CJEM Articles: overdose

Background: Inadequate hospital stocking and the unavailability of essential antidotes is a worldwide problem with potentially disastrous repercussions for poisoned patients. Research indicates minimal progress has been made in the resolution of this issue in both urban and rural hospitals. In response to this issue the British Columbia Drug and Poison Information Centre developed provincial antidote stocking guidelines in 2003. We sought to determine the compliance with antidote stocking in BC hospitals and any factors associated with inadequate supply.

Methods: A 2-part survey, consisting of hospital demographics and antidote stocking information, was distributed in 2005 to all acute care hospital pharmacy directors in BC. The 32 antidotes examined (21 deemed essential) and the definitions of adequacy were based on the 2003 BC guidelines. Availability was reported as number of antidotes stocked per hospital and proportion of hospitals stocking each antidote. For secondary purposes, we assessed factors potentially associated with inadequate stocking.

Results: Surveys were completed for all 79 (100%) hospitals. A mean of 15.6 ± 4.9 antidotes were adequately stocked per hospital. Over 90% of hospitals had adequate stocks of N-acetylcysteine, activated charcoal, naloxone, calcium salts, flumazenil and vitamin K; 71%-90% had adequate dextrose 50% in water (D₅₀W), ethyl alcohol or fomepizole, polyethylene glycol electrolyte solution, protamine sulfate, and cyanide antidotes; 51%-70% had adequate folic acid, glucagon, methylene blue, atropine, pralidoxime, leucovorin, pyridoxine, and deferoxamine; and <50% had adequate isoproterenol and digoxin immune F_ab. Only 7 (8.9%) hospitals sufficiently stocked all 21 essential antidotes. Factors predicting poor stocking included small hospital size (p < 0.0001), isolation (p = 0.01) and rural location (p < 0.0001).

Conclusion: Although antidote stocking has improved since the implementation of the 2003 guidelines, essential antidotes are absent in many BC hospitals. Future research should focus on determining the reasons for this situation and the effects of corrective interventions.

The management of ethylene glycol poisoning is reviewed, with a focus on the use of the new antidote fomepizole. Ethylene glycol is a widely used industrial agent that is also easily obtained commercially, usually as radiator antifreeze. Ingestion of as little as 30 to 60 mL can result in death or serious permanent disability. Traditional management of poisoning includes the use of ethanol, with or without hemodialysis. Activated charcoal is not indicated, and gastric lavage may be beneficial only in the first hour after ingestion. Cofactors such as pyridoxine and thiamine may be beneficial in patients deficient in these vitamins. A new antidote, fomepizole, has recently been approved for use in Canada. Like ethanol, it is a competitive inhibitor of alcohol dehydrogenase. Potential benefits of fomepizole include its ease of administration and lack of serious adverse effects. Fomepizole may be recommended over ethanol in situations in which avoidance of ethanol-induced side effects is imperative or when ethanol is not readily available. Further studies are required to verify its comparative efficacy and cost-effectiveness compared to ethanol.

Salicylates are widely available and potentially lethal. Clinical and laboratory findings associated with enteric-coated acetylsalicylic acid (ECASA) ingestion may be delayed more than 24 hours. When dealing with patients who have a history of significant ingestion, emergency physicians should consider initiating therapy regardless of initial salicylate levels. Prolonged observation may be necessary in cases of suspected ECASA overdose.