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Drug Reference

chloroquine

Antimalarial· Brands: Aralen, Nivaquine, Resochin, Chloroquine PhosphateIMIVPO

Mechanism of action
Chloroquine is a 4-aminoquinoline that concentrates in the acidic food vacuoles of Plasmodium parasites, preventing the polymerisation of toxic heme to hemozoin, leading to parasite death from heme accumulation. It also has immunomodulatory and anti-inflammatory properties, useful in autoimmune conditions.
Pharmacokinetics
Chloroquine is rapidly and almost completely absorbed from the gastrointestinal tract. It is extensively bound to plasma proteins and accumulates in tissues, particularly liver, spleen, kidney, and lungs. It is metabolised by cytochrome P450 enzymes in the liver to active metabolites and is slowly eliminated with a half-life of 1 to 2 months. Renal excretion is the main route of elimination.
Indications & dosing

Acute uncomplicated malaria (chloroquine-sensitive Plasmodium spp.)

Then 300 mg base at 6, 24 and 48 hours; total 1500 mg base. Confirm local chloroquine sensitivity.

  • adult · PO: 600 mg base once · Then 300 mg base at 6, 24 and 48 hours; total 1500 mg base. Confirm local chloroquine sensitivity.

Acute uncomplicated malaria (chloroquine-sensitive Plasmodium spp.)

Then 5 mg/kg base at 6, 24 and 48 hours; maximum 600 mg per dose.

  • pediatric · PO: 10 mg/kg base once · Then 5 mg/kg base at 6, 24 and 48 hours; maximum 600 mg per dose.

Malaria prophylaxis (chloroquine-sensitive areas)

Start 1 week before travel, continue weekly during exposure and for 4 weeks after leaving.

  • adult · PO: 300 mg base once weekly · Start 1 week before travel, continue weekly during exposure and for 4 weeks after leaving.

Systemic lupus erythematosus (steroid-sparing agent)off-label

Monitor for retinal toxicity; requires ophthalmological review.

  • adult · PO: 150 mg base daily · Monitor for retinal toxicity; requires ophthalmological review.

Rheumatoid arthritis (second-line DMARD)off-label

Monitor for ocular toxicity; therapeutic response may take 4–6 weeks.

  • adult · PO: 150 mg base daily · Monitor for ocular toxicity; therapeutic response may take 4–6 weeks.
Contraindications & precautions
  • Known hypersensitivity to chloroquine or other 4-aminoquinolines · Cross-hypersensitivity may occur within the class.
  • Pre-existing retinopathy or maculopathy · Chloroquine can exacerbate retinal damage; avoid unless benefit outweighs risk.
  • Porphyria · May precipitate acute porphyric attacks.
  • Severe hepatic impairment · Drug accumulates; consider dose reduction or alternative.
  • Myasthenia gravis · May worsen neuromuscular weakness.
  • G6PD deficiency · Chloroquine is generally considered safe in G6PD deficiency; haemolysis has been reported only very rarely, mainly with high-dose or prolonged therapy.
  • Perform baseline and regular ophthalmological examination (including slit-lamp and fundoscopy) during prolonged treatment.
  • Avoid concurrent use with QT-prolonging drugs and monitor ECG in at-risk patients.
  • Monitor blood glucose, as hypoglycaemia can occur, especially in patients on antidiabetic therapy.
  • Use with caution in renal impairment; adjust dose according to renal function.
  • Use caution in patients with hepatic impairment; monitor liver function.
  • In patients with G6PD deficiency, monitor for haemolysis.
Adverse effects
  • Nausea
  • Headache
  • Pruritus
  • Reversible visual disturbances (blurring, diplopia)
  • Retinopathyserious
  • Cardiomyopathyserious
  • Hypoglycaemiaserious
  • QT prolongationserious
  • Severe cutaneous adverse reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis)serious
  • Blood dyscrasias (e.g., agranulocytosis, pancytopenia)serious
Renal & hepatic adjustment
  • eGFR 30–50: Use with caution. For prolonged treatment, consider reducing dose or increasing dosing interval. No dose adjustment is usually required for short courses used in acute malaria.
  • eGFR 0–30: Avoid use. If treatment is essential, reduce dose significantly and monitor closely for toxicity. (avoid)
  • Hepatic impairment (moderate): Use with caution; no specific dose adjustment usually required.
  • Hepatic impairment (severe): Use with caution; consider dose reduction and monitor closely for adverse effects.
Monitoring, pregnancy & toxicity
  • Ophthalmological examination · At baseline and every 6-12 months during long-term therapy
  • Full blood count · Periodically during long-term therapy
  • Liver function tests · Periodically during long-term therapy
  • Renal function (creatinine) · At baseline and periodically in patients with renal impairment
  • ECG (QT interval) · Consider in patients with cardiac disease or with concurrent QT-prolonging drugs
  • Pregnancy: Chloroquine is safe and recommended for use in pregnancy for both malaria prophylaxis and treatment. It has been widely used without evidence of harm to the fetus.
  • Toxicity: Cardiovascular toxicity: arrhythmias, hypotension, and collapse · Immediate hospitalization, ECG monitoring, and supportive care. In severe cases, diazepam and adrenaline may be used as per poison management protocols.
  • Toxicity: Visual disturbances: blurred vision, corneal deposits, and retinopathy · Discontinue therapy and refer for ophthalmological assessment.
  • Toxicity: Gastrointestinal symptoms: nausea, vomiting, and diarrhoea · Symptomatic treatment; may be reduced by taking with food.
Antidotes & reversal
  • Diazepam (high-dose) with adrenaline · Severe chloroquine poisoning: high-dose diazepam plus adrenaline reduces mortality (Riou protocol).
Clinical notes
Chloroquine is used for the treatment and prophylaxis of chloroquine-sensitive malaria, and for the management of systemic lupus erythematosus and rheumatoid arthritis. Dose is expressed as chloroquine base; doses and regimens vary by indication and region. Resistance among Plasmodium falciparum is widespread, so it is not recommended for falciparum malaria in many areas. Adverse effects include gastrointestinal upset, pruritus, headache, and retinopathy with long-term use. Regular ophthalmological monitoring is required for chronic therapy. Caution in severe hepatic or renal impairment, and in concurrent use with drugs that prolong QT interval.

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BNF; local formulary