Dietary fat unsaturation enhances drug metabolism in cebus but not in squirrel monkeys.

Antipyrine disappearance and sleeping time following barbiturate anesthesia were assessed to evaluate the effects of dietary corn oil and coconut oil on the drug-metabolizing enzyme systems (DMES) in cebus (Cebus albifrons) and squirrel (Saimiri sciureus) monkeys. Plasma antipyrine clearance (half-life) was measured in both species before and after induction of DMES by i.v. injection of barbiturates on two consecutive days. Sleeping time was measured after administration of either pentobarbital or hexobarbital and proved to be the most demonstrable measure of diet-drug interaction. In neither cebus nor squirrel monkeys was antipyrine half-life significantly affected by dietary fat. Sleeping time for the coconut oil-fed squirrel monkeys was shorter than for those fed corn oil, whereas corn oil-fed cebus awoke sooner than the coconut oil-fed cebus. Thus, barbiturate but not antipyrine metabolism in monkeys can be influenced by dietary fat unsaturation, and the effect appears to be species dependent. Genetic differences in phospholipid metabolism are thought to underlie this difference.