PAM-2 Cl, HI-6, and HGG-12 in soman and tabun poisoning.

Acute sc toxicity of soman increased in the order, mice----rats----guinea pigs----dogs, being 12.6 times more toxic to dogs (LD50 = 0.05 mumol/kg) than to mice. It was 2.8 times more toxic than tabun to mice and 35 times more toxic to dogs. HI-6 was the least toxic and had similar toxicity values to the four animal species studied and HGG-12 the most toxic of the three oximes used. HGG-12 has shown the greatest interspecies variation (rats:dogs = 1:19.5). HI-6, HGG-12, and PAM-2 Cl (in conjunction with atropine and diazepam) revealed the best protective effect in soman-poisoned dogs, with the respective protective indices of 9, 6.3, and 3.5, followed by guinea pigs. In tabun poisoning the best, but relatively low, protective effect was found only in guinea pigs. The introduction of diazepam increased the protective effects of atropine-oxime combination in soman and tabun poisoning by 10 to 80%. We suggest that the high toxicity of soman and low toxicity of HI-6 may be anticipated in man. The inefficiency of HI-6, HGG-12, and PAM-2 Cl in tabun poisoning points either to the search of new compounds or to the use of the mixture of the oximes found to be effective against the known chemical warfare nerve agents.