Chapter 189. Folic Acid

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 is not effective for the treatment of poisoning by dihydrofolate reductase inhibitors (eg, methotrexate and trimethoprim). Leucovorin (See Leucovorin Calcium) is the proper agent in these situations.

Indications. Adjunctive treatment for methanol poisoning.

Contraindications. No known contraindications.

Adverse effects

1. Rare allergic reactions have been reported after intravenous administration.

2. Use in pregnancy. FDA Category A (See Introduction in Section III). Folic acid is a recommended supplement.

Drug or laboratory interactions. This agent may decrease hydantoin levels by enhancing the metabolism of hydantoin.

Dosage and method of administration. The dose required for methanol or ethylene glycol poisoning is not established, although 50 mg IV (children: 1 mg/kg) every 4 hours for six doses has been recommended.

Formulations

1. Parenteral. Sodium folate (Folvite), 5 mg/mL, 10-mL vials.

2. Suggested minimum stocking levels to treat a 100-kg adult for the first 8 hours and 24 hours: folate sodium, first 8 hours: 100 mg or two vials (5 mg/mL, 10 mL each); first 24 hours: 300 mg or six vials (5 mg/mL, 10 mL each).