FOLIC ACID (VITAMIN B9, PTEROYLGLUTAMIC ACID)
| FOLIC ACID (VITAMIN B9, PTEROYLGLUTAMIC ACID) (fol'ic) Apo-Folic  , Folacin, Novofolacid FOLATE SODIUM Folvite Sodium Classifications: vitamin b9; Therapeutic: vitamin supplement Pregnancy Category: A |
Availability
0.4 mg, 0.8 mg, 1 mg tablets; 5 mg/mL injection
Action
Vitamin B9 essential for nucleoprotein synthesis and maintenance of normal erythropoiesis. Acts against folic acid deficiency that results in production of defective DNA that leads to megaloblast formation and arrest of bone marrow maturation.
Therapeutic Effect
Stimulates production of RBCs, WBCs, and platelets in patients with megaloblastic anemias.
Uses
Folate deficiency, macrocytic anemia, and megaloblastic anemias associated with malabsorption syndromes, alcoholism, primary liver disease, inadequate dietary intake, pregnancy, infancy, and childhood.
Contraindications
Folic acid alone for pernicious anemia or other vitamin B12 deficiency states; normocytic, refractory, aplastic, or undiagnosed anemia; neonates.
Cautious Use
Pregnancy (category A).
Route & Dosage
| Therapeutic Adult: PO/IM/SC/IV ≤1 mg/d Child: PO/IM/SC/IV ≤1 mg/d Maintenance Adult: PO/IM/SC/IV ≤0.4 mg/d Child: PO/IM/SC/IV ≤4 y, up to 0.3 mg/d; >4 y, up to 0.1 mg/d Infant: PO/IM/SC/IV 0.1 mg/d |
Administration
| Intravenous PREPARE: Direct/Continuous: Given undiluted. ADMINISTER: Direct/Continuous: Give over 30–60 sec. May also add to a continuous infusion. INCOMPATIBILITIES Solution/additive: Calcium gluconate, chlorpromazine, dextrose 40% in water, doxapram. |
- Store at 15°–30° C (59°–86° F) in tightly closed containers protected from light, unless otherwise directed.
Adverse Effects (≥1%)
Reportedly nontoxic. Slight flushing and feeling of warmth following IV administration.Diagnostic Test Interference
Falsely low serum folate levels may occur with Lactobacillus casei assay in patients receiving antibiotics such as tetracyclines.
Interactions
Drug: Chloramphenicol may antagonize effects of folate therapy; phenytoin metabolism may be increased, thus decreasing its levels.Pharmacokinetics
Absorption: Readily from proximal small intestine. Peak: 30–60 min PO. Distribution: Distributed to all body tissues; high concentrations in CSF; crosses placenta; distributed into breast milk. Metabolism: In liver to active metabolites. Elimination: Small amounts in urine in folate-deficient patients; large amounts excreted in urine with high doses.Nursing Implications
Assessment & Drug Effects
- Obtain a careful history of dietary intake and drug and alcohol usage prior to start of therapy. Drugs reported to cause folate deficiency include oral contraceptives, alcohol, barbiturates, methotrexate, phenytoin, primidone, and trimethoprim. Folate deficiency may also result from renal dialysis.
- Keep physician informed of patient's response to therapy.
- Monitor patients on phenytoin for subtherapeutic plasma levels.
Patient & Family Education
- Remain under close medical supervision while taking folic acid therapy. Adjustment of maintenance dose should be made if there is threat of relapse.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; 
Prototype drug