Trihexyphenidyl Enhances Physostigmine Prophylaxis against Soman Poisoning in Guinea Pigs

Trihexyphenidyl Enhances Physostigmine Prophylaxis against SomanPoisoning in Guinea Pigs. LIM, D. K., HOSFCINS, B., and Ho,I. K. (1991). Fundam. Appl. Toxicol. 16, 482–489. Theprotective effects of simultaneous and continuous administrationof physostigmine and trihexyphenidyl against soman-induced toxicitywere studied in guinea pigs. Not only did trihexyphenidyl reducephysostigmine-induced toxicity when it was administered continuouslyto the animals along with physostigmine, the combination affordedgreater protection from soman lethality than did either agentadministered alone. The combination pretreatment also gave betterprotection against soman-induced body weight loss and decreasedwater consumption and attenuated the down-regulation of cholinergicreceptors which occurred when physostigmine alone was used.The onsets of other soman-induced toxicity signs were delayedsignificantly by the combination pretreatment regimen. Theseresults suggest that simultaneous administration of the combinationof physostigmine and trihexyphenidyl may be more useful thanphysostigmine alone as prophylaxis against soman poisoning.