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Pronunciation:

(FOE lik AS id)

Synonyms:

Folacin; Folate; Pteroylglutamic Acid

Generic Available:

Yes

Canadian Brand Names:

Apo-Folic®

Use:

Treatment of megaloblastic and macrocytic anemias due to folate deficiency; dietary supplement to prevent neural tube defects

Pregnancy Risk Factor:

A/C (dose exceeding RDA recommendation)

Lactation:

Enters breast milk/compatible

Contraindications:

Pernicious, aplastic, or normocytic anemias

Warnings/Precautions:

Doses >0.1 mg/day may obscure pernicious anemia with continuing irreversible nerve damage progression; the dose that masks anemia is controversial, but doses of 400 mcg daily (or even less) have been reported. Resistance to treatment may occur with depressed hematopoiesis, alcoholism, deficiencies of other vitamins. Injection contains benzyl alcohol (1.5%) as preservative (use care in administration to neonates).

Adverse Reactions:

Slight flushing, general malaise, pruritus, rash, bronchospasm, allergic reaction

Drug Interactions:

Decreased effect: In folate-deficient patients, folic acid therapy (>15 mg/day) may increase phenytoin metabolism. Phenytoin, primidone, para-aminosalicylic acid, and sulfasalazine may decrease serum folate concentrations and cause deficiency. Oral contraceptives may also impair folate metabolism producing depletion, but the effect is unlikely to cause anemia or megaloblastic changes. Concurrent administration of chloramphenicol and folic acid may result in antagonism of the hematopoietic response to folic acid; dihydrofolate reductase inhibitors (eg, methotrexate, trimethoprim) may interfere with folic acid utilization.

Stability:

Incompatible with oxidizing and reducing agents and heavy metal ions

Compatibility:

Stable in D5W, D20W, NS, fat emulsion 10%; not stable in D40W, D50W

Y-site administration: Compatible: Famotidine

Compatibility in syringe: Incompatible: Doxapram

Compatibility when admixed: Incompatible: Calcium gluconate

Mechanism of Action:

Folic acid is necessary for formation of a number of coenzymes in many metabolic systems, particularly for purine and pyrimidine synthesis; required for nucleoprotein synthesis and maintenance in erythropoiesis; stimulates WBC and platelet production in folate deficiency anemia

Pharmacodynamics/Kinetics:

Onset of effect: Peak effect: Oral: 0.5-1 hour

Absorption: Proximal part of small intestine

Dosage:

Infants: 0.1 mg/day

Children <4 years: Up to 0.3 mg/day

Children >4 years and Adults: 0.4 mg/day

Pregnant and lactating women: 0.8 mg/day

RDA:

Adult male: 0.15-0.2 mg/day

Adult female: 0.15-0.18 mg/day

Elderly: Vitamin B12 deficiency must be ruled out before initiating folate therapy due to frequency of combined nutritional deficiencies: RDA requirements (1989): 200 mcg/day (0.2 mg) minimum

Administration:

Oral preferred, but may also be administered by deep I.M., SubQ, or I.V. injection; a diluted solution for oral or for parenteral administration may be prepared by diluting 1 mL of folic acid injection (5 mg/mL), with 49 mL sterile water for injection; resulting solution is 0.1 mg folic acid per 1 mL

Reference Range:

Therapeutic: 0.005-0.015 mcg/mL

Test Interactions:

Falsely low serum concentrations may occur with the Lactobacillus casei assay method in patients on anti-infectives (eg, tetracycline)

Patient Education:

Inform prescriber of all prescriptions, OTC medications, or herbal products you are taking, and any allergies you have. Do not take any new medication during therapy unless approved by prescriber. Take exactly as prescribed. Toxicity can occur from elevated doses. Increased intake of foods high in folic acid (eg, dried beans, nuts, bran, vegetables, fruits) may be recommended by prescriber. Excessive use of alcohol increases requirement for folic acid. May turn urine more intensely yellow. Report skin rash. Pregnancy precaution: Inform prescriber if you are pregnant.

Cardiovascular Considerations:

Epidemiological evidence suggests that total plasma homocysteine level may be an independent cardiovascular risk factor. Plasma homocysteine levels are strongly influenced by genetics and diet (folic acid, pyridoxine/vitamin B6, and cyanocobalamine/vitamin B12). These vitamins help to break down homocysteine in the body.

Schnyder, et al, studied the effects of homocysteine-lowering therapy (folic acid 1 mg/day, vitamin B6 10 mg/day, vitamin B12 0.4 mg/day) in patients with coronary artery disease after successful angioplasty in the Swiss Heart Study. This randomized, double-blind, placebo-controlled trial looked at a composite endpoint (death, nonfatal MI, repeat revascularization) 6 months and 1 year after angioplasty. Homocysteine-lowering therapy significantly decreased the incidence of major adverse events, primarily due to a reduced rate of target lesion revascularization. Investigators in the Folate After Coronary Intervention Trial randomized patients who underwent successful coronary stenting procedures to placebo or folic acid (1.2 mg/day), vitamin B6 (4.8 mg/day), and vitamin B12 (0.06 mg/day). Vitamin supplementation was associated with increased restenosis in these PCI patients.

