Phagocytic activity of the rat reticuloendothelial system and the pharmacokinetics of an anticholinesterasic insecticide: carbaryl.

1. The pharmacokinetics of [14C]carbaryl administered intravenously and orally were studied in male rats whose reticuloendothelial system (RES) was inhibited by colloidal carbon or activated by glyceryl trioleate. 2. A time course for [14C]carbaryl blood concn. was fitted to a two-compartment open model following single intravenous administration. A single exponential decay was noted following intragastric administration. 3. The constant blood elimination of [14C]carbaryl decreased significantly in animals with the RES inhibited and increased in those whose RES was activated compared to control animals. 4. There was an increase in carbaryl concn. in the tissue compartment in animals with the RES activated, but no change in animals with the RES inhibited. 5. The equivalent [14C]carbaryl concn. of liver and lungs were decreased or increased in animals with the RES inhibited or activated respectively.