[The kinetics of neostigmine degradation in aqueous solution].
The concentration course of the degradation products of aqueous temperature-stressed solutions of neostigmine bromide (1) shows, that 1 simultaneously is hydrolyzed to 3-hydroxyphenyltrimethylammonium bromide (2) and demethylated to 3-dimethylaminophenyldimethylcarbamate (4). The ester hydrolysis is the rate-determining predominant reaction and of pseudo first-order. Under temperature-stressed conditions only, the demethylation to 4 followed by consecutive reactions proceeds at a measurable rate. The kinetic parameters of the ester hydrolysis calculated from the results of isothermic short-term tests permit the prediction of a five-year stability of 2% neostigmine solutions in the therapeutically relevant pH-value range from 3 to 7. On the basis of the kinetic results the possible reaction mechanisms and the influence of selected components on the rate of the hydrolysis and demethylation are discussed.
D003640:Dealkylation; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009388:Neostigmine / Q000032:analysis*; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics
D012996:Solutions; D009388:Neostigmine
Zur Kinetik des Neostigminabbaus in wässriger Lösung.