Value of preapproval safety data in predicting postapproval hepatic safety and assessing the legitimacy of class warning.

Objective: The objective of this study was to systematically evaluate whether preapproval safety data for nonhepatotoxic drugs and hepatotoxic drugs can be compared to improve preapproval prediction of postapproval hepatic safety and to assess the legitimacy of applying class warnings.

Methods: Drugs within a therapeutic class that included at least one drug that had been withdrawn from the market because of liver toxicity or had a warning of potential liver toxicity issued by major regulatory agencies, and at least one drug free from such regulatory action, were identified and divided into two groups: drugs with and drugs without regulatory action. Preapproval clinical data [including the elevation rates of alanine aminotransferse (ALT) and withdrawal due to liver toxicity, the number of patients with combined elevation of ALT and bilirubin, and liver failure] and nonclinical data (including chemical structures, metabolic pathways, and other significant findings in animal studies) were compared between the two groups.

Results: Six drug classes were assessed in this study: thiazolidinediones, cyclooxygenase-2 inhibitors, fluoroquinolones, catechol-O-methyltransferase (COMT) inhibitors, leukotriene receptor inhibitors, and endothelin receptor antagonists. In two classes (COMT inhibitors and endothelin receptor antagonists), drugs with regulatory action had significantly higher rates of ALT elevation of more than threefold and greater numbers of patients with combined elevation of ALT and bilirubin than drugs without regulatory action. Drugs with regulatory action also had chemical structures or metabolic pathways associated with the toxicity. The legitimacy of class warnings was refuted in all six classes of drugs.

Conclusion: Preapproval safety data may help predict postapproval hepatic safety and can be used to assess the legitimacy of applying class warnings.