Metabolism and autoradiographic distribution of delta-8- and delta-9-tetrahydrocannabinol in some organs of the monkey Callithrix jacchus.

Metabolism and autoradiographic distribution of the two isomeric tetrahydrocannabinols, (2,4-14-C)-delta-8-THC and (2,4-14-C)-delta-9-THC, were studied in the marmoset Callithrix jacchus. Of the two cannabinoids, delta-8-THC had a slower initial rate of biotransformation to the psychopharmacologically more potent 11-hydroxylated metabolite. This may explain the minor psychopharmacological activity of the delta-8-isomer. In glandular tissues an accumulation of unchanged delta-9-THC was observed. Autoradiography revealed characteristic label distributions in some organs 30 min after the administration of the drugs. This labelling pattern was found to be changed after a 6-hr incorporation period. The autoradiographic distribution of delta-8 and delta-9-THC appeared to be identical.