Central muscle relaxant properties of 2,6-dimethylphenethylurea and related compounds

Abstract

Abstract Twenty-eight phenylalkylureas with alkyl, hydroxy, methoxy or chloro-substituents in the aryl ring have been synthesized and tested for central depressant and muscle relaxant properties. In this series, the dimethylphenethylureas with at least one ortho-methyl group show unexpectedly selective muscle relaxant activity. 2,6-Dimethylphenethylurea inhibits polysynaptic reflexes more readily than monosynaptic ones, but also depresses muscle contractions by an action independent of its effect on interneuronal transmission. It is a weak anticonvulsant, suppresses rage episodes in “fighting” mice, and has no selective blocking action on conditioned responses. It thus has a pharmacological profile resembling those of mephenesin and meprobamate, but distinct from either, and differing still more from those of phenobarbitone, chlordiazepoxide or chlorpromazine. However, tolerance to its action develops readily.