The French Military Health Service (SSA) has developed an innovative drug product, as a treatment against neurotoxic organophosphate
poisoning (NOP). It contains three drug substances: an anticholinergic, an anticonvulsant and a cholinesterase reactivator. Testing stability
study, in normal conditions, over 18 months, for this speciality, has given unexpected results. Indeed, one of the drug substances, avizafone
(pro-drug of diazepam), breaks down partially into a compound which migrates into the plastic container where this degradation product is
demethylated after absorption. Mass spectrometry with negative chemical ionisation (negative CI-MS) was used, to monitor decomposition
of the drug substance. This method first showed migration of the degradation product and has been used to monitor its evolution during the
stability testing study. The demethylation seems to be due to an additive product present in the plastic. The degradation products remain
trapped in the container holding the pharmaceutical formulation.