Coartem (Novartis) — originator brand; WHO prequalified; most widely used globally · Coartem Dispersible (Novartis) — paediatric dispersible formulation (not the adult formulation but same compound) · Riamet (Novartis) — brand name used in Europe and some high-income markets · Artemether/Lumefantrine Tablets 20/120 mg (multiple WHO-prequalified generic manufacturers: Cipla, Ajanta Pharma, Ipca Laboratories, Guilin Pharmaceutical — generic brands widely used in sub-Saharan Africa including Uganda)
Clinical safety rating
cautionAnimal studies have demonstrated safety
Artemether is rapidly converted to dihydroartemisinin, which produces free radicals that damage parasite proteins and membranes. Lumefantrine inhibits heme detoxification in the parasite food vacuole.
| Metabolism | Artemether is metabolized by CYP3A4 to dihydroartemisinin. Lumefantrine is metabolized by CYP3A4. |
| Excretion | Primarily fecal (biliary) elimination of unchanged drug and metabolites; renal excretion is negligible (<1% for artemether and <0.1% for lumefantrine). Artemether is extensively metabolized by CYP3A4/5 to dihydroartemisinin, which is further glucuronidated and excreted in bile. Lumefantrine is metabolized by CYP3A4 to desbutyl-lumefantrine; both parent and metabolite are eliminated via feces. |
| Half-life | Artemether: terminal elimination half-life approximately 1–2 hours. Dihydroartemisinin: approximately 1–2 hours. Lumefantrine: terminal elimination half-life 4–5 days (range 2–6 days) in patients with uncomplicated malaria; prolonged half-life contributes to post-treatment prophylaxis but may lead to accumulation with repeated dosing. |
| Protein binding | Artemether: 95% bound to plasma proteins (primarily albumin and α1-acid glycoprotein). Dihydroartemisinin: 93% bound. Lumefantrine: >99% bound to high-density lipoproteins (HDL) and, to a lesser extent, to albumin and α1-acid glycoprotein. |
| Volume of Distribution | Artemether: Vd approximately 2–5 L/kg, indicating extensive tissue distribution. Dihydroartemisinin: Vd 0.5–1.5 L/kg. Lumefantrine: Vd extremely large, ranging from 10–30 L/kg (reported up to 31 L/kg), reflecting extensive tissue binding and accumulation in erythrocytes and organs (liver, lung, kidney). |
| Bioavailability | Oral bioavailability: Artemether is 30–40% due to extensive first-pass metabolism by CYP3A4/5 to dihydroartemisinin, which has 80% oral bioavailability. Lumefantrine has highly variable and food-dependent bioavailability; absorption increases 2–16 fold when taken with a high-fat meal. Bioavailability is approximately 5–10% in the fasted state and up to 85% when administered with fat-containing food. The combination is formulated to enhance lumefantrine absorption with a fixed ratio of artemether:lumefantrine 1:6. |
| Onset of Action | Oral administration: Onset of antiparasitic effect within 2–4 hours, with reduction in parasitemia typically seen by 24 hours. Peak plasma concentrations of artemether and dihydroartemisinin occur at approximately 2 hours post-dose; lumefantrine peaks at about 4–6 hours. Clinical improvement in fever and symptoms may begin within 12–24 hours. |
| Duration of Action | Artemether and dihydroartemisinin: Rapid elimination; antimalarial activity lasts approximately 6–8 hours. Lumefantrine: Prolonged elimination half-life provides schizonticidal activity for 4–5 days after a standard 3-day course; a second peak is observed due to fat absorption with food. The combination ensures a 28-day cure rate >95% for uncomplicated P. falciparum malaria. |
| Molecular Weight | Artemether: 298.38 g/mol (sesquiterpene lactone endoperoxide derivative). Lumefantrine (benflumetol): 528.89 g/mol (fluorene derivative). The fixed-dose combination tablet contains 20 mg artemether and 120 mg lumefantrine per tablet. |
Oral, 4 tablets (each containing 20 mg artemether and 120 mg lumefantrine) at 0, 8, 24, 36, 48, and 60 hours (total 6 doses). For patients ≥35 kg, alternatively 4 tablets at 0, 8, 24, 36, 48, and 60 hours.
