Analgesic effects of N-acetylmuramyl-L-alanyl-D-isoglutamine in decreasing the acetic acid-induced abdominal-writhing response.

A new pharmacological action of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) is described. Pretreatment of male ddY mice with MDP, but not its biologically inactive analogs, significantly decreased the frequency of acetic acid-induced writhing movements more effectively than did acetylsalicylic acid (aspirin). The analgesic effect of MDP, however, was less than that of a narcotic antagonist, pentazocine.