Gas chromatographic and mass spectrometric studies on the metabolism and pharmacokinetics of delta 1-tetrahydrocannabinol in the rabbit.

Gas chromatography-mass spectrometry has been used to investigate the in vivo hepatic metabolism of delta 1-tetrahydrocannabinol (delta 1-THC) in the New Zealand white rabbit. Sixteen metabolites were identified and shown to be present in different relative amounts compared with the hepatic metabolites of delta 1-THC produced by other species. The metabolic profile was also different from that reported from rabbit urine particularly with regard to the lower relative concentrations of acidic metabolites in the liver. The pharmacokinetics of delta 1-THC has been studied in the rabbit using the recently developed GC-MS method based on metastable ion monitoring. This revealed a terminal plasma delta 1-THC half life ranging from 34.16 to 59.30 h (mean 46.75 h) after a single dose and THC fat/plasma ratio of 10(3)-10(4):1.