UMEM Educational Pearls

Various intial doses of naloxone (0.4 to 2 mg) are administered to reverse the signs and symptoms of opioid toxicity. However, there is limited data regarding the duration of action of naloxone is correlated to the administered dose.

A recently published retrospective study investigated whether initial naloxone doses (IV), low-dose (0.4 mg) vs. high-dose (1-2 mg), lead to different time to recurrence of opioid toxicity.

 

Study sample: 274 patient screened but 84 patients were included.

1. Low-dose naloxone (0.4 mg IV): 42
   • Mean age: 50
   • History of opiod/heroin use: 33 (78.6%)
   • Positive opioid/opiate on drug screening: 27 (64%)
   • Median time to repeat naloxone dose: 72 min (IQR: 46 - 139)
   • 12 patients (29%) required continuous naloxone infusion

 

2. High-dose naloxone (1 - 2 mg IV): 42

• Mean age: 48
• History of opiod/heron use: 32 (76.2%)
• Positive opioid/opiate on drug screening: 26 (62%)
• Median time to repeat naloxone dose: 77 min (IQR: 44 - 126)
• 17 patients (41%) required continuous naloxone infusion

Higher rate of adverse effects (withdrawal symptoms - vomiting, agitation, tachycardia, etc.) were observed in high-dose group (41% vs. 31%) but this was not statistically signficant. 

Conclusion:

1. High-dose naloxone (1 - 2 mg) does not result in longer duration of reversal of opioid toxicity.
2. Duration of opioid toxicity reversal by naloxone administration were similar to previously reported duration of action of naloxone (30 to 90 min).
3. Note: there are several lmitations to the study study including retrospective design - documentation issues, small sample size, patient selection - patients were included if positive response to naloxone was observed, unknown opioid exposure, variable dosing in high-dose group (1 to 2 mg vs. 0.4 mg) and naloxone was given via IV only.   

References

Wong F et al. Comparison of lower-dose versus higher-dose invetravenous naloxone on time to recurrence of opioid toxicity in the emergency department. Clin Toxicol (Phila) 2018 Jul 23:1-6. doi: 10.1080/15563650.2018.1490420. [Epub ahead of print]