New simulators in the prophylaxis against soman poisoning: structural specificity for the depot site(s).

The oxime HI-6 is effective as an antidote in the soman poisoned (6-8LD50) rat, however, successfully treated animals subsequently show a gradual relapse of signs of poisoning and eventually die after several hours. The relapse is caused by the reappearance of soman at specific sites, after having been elsewhere in the body. Diaphragms isolated from poisoned rats successfully treated with HI-6 also showed a 'secondary' relapse of poisoning. Eight compounds chemically related to soman-soman-simulators--have been tested as prophylactic agents, for their potency in preventing the reappearance of poisoning. The idea was that such compounds may block the non-synaptic binding sites for soman. Three of the 8 compounds proved very effective, which gave some insight into the chemical structure needed for this type of prophylactic action.