A comparison of the efficacy of a new asymmetric bispyridinium oxime BI-6 with currently available oximes and H oximes against soman by in vitro and in vivo methods.

The reactivating and therapeutic efficacy of a new acetylcholinesterase reactivator, designated BI-6(1-/2-hydroxyiminomethylpyridinium/-4-/carbamoylpyridinium+ ++/-2-butene dibromide), against the organophosphate soman was compared with oximes at present used (pralidoxime, obidoxime, methoxime) and H oximes (HI-6, HLö-7) using in vitro and in vivo methods. H oximes HI-6 and HLö-7 seem to be the most efficacious acetylcholinesterase reactivators against soman according to the evaluation of their reactivating and therapeutic efficacy in vitro as well as in vivo. The new oxime BI-6 is not as effective as the H oximes against soman, nevertheless it is significantly more effective against soman than the currently available oximes, pralidoxime, obidoxime and methoxime, which failed to protect rats poisoned with supralethal doses of soman. Our results confirm that the reactivating efficacy of oximes evaluated by the methods in vitro closely correlates not only with the potency of oximes in vivo in reactivating soman-inhibited acetylcholinesterase but also with the ability to protect rats poisoned with supralethal doses of soman.