From the Guidelines
Pyridoxine (vitamin B6) is used as an adjunctive treatment in ethylene glycol poisoning by inhibiting the metabolism of toxic metabolites, with a recommended dose of 50 mg IV every 6 h, as stated in the espen micronutrient guideline 1. When ethylene glycol is ingested, it is metabolized by alcohol dehydrogenase to glycoaldehyde, which is further converted to glycolic acid, glyoxylic acid, and finally oxalic acid.
- These metabolites, particularly glycolic acid and oxalic acid, cause metabolic acidosis and kidney damage through calcium oxalate crystal formation.
- Pyridoxine works by acting as a cofactor for the enzyme alanine:glyoxylate aminotransferase, which converts glyoxylic acid to glycine instead of oxalic acid, thereby reducing the formation of the most toxic metabolite. The use of pyridoxine in this context is supported by the espen micronutrient guideline, which recommends its use in the treatment of ethylene glycol poisoning 1.
- The guideline suggests that pyridoxine should be administered at a dose of 50 mg IV every 6 h, although it does not specify the duration of treatment.
- In clinical practice, pyridoxine is typically administered alongside the primary treatments of fomepizole or ethanol (which block alcohol dehydrogenase) and hemodialysis.
- It is essential to administer pyridoxine as soon as ethylene glycol poisoning is suspected, as it is most effective when administered early in the poisoning course. While pyridoxine alone is insufficient to treat ethylene glycol toxicity, it serves as a valuable adjunct by redirecting metabolism away from the formation of harmful oxalate crystals, as noted in the espen micronutrient guideline 1.
From the Research
Mechanism of Ethylene Glycol Poisoning
- Ethylene glycol poisoning causes metabolic acidosis and renal failure due to the formation of toxic metabolites 2, 3
- The standard treatment for ethylene glycol poisoning includes inhibition of alcohol dehydrogenase with ethanol or fomepizole, and adjunctive hemodialysis 2, 4
Role of Fomepizole in Treatment
- Fomepizole is a newer agent with a specific indication for the treatment of ethylene glycol poisoning 4
- Fomepizole inhibits the formation of toxic metabolites, preventing renal injury and metabolic acidosis 2, 5
- Initiation of fomepizole therapy before the serum creatinine concentration rises can minimize renal impairment 4
Interaction with Pyridoxine (Vitamin B6)
- There is no direct evidence in the provided studies regarding the interaction between ethylene glycol and pyridoxine (Vitamin B6)
- The mechanism of ethylene glycol poisoning and its treatment with fomepizole is well-established, but the role of pyridoxine in this context is not mentioned in the provided studies 2, 3, 5, 4, 6