Management of Methanol and Ethylene Glycol Poisoning

Introduction

Accidental ingestion of ethylene glycol and methanol can cause serious conditions like brain injury, renal dysfunction, and blindness and may also result in death. Even a very low concentration of ethylene glycol and methanol can cause toxic effects in the body. Methanol and ethylene glycol poisoning may occur as a result of a suicidal attempt or due to accidental drinking. Symptoms like vomiting, loss of consciousness, poor coordination, and seizures may develop within a few hours. Early identification of alcohol poisoning and timely, effective treatment can reduce the severity of the poisoning.

What Is Methanol and Ethylene Glycol Poisoning?

Methanol (methyl alcohol) is a light, flammable, colorless, volatile liquid with an alcohol smell similar to that of ethanol. Methanol poisoning can occur due to accidental drinking, suicidal attempts, and drinking water used for cleaning windshields in vehicles (windshield water). After reaching the body, methanol is converted into formate, formaldehyde, and formic acid. These compounds produced as a byproduct of methanol breakdown will cause toxicity and health effects. Toxicity can affect most organs and, if untreated, will lead to death. Early identification and medical management can reduce the impact and death.

Ethylene glycol is a colorless, odorless,sweet-tasting liquid mainly used for the manufacture of polyester fibers and antifreeze formulations (to reduce the freezing point of liquids). Poisoning can occur due to a suicidal attempt or due to accidental drinking. Ethylene glycol can cause severe toxic effects even in very low concentrations. After reaching the body, it is metabolized to oxalic acid and glycolic acid. Toxicity will cause the deposition of calcium oxalate crystals in the urine and eventually leads to kidney failure.

What Are the Symptoms of Methanol and Ethanol Glycol Poisoning?

Initial Symptoms- Initial symptoms of methanol poisoning develop within a few hours. It includes:

• Central nervous system depression.

• Unconsciousness.

• Lack of coordination.

• Pain and gastric irritation

• Headache.

• Confusion.

• Dizziness.

Late Symptoms - It occurs after 10 to 30 hours of poisoning. It includes:

• Blurring or complete vision loss.

• Retinal edema.

• Tachypnea.

• Brain hemorrhage (putaminal hemorrhage).

• Hyperemia.

• Cardiac failure.

• Renal failure.

• Cerebral edema.

• Respiratory failure and death.

Symptoms of ethylene glycol poisoning are divided into three stages based on the time of onset and severity. It includes:

• Stage 1 - It develops within 30 minutes to 12 hours after ingestion and consists of gastrointestinal and neurological symptoms. Nausea, stomach irritation, vomiting, confusion, headache, abnormal eye movements, lack of muscle coordination, excessive urination, and thirst are the common features of this stage.

• Stage 2 - After initial symptoms, intense internal damage develops after 12 to 36 hours. These symptoms occur as a result of the toxic effects of ethylene glycol metabolites formed in the body. It consists of dehydration, hyperventilation, high blood pressure, heart rate, muscle spasms, and congestive heart failure.

• Stage 3 - It occurs within 36 to 72 hours. Kidney failure occurs as a result of the toxic effects of ethylene glycol. Depression, coma, seizure, loss of appetite, presence of protein and blood cells in the urine, increased blood levels of potassium, and acute kidney failure are the advanced symptoms of ethylene glycol poisoning.

What Are the Diagnostic Tests Used for Methanol and Ethylene Glycol Poisoning?

Diagnostic tests used to identify the presence of methanol and ethylene glycol in the body includes the following:

• Osmolal gap.

• Lactate gap.

• Anion gap.

• Gas chromatography.

• Urine examination for calcium oxalate crystals.

• Calcium levels.

What Are the Treatment Options for Methanol and Ethylene Glycol Poisoning?

• Stabilization - Initial treatment for methanol and ethylene glycol poisoning is stabilization. It primarily involves airway management. Airway management will help to relieve and prevent respiratory obstruction.

• Decontamination - It can be used when the patient is admitted to the hospital shortly after the poisoning. Methanol and ethylene glycol are rapidly absorbed in the body, and hence gastrointestinal washing is not effective. Gastric contents can be aspirated using a nasogastric (NG) tube if the patient is presented to the hospital immediately after poisoning.

• Alcohol Dehydrogenase Blockade - Adverse health effects after methanol and ethylene glycol poisoning occur due to the formation of toxic metabolites. Alcohol dehydrogenase enzyme (ALDH) present in the liver converts methanol to formaldehyde and formic acid (formate). Formic acid causes hypoxia, an imbalance in the acid-base balance (metabolic acidosis), and metabolic disturbances. After reaching the cells, ethylene glycol molecules are converted to oxalic acid and glycolic acid. Oxalic acid will cause nephrotoxicity and kidney damage. Fomepizole (4 methyl pyrazole) can be used for the treatment of methanol and ethylene glycol poisoning. This drug reduces the formation of toxic metabolites like formaldehyde and formic acid from methanol and oxalic acid and glycolic acid from ethylene glycol. It is achieved by the competitive inhibition of the alcohol dehydrogenase enzyme. Thus methanol and ethylene glycol is excreted in the urine in a less toxic form.

• Use of Ethanol - Ethanol is used in conditions when fomepizole is not available. Ethanol has a very high affinity for alcohol dehydrogenase enzyme (ALDH) and thus prevents the conversion of methanol and ethylene glycol to toxic metabolites.

• Hemodialysis - It can be done to increase the elimination of methanol, ethylene glycol, and its metabolites from the body. It is done in cases of acute kidney failure, metabolic acidosis, and severe electrolyte imbalance.

• Fluids and Electrolytes - Sodium bicarbonate is used to treat metabolic acidosis and electrolyte imbalance.

• Folinic Acid (Leucovorin) - It is used to reduce toxicity by increasing the metabolism of formic acid, which is formed from methanol.

• Thiamine (Vitamin B1) and Pyridoxine (Vitamin B6) - These vitamins will help to increase the metabolism of toxic byproducts to less toxic compounds and their excretion in urine.

Conclusion

Accidental ingestion of methanol and ethylene glycol will cause serious health conditions. Toxic metabolites released from these alcohols will cause damage to tissues and organs. Safety measures must be followed to prevent accidental drinking and toxicity. Early identification of poisoning and immediate medical management can reduce the impact of toxicity and save lives.