According to a recent prospective study, how effective is a single, large dose of intramuscular naloxone in reversing opioid toxicity in adult patients in the outpatient setting?
In the cited reference, a single 1.6 mg IM dose of naloxone was effective in initially reversing respiratory depression in 97% of opioid presentations; however the study was limited by the time period studied, in which non-fentanyl/fentanyl-derivative opioids may have comprised the majority of exposures (though confirmatory testing was not performed).
Isoardi KZ, Parker L, Harris K, Rashford S, Isbister GK. Acute Opioid Withdrawal Following Intramuscular Administration of Naloxone 1.6 mg: A Prospective Out-Of-Hospital Series. Ann Emerg Med. 2022 Aug;80(2):120-126. doi: 10.1016/j.annemergmed.2022.03.004. Epub 2022 Apr 29. PMID: 35491292.