Benzodiazepine receptor ligands. Synthesis and preliminary pharmacological evaluation of some 3,7-disubstituted-4H-[1,2,4]triazino[3,4-a]phthalazines and 3,7-disubstituted-4H-[1,2,4]triazino[3,4-a]phthalazine-4-ones.

Some disubstituted triazinophthalazines and traizinophthalazinones were synthesized and tested in vitro for inhibition of the 3H-diazepam (3H-DZ) specific binding to benzodiazepine receptors (BZRs) in membranes from synaptosomes of rat brain and in vivo for their effects on the conditioned behaviour (rat). These compounds showed Ki values (nM) in the in vitro test ranging from 220 to more than 3000 and some of them had approximate ED50S of 30 mg/kg, i.p. (rat) in the conditioned avoidance behaviour test (CR2).