Interaction of metamizol with some hypnotics in rats.

Metamizol (sodium N-(1,5-dimethyl-3-oxo-2-phenylpyrazolin-4-yl)-N-methylamino-methylsulphonate; Dipyrone) a non-narcotic analgesic was tested for hypnotic potentiating effect. Metamizol potentiated the hypnosis induced by pentobarbital, barbital and chloral hydrate. This effect was dose-dependent and was inversely proportional to the duration of the analgesic pretreatment. An augmented hypothermia and competition at drug metabolizing sites seem to be the mechanisms involved in the observed effect.