Pharmacological effects of triazolo[4,3-d] and tetrazolo[1,5-a][1,4]benzodiazepines on the central nervous system

A series of tricyclic 1,4-benzodiazepines, fundamentally 5H-s-triazolo[4,3- d] and tetrazolo[1,5-a][1,4]benzodiazepines, were tested for acute toxicity and central nervous system effects in mice. All of these compounds, but es pecially 3, 4 and 5, showed a clear central depressant activity. Compounds 3, 4 and 5 also showed a moderate activity in antagonizing the deleterious effects produced by cardiazol but were ineffective in counteracting those e licited by strychnine. These same compounds 3, 4 and 5 presented a remarkab le benzodiazepine-like action with a pharmacological profile similar to tha t of chlordiazepoxide.