Comparison of the effects of 11-palmitoyloxy-delta 9-tetrahydrocannabinol with delta 9-tetrahydrocannabinol and 11-hydroxy-delta 9-tetrahydrocannabinol on the hepatic microsomal drug-metabolizing enzyme system.

Delta 9-THC and 11-OH-delta 9-THC appear to in vivo affect the metabolism of both Type I and Type II substrates involving cytochrome P-450 as well as to affect the metabolism of a substrate requiring cytochrome P-448. These effects could not be observed significantly in in vitro experiments at the concentrations used. 11-Palmitoyloxy-delta 9-THC does not appear to affect the metabolism of either Type I or Type II substrates but does appear to affect those substrates requiring P-448. From these studies it appears that long-retained delta 9-THC metabolite 11-palmitoyloxy-delta 9-THC, as well as delta 9-THC and 11-OH-delta 9-THC, could alter in vivo the metabolism and activity of certain drugs and other foreign compounds.