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Introduction

  1. Pharmacology. Folic acid is a B-complex vitamin that is essential for protein synthesis and erythropoiesis. In addition, the administration of folate to patients with methanol poisoning may enhance the conversion of the toxic metabolite formic acid to carbon dioxide and water, based on studies in folate-deficient primates. Note: Folic acid requires metabolic activation and may not be effective for the treatment of acute poisoning by dihydrofolate reductase inhibitors (eg, methotrexate and trimethoprim); leucovorin is the proper agent in these situations.
  2. Indications.
    1. Adjunctive treatment for methanol poisoning.
    2. The role of folate supplementation in the treatment of acute or chronic arsenic poisoning is unknown.
  3. Contraindications. No known contraindications.
  4. Adverse effects
    1. Rare allergic reactions have been reported after intravenous administration.
    2. Use in pregnancy. FDA Category A (Introduction). Folic acid is a recommended supplement.
  5. Drug or laboratory interactions. This agent may decrease phenytoin levels by enhancing its metabolism.
  6. Dosage and method of administration. The dose required for methanol poisoning is not established, although 1-2 mg/kg (typical doses are 50-70 mg IV) every 4-6 hours has been recommended. Folic acid is removed by hemodialysis and should be continued during extracorporeal treatment.