Pharmacology of the Spinal Action of Ketorolac, Morphine, ST-91, U50488H, and L-PIA on the Formalin Test and an Isobolographic Analysis of the NSAID Interaction

Abstract

These observations offer systematic support for the powerful interaction between NSAIDs and opioids and certain other analgesics in clinical pain states. These studies also demonstrate that spinal synergy is not a common property of all interactions. Thus, the NSAID synergy appears to occur with agents that exert a concurrent action both pre- and postsynaptic to the primary afferents.