Ethylene glycol toxicity: closing in on rational, evidence-based treatment

Antifreeze on a freezing morning: ethylene glycol poisoning in a 2-year-old

This case report describes the presentation and management of a 2-year-old child who ingested a potentially fatal amount of ethylene glycol (EG). There are few published cases worldwide of EG poisoning in children managed with fomepizole. All cases described in the literature were managed in a paediatric intensive care unit. In this case, the child presented irritable, pale and confused with high anion gap metabolic acidosis. As there were no paediatric intensive care beds available in the region, the child was successfully managed in a high dependency area in our district general hospital. The child fully recovered and was discharged home in 7 days. The authors believe that multi-disciplinary team management and the use of fomepizole contributed to the positive outcome and this case raised many useful learning points.

Treatment of patients with ethylene glycol or methanol poisoning: focus on fomepizole

Ethylene glycol (EG) and methanol are responsible for life-threatening poisonings. Fomepizole, a potent alcohol dehydrogenase (ADH) inhibitor, is an efficient and safe antidote that prevents or reduces toxic EG and methanol metabolism. Although no study has compared its efficacy with ethanol, fomepizole is recommended as a first-line antidote. Treatment should be started as soon as possible, based on history and initial findings including anion gap metabolic acidosis, while awaiting measurement of alcohol concentration. Administration is easy (15 mg/kg-loading dose, either intravenously or orally, independent of alcohol concentration, followed by intermittent 10 mg/kg-doses every 12 hours until alcohol concentrations are <30 mg/dL). There is no need to monitor fomepizole concentrations. Administered early, fomepizole prevents EG-related renal failure and methanol-related visual and neurological injuries. When administered prior to the onset of significant acidosis or organ injury, fomepizole may obviate the need for hemodialysis. When dialysis is indicated, 1 mg/kg/h-continuous infusion should be provided to compensate for its elimination. Side-effects are rarely serious and with a lower occurrence than ethanol. Fomepizole is contraindicated in case of allergy to pyrazoles. It is both efficacious and safe in the pediatric population, but is not recommended during pregnancy. In conclusion, fomepizole is an effective and safe first-line antidote for EG and methanol intoxications.

Compliance With Poison Center Fomepizole Recommendations is Suboptimal in Cases of Toxic Alcohol Poisoning

We sought to examine hospital compliance with poison center antidotal alcohol dehydrogenase inhibition recommendations in cases of ethylene glycol (EG) and methanol (ME) ingestion. A 2-year analysis of all potential EG and ME ingestion cases reported to a regional poison center was conducted. Excluded from analysis were exposures without an ingestion, without a confirmatory EG or ME serum assay, or without complete medical charting. During the study period, 579 EG or ME exposures were reported to the poison center: 133 cases met study eligibility as an ingestion. Of the 133 cases, 102 (77%) had complete data and were included in the analysis. Immediate alcohol dehydrogenase inhibition was recommended by the poison center in 79 of the 102 cases. Fomepizole was recommended in 61/79 (77%); ethanol was recommended as an alternative therapeutic choice in 32/61 (52%) of these cases if fomepizole was not immediately available. Ethanol alone was recommended in 18/79 (23%). Fomepizole was eventually administered in 39/61 (64%) cases where recommended. The mean time to antidote administration was 3 times longer in cases where a choice in antidote was given [57 min (95% confidence interval, 43-70) vs. 146 min (95% confidence interval, 93-200)]. Despite its ease of administration, fomepizole is used less frequently than recommended by poison center staff. Delays to antidote administration occurred more commonly in cases where the poison center gave a choice in antidotal therapy.

Ethylene glycol poisoning in the Czech Republic (2000-2002)

BACKGROUND

The objective of the study was to evaluate the severity of kidney damage retrospectively and to analyze prognostic factors following ethylene glycol (EG) poisonings.

METHODS

Data concerning the clinical course of patients with EG poisoning between 2000 and 2002 were analyzed. The chi2 test, Student's t test, Fisher's test and the calculation of linear correlation coefficients were used for statistical analysis.

