Metabolism of N-isopropylacetanilide in rat.

1. Radioactivity from oral doses of N-isopropyl[1-14C]acetanilide was excreted in urine (53.5%), faeces (8.1%) and expired air (17.0%) of rat. 2. Enterohepatic circulation occurred during formation of approximately 34% of the metabolites. N-isopropylacetanilide was metabolized by oxidation in all moieties of the molecule with subsequent conjugation with glucuronic and sulphuric acids. 3. The sulphate ester of 4'-hydroxyacetanilide (acetaminophen) was the major metabolite (28 % of the dose).