Folic acid

From WikiMD's Wellness Encyclopedia

Folic Acid, commonly known as vitamin B9 and folacin, belongs to the group of B vitamins. The synthesized version of folic acid, once consumed, is transformed by the body into folate. Due to its stability during processing and storage, manufactured folic acid finds its application both as a dietary supplement and a food fortification agent.

Folic acid structure
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Folic-acid-3D-balls

Therapeutic Uses

Folic acid plays a pivotal role in treating megaloblastic anemias resulting from its deficiency. Such anemias may manifest in conditions like tropical or non-tropical sprue or arise due to nutritional imbalances during pregnancy, infancy, or childhood. As the human body lacks the capability to synthesize folate, it is an essential nutrient and needs to be sourced from the diet. It's abundantly found in numerous foods. In the U.S., the recommended daily folate intake for adults is pegged at 400 micrograms, either from foods or dietary supplements.

Folic acid crystals

Pharmacodynamics: Mechanism of Action

Folic acid exerts its therapeutic effects by transforming megaloblastic bone marrow into a normoblastic form. In humans, the external source of folate is indispensable for nucleoprotein synthesis and maintaining consistent erythropoiesis. Folic acid, as a precursor to tetrahydrofolic acid, is crucial for transformylation reactions during the biosynthesis of nucleic acids' purines and thymidylates. This process's disruption, especially in patients with a folic acid deficiency, often culminates in DNA synthesis defects, leading to the formation of megaloblasts and subsequently causing megaloblastic and macrocytic anemias.

Post oral administration, folic acid is rapidly absorbed from the proximal section of the small intestine. The body enzymatically reduces conjugated folates present in the food to folic acid before absorption. This nutrient's appearance in the plasma is observed approximately within 15 to 30 minutes post oral intake, reaching peak levels within an hour. Intravenously administered folic acid is rapidly cleared from the plasma.

Metabolism and Distribution

Folic acid undergoes metabolism in the liver to form 7,8-dihydrofolic acid, which further transforms into 5,6,7,8-tetrahydrofolic acid. This process involves the enzymes reduced diphosphopyridine nucleotide (DPNH) and folate reductases. While tetrahydrofolic acid derivatives are distributed across all body tissues, their primary storage site is the liver.

Clinical Indications and Administration

The preferred route of administration is oral. However, for certain patients, especially those receiving parenteral or enteral alimentation, parenteral administration might be essential. For dosages, it is advised to administer up to 1 mg daily for both adults and children. The maintenance dosage varies with age and specific conditions like pregnancy. However, folic acid should not be administered in doses greater than 0.1 mg unless vitamin B12 deficiency-induced anemia has been addressed with cobalamin.

Product Availability

  • Folic Acid Tablets:
  • 1 mg (debossed MP 727)
  • Available in various quantities.
  • Folic Acid Injection:
  • USP 50 mg per 10 mL (5 mg per mL)
  • Side Effects and Precautions

Patients should be aware that high doses of folic acid can potentially mask the hematologic symptoms of pernicious anemia while allowing its neurologic manifestations to progress. This could cause irreversible nervous system damage.

Drug interactions include a potential antagonistic effect with the anticonvulsant phenytoin. Also, there might be decreased levels of folate due to the intake of certain medications or conditions like renal dialysis, alcohol consumption, and alcoholic cirrhosis.

Contraindications

Patients known to be allergic to folic acid should avoid its intake. Also, it's vital to understand that folic acid isn't the correct therapeutic agent for treating pernicious anemia and other megaloblastic anemias caused by a Vitamin B12 deficiency.

Emergency Situations

In cases of overdose, it's crucial to contact the poison control center. For residents of the United States, they should call 1-800-222-1222 or access information online at poisonhelp.org/help. In severe cases, where the affected individual has collapsed or isn't responsive, immediate medical attention by calling emergency services (in the U.S., dial 911) is paramount.

Use in Specific Populations

Pregnancy: Folic acid is generally safe during pregnancy and is critical to prevent fetal damage due to megaloblastic anemia. Nursing Mothers: It's excreted in the milk, making supplementation necessary in certain cases. Pediatric Use: Dosage varies based on the age and health condition of the child.

Special precautions

This product contains aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired. Premature neonates are particularly at risk because their kidneys are immature, and they require large amounts of calcium and phosphate solutions, which contain aluminum.

Research indicates that patients with impaired kidney function, including premature neonates, who receive parenteral levels of aluminum at greater than 4 to 5 mcg/kg/day accumulate aluminum at levels associated with central nervous system and bone toxicity.  Tissue loading may occur at even lower rates of administration.

Folic acid alone is improper therapy in the treatment of pernicious anemia and other megaloblastic anemias where Vitamin B 12 is deficient.

This product contains benzyl alcohol.  Benzyl alcohol has been reported to be associated with a fatal “Gasping Syndrome” in premature infants.

Storage

  • Store at 20° to 25°C (68° to 77°F)
Folic acid Resources
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Contributors: Prab R. Tumpati, MD