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Folic Acid

Class: Vitamin B Complex
VA Class: VT102
CAS Number: 59-30-3

Medically reviewed by Drugs.com. Last updated on Dec 22, 2020.

Introduction

Water-soluble, B complex vitamin.

Uses for Folic Acid

Anemia

Treatment of megaloblastic anemias due to folic acid deficiency as may be seen in tropical or nontropical sprue, nutritional anemias, and in anemias of pregnancy, infancy, and childhood.

Dietary Requirements

Adequate intake of folate needed to prevent megaloblastic changes in the bone marrow and other rapidly dividing cells.

Adequate intake of folate can be accomplished through consumption of foodstuffs, including folate-fortified foodstuffs, use of dietary supplements, or both.

Prevention of Neural Tube Defects

Prophylactic therapy before and during pregnancy to reduce the risk of fetal neural tube defects, including spina bifida, anencephaly, and encephalocele.

Cardiovascular Risk Reduction

No important benefit or harm of folic acid supplementation on the risk of cardiovascular disease, coronary heart disease, stroke, or all-cause mortality in patients with vascular disease.

Folic Acid Dosage and Administration

Administration

Usually administered orally. May be administered by IM, sub-Q, or IV injection when oral administration is not feasible or when malabsorption is suspected. However, most individuals with malabsorption are able to absorb oral folic acid.

Dosage

Dosage of sodium folate injection is expressed in terms of folic acid.

The Recommended Dietary Allowance (RDA) is expressed in terms of dietary folate equivalents/day. Dietary food folate equivalents (DFE) are calculated as follows: 1 mcg of dietary folate equivalent = 1 mcg of food folate = 0.5 mcg of folic acid taken in the fasting state = 0.6 mcg of folic acid taken with food.

Pediatric Patients

Anemia
Oral or Parenteral

Up to 1 mg folic acid daily; some patients may require larger doses.

Usual maintenance dosage: 0.1 mg daily for infants, 0.3 mg daily for children <4 years of age, 0.4 mg daily for children ≥4 years of age.

Higher maintenance dosages may be required in patients with hemolytic anemia, chronic infections, and those receiving anticonvulsants.

Dietary Requirements
Oral

The Adequate Intake (AI) of folate for healthy infants <6 months of age is 65 mcg daily and for those 6–12 months of age is 80 mcg daily.

The RDA for healthy children 1–3, 4–8, 9–13, or 14–18 years of age is 0.15, 0.2, 0.3, or 0.4 mg of DFE daily, respectively.

Adults

Anemia
Oral or Parenteral

Up to 1 mg folic acid daily; some patients may require larger doses.

Usual maintenance dosage: 0.4 mg daily.

Usual maintenance dosage for pregnant and lactating women: 0.8 mg daily.

Higher maintenance dosages may be required in alcoholics, patients with hemolytic anemia, chronic infections, and patients receiving anticonvulsants.

Dietary Requirements
Oral

RDA for healthy adults: 0.4 mg DFE daily.

RDA for lactating women: 0.5 mg DFE daily. Folate intake exceeding this RDA may be needed by mothers nursing more than one infant.

Prevention of Neural Tube Defects
Oral

National Academy of Sciences: 0.4 mg of folic acid daily through fortified foods and/or supplements in addition to food folate consumed from a varied diet recommended for women of childbearing potential.

The US Preventive Services Task Force: 0.4–0.8 mg of folic acid daily from supplements; initiate 1 month before conception and continue during the first 2–3 months of pregnancy.

For women with a history of prior pregnancy complicated by neural tube defects: 4 mg folic acid daily initiated 1 month before and continued for 3 months after conception. Such women should maintain the lower level of folic acid intake (i.e., 0.4 mg daily) during other periods of continued childbearing potential.

RDA for pregnant women: 0.6 mg DFE daily. Folate intake exceeding this RDA may be needed by women who are pregnant with more than one fetus.

Cautions for Folic Acid

Contraindications

  • Known intolerance.

Warnings/Precautions

Warnings

Pernicious Anemia/Undiagnosed Anemia

Not indicated for pernicious anemia and other megaloblastic anemias due to vitamin B12 deficiency. Do not use in patients with undiagnosed anemia since folic acid may obscure the diagnosis of pernicious anemia by alleviating hematologic manifestations while allowing neurologic complications to progress.

Sensitivity Reactions

Allergic reactions (erythema, rash, itching, general malaise, bronchospastic respiratory difficulty, anaphylaxis) reported rarely.

Specific Populations

Pregnancy

Category A.

Lactation

Distributed into milk.

Common Adverse Effects

Relatively nontoxic.

Interactions for Folic Acid

Administration of phenytoin, primidone, barbiturates, methotrexate, nitrofurantoin, alcohol, or pyrimethamine may result in folate deficiency.

Phenytoin

Possible increase in seizure frequency.

Chloramphenicol

Possible delayed response to folic acid

Folic Acid Pharmacokinetics

Absorption

Bioavailability

Well absorbed from the GI tract. Synthetic folic acid is almost 100% bioavailable following oral administration in fasting individuals; folate in food is about 50% bioavailable.

Food

Synthetic folic acid is 85–100% bioavailable following oral administration with a meal.

Distribution

Extent

Distributed into all body tissues including the CNS; stored mainly in the liver.

Elimination

Metabolism

Metabolized in the liver.

Elimination Route

Up to 90% of a dose in urine; small amounts in feces.

Stability

Storage

Oral

Tablets

15–30°C.

Parenteral

Injection

15–30°C.

Compatibility

For information on systemic interactions resulting from concomitant use, see Interactions.

Parenteral

Solution CompatibilityHID

Compatible

Amino acids 4.25%, dextrose 25%

Dextrose 20% in water

Incompatible

Dextrose 40 or 50% in water

Variable

Fat emulsion 10%, IV

Drug Compatibility
Y-Site CompatibilityHID

Compatible

Famotidine

Actions

  • Folic acid is prepared synthetically. Naturally occurring conjugates of folic acid (food folate; pteroylpolyglutamates) are present in a wide variety of foods, particularly liver, kidneys, yeast, leafy green vegetables, other vegetables, citrus fruits and juice, and legumes.

  • An exogenous source of folate is required for nucleoprotein synthesis and the maintenance of normal erythropoiesis.

  • Folic acid is not metabolically active as such, but is the precursor of tetrahydrofolic acid which is involved as a cofactor for 1-carbon transfer reactions in the biosynthesis of purines and thymidylates of nucleic acids.

  • Folate supplementation before and during pregnancy associated with a reduction in risk for fetal neural tube defects.

Advice to Patients

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs.

  • Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Folic Acid

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Bulk

Powder*

Oral

Tablets

0.4 mg*

Folic Acid Tablets

0.8 mg*

Folic Acid Tablets

1 mg*

Folic Acid Tablets

Sodium Folate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Parenteral

Injection

equivalent to folic acid 5 mg/mL

Folic Acid Injection

AHFS DI Essentials™. © Copyright 2021, Selected Revisions January 1, 2010. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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