Abstract: Novel quaternary pyridinium compounds useful in inhibiting acetylcholinesterase in mammals of the general structure: ##STR1## or pharmaceutically acceptable salts thereof, where R.sub.5 is pentafluorophenyl, phenyl monosubstituted with K, phenyl disubstituted with K, phenyl trisubstituted with K, or naphthyl; R.sub.6 is H, C.sub.1-6 alkyl, phenyl, pentafluorophenyl, phenyl mono, di, or trisubstituted with K, C.sub.1-6 alkyl with an attached phenyl group, C.sub.1-6 alkyl with an attached phenyl group mono, di, or trisubstituted with K; K is halogen, COOH, OH, CN, NO.sub.2, NH.sub.2, C.sub.1-6 alkyl, C.sub.1-6 fluorinated alkyl, C.sub.1-6 alkoxy, C.sub.1-6 alkylamine, C.sub.1-6 alkyl--O--CO--, C.sub.1-6 alkyl--CO--NH--, C.sub.1-6 alkyl--NH--CO--NH--, C.sub.1-6 alkyl--NH--CO--O--, C.sub.1-6 alkyl--NH--CO--, or (C.sub.1-6 alkyl).sub.2 N--CO--; X is OH, C.sub.1-6 alkyl--NH--CO--O--, (C.sub.1-6 alkyl).sub.2 --N--CO--O--, C.sub.1-6 fluoroalkyl--NH--CO--, or (C.sub.1-6 fluoroalkyl).sub.

Abstract: Methods for using novel quaternary pyridinium compounds in inhibiting acetylcholinesterase in mammals, specifically using the quaternary pyridinium compounds in the prophylaxis and treatment of organophosphate poisoning and mammalian dementia by mimicking or opposing the actions of the natural neurotransmitter acetylcholine.