Anaes SAQs · Anaesthetic adjuncts

Opioid receptors, biased agonism and opioid-induced hyperalgesia

Primary — the three classical receptors (mu/kappa/delta) plus NOP, all Gi/Go-coupled; the mu effects (analgesia, euphoria, respiratory depression, miosis, constipation); the kappa effects (spinal analgesia, dysphoria, psychotomimetic, less respiratory depression); the delta effects (analgesia, convulsant at high dose); the Gi/Go mechanism (inhibit adenylate cyclase, close Ca, open K, hyperpolarise); the biased agonism (G-protein versus beta-arrestin, oliceridine); the tolerance (desensitisation, downregulation, internalisation); the OIH (paradoxical hyperalgesia, NMDA, descending facilitation, glia, dynorphin); the OIH management (reduce/rotate opioid, ketamine, methadone, alpha-2 agonists, multimodal); the tolerance versus dependence versus addiction.