An Investigation of the Role of the Specific Opioid Antagonist Naloxone in Clinical Toxicology

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Abstract
1 An assessment of the current role of naloxone in clinical toxicology has been made in a series of three separate epidemiological studies. 2 Through the National Poisons Information Service we found that the role of naloxone in opioid poisoning is often not appreciated by the enquirer and that toxicological screening is often requested before the diagnostic use of naloxone. 3 The recommended dose of naloxone (0.4-1.2 mg i.v.) is not always adequate. In 51 cases where naloxone was effective, doses of up to 3.2 mg were necessary (mean 1.8 ± 0.3 mg SEM i.v.). 4 In 31 cases of non-opioid poisoning, naloxone in doses of 0.4-1.2 mg i.v. caused no deterioration, whilst six patients in whom no opioids were detected showed clinical improvement. 5 In 300 cases of suspected ethanol-induced coma, 49 showed reversal of coma with naloxone, and in 38 cases ethanol was the sole cause of coma (mean plasma concentration 3.54 ± 0.62 g/l SEM). 6 These results suggest that the role of naloxone in clinical toxicology is not fully appreciated. There is a need for further education as to its indications in opioid poisoning, together with additional studies to define more accurately the dose/response relationship. In addition, the role of naloxone in coma induced by ethanol and certain other non-opioids needs to be evaluated further.