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (CrCl <30 mL/min); use with caution. |
| Liver impairment | No dose adjustment for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C); avoid use. |
| Pediatric use | Weight-based dosing: 5-<15 kg: 1 tablet per dose; 15-<25 kg: 2 tablets per dose; 25-<35 kg: 3 tablets per dose; ≥35 kg: 4 tablets per dose. Administer at 0, 8, 24, 36, 48, and 60 hours. Crush tablets if needed for children <5 kg. |
| Geriatric use | No specific dose adjustment required. Monitor for QT prolongation and electrolyte disturbances due to potential age-related decline in cardiac conduction. |
| 1st trimester | Caution — use when benefit outweighs risk, which is almost always the case with active falciparum malaria. WHO 2023 guidelines state that ACTs including AL are acceptable in the first trimester when they are the only effective treatment available, acknowledging that untreated falciparum malaria poses far greater risk (miscarriage, maternal death) than the theoretical teratogenic risk extrapolated from animal data. Preferred regimen where feasible remains quinine 10 mg/kg PO TID × 7 days plus clindamycin 450 mg PO TID × 7 days. If quinine is unavailable, not tolerated, or where compliance with the 7-day quinine regimen is unlikely, AL is appropriate. Animal embryotoxicity data at supratherapeutic doses should not preclude treatment in an acutely ill pregnant woman. Document indication, gestational age, and treatment rationale clearly. |
| 2nd trimester | First-line. WHO-recommended treatment for uncomplicated P. falciparum malaria. Administer as standard 6-dose regimen with fatty food. Monitor for hypoglycaemia, anaemia, and preterm labour as malaria complications. Lumefantrine AUC is reduced in pregnancy — reassess at Day 28 for recrudescence or re-infection. Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine is the recommended prevention strategy for the next pregnancy — AL is not used for IPTp. |
| 3rd trimester | First-line. WHO-recommended treatment for uncomplicated P. falciparum malaria. Heightened vigilance for fetal complications: continuous fetal monitoring during acute illness, ultrasound assessment for fetal growth restriction, and uterine activity monitoring for preterm labour. Hypoglycaemia monitoring is especially important as both falciparum malaria and the physiological insulin response of late pregnancy predispose to severe hypoglycaemia. If delivery occurs within 28 days of AL treatment, inform neonatologist. IV artesunate is mandatory for any features of severe malaria. At term, neonatal monitoring for jaundice is advisable given malaria-associated haemolysis in the mother and potential (low) neonatal drug exposure via placenta. |
Clinical note
Artemether-lumefantrine (AL) is a fixed-dose artemisinin-based combination therapy (ACT) and the WHO-recommended first-line treatment for uncomplicated Plasmodium falciparum malaria in the second and third trimesters of pregnancy. In the first trimester, data are more limited but increasingly reassuring: large observational studies including the WHO-coordinated WWARN database and the PREGACT trial have not demonstrated increased rates of miscarriage, stillbirth, or major congenital malformations compared to quinine. WHO updated guidance (2015, reaffirmed 2023) endorses ACT use — including AL — in the first trimester when it is the only available effective treatment, acknowledging that untreated or undertreated falciparum malaria in pregnancy carries high risks of maternal death, severe anaemia, hypoglycaemia, pulmonary oedema, cerebral malaria, miscarriage, preterm birth, fetal growth restriction, and perinatal death. Quinine plus clindamycin remains the preferred regimen in settings where first-trimester ACT alternatives exist and clinical capacity allows. The drug is not indicated for severe or complicated malaria (IV artesunate is the standard of care) or for non-falciparum species without falciparum co-infection.
