Haloarene derivatives of carbamazepine with reduced bioactivation liabilities: 2-monohalo and 2,8-dihalo derivatives.

The anticonvulsant carbamazepine 1 is associated with aderse drug reactions (ADRs), including hepatotaxicity; oxidative Metabolism of 1 has been implicated in the pathogenesis of the ADRs. We report the synthesis and evaluation of 2-monohalo and 2,8-dihalo analogues of 1 that were intended to minimize reactive metabolite formation via arene oxidation and 10,11-epoxidation. Halo analogues were obtained either by rearrangement of halogenated N-arylindoles or from specifically halogenated iminodibenzyl derivatives. In rat hepatocytes, none of the :analogues underwent oxidative dehalogenation or glutathiohe adduction. Some formation of the 10,11 epoxide still. occurred, but :aromatic hydroxylation was not seen with the exception of 2-fluoro, which allowed minor monohydroxylation. Complete inhibition of aromatic hydroxylation required at least monochlorination or difluorination of 1. In human liver microsoms, difluoro analogue 5b underwent 10,11-epoxidation but gave no arene oxidation.