Article Text


Intravenous or intramuscular/subcutaneous naloxone in opioid overdose
  1. Simon Clarke, Specialist Registrar,
  2. Paul Dargan, Specialist Registrar
  1. Department of Emergency Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK;
  1. kevin.mackway-jones{at}


A short cut review was carried out to establish whether intramuscular/subcutaneous naloxone is better than intravenous naloxone in opioid overdose. Altogether 185 papers were found using the reported search, of which two presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. A clinical bottom line is stated.

Statistics from

Report by Simon Clarke,Specialist RegistrarChecked by Paul Dargan, Specialist Registrar

Clinical scenario

A 30 year old man who is a known opioid addict is brought to the emergency department after an overdose of heroin. He had a Glasgow Coma Scale score of 3, a respiratory rate of 4 breaths per minute, and pinpoint pupils. You are aware that many addicts self discharge on reversal of opioid intoxication (possibly due to precipitation of acute withdrawal symptoms), and that because naloxone has a shorter duration of action than most opioid agonists, there is a risk of harm to the patient if he becomes renarcotised away from the hospital. You wonder if use of the intramuscular or subcutaneous route reduces this risk by prolonging the duration of action of naloxone.

Three part question

In [patients acutely intoxicated with opioids] does [intramuscular/subcutaneous or intravenous naloxone] reduce [the need for subsequent doses and risk of death from recurrent opioid toxicity]?

Search strategy

Medline 1966–09/2001 using the OVID interface. [{exp naloxone OR “naloxone”.mp} AND {exp narcotics OR “opioid”.mp OR “opiate”.mp OR (morphine OR buprenorphine OR codeine OR dextromoramide OR diphenoxylate OR dipipanone OR dextropropoxyphene OR diamorphine OR dihydrocodeine OR alfentanil OR fentanyl OR remifentanil OR meptazinol OR methadone OR nalbuphine OR oxycodone OR pentazocine OR pethidine OR phenazocine OR tramadol).mp} AND {exp overdose OR “overdos$”.mp OR exp poisons OR “poison$”.mp OR “acute intoxic$”.mp OR “acute toxic$”.mp}] LIMIT to human AND English.

Search outcome

Altogether 185 papers were found of which two addressed the question directly (table 3).

Table 3


Both studies were set in the prehospital environment and different criteria were used to define opioid intoxication, which means that it is difficult to assess applicability to other patient populations. In Sporer's study there were 16 patients who were found to be asystolic at the scene; these have been excluded from this discussion because no note was made of which treatment was given, and, in any case, none of this group survived.


There is no evidence from these studies to suggest that the subcutaneous or intramuscular routes are inferior to IV administration of naloxone, but significant theoretical concerns have not been addressed, requiring further research. They may be useful alternative routes if intravenous access is difficult to obtain.

Report by Simon Clarke,Specialist RegistrarChecked by Paul Dargan, Specialist Registrar


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