The efficacy of monopyridinium (2-PAAM, 2-PAEM) and bispyridinium (obidoxime, HI-6) oximes against mevinphos in mice.

The efficacy of two new monopyridinium oximes (2-PAAM, 2-PAEM) and two bispyridinium oximes (obidoxime. HI-6) was tested in combination with atropine sulphate against acute poisoning with the organophosphorus insecticide mevinphos in mice. When mice were treated two min. after mevinphos poisoning, no significant differences in the therapeutic effect of tested oximes were observed. The oximes increased the 24 hr LD50 values of mevinphos about two times in comparison with the 24 hr LD50 values of mevinphos in mice protected with atropine sulphate alone and more than three times in comparison with non-treated intoxicated animals. On the other hand, both monopyridinium oximes were significantly more efficacious than HI-6 and as efficacious as obidoxime when they were administered 30 sec. after mevinphos poisoning. Both monopyridinium oximes and obidoxime increased the 24 hr values of mevinphos almost three times in comparison with the 24 hr values of mevinphos in mice protected with atropine sulphate alone and about twenty-five times in comparison with non-treated intoxicated animals, while the oxime HI-6 less than two times in comparison with the 24 hr values of mevinphos in mice protected with atropine sulphate alone and about fifteen times in comparison with non-treated intoxicated animals. Use of new monopyridinium oximes seems to be the improvement in the antidotal treatment of poisoning with organophosphorous insecticide mevinphos in comparison with HI-6 but not in comparison with obidoxime when oximes are used in equimolar doses.