chloroquine phosphate: clinical use

Prescribing considerations

• Confirm destination suitability and likely parasite susceptibility.
• Assess cardiac disease, QT risk factors, electrolytes and concurrent QT-prolonging medicines.
• Review renal and hepatic function, epilepsy or neurological disease, psoriasis, porphyria, myasthenia gravis, severe gastrointestinal disease and G6PD deficiency.
• Warn about hypoglycaemia, visual symptoms, psychiatric reactions and overdose toxicity.
• For travel prophylaxis, current UK guidance advises against chloroquine in epilepsy, while product information calls for careful risk assessment.

Contraindications and cautions

• Hypersensitivity to chloroquine or formulation ingredients.
• Concomitant amiodarone.
• For malaria prophylaxis, epilepsy is contraindicated in current UK travel guidance.

Monitoring

• Check blood glucose promptly if symptoms suggest hypoglycaemia.
• Stop treatment and obtain an ECG if arrhythmia symptoms develop.
• Use product-specific ophthalmic surveillance criteria for prolonged or high cumulative exposure; investigate new visual disturbances promptly.
• Consider full blood counts during extended treatment and monitor for cardiomyopathy, hepatic toxicity and neuromuscular toxicity.
• Monitor ciclosporin or digoxin where clinically indicated.

Clinical pharmacology

An aminoquinoline active against susceptible blood-stage Plasmodium species. Oral absorption is substantial, tissue distribution and retention are extensive, metabolism is mainly hepatic, and elimination is slow and partly renal.

Formulation and product differences

• Avloclor is a scored tablet taken after food; its excipients include maize starch and magnesium stearate.
• Malarivon is an oral syrup containing sucrose, propylene glycol, parabens and Ponceau 4R; consider these excipients in young children, diabetes, pregnancy and hepatic or renal disease.
• Tablet and syrup quantities are not directly interchangeable because their chloroquine-base content differs.