Rilmazafone hydrochloride (450191S) is a new sleep inducer.
When the animals are pretreated with high doses of Rilmazafone hydrochloride (450191-S; 200 or 600 mg/kg for 5 or 3 days, respectively) to induce hepatic drug-metabolizing enzymes, plasma concentrations of the metabolites after oral administration of a dose of 200 mg/kg of Rilmazafone decrease markedly depending on the induced enzyme activity. Pretreatment of rats with phenobarbital also causes decreased plasma levels of metabolites, which are almost the same as those in Rilmazafone-pretreatment. On the other hand, administration of beta-naphthoflavone to rats leads to higher plasma levels of metabolites, and slower elimination compared with those in the control and Rilmazafone or Phenobarbital pretreated rats. Rilmazafone is demonstrated to stimulate the hepatic drug-metabolizing enzymes in rats, mice and dogs, which is accompanied by a marked reduction in the pharmacological activity of pentobarbital in rats. The induction of hepatic enzyme activities by Rilmazafone is detected only when the plasma concentrations of its metabolites are very high[1].
[1]. Matsubara T, et al. Effect of change of hepatic drug-metabolizing activity on plasma concentrations of major metabolites of the new sleep inducer 450191-S, a 1H-1,2,4-triazolyl benzophenone derivative. Jpn J Pharmacol. 1987 Aug;44(4):429-36.