DESCRIPTION

Ethanol is a short-chain alcohol used for the treatment of ethylene glycol or methanol poisoning.

FORMS AND USES

Ethanol (ethyl alcohol USP) is available in a 95% concentration in vials or in dilute forms (5% or 10%) ready for administration. The preferred agent for ethylene glycol or methanol poisoning is fomepizole, owing to ease of administration and reduced costs for ancillary and ICU care.

MECHANISM OF ACTION

• Ethanol, methanol, and ethylene glycol are all metabolized by the enzyme alcohol dehydrogenase.
• The products of metabolism from methanol and ethylene glycol are responsible for their toxicity.
• The affinity of alcohol dehydrogenase for ethanol is much higher than for methanol or ethylene glycol; by providing ethanol in sufficient quantity to saturate alcohol dehydrogenase, the metabolism and therefore the toxicity of methanol or ethylene glycol can be blocked.

DRUG AND DISEASE INTERACTIONS

• The effects of CNS depressant drugs is increased by ethanol.
• Ethanol may produce acute flushing, vomiting, and hypotension when the patient has taken disulfiram, metronidazole, or numerous other antimicrobials; oral sulfonylurea agents (chlorpropamide, glipizide, others); several industrial agents (carbon disulfide, trichloroethylene, ethylene dibromide, thiuram, etc.); chloral hydrate, monamine oxidase inhibitors (tranylcypramine, procarbazine); or Coprinus mushrooms ("inky caps"). See also SECTION IV, Disulfiram chapter.

PREGNANCY AND LACTATION

• US FDA Pregnancy Category X. Studies have demonstrated fetal abnormalities or there is evidence of fetal risk based human risk and the risk clearly outweighs any possible benefit.
• However, ethanol therapy should not be withheld in pregnant patients because the risk of methanol and ethylene glycol toxicity outweigh the risk of ethanol therapy.

Section Outline:

• DESCRIPTION
• FORMS AND USES
• MECHANISM OF ACTION
• DRUG AND DISEASE INTERACTIONS
• PREGNANCY AND LACTATION

• Ethylene glycol ingestion
  • Ethanol therapy should be instituted for an ethylene glycol level over 20 mg/dl or for any degree of metabolic acidosis or other toxic effect (coma, renal injury) in the setting of possible ethylene glycol ingestion.
  • If levels are not immediately available, therapy should be instituted for a reliable history of ingestion while further evaluation is performed.
• Methanol ingestion
  • Ethanol therapy should be instituted for a methanol level over 20 mg/dl or for any degree of metabolic acidosis or other toxic effect (coma, visual complaints) in the setting of possible methanol ingestion.
  • If levels are not immediately available, therapy should be instituted for a reliable history of ingestion while further evaluation is performed.
• Unexplained increased anion gap acidosis not improving with hydration while further evaluation is performed
• Unexplained osmolar gap while further evaluation is performed

CONTRAINDICATIONS

Preexisting ethanol intoxication. Patients with a measurable blood ethanol level should have ethanol dosing adjusted as directed in the section on "Dosage and Method of Administration."

ADVERSE EFFECTS

• Patients may have significant CNS depression and require airway management.
• Ethanol is very irritating to vessels and may cause phlebitis.
• Hypoglycemia may occur, especially in children or diabetic patients; glucose should always be added to intravenous fluid and serum glucose levels followed closely.
• Because large volumes of water are infused with ethanol, fluid overload and hyponatremia may occur.
• Ethanol infusion may exacerbate gout.
• Ethanol impairs cardiovascular function and may compromise hemodynamic status in seriously ill patients.

Section Outline:

• CONTRAINDICATIONS
• ADVERSE EFFECTS

The goal of therapy for methanol or ethylene glycol ingestion is to maintain a blood ethanol level of 100 to 150 mg/dl.

Loading Dose

• The patient should be treated with 10 cc/kg of 10% ethanol infused intravenously over 30 minutes.
• A loading dose is not needed if the preexisting serum ethanol level is greater than 100 mg/dl.

Maintenance Dose

The maintenance dose is 1 cc/kg/h infusion of 10% ethanol; the chronic alcoholic should be treated with 2 cc/kg/h infusion of 10% ethanol.

Oral Dosages

• If an intravenous formulation is not available, oral loading using the same amount is acceptable.
• To load, the patient should ingest four 1-ounce "shots" of a 40% (80 proof) ethanol.
• For maintenance, the patient should ingest one 1-ounce shot orally every hour.
• Ethanol level should be monitored hourly.

Ethanol Levels and Repeat Boluses

• Ethanol levels should be obtained immediately after the loading dose infusion and followed hourly until stable for 4 hours, and then obtained every 4 hours until the ethylene glycol or methanol level is below 20 mg/dl.
• If low ethanol levels are detected, the patient should receive a repeat bolus of ethanol in addition to increasing the rate.
  • Patients with a blood ethanol level of 0 to 50 mg/dl should receive a bolus of 10 cc/kg of 10% ethanol and have the infusion rate doubled.
  • Patients with levels of 50 to 80 mg/dl should receive a bolus of 5 cc/kg of 10% ethanol and have the rate increased by 50%.
  • Patients with ethanol levels of 80 to 100 mg/dl should receive a bolus of 2.5 cc/kg of 10% ethanol and the rate increased by 25%.

Dialysis Patients

• The infusion rate should be doubled or tripled during the dialysis session.
• Ethanol levels should be followed hourly.

Section Outline:

• Loading Dose
• Maintenance Dose
• Oral Dosages
• Ethanol Levels and Repeat Boluses
• Dialysis Patients

• If clinical suspicion is high, ethanol therapy should not be withheld while awaiting ethylene glycol or methanol levels.
• Ethanol levels should be followed closely to assure therapeutic levels.
• Children may be more prone to hypoglycemia.
• Elderly patients may be more prone to CNS depression from ethanol.

Toxic effect of alcohol: ethylene glycol or methanol.

See Also: SECTION IV, Disulfiram chapter.

RECOMMENDED READING

Bryson PD. Ethylene glycol/methanol. In: Comprehensive review in toxicology. Washington, DC: Taylor & Francis, 1996:394-408.

Author: Kennon Heard

Reviewer: Katherine M. Hurlbut