Synthese und pharmakologische Wirkung von 2,3-Benzo-5,7-dioxo-4,5,6,7-tetrahydro-1,4-diazepinen. 2. Mitteilung über heterocyclische Siebenringe

[1,5-Benzodiazepines. 2. Diametrically opposite central nervous system actions of the two stereoisomers of 3,3-dialkyl-1,5-benzodiazepine-2,4-diones]

I.p. applicated S(+)-1, R(-)-1 und rac. 1 prolonged hexobarbital sleeping in rats. The rac. 8-chloro compound 3 given i.p. produced no prolongation. Determination of rac. 1 in serum and tissues of rats 30 min after i.p. administration of 50 mg/kg showed that rac. 1 was detectable in serum and brain, yet its concentration was below the limit of determination. I.v. applicated, the enantiomers of 1 and 3 showed diametrically opposite CNS-effects: The S(+)-enantiomers were convulsively active as pentetrazol, whereas the R(-)-enantiomers were CNS depressant active prolonging hexobarbital sleeping time dose-dependently. High doses of diazepam antagonized dose-dependently the convulsive action of S(+)-1 supporting the hypothesis that this enantiomer acted as a strong inverse agonist, whereas R(-)-1 produced weak agonistic activity at the benzodiazepine binding site of the GABA-receptor.--Enantioselective differences for the binding of the 1-enantiomers to human serum albumin were found, too. R(-)-1 was bound to a greater extent than S(+)-1.