Fomepizole as an adjunct in acetylcysteine treated acetaminophen overdose patients: a case series.

Acetaminophen (N-acetyl-para-aminophenol or APAP) is the leading cause of acute liver failure worldwide. Standard therapy for APAP overdose is with IV N-acetylcysteine (NAC). However, overdose patients treated with NAC can still incur hepatotoxicity in some circumstances. Fomepizole has proven safety in methanol and ethylene glycol poisoning and is a potent CYP2E1 and c-Jun-N-terminal Kinase (JNK) inhibitor that is effective even in the metabolic phase. We present a case series of 14 patients who had elevated APAP levels after overdose who were treated with fomepizole as an adjunct to standard IV-NAC. Fomepizole adjunctive therapy either completely prevented any hepatotoxicity, mitigated the effects, or reversed significant hepatocellular injury.