S-adenosylmethionine (SAMe) is a hepatoprotective antioxidant. This study was designed to test treatment effects of SAMe in a feline model of acetaminophen-induced oxidative damage. One group of cats was given SAMe for 14 days, one group was given a single dose of acetaminophen, and a third group received a single dose of acetaminophen followed by 14 days of SAMe treatment, beginning 1 hour after the acetaminophen.

All cats receiving acetaminophen had a significant increase in methemoglobin and Heinz body formation. SAMe-treated cats had a numerically lower percentage of Heinz body formation and a smaller decrease in packed cell volume (PCV) than those receiving acetaminophen only.
Cats treated with SAMe 1 hour following acetaminophen ingestion were protected against formation of Heinz bodies and PCV decline over time.

COMMENTARY: Cats that ingest acetaminophen should be treated promptly with SAMe to ameliorate the toxic effects. A pertinent question is how soon treatment must begin to be effective, because beginning treatment within 1 hour may not be possible in most cases.

S-Adenosylmethionine (SAMe) in a feline model of acetaminophen-induced oxidative damage. Webb CB, Twedt DC, Fettman MR. ACVIM Proceedings, 2002, p 792.