Folic%252520acid

# Folic Acid ## Overview Folic acid (vitamin B9) is a water-soluble B vitamin essential for DNA synthesis, repair, and erythropoiesis. Exogenous supplementation is required to prevent or treat deficiency states. ## Primary Indications * Treatment and prophylaxis of folate deficiency anemia. * Prevention of neural tube defects (NTDs) in pregnancy. * Adjunct therapy in methotrexate treatment. * Comorbidity management in chronic hemolytic anemia or dialysis. ## Adult Dosing * **Deficiency/Anemia:** 1 mg daily. Maintenance: 0.4–0.8 mg daily. * **Pregnancy (Prevention of NTDs):** 0.4–0.8 mg daily starting at least one month before conception and continuing through the first trimester. High-risk patients (previous NTD-affected pregnancy): 4–5 mg daily. * **Methotrexate Supplementation:** 1–5 mg daily (non-folate days preferred) to prevent stomatitis and hematologic toxicity. ## Pediatric Dosing * **Infants:** 0.1 mg daily. * **Children 1–3 years:** 0.15 mg daily. * **Children 4–8 years:** 0.2 mg daily. * **Children 9–13 years:** 0.3 mg daily. * **Adolescents (14+ years):** 0.4 mg daily. * *Note: Dosing for therapeutic deficiency may require higher concentrations; consult local pediatric guidelines.* ## Dose Adjustments * **Renal/Hepatic Impairment:** No specific adjustment required; however, patients on chronic dialysis may require higher maintenance doses (e.g., 1–5 mg daily) due to dialysate loss. ## Contraindications * Hypersensitivity to folic acid. * Undiagnosed anemia (specifically vitamin B12 deficiency). **Warning:** Folic acid can mask symptoms of B12 deficiency (pernicious anemia) while allowing irreversible neurologic damage to progress. ## Adverse Effects * Generally well-tolerated. * Rare: Allergic reactions (rash, pruritus, dyspnea), GI disturbances (nausea, abdominal distension), and bitter taste. ## Key Drug Interactions * **Methotrexate:** Folic acid can decrease the efficacy of methotrexate in chemotherapy. * **Anticonvulsants (Phenytoin, Carbamazepine, Valproate):** Folic acid may decrease serum concentrations of these agents, potentially increasing seizure frequency. * **Sulfonamides/Pyrimethamine:** May interfere with folate metabolism. ## Monitoring * Complete blood count (CBC) and mean corpuscular volume (MCV) to assess hematologic response. * Serum folate and vitamin B12 levels if masking of deficiency is suspected. ## Clinical Pearls * Do not treat megaloblastic anemia with folic acid until vitamin B12 deficiency is definitively ruled out. * Folic acid is often dosed as "folate equivalents" in dietary contexts, but pharmaceutical folic acid has higher bioavailability than dietary folates. * Always ensure the patient's B12 status is stable before initiating high-dose folic acid (≥1 mg/day) long-term. *** **Educational Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Consult current prescribing information (e.g., package inserts, Lexicomp, or UpToDate) and local institutional protocols before prescribing or administering any medication.