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Successful use of fomepizole during second trimester of pregnancy

Author/s Harbon SCD, Thompson JP
Year 2014
Type of publication Conference proceeding

Objective: To report a use of fomepizole during second trimester of pregnancy.

Case report: A 26-year-old female, 16 weeks pregnant, presented to the emergency department 5 h post-ingestion of 200 mL of concentrated ethylene glycol. She presented with general malaise and was found to have a metabolic acidosis (pH 7.31, bicarbonate 10 mmol/L, pO2 16.0 kPa, pCO2 2.7 kPa, base excess −14.0 mmol/L). Admission blood results were not available to calculate the osmolar and anion gaps; subsequent results at approximately 4 h post-ingestion showed a normal anion gap of 12.2. Her plasma osmolarity, however, was 315 mOsm/kg, with a suggested osmolar gap of 32 mOsm/L. An ethylene glycol concentration of 2500 mg/L was later confirmed. There have been no studies on the safety of fomepizole in human pregnancy and therefore the risks posed to the fetus are unknown. Fomepizole has been used in pregnancy without adverse effects. The National Poisons Information Service (NPIS) may advise treating pregnant patients with fomepizole as opposed to ethanol which is contraindicated in pregnancy. In this case, it was suggested that if the osmolar gap was found to be raised, fomepizole should be administered, with consideration given for the role of hemodialysis. Ethanol was not recommended due to the known teratogenic effects. Follow-up of the patient revealed that she was treated with an initial dose of 720 mg of fomepizole and a further dose of 480 mg 12 h later. The patient made a complete recovery and was discharged on day four. The pregnancy continued uneventfully to full term, no abnormalities or complications were noted. The baby required a brief stay in the Special Care Baby Unit for an unassociated mild hypothermia.

Conclusion: Use of fomepizole to treat ethylene glycol poisoning during the second trimester of pregnancy was not associated with any adverse effects.


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