Makindo Medical Notes.com

In a chloroquine overdose hypokalaemia should NOT be normalised immediately. It may actually be cardio protective. Avoid toxicity in obese patients by using the ideal body-weight. Ocular toxicity is unlikely if the dose of chloroquine phosphate <= 4 mg/kg daily (= chloroquine base approx. 2.5 mg/kg daily)

About: Always check the BNF link here

• Chloroquine is a 4-aminoquinoline drug
• Active against all forms of malaria except Falciparum where resistance is almost universal
• Chloroquine and hydroxychloroquine belong to the quinolone family
• Except for the treatment of malaria because it is far less toxic to the retina, hydroxychloroquine has replaced chloroquine

Indication/Doses: always check BNF

• Active RA/SLE expert advice: Chloroquine 155 mg/day or max 2.5 mg/kg/day
• Non-falciparum malaria: Chloroquine 620 mg, then 310 mg after 6 h, then 310 mg on days 2 and 3; total cumulative dose 25 mg/kg of base, and PRIMAQUINE 15-30 mg OD in vivax and ovale for 14 days.
• Take expert guidance. Primaquine may cause haemolysis in G6PD-deficient individuals. Can worsen MG, psoriasis and epilepsy.

Mode of action

• Inhibits erythrocytic stage of malaria life cycle
• It is not effective against exoerythrocytic forms of the parasite.
• Tends to collect in lysosomes

Contraindications

• Avoid in epilepsy

Side effects

• GI disturbance, Visual disturbance and retinal damage in overdose
• Depigmentation, Alopecia, Seizures

Managing Chloroquine toxicity

• There is nausea, agitation, drowsiness, altered vision and coma
• ECG shows widened QRS and prolonged QTc and there is a risk of VT, Torsade and VF
• Hypokalaemia must NOT be normalised immediately. It may actually be cardioprotective
• NaHCO₃ should be considered for prolonged QRS > 120 ms
• Activated charcoal and gastric lavage should be considered if the early presentation
• High dose iv Diazepam may be protective

References

• Summary Product Characteristics