MALARONE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MALARONE (MALARONE).
Atovaquone is a selective inhibitor of the mitochondrial electron transport chain at the cytochrome bc1 complex (Complex III), disrupting pyrimidine synthesis and ATP generation in Plasmodium species. Proguanil, via its metabolite cycloguanil, inhibits dihydrofolate reductase (DHFR), blocking DNA synthesis. Synergistic activity against erythrocytic and exoerythrocytic stages.
| Metabolism | Atovaquone is highly protein-bound and undergoes limited hepatic metabolism (glucuronidation) with enterohepatic recirculation, excreted primarily in feces. Proguanil is extensively metabolized by CYP2C19 to its active metabolite cycloguanil, with additional minor pathways involving CYP3A4. Cycloguanil is further metabolized and excreted renally. |
| Excretion | Atovaquone: 94% excreted unchanged in feces via biliary elimination, 6% in urine. Proguanil: 40-60% excreted unchanged in urine; cycloguanil (active metabolite) and proguanil metabolites also cleared renally. |
| Half-life | Atovaquone: 50-70 hours (mean ~60 h); proguanil: 12-21 hours (mean ~16 h); cycloguanil: 10-16 hours. Long half-life of atovaquone allows single-dose treatment, but may delay parasite clearance. |
| Protein binding | Atovaquone: >99.9% bound to plasma proteins (primarily albumin). Proguanil: 75-80% bound. |
| Volume of Distribution | Atovaquone: Vd ≈ 0.5-1.0 L/kg (large distribution due to high lipophilicity). Proguanil: Vd ≈ 20-40 L/kg (extensive tissue binding). Atovaquone's low Vd reflects high protein binding. |
| Bioavailability | Atovaquone: oral bioavailability is low (23-47%) and highly variable; increases 2-fold when taken with fatty food (mandatory). Proguanil: well absorbed (70-90% bioavailability). |
| Onset of Action | Oral: Therapeutic effect against blood-stage Plasmodium typically within 24-48 hours; clinical improvement often noted by day 2-3. |
| Duration of Action | Single treatment course (3 tablets once daily for 3 days) provides radical cure for uncomplicated falciparum malaria. Prophylaxis: continued for 7 days after leaving endemic area. |
For malaria treatment: 4 tablets (each containing atovaquone 250 mg/proguanil 100 mg) orally once daily for 3 consecutive days. For malaria prophylaxis: 1 tablet (atovaquone 250 mg/proguanil 100 mg) orally once daily starting 1-2 days before travel, continued during travel and for 7 days after leaving endemic area.
| Dosage form | TABLET |
| Renal impairment | CrCl ≥50 mL/min: No adjustment needed. CrCl 30-49 mL/min: Use with caution, avoid for prophylaxis. CrCl <30 mL/min: Contraindicated. |
| Liver impairment | No specific dose adjustments for Child-Pugh A or B; use with caution in severe hepatic impairment (Child-Pugh C) due to limited data. |
| Pediatric use | Weight-based dosing: 5-8 kg: 1/2 pediatric tablet (63.75 mg atovaquone/25 mg proguanil) orally once daily for 3 days (treatment) or prophylaxis; 9-10 kg: 3/4 pediatric tablet; 11-20 kg: 1 pediatric tablet; 21-30 kg: 2 pediatric tablets; 31-40 kg: 3 pediatric tablets; >40 kg: adult dose. Pediatric tablet: atovaquone 62.5 mg/proguanil 25 mg. |
| Geriatric use | No specific dose adjustment required; use caution due to age-related renal decline; monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MALARONE (MALARONE).
| Breastfeeding | Excreted in breast milk in small amounts; M/P ratio not established for atovaquone-proguanil. Use with caution, especially in infants with G6PD deficiency due to hemolysis risk. |
| Teratogenic Risk | First trimester: Avoid due to potential teratogenicity; animal studies show fetal toxicity. Second and third trimesters: Use only if benefit outweighs risk; limited human data suggests no major malformations but possible fetal anemia and hemoglobinuria. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
["Absolute: Known hypersensitivity to atovaquone, proguanil, or any component","Absolute: Prophylaxis in pregnant women (due to teratogenic potential in animal studies, though risk-benefit considered in treatment)","Relative: Severe renal impairment (CrCl <30 mL/min) may reduce efficacy and increase toxicity; contraindicated for prophylaxis, use caution for treatment"]
| Precautions | ["Risk of severe hepatotoxicity, including liver failure and transplant, especially with prolonged courses for prophylaxis","Risk of hypersensitivity reactions including anaphylaxis, Stevens-Johnson syndrome, and angioedema","May cause severe vomiting and diarrhea, leading to suboptimal absorption; consider antiemetics","Use with caution in patients with hepatic or renal impairment; dose adjustment may be needed for severe renal impairment (CrCl <30 mL/min)"] |
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| Monitor maternal CBC, liver and renal function, and G6PD status. Fetal ultrasound for growth and anatomy if exposed in first trimester; monitor for neonatal jaundice and hemolysis if near term. |
| Fertility Effects | No evidence of adverse effects on human fertility. Animal studies show no impairment. |