## Antimalarial Choice and Adverse Effects in *P. falciparum* Malaria ### Why Option D (Artemisinin Derivatives and G6PD Deficiency) is INCORRECT **Key Point:** Post-artemisinin delayed haemolysis (PADH) is a recognized complication of artemisinin-based therapy, particularly in patients treated for severe malaria with high parasitemia. However, PADH is **not specifically linked to G6PD deficiency**. It is a non-immune haemolysis that occurs 1–3 weeks after treatment, attributed to the delayed clearance of once-parasitized red blood cells that were "pitted" by the spleen. G6PD deficiency is classically associated with oxidant-stress haemolysis caused by **primaquine** and dapsone — not artemisinin derivatives. **High-Yield (KD Tripathi, Essentials of Medical Pharmacology, 8th ed.):** Artemisinins are generally considered safe in G6PD-deficient patients. The drug most contraindicated in G6PD deficiency among antimalarials is **primaquine**, which causes intravascular haemolysis via oxidative stress. Linking PADH to G6PD deficiency in Option D is factually inaccurate. ### Why the Other Options are CORRECT | Option | Statement | Accuracy | |--------|-----------|----------| | A | Atovaquone-proguanil: effective for uncomplicated *P. falciparum*, expensive, unsuitable for severe malaria | ✓ Correct. Atovaquone-proguanil is approved for uncomplicated *P. falciparum* malaria but is not recommended for severe or high-parasitemia disease (WHO guidelines). | | B | Quinine: hypoglycemia, cinchonism, cardiac contraindication | ✓ Correct. Quinine stimulates insulin secretion causing hypoglycemia; cinchonism (tinnitus, vertigo, visual disturbances) is a well-known adverse effect; it prolongs QT interval and is contraindicated in arrhythmias (Harrison's, 21st ed.). | | C | Chloroquine contraindicated in *P. falciparum* due to resistance; retinopathy after prolonged use | ✓ Substantially correct. Chloroquine IS contraindicated in *P. falciparum* due to widespread resistance. While the ">5 years" qualifier is a simplification, the core clinical teaching — that retinopathy is a dose/duration-dependent toxicity requiring long-term use — is accepted in standard curricula (AAO guidelines: risk increases significantly after 5 years or cumulative dose >1000 g). This option is more correct than Option D. | **Clinical Pearl:** In this patient with 4% parasitemia and jaundice indicating severe malaria, **IV artesunate** is the WHO-recommended first-line treatment. Post-artemisinin delayed haemolysis is a real phenomenon but is NOT driven by G6PD deficiency — it is a splenic "pitting" mechanism affecting once-parasitized RBCs regardless of G6PD status. **Mnemonic — G6PD Danger Drugs (DAMP):** - **D**apsone - **A**ntimalarials — **Primaquine** (NOT artemisinins) - **M**ethylene blue (paradoxically) - **P**henazopyridine ```mermaid flowchart TD A[P. falciparum — Severe Malaria]:::outcome --> B[IV Artesunate — First Line]:::action B --> C{PADH risk?}:::decision C -->|Yes — high parasitemia| D[Monitor Hb at 3–4 weeks]:::action C -->|G6PD deficiency?| E[NOT a specific risk factor for PADH]:::urgent E --> F[Primaquine — AVOID in G6PD deficiency]:::urgent ```
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