Abstract: Incubation of camazepam [3-(N,N-dimethyl) carbamoyloxy-7-chloro-1-methyl-1,3-dihydro-5-phenyl-2H-1, 4-benzodiazepin-2-one] with rat liver microsomes and cofactors produced a 3-(N-methyl-N-hydroxymethyl) carbamoyloxy derivative as the most abundant metabolite. This metabolite was thermally unstable and was isolated from a metabolite mixture by normal-phase High-Performance Liquid Chromatography. Its structure was established by chemical ionization and ²⁵²Cf plasma desorption time-of-flight mass spectral analyses.

Key words: Camazepam, Thermally-labile metabolite, HPLC, Mass Spectra, 252Cf Plasma Desorption, Mass Spectrometry