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Article Reviews

Ashton H, Hassan Z. Best evidence topic report. Intranasal naloxone in suspected opioid overdose. Emerg Med J. 2006 Mar;23(3):221-3.

Naloxone administration is indicated for reversal of opioid anesthesia, in cases of respiratory or central nervous system (CNS) depression from known opioid overdose, or in cases of respiratory or CNS depression when opioid overdose is suspected. Naloxone acts by competitively binding at the µ, ? and d opiate receptors. Naloxone is highly lipophilic, so distribution to the brain is rapid. Naloxone is usually administered by the i.v. route, and this is most commonly recommended by textbook chapters and journal reviews of this antidote. Intravenous administration intuitively seems ideal: onset is rapid and titration by this route is easiest. Within 1-2 min of administration, 1 mg i.v. naloxone blocks the effect of 25 mg i.v. heroin for 30-60 min. Naloxone also has been used successfully by i.m., s.c., sublingual, intralingual, endotracheal, and nasal routes. However, bioavailabilty of naloxone, optimal dosing, and onset of action via these routes has been well established only for intravenous and oral dosing. Our patient's clinical presentation suggests some circumstances when nebulized naloxone may be considered over other routes of administration.

First, patients with a history of intravenous narcotic abuse may have developed scarred peripheral veins making venous access difficult. Poor venous access may delay antidote administration in a hypoxic patient, and difficulty starting an i.v. may put the health care practitioner at risk for a needlestick injury and potential exposure to blood-borne pathogens. A recent pre-hospital study comparing i.v. and subcutaneous administration of naloxone demonstrated no difference to onset of narcosis reversal in the two groups. Both groups had a mean onset of 9 min to reversal of narcosis, and it was hypothesized that slower s.c. absorption was offset by the delay to establishing i.v. access. However, even s.c. administration requires the use of a needle, which may put the healthcare giver at risk for needlestick injury in a combative or semi-arousable patient. As our patient had poor venous access but some respiratory drive, nebulized naloxone was given during a careful evaluation for appropriate i.v. access. Remarkably, our patient responded in 5 min after both nebulizer trials, a full 4 min quicker than the mean response time in the i.v. or s.c. groups in the parenteral trial.

Second, administration of intravenous naloxone may have the effect of precipitating a violent withdrawal syndrome in narcotic-habituated patients. Not only is withdrawal extremely uncomfortable for the patient, but health care providers are again at risk for harm from these patients after antidote administration. If nebulized naloxone effectively reverses narcosis, it may allow the patient to self-titrate the antidote by removing the mask when awake and alert. It has been observed that patients awakened too quickly often exhibit poor impulse control. Indeed, with nebulized naloxone our patient did not exhibit the violent withdrawal symptoms described by Tandberg and others when the dose could not be titrated. A recent abstract describing prehospital use of intranasal naloxone seems promising, because needles are avoided and ...