National audit of antidote stocking in acute hospitals in the UK.

BACKGROUND: Inadequate stocking of essential antidotes in hospitals for the treatment of poisoned patients has been reported worldwide. Joint National Poisons Information Service (NPIS)/College of Emergency Medicine (CEM) guidelines for antidote stocking in UK emergency departments and acute hospitals were published in 2008. AIM: To determine the impact of these guidelines by surveying the availability of antidotes in acute hospitals in the UK. METHODS: A two-page questionnaire consisting of antidote stocking information was distributed in 2010 to the Chief Pharmacist in all acute hospitals in the UK. The availability of 28 antidotes in the NPIS/CEM antidote guidelines as well as that of Intralipid was surveyed. RESULTS: Surveys were completed for 196 of the 224 (87.5%) hospitals. Over 90% of hospitals had acetylcysteine, activated charcoal, dantrolene, desferrioxamine, naloxone, flumazenil and vitamin K available within the recommended time period. Pralidoxime was reported to be held in only 33% of hospitals, though pralidoxime is supplied by the Department of Health to 95 hospitals in the UK that act as holding centres. Cyproheptadine and viper venom antiserum were held in around 50% of acute hospitals. For the treatment of cyanide and toxic alcohol poisoning, more than one antidote is available. For cyanide poisoning, most hospitals held at least one antidote (usually dicobalt edetate) but 9 (5%) held none of the four antidotes. For toxic alcohol and glycol poisoning, most hospitals held ethanol for intravenous use but not fomepizole and 30 (15%) did not stock any antidote for toxic alcohol poisoning. CONCLUSION: Stocking of less commonly used antidotes is inconsistent. This is likely to result in delayed access to treatment and worse patient outcomes.

Management of poisoning with ethylene glycol and methanol in the UK: a prospective study conducted by the National Poisons Information Service (NPIS).

BACKGROUND: Poisoning with methanol and ethylene glycol can cause serious morbidity and mortality. Specific treatment involves the use of antidotes (fomepizole or ethanol) with or without extracorporeal elimination techniques. METHODS: A prospective audit of patients with methanol or ethylene glycol poisoning reported by telephone to the National Poisons Information Service (NPIS) in the UK was conducted during the 2010 calendar year and repeated during the 2012 calendar year. The study was conducted to determine the frequency of clinically significant systemic toxicity and requirement for antidote use and to compare outcomes and rates of adverse reaction and other problems in use between ethanol and fomepizole. RESULTS: The NPIS received 1315 enquiries involving methanol or ethylene glycol, relating to 1070 individual exposures over the 2-year period. Of the 548 enquiries originating from hospitals, 329 involved systemic exposures (enteral or parenteral as opposed to topical exposure), of which 216 (66%) received an antidote (204 for ethylene glycol and 12 for methanol), and 90 (27%) extracorporeal treatment (86 for ethylene glycol and 4 for methanol). Comparing ethanol with fomepizole, adverse reactions (16/131 vs. 2/125, p < 0.001) and administration errors, lack of monitoring, or inappropriate use (45/131 vs. 6/125, p < 0.0001) were reported more commonly, whereas non-availability and inadequate stocks were reported less commonly (6/125 vs. 33/131, p < 0.0001). Eight fatalities and complications or sequelae occurred in 21 patients. Poor outcome (death, complications, or sequelae) was significantly associated with older age, higher poisoning severity scores, and lower pH on admission (p < 0.001). CONCLUSIONS: Systemic poisoning with ethylene glycol or methanol results in hospitalisation at least 2-3 times per week on average in the UK. No difference in outcome was detected between ethanol and fomepizole-treated patients, but ethanol was associated with more frequent adverse reactions.

Extracorporeal elimination in acute valproic acid poisoning.

INTRODUCTION: Valproic acid (VPA) is an antiepileptic drug that is now used for a variety of neurological and psychiatric indications. Clinical manifestations of severe VPA poisoning include central nervous system depression, hypotension, electrolyte and acid-base disturbances, and hyperammonemia. Although extracorporeal methods have been used to enhance VPA elimination, the indications for and effectiveness of these methods have not been fully characterized. METHODS: A systematic literature search was performed, which identified 31 reports of the use of extracorporeal elimination in VPA poisoning. RESULTS: VPA has a low molecular weight of 144 Da and a low volume of distribution, but at therapeutic concentrations, it is highly protein bound (85-95%). Protein-binding studies during hemodialysis demonstrate that at high VPA concentrations protein binding is saturated, allowing substantial clearance of the free VPA fraction. Case reports consistently show that during hemodialysis the elimination half-life of VPA can be reduced to around 2 h and the enhanced VPA clearance is often associated with improvement clinically. Hemoperfusion also enhances VPA elimination, but its effectiveness may be limited by column saturation. "In-series" hemodialysis and hemoperfusion have been used, but the combination offers little benefit over hemodialysis alone. Continuous renal replacement techniques are increasingly being used although continuous venovenous hemofiltration and continuous venovenous hemodiafiltration do not appear to be as effective as hemodialysis. No controlled trials are available comparing clinical outcomes with or without extracorporeal elimination in VPA poisoning. Novel techniques such as slow low-efficiency dialysis with filtration and supplementation of the dialysate with albumin are being evaluated. INDICATIONS: Extracorporeal methods of elimination should be considered in patients with features of severe VPA poisoning (coma or hemodynamic compromise) and plasma VPA concentration >850 mg/L (coma is more likely to be present at concentrations >850 mg/L), particularly if severe hyperammonemia and electrolyte and acid-base disturbances are present. CONCLUSIONS: Based on limited anecdotal evidence, hemodialysis appears to be the extracorporeal method of choice to enhance VPA elimination in acute poisoning. Controlled, randomized trials are required to better characterize the effect of extracorporeal treatment on clinical outcome.