Toxicological and pharmacological investigations of pinazepam (7-chloro-1-propargyl-5-phenyl-3H-1,4-benzodiazepin-2-one): a new psychotherapeutic agent.

The pharmacological and toxicological properties of 7-chloro-1-propargyl-5-phenyl-3H-1,4-benzodiazepin-2-one (pinazepam) were investigated and compared with those of diazepam. In mouse and rat acute toxicity, in rat motor coordination and in rat metrazol convulsion tests pinazepam was compared with oxazepam too. Pinazepam, which is characterized by the presence of a propargylic side chain, showed a lower toxicity, hypnotic activity and muscular-relaxant activity than diazepam. Pinazepam and diazepam showed, however, similar activity in reducing aggressive behaviour in mice, stimulating the exploratory behaviour in rats and in potentiating hexobarbital narcosis. No clear-cut differences were observed in the anticonvulsant properties of the two drugs when tested against metrazol, strychnine and electroshock induced seizures. Pinazepam differs from diazepam for its longer duration of action. The main metabolic product found in the urine of rats and dogs treated with pinazepam was oxazepam.