Paper II
2015 February (2010 Scheme) · 40 marks · 120 min

Question

Classify drugs used in treatment of malaria. Explain the mechanism of action, adverse effects and dose of any one such drug. Which drug is used for radical cure of acute vivax malaria.

Q16 marksEssays

Answer

Classification of antimalarial drugs (by stage of action)

  • Tissue schizonticides (causal prophylactic/radical cure): Primaquine, Proguanil
  • Blood schizonticides: Chloroquine, Quinine, Artemisinin derivatives, Mefloquine, Sulfadoxine-pyrimethamine
  • Gametocytocides: Primaquine, Chloroquine (except falciparum)
  • Sporontocides: Proguanil, Primaquine

Mechanism, adverse effects and dose of Chloroquine

  • Mechanism: Concentrates in the parasite’s food vacuole, inhibits haem polymerase (which normally converts toxic free haem into inert haemozoin), leading to accumulation of toxic free haem that damages the parasite’s membranes and kills it
  • Adverse effects: GI upset, pruritus, headache, retinopathy/corneal deposits with prolonged use, cardiotoxicity with rapid IV administration, haemolysis in G6PD deficiency
  • Dose: 25 mg/kg base over 3 days (e.g., 10 mg/kg on day 1, 10 mg/kg on day 2, 5 mg/kg on day 3) for treatment of sensitive malaria

Radical cure of acute vivax malaria

  • Primaquine, given along with a blood schizonticide (chloroquine), to eradicate the dormant hepatic hypnozoites and prevent relapse (after excluding G6PD deficiency)

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