Chloroquine Phosphate

Category: Antimalarial drug
Form: Oral tablets

Uses:

• Prevention and treatment of malaria caused by Plasmodium species (P. vivax, P. ovale, P. malariae, and sensitive P. falciparum).

• Sometimes used in certain autoimmune diseases (off-label), such as rheumatoid arthritis or lupus, due to its anti-inflammatory effects.

Mechanism of Action:

• Chloroquine interferes with parasite’s ability to digest hemoglobin inside red blood cells.

• Accumulates in the parasite’s food vacuole and inhibits heme polymerization, leading to toxic buildup of heme, which kills the parasite.

• Also has immunomodulatory effects, explaining its use in autoimmune conditions.

Administration:

• Taken orally, with or without food.

• Dosage depends on whether it is used for malaria treatment or prophylaxis and patient’s age/weight.

• For prophylaxis, often taken once weekly starting 1–2 weeks before travel to malaria-endemic areas and continued for 4 weeks after leaving.

Side Effects:

• Common: nausea, vomiting, stomach upset, headache, dizziness.

• Other: itching (especially in dark-skinned individuals), loss of appetite, mild skin rash.

• Rare but serious:

  • Eye toxicity (retinopathy) with long-term use

  • Heart rhythm disturbances (QT prolongation)

  • Severe allergic reactions, blood disorders

Precautions:

• Avoid in patients with retinal or visual field abnormalities, severe liver or kidney disease.

• Regular eye exams are recommended for long-term use.

• Use cautiously in cardiac patients due to potential heart rhythm effects.

• Not recommended in pregnancy or breastfeeding unless prescribed by a doctor.

• Can interact with other drugs, especially those affecting heart rhythm.

Summary:
Chloroquine Phosphate is an oral antimalarial drug used for prevention and treatment of malaria and sometimes for autoimmune conditions. It works by disrupting parasite metabolism inside red blood cells. Common side effects are gastrointestinal upset and headache, while rare but serious effects include retinopathy and heart rhythm disturbances, especially with long-term use.