From the Guidelines
Pyridoxine (Vitamin B6) is used as an antidote for isoniazid overdose, as well as ethylene glycol poisoning. The use of pyridoxine in these contexts is supported by recent clinical guidelines, including the 2022 espen micronutrient guideline published in Clinical Nutrition 1.
Key Points
- In cases of isoniazid overdose, pyridoxine should be administered in a dose equal to the amount of isoniazid ingested, typically 1 gram of pyridoxine for each gram of isoniazid, given intravenously, up to a maximum of 5 grams 1.
- For ethylene glycol poisoning, pyridoxine is recommended at a dose of 50 mg IV every 6 hours 1.
- The mechanism behind pyridoxine's effectiveness in isoniazid toxicity involves replenishing depleted pyridoxal-5-phosphate, which serves as a cofactor for glutamic acid decarboxylase, an enzyme crucial for converting glutamate to GABA, an inhibitory neurotransmitter.
- Prompt administration of pyridoxine is essential in cases of suspected isoniazid overdose, especially when seizures are present, as it directly addresses the underlying mechanism of toxicity.
Administration Details
- The dose and administration route of pyridoxine may vary depending on the specific context of poisoning or toxicity.
- For isoniazid overdose, the dose is typically 1 gram of pyridoxine for each gram of isoniazid ingested, given intravenously, with a maximum dose of 5 grams 1.
- For ethylene glycol poisoning, a dose of 50 mg IV every 6 hours is recommended 1.
From the FDA Drug Label
Patients who acutely ingest > 80 mg/kg should be treated with intravenous pyridoxine on a gram per gram basis equal to the isoniazid dose If an unknown amount of isoniazid is ingested, consider an initial dose of 5 grams of pyridoxine given over 30 to 60 minutes in adults, or 80 mg/kg of pyridoxine in children. If the dose of isoniazid is known, the patient should be treated initially with a slow intravenous bolus of pyridoxine, over 3 to 5 minutes, on a gram per gram basis, equal to the isoniazid dose.
Pyridoxine (Vitamin B6) is used as an antidote for isoniazid overdosage. The dose of pyridoxine is given on a gram per gram basis equal to the isoniazid dose, or an initial dose of 5 grams in adults or 80 mg/kg in children if the amount of isoniazid ingested is unknown 2.
From the Research
Pyridoxine as an Antidote
Pyridoxine, also known as Vitamin B6, is used as an antidote for isoniazid poisoning. The evidence suggests that pyridoxine can effectively reverse the symptoms of isoniazid intoxication, including seizures, metabolic acidosis, and coma.
Mechanism of Action
- Pyridoxine works by counteracting the effects of isoniazid on the nervous system, which can cause seizures and other neurological symptoms 3, 4, 5, 6, 7.
- The dose of pyridoxine required to reverse the symptoms of isoniazid intoxication is typically equivalent to the amount of isoniazid ingested 3, 6, 7.
Clinical Evidence
- Studies have shown that pyridoxine can be effective in treating isoniazid-induced seizures, metabolic acidosis, and coma 4, 5, 6, 7.
- In some cases, large doses of pyridoxine may be required to completely reverse the symptoms of isoniazid intoxication 4, 5, 6.
- Pyridoxine can be administered orally or intravenously, depending on the severity of the poisoning and the availability of the medication 3, 6.