Investigations on the synthesis and pharmacological properties of amides of 7-methyl-3-phenyl-1-[2-hydroxy-3-(4-phenyl-1-piperazinyl)propyl]-2,4- dioxo-1,2,3,4-tetrahydropyrido[2,3-d]-pyrimidine-5-carboxylic acid.

Synthesis of amides of 7-methyl-3-phenyl-2,4-dioxo-1,2,3,4- tetrahydropyrido[2,3-d]pyrimidine-5-carboxylic acid (6-10) and their 1-[2-hydroxy-3(4-phenyl-1-piperazinyl)propyl] derivatives (11-15) are described. Some of them displayed strong analgesic activity.