Mass spectrometry study of increased breakdown of an anticonvulsivant drug substance: Avizafone

The French Military Health Service (SSA) developed a new pharmaceutic speciality as a treatment against neurotoxic organophosphate poisoning (NSP), as a substitute for existing therapeutics. The Armed Forces Central Pharmacy (PCA) is in charge of the development of therapeutic formulation and stability studies. This product includes three drug substances: atropine, pralidoxime and avizafone, an amine prodrug of diazepam, soluble in water. The PCA performed a stability study of this formulation according to the International Conference on Harmonization (ICH) recommendations: it was used to display interaction between the molecules and the plastic of the cartridge (the container turned yellow). Since no degradation product of atropine and pralidoxime was observed, a complementary evaluation of avizafone and its main known degradation products (diazepam, carbostyril and methylaminobenzochlorophenone [MACB]) was initiated. The results were used to determine the degradation products obtained under different conditions and the kind of mechanisms, which may occur as the formulation ages: adsorption or absorption by the bulk and/or increasing degradation products. The analytical methods developed here are a direct sample analysis by mass spectrometry (MS) using different ionization modes and liquid chromatography (LC) with UV detection to confirm the results obtain with MS.