Opioid analgesia: recent developments

Abstract

Purpose of review: Opioids are potent drugs for the treatment of severe pain, but they are burdened by detrimental side-effects, such as respiratory depression, addiction, sedation and constipation. Their clinical application is undisputed in acute (e.g. perioperative) and cancer pain, but their use in chronic nonmalignant pain has met increasing scrutiny and has contributed to the opioid crisis. Thus, novel analgesics with reduced side-effects are badly needed.

Recent findings: Current research topics include enkephalinase inhibitors, allosteric and multivalent ligands, biased opioid receptor signaling and selective activation of peripheral opioid receptors in injured tissues.

Summary: Opioids still appear to be most promising among current approaches in the development of analgesics. Basic knowledge about pathophysiology of clinical pain and novel insights in pharmacology suggest that the most interesting perspectives are augmenting endogenous opioid actions and selectively targeting peripheral opioid receptors. The latter approach is additionally supported by evidence from clinical studies. Some biased, multivalent and peripherally selective agonists have advanced to phase III trials, but novel drugs have not become available for clinical application. Future strategies in analgesic drug development might include public-private partnerships and nonprofit pharmaceutical companies, as exemplified by the AIDS crisis and proposals to combat antibiotic resistance.