Comparison of lower-dose versus higher-dose intravenous naloxone on time to recurrence of opioid toxicity in the emergency department.

INTRODUCTION: The initial dose of naloxone administered to patients who present to the emergency department (ED) with opioid overdose is highly variable. The objective of this study was to determine if the initial dose of intravenous (IV) naloxone given to these patients was associated with the time to recurrence of opioid toxicity.

METHODS: This was a multicenter retrospective cohort study, conducted at two academic EDs in the United States. Consecutive adults who had a positive response to naloxone for opioid overdose in the ED were included. Patients were categorized into two groups based on initial IV naloxone dose administered: 0.4 mg (lower-dose) or 1-2 mg (higher-dose). The main outcome measure was the time to recurrence of opioid toxicity requiring a second dose of naloxone. Secondary outcomes included the need for naloxone continuous infusion and adverse events.

RESULTS: The study included 84 patients with 42 patients receiving lower-dose and 42 patients receiving higher-dose naloxone. Median time to re-dose of naloxone was similar between the lower-dose (72 [IQR 46-139] minutes) and higher-dose (70 [IQR 44-126] minutes) groups (p=.810). There were 12 patients (29%) in the lower-dose group and 17 patients (41%) in the higher-dose group who subsequently required continuous infusions (p=.359). The proportion of patients with adverse events was similar between lower-dose and higher-dose groups (31% versus 41%, p=.495). There was no difference in the incidence of specific withdrawal related adverse effects.

CONCLUSIONS: The initial dose of naloxone given to patients in the ED does not influence the time to recurrence of opioid toxicity.