Chin Med J (Taipei) 1998;61:S14.

Antidotes for Methanol and Ethylene Glycol Poisonings

Chen [陳靖博]

Section of Nephrology, Chang Gung Memorial Hospital-Kaohsiung

Abstract

Mehanol(MeOH) and Ethylene Glycol(EG) poisonings share many characteristics, both clinically and biochemically. Both alcohols are metabolized to toxic metabolites by the enzyme alcohol dehydrogenase. Ethanol is a competitive antagonist for the enzyme alcohol dehydrogenase.

Ethanol Therapy:

Indications: A. anion gap Metabolic acidosis with a history of MeOH and EG ingestion; B. blood level of MeOH or EG > 20mg/dI; C. any symptomatic patient with a history of MeOH or EG ingestion.

Dose, Concentration, and Precaution: Loading dose 0.8g/kg, Maintenance dose 130mg/kg/h, 250-350mg/kg/h, when perform hemodialysis higher doses are required in chronic alcoholics pediatric loading and maintenance dose should be the same as adults serum ethanol level 100-150mg/dl. Concentration: iv 5-10%, oral 20-30%. Precautions: hypoglycemia, especially in the children, CNS depression, dehydration, fluctuating serum concentration.

Duration: criteria: A. Blood level of MeOH, EG < 10mg/dl; B. Blood level of formate < 1.2mg/dl or glycolic acid metabolite is no longer detectable; C. Acidosis, clinical CNS findings, electrolytes abnormalities, serum amylase, osmolal gap have resolved.

If No Serum MeOH Concentration Available: A. A minimum 5 days of MeOH poisoning, 3 days of EG poisoning in the abscence of dialysis; B. One day when dialysis has been performed; C. clinical findings have been resolved.

Other Antidotes:
4-Methylpyrazole(4-MP, Fomepizole)
1. A potent, long acting inhibitor of alcohol dehydrogenase;
2. Used in European countries;
3. Currently in the United States there are META (Methylpyrazole for Toxic Alcohols) trials ongoing. 15mg/kg iv as loading dose; 10mg/kg iv q 12 hrs for 48 hrs; 15mg/kg iv after 48 hrs, dosing is continued until MeOH of EG levels < 20mg/dl.
4. Adverse effects: pain on injection site, abdomen pain, skin rash, nausea, headache, dizziness, transient increase in serum transaminases.

Other Specific Antidotes for Methanol Poisoning:
1. Folic Acid. 50-75mg, q4h iv for 24hr.
2. 5-Fomyltetrahydrofolic Acid (5-FTHFA, Folinic Acid, Citrovorum Factor, Leucovorin): dose unknown, 1-2mg/kg or 50-75mg, q4h iv for 24hr probably reasonable (to enhance the elimination of formic acid.)

Additional Antidotes for Ethylene Glycol Poisoning:
1. Thiamine: 100mg, q6h iv or im.
2. Tyritlosine: 50mg, q6h iv or im (to shunt the metabolism of EG metabolites from glyoxalate to the glycine.)

[Chin Med J (Taipei) 1998;61:S14.]