Liem and colleagues randomized 593 patients with stable coronary artery disease to either folic acid supplementation (0.5 mg/day) or none in an open-label study. All patients were being treated with a HMG-CoA reductase inhibitor. The primary endpoint was a composite of vascular events and all cause mortality. Patients were followed up for 2 years. Patients treated with folic acid had a significant reduction in plasma homocysteine levels but the primary end point was encountered by a similar number of patients in both groups. The authors concluded that folic acid does not seem to reduce clinical endpoints in patients with stable coronary artery disease. Further investigation is required to sort out the discrepancies in these trials.

Dental Health: Effects on Dental Treatment:

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

No information available to require special precautions

Mental Health: Effects on Mental Status:

May cause drowsiness

Mental Health: Effects on Psychiatric Treatment:

None reported

Dosage Forms:

Injection, solution, as sodium folate: 5 mg/mL (10 mL) [contains benzyl alcohol]

Tablet: 0.4 mg, 0.8 mg, 1 mg

Extemporaneously Prepared:

A 1 mg/mL folic acid solution may be prepared by crushing fifty 1 mg tablets. Dissolve in a small amount of distilled water, then add sufficient distilled water to make a final volume of 50 mL. Adjust the pH to 8 with sodium hydroxide. It is stable for 42 days at room temperature.

Nahata MC and Hipple TF, Pediatric Drug Formulations, Harvey Whitney Books Company, 1992.

International Brand Names:

Acfol® (ES, PT); Acide Folique CCD® (FR); Acid Folic® (RO); Acido Folico® (AR, EC); Acido Folico Aspol® (ES); Acido Folico Ecar® (CO); Acido Folico Fada® (AR); Acido Folico L.CH.® (CL); Acidum Folicum® (BG, PL); Acidum folicum Hänseler® (CH); Acidum Folicum Leciva® (CZ); Acidum folicum Streuli® (CH); Acifol® (AR); Acifolico® (BR); AF Valdecasas® (MX); Andreafol® (CH); Apo-Folic® (CA, NZ); Bio-Folic® (BE); Blackmores Folic Acid® (TH); Cardioguard® (IE); Clonfolic® (IE); Conacid® (AR); DreisaFol® (DE); Drossafol® (CH); Egestan Folico® (AR); Endofolin® (BR); Femisanit® (DE); Flonak® (YU); Florafol Folsäure® (DE); Folac® (BD); Folacid® (PL); Folacin® (BR, HR, SE, SI); Folan® (YU); Folarell® (DE); Fol-ASmedic® (DE); Folavit® (BE, ID); Folbiol® (TR); Folcur® (DE); Folettes® (AU); Folgamma® (DE); Foliamin® (HK, JP, TH); Folic Acid® (AU, CY, GB, IL, NZ, SG, ZA); Folic Acid Injection® (AU, GB); Folicare® (GB); Folicil® (PT); Folifem® (PL); Folifort® (PL); Folik® (PL); Folimet® (DK); Folimin® (PL); Folina® (IT); Folinsyre SAD® (DK); Foliphar® (BE); Folisanin® (CL); Folison® (BD); Folisyx® (DE); Folitab® (DO); Folivit® (TH); Fol Lichtenstein® (DE); Folovit® (PL); Folsan® (AT, DE); Folsäure-biosyn® (DE); Folsäure Dr. Hotz® (DE); Folsäure Heumann® (DE); Folsäure-Hevert® (DE); Folsäure-Injektopas® (DE); Folsäure-ratiopharm® (DE); Folsäure Stada® (DE); Folsav® (HU); Folsyre® (NO); Folverlan® (DE); Folvite® (CH, FI); Gravida® (BE); Gravi-Fol® (DE); Huma-Folacid® (HU); Ingafol® (IN); Kwas foliowy® (PL); Lafol® (DE); Lexpec® (GB); Megafol® (AU); Mithra Folic® (BE); Oncofolic® (DE); Preconceive® (GB); RubieFol® (DE); Speciafoldine® (FR); Tanvimil Folico® (AR); Tifol® (PL); Travital Folic Acid® (BE); VoriNa® (DE)

References

Davis RE, "Clinical Chemistry of Folic Acid,"Adv Clin Chem, 1986, 25:233-94.

Department of Health and Human Services, Food and Drug Administration, Nutrition Labeling, Federal Register, 1980, 45:69043.

Lambie DG and Johnson RH, "Drugs and Folate Metabolism,"Drugs, 1985, 30(2):145-55.

Lewis DP, Van Dyke DC, Willhite LA, et al, "Phenytoin-Folic Acid Interaction,"Ann Pharmacother, 1995, 29(7-8):726-35.

Liem A, Reynierse-Buitenwerf GH, Zwinderman AH, et al, "Secondary Prevention With Folic Acid: Effects on Clinical Outcomes,"J Am Coll Cardiol, 2003, 41(12):2105-13.

Olszewski AJ, Szostak WB, Bialkowska M, et al, "Reduction of Plasma Lipid and Homocysteine Levels by Pyridoxine, Folate, Cobalamin, Choline, Riboflavin, and Troxerutin in Atherosclerosis,"Atherosclerosis, 1989, 75(1):1-6.

Savage DG and Lindenbaum J, "Folate-Cobalamin Interactions," Bailey LB, ed, Folate in Health and Disease, New York: Marcel Dekker, Inc, 1995:237-285.

Schnyder G, Roffi M, Flammer Y, et al, "Effect of Homocysteine-Lowering Therapy With Folic Acid, Vitamin B12, and Vitamin B6 on Clinical Outcome After Percutaneous Coronary Intervention: The Swiss Heart Study: A Randomized Controlled Trial,"JAMA, 2002, 288(8):973-9.

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