Folic%25252520acid

# Folic acid ## Overview Folic acid (Vitamin B9) is a water-soluble B vitamin essential for DNA synthesis, repair, and erythropoiesis. Supplemental folic acid is synthetic and more bioavailable than naturally occurring folates. ## Primary Indications * Treatment and prevention of folate deficiency anemias. * Prevention of neural tube defects (NTDs) during preconception and pregnancy. * Reduction of hematologic/GI toxicity in patients receiving methotrexate. * Hyperhomocysteinemia. ## Adult Dosing * **Folate Deficiency:** 0.4–1 mg daily. * **Pregnancy (Prevention of NTDs):** 0.4–0.8 mg daily (starting at least 1 month before conception through the first trimester). High-risk patients (prior NTD or epilepsy) may require 4–5 mg daily per clinical guidance. * **Methotrexate Toxicity Supplementation:** 1–5 mg daily (or 5–10 mg weekly following methotrexate dose, depending on specific rheumatology/oncology protocols). ## Pediatric Dosing * **Folate Deficiency:** * **Infants:** 0.1 mg daily. * **Children (1–12 years):** 0.1–0.4 mg daily. * **Adolescents:** 0.4 mg daily. * **Maintenance/Prophylaxis:** 0.1–0.4 mg daily depending on diet and underlying conditions. ## Dose Adjustments * **Renal/Hepatic Impairment:** No specific dosage adjustments required, though patients with chronic malabsorption may require higher oral doses or parenteral administration. ## Contraindications * Known hypersensitivity to folic acid. * **Warning:** Do not use as monotherapy for pernicious anemia (Vitamin B12 deficiency), as it corrects hematologic abnormalities but may mask or allow progression of irreversible neurological damage. ## Adverse Effects * Generally well-tolerated. * Rare: Allergic reactions (rash, pruritus, bronchospasm). * High doses (>15 mg/day) may cause GI distress, insomnia, malaise, or altered taste. ## Key Drug Interactions * **Methotrexate:** Folic acid can reduce the efficacy of methotrexate in treating rheumatoid arthritis or psoriasis. Timing of doses must be carefully managed. * **Anticonvulsants (Phenytoin, Carbamazepine, Valproic acid):** Folic acid may decrease serum levels of these medications, potentially reducing seizure control. * **Sulfasalazine:** Decreases folic acid absorption. ## Monitoring * Monitor hemoglobin/hematocrit and reticulocyte counts to assess response to anemia therapy. * Monitor serum B12 levels if neurologic symptoms are present or if high-dose folic acid therapy is sustained. ## Clinical Pearls * Ensure that any patient presenting with macrocytic anemia is evaluated for Vitamin B12 deficiency before initiating high-dose folic acid to avoid masking neurological symptoms. * Folic acid is highly stable, but dietary folates are sensitive to heat and light. * Specific dosing for methotrexate rescue varies significantly by institution and specialty—verify local protocols. *** **Educational Disclaimer:** This information is for educational purposes only. Always consult current, reputable drug databases (e.g., Lexicomp, Micromedex) or institutional clinical guidelines before prescribing or administering medication. Confirm dosages based on the patient’s specific clinical status and local practice protocols.