Effects of various antidotal treatments on acetaminophen toxicosis and biotransformation in cats.

Oral N-acetylcysteine (NAC), IV NAC, and IV sodium sulfate were evaluated as treatments for cats dosed orally with toxic sublethal doses of acetaminophen (APAP). Six cats were given single oral doses of 120 mg of APAP/kg of body weight and the respective antidote at 4.5, 8.5, and 12.5 hours after APAP dosing in 3 separate trials. The cats were given each antidotal treatment in random order with at least 3 weeks separating the individual APAP-treated trials. Clinical signs, plasma APAP half-lives, clinical chemical values, and APAP urinary excretion and metabolites were studied. Results were compared (P less than 0.05) with each other and with those of a control group of 6 cats given identical APAP doses, but given no antidotal treatment. At the dosage levels used, oral NAC, IV NAC, and IV sodium sulfate were equally effective antidotes, as measured by decreased methemoglobinemia, increased whole blood reduced glutathione, decreased APAP half-lives, and increased urinary excretion of the APAP-sulfate conjugate. All the antidotal treatments produced results significantly different from those in the control cats.