Rilmazafone (previously known as 450191-S) is a water-soluble benzodiazepine prodrug developed in Japan. It has sedative and hypnotic effects. Rilmazafone induces impairment of motor function and has hypnotic properties. Rilmazafone has no effects on benzodiazepine receptors itself, but once inside the body is metabolised by aminopeptidase enzymes in the small intestine to form the active benzodiazepine 8-chloro-6-(2-chlorophenyl)-N,N-dimethyl-4H-1,2,4-triazolo benzodiazepine-2-carboxamide. Preclinical studies have shown its excellent effects inducing and maintaining sleep with little effect on the skeletal muscle. Earlier the clinical dose for this drug as a premedicant was found to be 2-4mg.