Rilmazafone[1] (リスミー, Rhythmy, previously known as 450191-S) is a water-soluble prodrug developed in Japan.

[2] Inside the human body, rilmazafone is converted into several benzodiazepine metabolites that have sedative and hypnotic effects.

It is therefore not classified as a benzodiazepine in several countries, including the United States, where it is not designated a controlled substance.

Rilmazafone has no effects on benzodiazepine receptors itself, nor does it produce any psychoactive effects prior to metabolism.

However, once inside the body it is metabolized by aminopeptidase enzymes in the small intestine to form the principal active benzodiazepine rilmazolam (8-chloro-6-(2-chlorophenyl)-N,N-dimethyl-4H-1,2,4-triazolo [1,5-a][1,4]benzodiazepine-2-carboxamide).