Comparison of intranasal and intramuscular naloxone in opioid overdoses managed by ambulance staff: a double-dummy, randomised, controlled trial

Abstract

Aims: To measure and evaluate clinical response to nasal naloxone in opioid overdoses in the pre-hospital environment. Design: Randomised, controlled, double-dummy, blinded, non-inferiority trial, and conducted at two centres. Setting: Participants were included by ambulance staff in Oslo and Trondheim, Norway, and treated at the place where the overdose occurred. Participants: Men and women age above 18 years with miosis, rate of respiration ≤8/min, and Glasgow Coma Score <12/15 were included. Informed consent was obtained through a deferred-consent procedure. Intervention and comparator: A commercially available 1.4 mg/0.1 mL intranasal naloxone was compared with 0.8 mg/2 mL naloxone administered intramuscularly. Measurements: The primary end-point was restoration of spontaneous respiration of ≥10 breaths/min within 10 minutes. Secondary outcomes included time to restoration of spontaneous respiration, recurrence of overdose within 12 hours and adverse events. Findings: In total, 201 participants were analysed in the per-protocol population. Heroin was suspected in 196 cases. With 82% of the participants being men, 105 (97.2%) in the intramuscular group and 74 (79.6%) in the intranasal group returned to adequate spontaneous respiration within 10 minutes after one dose. The estimated risk difference was 17.5% (95% CI, 8.9%–26.1%) in favour of the intramuscular group. The risk of receiving additional naloxone was 19.4% (95% CI, 9.0%–29.7%) higher in the intranasal group. Adverse reactions were evenly distributed, except for drug withdrawal reactions, where the estimated risk difference was 6.8% (95% CI, 0.2%–13%) in favour of the intranasal group in a post hoc analysis. Conclusion: Intranasal naloxone (1.4 mg/0.1 mL) was less efficient than 0.8 mg intramuscular naloxone for return to spontaneous breathing within 10 minutes in overdose patients in the pre-hospital environment when compared head-to-head. Intranasal naloxone at 1.4 mg/0.1 mL restored breathing in 80% of participants after one dose and had few mild adverse reactions.