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folic acid
V04CX02
Forms & Strengths
- Oral tablets 0.4 mg, 1 mg, 5 mg
- Oral solution 1 mg/mL
- Sublingual tablets 5 mg
- IV/IM injection 1 mg/mL
Adult Dosing
- Neural‑tube defect prevention: 0.4–1 mg PO daily, start ≥1 mo pre‑conception through 12 wk gestation
- Folate deficiency treatment: 1 mg PO daily (may split BID)
- Methotrexate rescue: 10 mg PO every 6 h for 2–3 d
- Anemia of chronic disease: 5 mg PO weekly
- Hemodialysis patients: 1 mg post‑dialysis
Pediatric Dosing
- Neonates (0–28 d): 0.1 mg PO/IM daily
- Infants 1‑12 mo: 0.1 mg PO daily
- Children 1‑12 yr: 0.2 mg PO daily (or 0.1 mg BID)
- Adolescents ≥13 yr: same as adult for deficiency (1 mg PO daily)
- Neural‑tube defect prevention in pregnant teens: 0.4 mg PO daily
Indications
- Prevention of folate deficiency
- Treatment of megaloblastic anemia due to folate deficiency
- Prevention of neural‑tube defects in pregnancy
- Adjunct in methotrexate, trimethoprim, pyrimethamine therapy
- Management of homocystinuria (with B6)
- Support in sickle‑cell disease and hemolytic anemias
Mechanism of Action
- Converted to tetrahydrofolate, a cofactor for thymidylate and purine synthesis
- Restores DNA synthesis in rapidly dividing cells
- Facilitates remethylation of homocysteine to methionine
Contraindications
- Known hypersensitivity to folic acid or excipients
- Severe vitamin B12 deficiency without B12 replacement (risk of neurologic worsening)
Adverse Reactions
- Nausea, loss of appetite, abdominal cramping
- Mild rash or pruritus
- Rare: insomnia, irritability, seizures in predisposed patients
Drug Interactions
- Anticonvulsants (phenytoin, carbamazepine, phenobarbital) increase folate metabolism → higher dose needed
- Methotrexate, trimethoprim, pyrimethamine: folic acid reduces toxicity but may diminish efficacy → timing adjustment
- Antacids containing aluminum or magnesium may reduce oral absorption
- Levodopa: high folate may reduce CNS availability of levodopa
- Vitamin B12 deficiency: folic acid can mask hematologic signs while neurologic damage progresses
Curated Content: Needs Vetting Before Put to Clinical Use