Abstract
BACKGROUNDPotent synthetic opioids, such as fentanyl, are increasingly abused, resulting in unprecedented numbers of fatalities from respiratory depression. Treatment with the high-affinity mu-opioid receptor partial agonist buprenorphine may prevent fatalities by reducing binding of potent opioids to the opioid receptor, limiting respiratory depression.METHODSTo characterize buprenorphine-fentanyl interaction at the level of the mu-opioid receptor in 2 populations (opioid-naive individuals and individuals who chronically use high-dose opioids), the effects of escalating i.v. fentanyl doses with range 0.075-0.35 mg/70 kg (opioid naive) and 0.25-0.70 mg/70 kg (chronic opioid use) on iso-hypercapnic ventilation at 2-3 background doses of buprenorphine (target plasma concentrations range: 0.2-5 ng/mL) were quantified using receptor association/dissociation models combined with biophase distribution models.RESULTSBuprenorphine produced mild respiratory depression, while high doses of fentanyl caused pronounced respiratory depression and apnea in both populations. When combined with fentanyl, buprenorphine produced a receptor binding-dependent reduction of fentanyl-induced respiratory depression in both populations. In individuals with chronic opioid use, at buprenorphine plasma concentrations of 2 ng/mL or higher, a protective effect against high-dose fentanyl was observed.CONCLUSIONOverall, the results indicate that when buprenorphine mu-opioid receptor occupancy is sufficiently high, fentanyl is unable to activate the mu-opioid receptor and consequently will not cause further respiratory depression in addition to the mild respiratory effects of buprenorphine.TRIAL REGISTRATIONTrialregister.nl, no. NL7028 (https://www.trialregister.nl/trial/7028)FUNDINGIndivior Inc., North Chesterfield, Virginia, USA.