Buprenorphine blood concentrations: A biomarker for analgesia.

Opioids, the frontline drugs for postsurgical analgesia, have been linked to diversion and abuse with lethal consequences. The search for safe analgesics with less harm potential has been decades long. However, clinical trials for safe opioid and nonopioid analgesics have relied on subjective pain reports, which are biased by placebo effects that increase the complexity of trials to develop new therapies to manage pain. Research in opioid naïve animals and humans demonstrates that blood concentrations of opioids that effectively saturate the morphine opioid receptor are tightly linked with patient reports and quantitative sensory tests for analgesia. Opioid drug concentrations can predict clinical responses. This report reviews preclinical and clinical evidence correlating buprenorphine pharmacokinetics with analgesia. More than 30 years of data confirm buprenorphine blood concentrations can be an objective biomarker of analgesia for moderate to severe acute postoperative pain.