly fatal in children.

Buy only NAFDAC-registered medications

Nigeria has a significant problem with counterfeit and substandard drugs. Always purchase medications from a licensed pharmacy and check the NAFDAC registration number on the package — verify at nafdac.gov.ng.