Studies on the metabolism of the antioxidant ethoxyquin, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline in the rat.

1. The metabolism of ethoxyquin (6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline) in rat has been investigated. Urinary metabolites were identified by combined g.l.c.-mass spectrometry. 2. The major metabolic reaction was de-ethylation which gave rise to 6-hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline and an oxidation product, 2,2,4-trimethyl-6-quinolone. Other reactions were hydroxylation to four different hydroxylated metabolites and one dihydroxylated metabolite. A total of 95% of the dose (100 mg/kg) was accounted for.