Plissonneau_2026_Toxicol.Lett_419_111893

BACKGROUND: Obesity and metabolic dysfunction-associated steatotic liver disease (MASLD) could impair hepatic drug metabolism by altering cytochrome P450 and conjugating enzyme activities, potentially affecting the pharmacokinetics and toxicity of antiseizure drugs (ASDs). OBJECTIVE: To investigate the impact of in vitro steatosis on the cytotoxicity and hepatic metabolism of six ASDs (carbamazepine, phenytoin, lamotrigine, levetiracetam, felbamate and sulthiame) in differentiated HepaRG cells. METHODS: HepaRG cells were exposed to fatty acid overload, oleic acid (300 microM) and stearic acid (150 microM), to induce steatosis and incubated with each ASD for 48 h. Cytotoxicity was assessed, and metabolic profiling was performed using liquid chromatography coupled with high resolution mass spectrometry. RESULTS: Steatotic conditions did not significantly increase cytotoxicity for any ASD. However, steatosis significantly reduced the formation of carbamazepine-10,11-epoxide (consistent with impaired CYP3A4 activity) and decreased production of levetiracetam's major metabolite L057 (likely via reduced carboxylesterase activity). No significant metabolic changes were observed for phenytoin, lamotrigine, felbamate or sulthiame. CONCLUSIONS: Hepatic steatosis selectively alters the metabolism of carbamazepine and levetiracetam in vitro without enhancing short-term cellular toxicity. These findings raise concerns about possible modifications in drug exposure, efficacy and tolerability in patients with MASLD, and underscore the need for further in vivo and clinical studies.