Context: To describe the role of opioid antagonist induction in reducing stress response and withdrawal symptoms.
Objective: Complexity of naltrexone induction is limiting broader applicability of opioid antagonist-assisted abstinence. The aim of this clinical trial was to assess the stress response to 2 low-dose naltrexone induction protocols under minimal oral sedation.
Design: Double-blind randomized controlled trial.
Setting: Open setting in-patient unit.
Participants: Adults with opioid use disorder, and at least a year-long history of opioid use.
Intervention protocol: Patients received either a single 12.5 mg naltrexone oral dose (SI group) or escalating dosage regimen starting from 50 μg up to a cumulative dose of 12.5 mg (ED group).
Main outcome measure: Differences in cortisol and adrenocorticotropic hormone (ACTH) concentrations 1 hour after the start of naltrexone induction.
Results: In all, 124 patients were enrolled and 68 remained in the trial at the point of randomization-33 in SI and 35 in ED group. Eight patients were excluded from final analysis. Plasma cortisol and ACTH concentrations were significantly higher in SI group; mean difference between groups 313 nmol/L (95% confidence interval [CI] 182-444, P < 0.001) and 36.9 pg/mL (95% CI 12.3-61.4, P = 0.004), respectively.
Secondary outcomes: SI patients experienced significant increases in plasma cortisol and ACTH concentrations, and withdrawal scores. In ED group these measures remained at or below baseline throughout the 24-hour period from start of naltrexone induction.
Conclusions: Contrary to a single 12.5-mg dose, the escalating naltrexone dosing regimen produced no significant increase in stress response and withdrawal scores during antagonist induction.