Known Drug Interactions with Artesunate
Artesunate, an antimalarial drug, has limited documented interactions compared to other artemisinins, but evidence points to risks with specific classes. It undergoes rapid metabolism via CYP2A6 to its active metabolite dihydroartemisinin (DHA), with minor roles for CYP2B6 and CYP3A4/5, potentially amplifying interactions with enzyme inducers or inhibitors.[1][2]
Interactions with Antimalarials
Artesunate shows no pharmacokinetic interactions with standard partners like mefloquine, lumefantrine, or amodiaquine in fixed-dose combinations (e.g., artemether-lumefantrine). However, combining with quinine or quinidine raises ECG risks like QT prolongation, though less severe than with other artemisinins.[2][3]
Impact of CYP Inducers and Inhibitors
- Inducers (e.g., rifampicin, phenytoin, carbamazepine): Reduce DHA exposure by up to 50-80%, potentially causing treatment failure. Avoid co-administration or monitor closely.[1][4]
- Inhibitors (e.g., ketoconazole): Increase DHA levels by 2-3 fold, risking toxicity like neurotoxicity. Dose adjustments may be needed.[2]
No major interactions reported with CYP3A4 substrates like midazolam, but caution applies.[1]
Interactions with Other Drug Classes
- Antiretrovirals: Efavirenz or ritonavir (CYP inducers/inhibitors) alter artesunate pharmacokinetics; spacing doses or monitoring recommended.[4]
- Antiepileptics: Phenytoin or phenobarbital accelerate clearance, reducing efficacy.[2]
- Others: No significant interactions with paracetamol, ibuprofen, or oral contraceptives. Grapefruit juice (CYP3A4 inhibitor) may slightly elevate levels, but data is sparse.[3]
What Happens in Overdose or Special Cases?
In renal/hepatic impairment, accumulation risks rise without dose adjustment. Pediatric and pregnant use shows no unique interactions, but data is limited.[3] No confirmed herb-drug interactions, though St. John's wort (inducer) warrants avoidance.
How to Check for Personalized Risks
Consult tools like Lexicomp or Micromedex for patient-specific factors. Report suspected interactions to pharmacovigilance databases.[1]
Sources
[1]: FDA Artesunate Label
[2]: ScienceDirect: Pharmacokinetics of Artemisinin Derivatives
[3]: WHO Artemisinin Guidelines
[4]: PubMed: Drug Interactions with Artemisinin Antimalarials