Determination of a pyrimido-benzazepine anxiolytic agent and its 5-hydroxy metabolite in whole blood, plasma and urine by gas--liquid chromatography with electron-capture detection and by high-performance liquid chromatography

Electron-capture gas--liquid chromatographic and reversed-phase high-performance liquid chromatographic assays are described for the quantitation of the compound, 9-chloro-7-(2-chlorophenyl)-5H-pyrimido 5,4-d] 2]-benzazepine, I], a member of the benzazepine class of compounds undergoing clinical evaluation as anxiolytic agents. Studies on the biotransformation of I] in the rat and dog showed that the compound was metabolized mainly by hydroxylation to yield the 5-hydroxy compound, II], 9-chloro-7-(2-chlorophenyl)-5H-pyrimido 5,4-d] 2]-benzazepin-5-ol (major metabolite), along with the formation of lesser amounts of the N-oxide, III], 9-chloro-7-(2-chlorophenyl)-5H-pyrimido 5,4-d] 2]-benzazepine 3-oxide, and the phenolic analogue, IV], 3-chloro-4-(9-chloro-5H pyrimido-5,4-d] 2] benzazepin-7-yl)phenol. This report describes the quantitation of I] and II] (major metabolite) in plasma using the above analytical techniques, both in preclinical studies in the dog and in clinical pharmacokinetic studies in man.