In situ intestinal absorption of 2-chloro-N-isopropylacetanilide (propachlor) and non-biliary excretion of metabolites into the intestinal tract of rats, pigs and chickens.

1. Propachlor was absorbed from in situ intestinal loops of rats and pigs, with absorption half-times of 7.5 and 16.5 min, respectively. 2. Water-soluble 14C-labelled metabolites that accumulated in the intestinal loops accounted for 31%, 53%, and 25% of the starting 14C for rats, pigs and chickens, respectively. 3. Propachlor(S)cysteine was identified as the major metabolite in the pig intestinal lumen (43% of the water-soluble 14C). 4. It is concluded that intestinal metabolism and intestinal excretion of water-soluble metabolites of propachlor are important physiological processes that occur in a variety of animal species. These processes provide a route by which metabolites of xenobiotics may reach the intestinal lumen in animals which are poor biliary excretors.