RESULTS

Thirty-three discharge records were obtained. Three patients died, and 11 patients developed acute renal failure (mean maximum serum creatinine level 618 micromol/l). Upon discharge, serum creatinine levels were still elevated in 10 patients. In all but 1 patient, renal function completely normalized within 20 months after intoxication.

CONCLUSION

Adult men are the most endangered segment of the population. The most important prognostic factors are the ingested dose and early antidotal treatment. EG toxic kidney damage is reversible.

Current recommendations for treatment of severe toxic alcohol poisonings

BACKGROUND

Ethylene glycol (EG) and methanol are responsible for accidental, suicidal, and epidemic poisonings, resulting in death or permanent sequelae. Toxicity is due to the metabolic products of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase. Conventional management of these intoxications consists of ethanol and hemodialysis. Fomepizole, a potent ADH inhibitor, has largely replaced antidotal ethanol use in France and two recent prospective U.S. trials definitively established its efficacy. Fomepizole appears safer than ethanol and while no comparative study of efficacy exists, fomepizole is recommended as the first-line antidote.

FOCUS

Fomepizole, administered early in EG intoxication, prevents renal injury. In the absence of renal failure, EG clearance is rapid, avoiding the need for prolonged fomepizole administration. The long elimination half-life of methanol poisonings, with absent hemodialysis, necessitates prolonged administration of fomepizole. In the U.S. trials, patients were dialyzed when plasma EG or methanol concentrations were >/=0.5 g/l. However, EG-poisoned patients treated with fomepizole prior to the onset of significant acidosis may not require hemodialysis. Indeed, fomepizole may also obviate the need for hemodialysis in selected methanol-poisoned patients, in the absence of neurological and ocular impairment or severe acidosis. When dialysis is indicated, 1 mg.kg.h continuous infusion of fomepizole should be provided to compensate for its elimination.

CONCLUSIONS

Fomepizole is an effective and safe first-line recommended antidote for EG and methanol intoxication. In selected patients, fomepizole may obviate the need for hemodialysis.

Extracorporeal therapies for acute intoxications

Intoxications frequently perturb acid-base and electrolyte status, intravascular volume, and renal function. In selected cases, extracorporeal techniques effectively restore homeostasis and augment intoxicant removal. The use of 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, is a new and effective treatment for patients exposed to toxic alcohols. In this section, practical approaches to commonly encountered intoxicants and the use of extracorporeal techniques are critically reviewed.

Role of fomepizole in the management of ethylene glycol toxicity

OBJECTIVE

To systematically review English-language articles on fomepizole administration in patients with ethylene glycol poisoning.

DATA SOURCES

MEDLINE, EMBASE, Current Contents, and PubMed. Search terms were fomepizole, 4-methylpyrazole, and ethylene glycol. The search was supplemented with a bibliographic review of all relevant articles.

STUDY SELECTION

All published reports of fomepizole administration in patients with ethylene glycol poisoning were reviewed, irrespective of study design. We identified one clinical trial and subsequent pharmacokinetic study, one case series, and 13 case reports.

RESULTS

Fomepizole has been investigated in 70 patients in open, unblinded studies. Most patients received an intravenous loading dose, with subsequent variable maintenance doses every 12 hours until plasma ethylene glycol levels became undetectable. Additional hemodialysis treatment generally was administered when patients had renal insufficiency or ethylene glycol levels above 50 mg/dl. Many patients had detectable ethanol levels either because of coadministration or as a result of adjunctive treatment at a referring center. Poorer patient outcomes, such as death and renal insufficiency, were associated with later clinical presentation time after ingestion. At therapeutic fomepizole levels (> 8.6 mg/ml), the half-life of ethylene glycol was prolonged to over 19 hours. Fomepizole appeared to be well tolerated by most patients.

CONCLUSION

Fomepizole is an effective alcohol dehydrogenase inhibitor that decreases production of ethylene glycol metabolites. Reduced mortality and morbidity are undetermined because of the small number of patients evaluated to date. Data on comparative efficacy of fomepizole versus ethanol and data on administration of fomepizole in children are limited.