Central action of new derivatives of tetrahydropirimidinedione-4,6.

: The central action and LD50 of 11 new 2,5-substituted derivates of tetrahydropirimidinedione-4,6 with an aryl group at C2 were investigated. The most favorable action was exerted by 2-furfurylamine derivatives with an alkil or benzyl group at C5. These compounds acted in doses of 0.0025--0.01 of their LD50 synergistically with chloral hydrate and strongly with hexobarbital, delayed convulsions induced with pentetrazole and potentiated the central action of DOPA in mice pargyline-inhibited MAO activity. They did not antagonize electrogenic convulsions, amphetamine potentiated motility and the action of reserpine, and had no analgetic action. Their LD50s were 670-- 1660 mg/kg.