Folic acid: Indication, Dosage, Side Effect, Precaution

Generic Medicine Info Patient Medicine Information

This information is not country-specific. Please refer to the Malaysia prescribing information.

Generic Medicine Info

Indications and Dosage

Oral
Prophylaxis in chronic haemolytic states

Adult: 5 mg every 1-7 days depending on the underlying disease.

Oral
Folate-deficient megaloblastic anaemia

Adult: 5 mg daily for up to 4 months; may increase to 15 mg daily in malabsorption states. Maintenance: 5 mg every 1-7 days. Alternatively, up to 1 mg daily; higher doses may be given in resistant cases. Dosage recommendations may vary among countries or individual products. Refer to specific product guidelines.
Child: >1 years Same as adult dose.

Oral
Prophylaxis of neural tube defect in pregnancy

Adult: In women with positive history of previous neural tube defects (NTD): 5 mg daily starting before pregnancy and continued through the 1st trimester. In women with no previous history of foetal NTD and no other predisposing factors: 0.4 mg daily until 10-12 weeks after the last menstrual period.

Parenteral
Folate-deficient megaloblastic anaemia

Adult: In severe cases or if gastrointestinal absorption is impaired: Up to 1 mg daily via IM, IV, or SC inj. Maintenance: 0.4 mg daily.
Child: Up to 1 mg daily via IM, IV, or SC inj. Maintenance: Infants 0.1 mg daily; <4 years Up to 0.3 mg daily; ≥4 years 0.4 mg daily.

Administration

May be taken with or without food.

Contraindications

Untreated cobalamin deficiency (including untreated pernicious anaemia or other causes e.g. lifelong vegetarians), malignant disease.

Special Precautions

Patient with folate-dependent tumours, haemolytic anaemia, alcoholism. Women with pre-existing diabetes, obesity, family history of neural tube defects, or previous pregnancy affected by neural tube defect. Not appropriate for monotherapy in pernicious, aplastic, or normocytic anaemias when anaemia is present with vitamin B₁₂ deficiency. Children. Pregnancy and lactation.

Adverse Reactions

Gastrointestinal disorders: Abdominal distension, flatulence, nausea, bitter or bad taste.
Immune system disorders: Rarely, allergic reactions (e.g. rash, pruritus, erythema, urticaria, dyspnoea, shock); allergic sensitisation.
Metabolism and nutrition disorders: Rarely, anorexia.

Pregnancy Category (US FDA)

PO: A

Monitoring Parameters

Establish cobalamin status in all megaloblastic states (not only in pregnancy).

Drug Interactions

May reduce the plasma concentrations of anticonvulsants (e.g. phenytoin, phenobarbital, carbamazepine, valproic acid). Enhances the efficacy of lithium. May decrease the therapeutic effect of methotrexate. Increased elimination with aspirin. Reduced absorption with sulfasalazine and triamterene. Chloramphenicol and sulfamethoxazole + trimethoprim may interfere with folate metabolism.

Food Interaction

Increased elimination with alcohol.

Action

Description:
Mechanism of Action: Folic acid is essential for the formation of coenzymes in many metabolic systems such as purine, pyrimidine, and methionine synthesis. It is also essential in nucleoprotein synthesis, maintenance of erythropoiesis, and stimulation of WBC and platelet production in folate-deficiency anaemia.
Synonym: folate.
Pharmacokinetics:
Absorption: Rapidly absorbed from the gastrointestinal tract, primarily from the proximal portion of the small intestine. Bioavailability: Approx 100% (folic acid supplement); 50% (dietary folate). Time to peak plasma concentration: 1 hour.
Distribution: Widely distributed to body tissues and stored mainly in the liver. Actively concentrated in the CSF and enters breast milk. Plasma protein binding: 70%, to albumin.
Metabolism: Metabolised in the liver and plasma where it is converted to the active metabolite, 5-methyltetrahydrofolate (5MTHF); undergoes enterohepatic circulation.
Excretion: Via urine.

Chemical Structure

Storage

Store between 20-25°C. Protect from light.

MIMS Class

Vitamins & Minerals (Pre & Post Natal) / Antianemics

ATC Classification

B03BB01 - folic acid ; Belongs to the class of folic acid and derivatives. Used in the treatment of anemia.

References

Anon. Folic Acid. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 06/05/2022.

Anon. Folic Acid. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 06/05/2022.

Buckingham R (ed). Folic Acid. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 06/05/2022.

Folic Acid 400 microgram Tablets (Alissa Healthcare Research Limited). MHRA. https://products.mhra.gov.uk. Accessed 06/05/2022.

Folic Acid Colonis 1 mg/mL Oral Solution (Colonis Pharma Limited). MHRA. https://products.mhra.gov.uk. Accessed 06/05/2022.

Folic Acid Injection, Solution (XGen Pharmaceuticals DJB, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 06/05/2022.

Folic Acid Tablet (Method Pharmaceuticals, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 06/05/2022.

Folic Acid Tablets BP 5 mg (Flamingo Pharma UK Ltd.). MHRA. https://products.mhra.gov.uk. Accessed 06/05/2022.

Joint Formulary Committee. Folic Acid. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 06/05/2022.

Royce Folic Acid Tablet (Royce Pharma Manufacturing Sdn.Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 10/05/2022.

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