Malaria Chemoprophylaxis Drugs:

• Chloroquine: No longer recommended due to widespread resistance.
• Mefloquine (Lariam): Weekly, 250 mg; effective against chloroquine-resistant strains.
  • Rationale: CDC recommends for areas with mefloquine-sensitive strains.
• Atovaquone-Proguanil (Malarone): Daily, 250/100 mg; well-tolerated, effective against multidrug-resistant strains.
  • Rationale: Preferred for travelers to high-resistance regions (e.g., Southeast Asia).
• Doxycycline: Daily, 100 mg; broad-spectrum, but photosensitivity risk.
  • Rationale: Alternative for mefloquine-intolerant patients.
• Tafenoquine (Arakoda): Weekly, 200 mg; long half-life, but contraindicated in G6PD deficiency.
  • Rationale: Newer option for P. vivax prevention.

• Prevention Rates:
  • Atovaquone-Proguanil: ~99% efficacy in clinical trials (Rationale: High barrier to resistance).
  • Mefloquine: ~95% efficacy (Rationale: Effective against most resistant strains).
  • Doxycycline: ~95% efficacy (Rationale: Broad-spectrum, but not for P. falciparum in some regions).

• Usage Guidelines:
  • Start 1–2 weeks before travel (except tafenoquine, which starts 1 day before).
  • Continue for 4 weeks post-exposure (except tafenoquine, which is 4 months for P. vivax).
  • Caution: G6PD testing required for tafenoquine; avoid mefloquine in psychiatric history.

• Perennial Malaria Chemoprevention (PMC):
  • Sulfadoxine-Pyrimethamine (SP): Monthly, 3 doses; used in sub-Saharan Africa.
    • Rationale: Cost-effective, but resistance limits efficacy (~50% in some regions).
  • Dihydroartemisinin-Piperaquine (DP): Monthly, 3 doses; higher efficacy (~80% in trials).
    • Rationale: First-line for seasonal malaria in Sahel.

Key Reference: CDC Yellow Book (2024), WHO Malaria Guidelines (2023).