Limitations of acetaminophen as a reference hepatotoxin for the evaluation of in vitro liver models

Acetaminophen is commonly used as a reference hepatotoxin to demonstrate that in vitro human liver platforms can emulate features of clinical drug-induced liver injury. However, the induction of substantial cell death in these models typically requires acetaminophen concentrations (∼10 mM) far higher than blood concentrations of the drug associated with clinical hepatotoxicity (∼1 mM). Using the cytochrome P450 inhibitor 1-aminobenzotriazole, we show that acetaminophen toxicity in cultured human, mouse, and rat hepatocytes is not dependent on N-acetyl-p-benzoquinonimine formation, unlike the in vivo setting. This finding highlights the limitation of using acetaminophen as a reference hepatotoxin for the evaluation of in vitro liver models. Hence, we make recommendations on the selection of reference hepatotoxins for this purpose.