The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.