Chloroquine Phosphate

Chloroquine Phosphate is a 4-aminoquinoline antimalarial and amoebicidal agent used for the suppression and clinical cure of malaria due to susceptible strains of Plasmodium falciparum, P. ovale, P. vivax and P. malariae. It is a rapidly acting blood schizontocide with some gametocytocidal activity. Its mechanism of action against blood schizonts remains unclear but it may act by influencing haemoglobin digestion by raising intravesicular pH in malaria parasite cells. It also interferes with synthesis of nucleoproteins by the parasite. Chloroquine is rapidly and almost completely absorbed from the gastro-intestinal tract when given by mouth. About 55% of chloroquine in the circulation is bound to plasma proteins. It is also used for amoebic hepatitis and abscess, discoid and systemic lupus erythematosus, and rheumatoid arthritis.

• Treatment of malaria
• Prophylaxis and suppression of malaria
• Treatment of amoebic hepatitis and abscess
• Treatment of discoid lupus erythematosus
• Treatment of systemic lupus erythematosus (SLE)
• Treatment of rheumatoid arthritis

Chloroquine Phosphate is a 4-aminoquinoline antimalarial and amoebicidal agent used for the suppression and clinical cure of malaria due to susceptible strains of Plasmodium falciparum, P. ovale, P. vivax and P. malariae. It is a rapidly acting blood schizontocide with some gametocytocidal activity. Its mechanism of action against blood schizonts remains unclear but it may act by influencing haemoglobin digestion by raising intravesicular pH in malaria parasite cells. It also interferes with synthesis of nucleoproteins by the parasite. Chloroquine is rapidly and almost completely absorbed from the gastro-intestinal tract when given by mouth. About 55% of chloroquine in the circulation is bound to plasma proteins.

Chloroquine influences Hb digestion by increasing intravesicular pH in malaria parasite cells and interferes with nucleoprotein synthesis of the parasite. It is also effective in extra intestinal amoebiasis. In RA chloroquine has a disease-modifying effect.

Adult Dose (as Chloroquine base):

Pediatric Dose: Malaria prophylaxis: 5 mg/kg weekly; Treatment: 10 mg/kg (1st dose), 5 mg/kg after 6 hours, then 5 mg/kg daily for 2 days; Rheumatoid arthritis: 3 mg/kg/day.

Renal Dose: May need to reduce dose in prolonged treatment.

Should be taken with food. Take in the dose and duration as advised by your doctor.

If you miss a dose of Chloroquine Phosphate, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.

Common Side Effects:

• Nausea, vomiting, diarrhea, stomach cramps
• Headache, dizziness
• Skin rash, pruritus, urticaria
• Hair loss
• Visual disturbances (blurred vision, difficulty focusing)

Serious Side Effects (Long-term/High doses):

• Retinopathy (retinal damage)
• Psychosis, seizures
• Leukopenia, aplastic anemia
• Hepatitis
• Myopathy
• Tinnitus, hearing loss

Potentially Fatal: Cardiac and respiratory arrest, CV collapse, convulsions, coma.

• Eyes should be examined before starting long-term treatment and monitored subsequently.
• Visual disturbances may render patients unfit to drive or operate machinery.
• Care is necessary in patients with impaired liver or renal function, porphyria, psoriasis, or history of epilepsy.
• Patients with G6PD deficiency should be observed for haemolytic anemia.
• Caution during pregnancy and lactation.
• Slow infusion is used upon IV admin to prevent cardiotoxicity.

• Hypersensitivity
• Known or suspected resistant P. falciparum infection
• Porphyria
• Retinal damage
• Concurrent hepatotoxic drugs

Concomitant therapy with phenylbutazone predisposes to dermatitis, antagonises effect of neostigmine and pyridostigmine, reduces bioavailability of ampicillin. Cimetidine inhibits metabolism of chloroquine raising plasma levels. Increased risks of ventricular arrhythmias with halofantrine or other arrhythmogenic drugs (e.g., amiodarone). Increased risk of convulsions with mefloquine. Antacids reduce absorption of chloroquine (separate by 4 hours). Increased toxicity with quinacrine.

Should be taken with food. Separate antacids by 4 hours.

There are no adequate and well-controlled studies evaluating the safety and efficacy of chloroquine in pregnant women. Usage during pregnancy should be avoided except in prophylaxis or treatment of malaria when benefit outweighs potential risk to fetus. Pregnancy Category D.

Because of the potential for serious adverse reactions in nursing infants from chloroquine, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account potential clinical benefit of drug to mother. Chloroquine enters breast milk.

Pediatric dose: Malaria prophylaxis: 5 mg/kg weekly; Treatment: 10 mg/kg (1st dose), 5 mg/kg after 6 hours, then 5 mg/kg daily for 2 days; Rheumatoid arthritis: 3 mg/kg/day.

Limited information is available regarding dose adjustment for elderly patients.

Renal Impairment: May need to reduce dose in prolonged treatment.

Caution is necessary in patients with liver impairment.

Chloroquine overdose can be fatal. Symptoms include headache, drowsiness, visual disturbances, cardiovascular collapse, seizures, and respiratory arrest. Immediate medical attention is required.

Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.

Chloroquine Phosphate