A new metabolic pathway of bromazepam involving attachment of a methylthio group.

1. The structures of three hitherto unidentified metabolites of bromazepam in the rat were elucidated using u.v., mass, n.m.r. and i.r. spectrometry. 2. All three metabolites contained a methylthio or corresponding oxidized group at the C-6' position of the pyridyl moiety. 3. Quantitative analysis of the metabolites determined after administration of [14C]bromazepam to rat revealed that the three metabolites together comprised about 6% of the total radioactivity excreted in the 24-h urine, or about 1% of the dose.