Evaluering av tre typer autoinjektor-regimer mot nervegassforgiftning

The Norwegian Armed Forces were the first in NATO to introduce emergency antidotes against nerve agents in autoinjectors. Autoinjectors in use in 2011 contain atropine, obidoxime (toxogonin), and diazepam. In 1989 pyridostigmine prophylaxis against the nerve agent soman was introduced in Norway. The purpose of such drugs is to enhance survivability and reduce injuries following exposure. Such drugs are supposed to be administered by the soldiers themselves or as buddy aid following specific procedures. More effective countermeasures against nerve agent poisoning are, however, needed because the current drugs in use do not protect the soldiers sufficiently. The central nervous system is particularly vulnerable. The purpose of the present study was to compare the antidotal capabilities of three different regimes in an animal model using Wistar albino rats; 1) atropine, obidoxime, diazepam, 2) atropine, HI-6, avizafone, and 3) scopolamine, HI-6, physostigmine against 2-4 LD50 doses of the nerve agent soman. The results showed that each regimen administered two times (1 and 5 minutes after soman exposure) effectively prevented or terminated epileptiform activity within 10 minutes. The regimens, however, differed markedly in life saving capabilities with the scopolamine, HI-6, physostigmine regimen raking highest, followed in descending order by the atropine, HI-6, avizafone and lastly by atropine, obidoxime, diazepam regimens respectively. Pretreatment with pyridostigmine increased the potency of the atropine, HI-6, avizafone regimen, but not the atropine, obidoxime, diazepam regimen. The latter regimen administered 3 times, 1, 5 and 9 minutes after soman exposure, did not ameliorate the insufficiency in this animal model. The scopolamine, HI-6, physostigmine regimen has excellent antidotal properties, but the very narrow therapeutic window (probably less that 1-2 minutes) makes this regimen unrealistic for use in a field situation. The atropine, HI-6, avizafone regimen constitutes a relatively efficacious therapy against soman intoxication, particularly when pyridostigmine is used as a pretreatment.