title: Effects of carbamates on whole blood cholinesterase activity: chemical protection against soman.
abstract: The toxicity (LD50) of several carbamates, all reversible inhibitors of cholinesterase (ChE), were determined in male rabbits. These include isopropyl methylphenyl carbamate (IMPC), pyridostigmine, neostigmine, benzpyrinium and physostigmine. When 1/9 of the LD50 of the above carbamates was individually combined with atropine (A) and benactyzine (B), mecamylamine (M) or chloropromazine (CPZ) and administered to rabbits in a pretreatment regimen, most animals could be protected from a 10 LD50 challenge of Soman. If CPZ, M or B was omitted from this regimen, no rabbits survived this challenge of Soman. The protection afforded against Soman was found to be related to reversible inhibition of ChE by the carbamates; reversible ChE inhibition varied with the route of injection and with the physical properties of the carbamate. Oral administration of pyridostigmine, a quaternary carbamate, provided protection for 24 hours. When the pretreatment included four components (pyridostigmine, A, M and B), the LD50 of Soman was raised 30.8 times in rabbits.
mesh_terms: D000818:Animals; D002219:Carbamates / Q000494:pharmacology* / Q000633:toxicity; D002802:Cholinesterases / Q000097:blood*; D007928:Lethal Dose 50; D008297:Male; D009943:Organophosphorus Compounds / Q000037:antagonists & inhibitors*; D011729:Pyridostigmine Bromide / Q000494:pharmacology; D011817:Rabbits; D012999:Soman / Q000037:antagonists & inhibitors* / Q000633:toxicity
chemical_list: D002219:Carbamates; D009943:Organophosphorus Compounds; D012999:Soman; D002802:Cholinesterases; D011729:Pyridostigmine Bromide