Do Resting Plasma β-Endorphin Levels Predict Responses to Opioid Analgesics?

This study evaluated whether resting plasma β-endorphin (BE) levels predicted responses to an opioid analgesic, and whether chronic pain status or sex moderated these effects. Methods: Participants included 73 individuals with chronic low back pain (CLBP) and 88 pain-free controls, all using no daily opioid analgesics. Participants attended 2 identical laboratory sessions during which they received either intravenous morphine (0.08 mg/kg) or saline placebo, with blood samples obtained before drug administration to assay resting plasma BE levels. Once peak drug activity was achieved in each session, participants engaged in an ischemic forearm pain task (ISC) and a heat pain task. Morphine analgesic effects were derived reflecting the difference in pain outcomes between placebo and morphine conditions. Results: In hierarchical regressions, significant Type (CLBP vs. control)×BE interactions (Ps
Source: The Clinical Journal of Pain - Category: Anesthesiology Tags: Original Articles Source Type: research