Phase I metabolism of ganstigmine. Rat, dog, monkey and human liver microsomal extracts investigated by liquid chromatography electrospray tandem mass spectrometry.

Ganstigmine, a new acetylcholinesterase inhibitor, was incubated with rat liver microsomes and the resulting metabolites were identified by high-performance liquid chromatographic/mass spectrometric (HPLC/MS) and HPLC/MS/MS analyses. The results showed the formation of eight main metabolites, among which geneseroline and molecules corresponding to mono-hydroxylated, demethylated and reduced ganstigmine. The metabolic profile drawn for humans, dog and monkey showed a pattern very similar to that of rat: only in the case of liver dog microsomes higher amounts of geneseroline and of a metabolite identified as demethylated and reduced drug were detected.