Protection against nerve agent-induced convulsive activity is a very important problem which is not solved yet. Pretreatment usually consists of reversible acetylcholinesterase inhibitor, such as pyridostig-mine or physostigmine, alone or associated with centrally acting antimuscarinic compound. Biperiden is a tertiary amine antimuscarinic compound with strong atropine-like bloking eflects in the central nervous system. It possess anti-N-methyl-D-aspartate (NMDA) activity as well. It is well known. that biperiden is very effective against soman-induced lethality and convulsions. In the present study, biperiden (1.25 mg/kg i.m.) was combined with difierent types of cholinesterase reactivators — HI-6, VT-89 (2,3) and VT-93 (2,3) (2 x 10⁴ mol/kg i.m.). The drug combinations were administered 15, 30 and 60 min prior to exposure to 2 LD₅₀ Soman and their antilethal and anticonvulsive activity were studied in rats. The studies showed that biperiden + HI-6 protected all animals from lethality and convulsive/subconvulsive activity especially when given 15 and 30 min before the challenge. The pretreatment regimen consisting of biperiden and VT-89 (2,3) was notable to prevent soman-induced lethality and convulsions. The third combination tested — biperiden + VT-93 (2,3) provided the Same anticonvulsive protection as biperiden + HI-6 when given 60 min prior to exposure to 2 LD₅₀ Soman.

Keywords: Biperiden; Cholinesterase reactivators; Soman; Anticonvulsive pretreatment