The ability of two types of pharmacological pretreatment (
pyridostigmine alone or
pyridostigmine in combination with two
anticholinergic drugs) to increase the resistance of rats and mice against
tabun and to increase the therapeutic efficacy of common antidotal treatment of
tabun-poisoned rats and mice was compared. A significant decrease in the LD50 values of
tabun was observed when mice as well as rats were pretreated with the prophylactic antidotal mixture consisting of
pyridostigmine,
benactyzine and trihexyphenidyle, designated
PANPAL.
Pyridostigmine-pretreated rats were also more resistant against acute lethal effects of
tabun but
pyridostigmine-induced resistance of rats was not so high as
PANPAL-induced resistance. In addition, the pharmacological pretreatment with
pyridostigmine alone was not able to protect mice against
tabun-induced acute toxicity. The pharmacological pretreatment with
pyridostigmine alone was able to increase the efficacy of currently used antidotal treatment (
obidoxime in combination with
atropine and
diazepam) of
tabun-induced
poisoning, but
PANPAL-induced increase in the efficacy of the same antidotal treatment was significantly higher than an increase induced by
pyridostigmine alone.
PANPAL-induced increase in the efficacy of antidotal treatment of
tabun poisoning was also observed in mice. These findings confirm that
PANPAL pretreatment of
tabun-poisoned rats and mice seems to be much more suitable than currently used
pyridostigmine alone.