Is subcutaneous or intramuscular naloxone as effective as intravenous naloxone in the treatment of life-threatening heroin overdose?

Clinical question " Is subcutaneous (SC) or intramuscular (IM) naloxone as effective as intravenous (IV) naloxone in the treatment of life-threatening heroin overdose? " An emergency department clinician was interested in comparing routes of administration of naloxone in light of anecdotal evidence suggesting that various routes may not be equally efficacious in restoring a patient to spontaneous breathing and consciousness. Patients presenting to an emergency department for the management of a heroin overdose were the focus of the search strategy. The search question was " How long does it take for patients to return to consciousness after administration of naloxone by various routes? ". In order to answer this question , a randomised controlled trial comparing the effects of SC or IM versus IV naloxone would be the ideal study design. Search The search terms " heroin " , " opioid overdose " , " naloxone " and " route of administration " were combined to identify relevant English-language articles published between 1966 and June 2000. Databases and websites searched included the Cochrane Library, Best Evidence, PubMed, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Smart Search and Bandolier. Studies other than those set in the emergency department (ie, those conducted in hospital wards or post-anaesthetic care units) were excluded, as the clinician had specified that we limit the search to pre-hospital or emergency department settings. The search yielded only one study that compared SC with IV naloxone for treating opioid overdose in this setting. No studies were found comparing the use of IM with IV naloxone. Summary of findings In a comparative study using historical controls, Wagner et al 1 compared naloxone administered intravenously or sub-cutaneously to patients in the community with suspected opioid overdose. The two intervention arms were 0.4 mg IV naloxone and 0.8 mg SC naloxone. The study was conducted sequentially in two phases: the IV phase, from 1 June to 30 June 1996, and the SC phase, from 1 July to 1 September 1996. Ambulance attendants in a regional district of British Columbia, Canada, administered naloxone to people meeting the British Columbia Ambulance Services' criteria for suspected overdose (ie, reduced consciousness, history suggestive of opioid use, and respiratory rate of less than 10 breaths per minute). The protocol also included a second dose of SC or IV naloxone if the first dose was not observed to be physiologically effective. The primary outcomes of interest …