| Placental transfer | Artemether and its active metabolite dihydroartemisinin (DHA): Both cross the placenta. DHA has been detected in cord blood following artemether treatment. Given the very short half-life (~1–2 hours), fetal exposure is transient. Animal data demonstrating embryotoxicity suggest sufficient placental transfer exists at high doses; at human therapeutic exposures, fetal concentrations are expected to be low and transient. Lumefantrine: Placental transfer is expected to be limited due to its extremely high lipophilicity (logP ~7), very high protein binding (>99%), and large molecular weight (528 g/mol). Quantitative cord blood data are sparse in humans, but pharmacokinetic modelling suggests low fetal lumefantrine exposure. Paradoxically, this low placental transfer of lumefantrine (the partner drug providing post-treatment prophylaxis) may contribute to the observed reduction in lumefantrine AUC in pregnancy and reduced post-treatment prophylactic effect in endemic settings — leaving pregnant women more vulnerable to rapid re-infection after treatment. |
| Breastfeeding | Both artemether and lumefantrine are excreted into breast milk in small quantities. Artemether and its active metabolite dihydroartemisinin (DHA) have very short half-lives and are expected to be present in milk at low concentrations. Lumefantrine has high lipophilicity and high protein binding; milk transfer is likely limited but quantitative data are sparse. The relative infant dose (RID) for lumefantrine has not been precisely established in human lactation studies, but based on pharmacokinetic modelling, infant exposure via breast milk is estimated to be low. Given that malaria itself poses grave risk to the breastfeeding mother and the infant if the mother is untreated, breastfeeding should continue during and after AL treatment. WHO explicitly endorses continued breastfeeding during ACT therapy. Monitor nursing infant for jaundice (theoretical haemolysis risk in G6PD-deficient neonates, though systemic neonatal lumefantrine exposure from breast milk is expected to be very low). |
| Lactation Rating | L3 — Moderately safe (Hale's Lactation Risk Category). Compatible with breastfeeding based on limited data; benefits of malaria treatment in the mother strongly outweigh theoretical infant risk. |
| Teratogenic Risk | FDA Pregnancy Category C. Artemether-lumefantrine is not recommended in the first trimester unless no alternative; animal studies show embryotoxicity at high doses. Second and third trimester: limited human data but appears safe; no increased risk of congenital malformations reported. Use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor for maternal adverse effects (QT prolongation, hepatotoxicity, nephrotoxicity). Fetal ultrasound to assess growth and well-being if used in second/third trimester. No specific fetal monitoring required outside standard prenatal care. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies show no impairment of fertility. Limited data; theoretical concerns from antimalarial effect on gametes not substantiated. |
■ FDA Black Box Warning
None
| Serious Effects |
Known hypersensitivity to artemether, lumefantrine, or any component of the formulation.Severe (complicated) malaria — AL is not appropriate; IV artesunate is mandatory. Indicators of severity include: impaired consciousness/cerebral malaria, respiratory distress, severe anaemia (Hb <7 g/dL), haemoglobinuria, hyperparasitaemia (>2% parasitaemia in non-immune, >5% in semi-immune), acute renal failure, jaundice, hypoglycaemia, circulatory collapse, abnormal bleeding.Concomitant use with halofantrine: absolute contraindication due to additive QTc prolongation risk and high risk of potentially fatal cardiac arrhythmia (torsades de pointes). Do not administer halofantrine within one month of AL.Concomitant use with other antimalarials unless under close monitoring — risk of additive QTc prolongation (mefloquine, quinine, chloroquine) and/or pharmacokinetic interactions.First trimester (relative/contextual contraindication per many national guidelines): preferred alternatives are quinine + clindamycin. However, WHO 2023 guidelines and clinical judgment may override this where quinine is unavailable and the alternative is untreated life-threatening malaria. This is a risk-benefit determination, not an absolute contraindication in the clinical sense.Severe hepatic impairment: no established safe dosing; use with extreme caution or avoid. Both artemether and lumefantrine are hepatically metabolised and may accumulate.Family history or personal history of congenital QTc prolongation, clinical history of symptomatic cardiac arrhythmias, or documented QTc >500 ms at baseline — relative contraindication requiring cardiology input.
| Precautions | QT interval prolongation, Arrhythmias, Recrudescence of infection, Hypersensitivity reactions, Use in hepatic impairment |
| Food/Dietary | High-fat meal increases absorption; grapefruit juice may increase lumefantrine levels; avoid concurrent use. |
| Clinical Pearls | Monitor ECG for QTc prolongation; administer with fatty food to enhance absorption; avoid in patients with severe hepatic impairment; pregnancy category C; caution with CYP3A4 inhibitors or inducers. |
| Patient Advice | Take with a high-fat meal or whole milk to improve absorption. · Complete the full 3-day course even if symptoms improve. · Seek medical attention for signs of severe malaria (e.g., altered consciousness, difficulty breathing). · Avoid grapefruit juice during treatment. · Use effective contraception if of childbearing potential. |
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