By exposing the mu-receptor (MOP-R) to more than one exogenous ligand, the administration during general anaesthesia of more than one opioid with principal action on the receptor may confound and lead to complications or unexpected outcomes. The giving of such a ‘mixed message’ can result in respiratory depression, excess sedation and delayed recovery to an unusual degree. We present a case of apparent extreme opioid sensitivity and discuss a possible mechanism. Such occurrences may be more common than previously realised.
PogozhevaI.D., LomizeA.L., MosbergH.I.Opioid receptor three-dimensional structures from distance geometry calculations with hydrogen bonding constraints.Biophys J1998; 75: 612–634.
3.
MetzgerT.G., FergusonD.M.On the role of extracellular loops of opioid receptors in conferring ligand selectivity.FEBS Lett1995; 375: 1–4.
4.
KvamT.M., BaarC., RakvagT.T.Genetic analysis of the murine mu opioid receptor: increased complexity of Oprm gene splicing.J Mol Med2004; 82: 250–255.
5.
BowdleT.A.Adverse effects of opioid agonists and agonist-antagonists in anaesthesia.Drug Safety1998; 19: 173–189.
6.
ShookJ.E., WatkinsW.D., CamporesiE.M.Differential roles of opioid receptors in respiration, respiratory disease, and opiate-induced respiratory depression.Am Rev Respir Dis1990; 142: 895–909.
7.
GharagozlouP., DemirciH., David ClarkJ., LamehJ.Activity of opioid ligands in cells expressing cloned mu opioid receptors.BMC Pharmacol2003; 3: 1–8.
8.
BotG., BlakeA.D., LiS., ReisineT.Fentanyl and its analogs desensitize the cloned mu opioid receptor.J Pharmacol Exp Ther1998; 285: 1207–1218.
9.
SubramanianG., PaterliniM.G., PortogheseP.S., FergusonD.M.Molecular docking reveals a novel binding site model for fentanyl at the mu-opioid receptor.J Med Chem2000; 43: 381–391.
10.
GalT.J.Naloxone reversal of buprenorphine-induced respiratory depression.Clin Pharmacol Ther1989; 45: 66–71.
