[The structure of degradation products of neostigmine bromide]

In aqueous temperature-stressed solutions of neostigmine bromide besides the known product of hydrolysis additional degradation products were discovered, detected by TLC and HPLC. By means of spectroscopic studies (1H-NMR, IR, UV, MS) and elemental analysis the isolated decomposition products were identified as 3-hydroxyphenyltrimethylammonium bromide (2), 3-dimethylaminophenol (3), 3-dimethylaminophenyl-dimethylcarbamate (4), 3-methylaminophenyl-dimethylcarbamate (5), 3-aminophenyl-dimethylcarbamate (6) and 4 (resp. 6)-bromo-3-dimethylaminophenyl-dimethylcarbamate (7). The structures of 2-7 were confirmed by comparison with synthesized authentic compounds.