An aqueous solution of trimedoxime bromide, atropine, and benactyzine hydrochloride was formulated to have maximum stability as an antidote in organophosphorus poisoning. The stability of the mixture in glass and plastic cartridges was determined. Glass cartridges were more desirable than plastic; there was less vapor loss, color formation, and anomo~ous reaction. Trimedoxime was stable, losing 1.4% of its potency after 1 year at 25" and atropine was more stable than trimedoxime. Considerable degradation of benactyzine occurred; 20% of its potency was lost after 1 year a t 25". Equations for predicting the shelf life of each ingredient at selected temperatures are presented. Keyphrases 0 Benactyzine-in formulation, kinetics and stability in glass and plastic 0 Atropine-in formulation, kinetics and stability in glass and plastic 0 Trimedoxime-in formulation, kinetics and stability in glass and plastic Parathion, O,O-diethyl-O-(4-nitrophenyl)phosphorothioate; malathion, O,O-dimethyl-S-(l,Z-dicarbethoxyethyl)phosphorodithioate; trimedoxime bromide, pyridinium-l,l'-(l,3-propanediyl~bis(4-(hydroxyimino)methyl)-dibromide; and benactyzine, N-hydroxy-a-penylbenzeneacetic acid Z-(diethylamino)ethyl fectiveness of a therapy could be enhanced significantly ester.