Makindo Medical Notes

⚠️ In chloroquine overdose, hypokalaemia should not be normalised immediately as it may be cardioprotective. 💡 To reduce ocular toxicity in long-term use, dose should not exceed chloroquine phosphate 4 mg/kg/day (≈ chloroquine base 2.5 mg/kg/day). In obese patients, use ideal body weight for dosing.

📖 About

• Chloroquine is a 4-aminoquinoline antimalarial drug.
• Active against non-falciparum malaria, but resistance in *Plasmodium falciparum* is now almost universal worldwide.
• Belongs to the same family as hydroxychloroquine, which is less retinotoxic and is therefore preferred in rheumatology (RA/SLE).
• Occasionally still used in malaria prophylaxis when travelling to areas with chloroquine-sensitive strains.

🩺 Indications & Doses (BNF – always check locally)

• Rheumatoid arthritis / SLE (specialist use): Chloroquine 155 mg/day PO (max 2.5 mg/kg/day).
• Non-falciparum malaria (sensitive strains):
  • Chloroquine base total dose 25 mg/kg over 3 days: 620 mg PO initially → 310 mg after 6 hrs → 310 mg daily for 2 more days.
  • Add primaquine 15–30 mg OD for 14 days in *P. vivax* / *P. ovale* to eradicate liver hypnozoites. ⚠️ Contraindicated in G6PD deficiency (risk of haemolysis).
• Not effective against exoerythrocytic stages except with primaquine.

⚙️ Mode of Action

• Acts on the erythrocytic stage of malaria parasite.
• Accumulates in parasite lysosomes, raising pH and disrupting haem detoxification.
• Also accumulates in host lysosomes, explaining some immunomodulatory effects.

🚫 Contraindications

• Epilepsy.
• Psoriasis (may exacerbate).
• Myasthenia gravis (may worsen symptoms).
• Hypersensitivity to 4-aminoquinolines.

⚠️ Side Effects

• GI upset: nausea, vomiting, diarrhoea.
• Neurological: dizziness, headache, seizures (in overdose).
• Ocular: blurred vision, corneal deposits, retinopathy with long-term use.
• Dermatological: alopecia, depigmentation.
• Overdose: coma, convulsions, arrhythmias, cardiovascular collapse.

🧪 Monitoring (long-term use)

• Baseline and regular (annual) ophthalmology exams for patients on long-term therapy (risk of retinal toxicity).
• Consider ECG if risk factors for QT prolongation.

🚨 Managing Chloroquine Toxicity

• Clinical features: nausea, agitation, drowsiness, visual disturbance, coma.
• Cardiac: QRS widening, QTc prolongation, ventricular tachyarrhythmias, torsades de pointes, VF.
• Management:
  • Airway, breathing, circulation (resuscitation priority).
  • Continuous ECG monitoring.
  • Do not immediately correct hypokalaemia — mild hypokalaemia may be cardioprotective.
  • Sodium bicarbonate if QRS >120 ms.
  • High-dose IV diazepam may reduce cardiotoxicity and seizures.
  • Activated charcoal or gastric lavage if very early presentation.

📚 References

• BNF: Chloroquine
• Summary of Product Characteristics
• NICE / UK malaria prevention guidance (PHE/UKHSA)