Efficacy of Atropine/Pralidoxime/Diazepam or Atropine/HI-6/Prodiazepam in Primates Intoxicated by Soman

We performed an experiment to characterize the toxicity of soman in cynomolgus monkeys when the organophosphorus intoxication was followed by a treatment with either the three-drug therapy atropine/pralidoxime/diazepam or the association atropine/HI-6/prodiazepam. Clinical, electrophysiological and histological approaches were combined. Our data demonstrate that the protection afforded against soman toxicity was better with the combination atropine/HI-6/prodiazepam compared to atropine/ pralidoxime/diazepam. This was observed transiently in term of vigilance and respiratory function of intoxicated animals, but particularly in term of their EEG- and ECG disturbances. Moreover, compared to those treated with atropine/pralidoxime/diazepam, animals treated with atropine/HI-6/prodiazepam recovered slightly sooner and did not exhibit prostration 2 days after intoxication although their rapidity of movements was not totally restored. The final recovery observed 3 weeks after intoxication was similar for the two groups. The value of the combination of atropine/HI-6/ prodiazepam vs atropine/pralidoxime/diazepam to counteract soman toxicity was also confirmed in term of brain neuroprotection since greater lesions were observed with the second three drug treatment three weeks after intoxication.