Gut–liver-on-a-chip enables mechanistic study and risk assessment of drug-induced liver injury and drug–drug interactions

systemic drug administration, we demonstrated the critical role of the intestinal barrier in modulating drug exposure, corresponding toxic responses and first-pass effects. Temporal profiling revealed progressive hepatic injury mechanisms involving mitochondrial dysfunction and activation of the apoptotic pathway. Pharmacological inhibition of cytochrome P450 attenuated victim-induced oxidative stress without affecting hepatic drug exposure, confirming enzyme-related bioactivation as the toxicity mechanism. Furthermore, transporter-mediated drug-drug interactions were functionally replicated, with perpetrator compounds altering substrate pharmacokinetics through competitive efflux inhibition and modified intestinal disposition. The ability of the platform to monitor drug exposure-toxicity relationships and drug-drug interactions was validated using combinations of perpetrator and victim drugs. This integrated approach advances applications of organ-on-chips by establishing causal relationships between drug exposure and toxicity, resolving the progression of temporal toxicity, and modeling drug-drug interactions, which are critical factors in predicting clinical hepatotoxicity and complex pharmacokinetic interactions.