ASCORBIC ACID (VITAMIN C)

ASCORBIC ACID (VITAMIN C)
Apo-C , Ascorbicap, Cecon, Cetane, Cevalin, CeVi-Sol , Flavorcee, Redoxon , Schiff Effervescent Vitamin C, Vita-C
ASCORBATE, SODIUM
(a-skor'bate)
Cenolate
Classifications: vitamin;
Therapeutic: vitamin supplement

Pregnancy Category: C

Availability

25 mg, 50 mg, 100 mg, 250 mg, 500 mg, 1000 mg tablets; 500 mg/mL injection

Action

Water-soluble vitamin essential for synthesis and maintenance of collagen and intercellular ground substance of body tissue cells, blood vessels, cartilage, bones, teeth, skin, and tendons. Unlike most mammals, humans are unable to synthesize ascorbic acid in the body; therefore it must be consumed daily.

Therapeutic Effect

Increases protective mechanism of the immune system, thus supporting wound healing. Necessary for wound healing and resistance to infection.

Uses

Prophylaxis and treatment of scurvy and as a dietary supplement.

Unlabeled Uses

To acidify urine; to prevent and treat cancer; to treat idiopathic methemoglobinemia; as adjuvant during deferoxamine therapy for iron toxicity; in megadoses will possibly reduce severity and duration of common cold. Widely used as an antioxidant in formulations of parenteral tetracycline and other drugs.

Contraindications

Use of sodium ascorbate in patients on sodium restriction; use of calcium ascorbate in patients receiving digitalis; pregnancy (category C).

Cautious Use

Excessive doses in patients with G6PD deficiency; hemochromatosis, thalassemia, sideroblastic anemia, sickle cell anemia; patients prone to gout or renal calculi.

Route & Dosage

Therapeutic
Adult: PO/IV/IM/SC 150–500 mg/d in 1–2 doses
Child: PO/IV/IM/SC 100–300 mg/d in divided doses

Prophylactic
Adult: PO/IV/IM/SC 45–60 mg/d
Child: PO/IV/IM/SC 30–60 mg/d

Urinary Acidifier
Adult: PO/IV/IM/SC 4–12 g/d in divided doses
Child: PO/IV/IM/SC 500 mg q6–8h

Administration

Oral
  • Give oral solutions mixed with food.
  • Dissolve effervescent tablet in a glass of water immediately before ingestion.
Intramuscular/Subcutaneous
  • Open ampules with caution. After prolonged storage, decomposition may occur with release of carbon dioxide and resulting increase in pressure within ampule.
  • Be aware that ascorbic acid injection may gradually darken on exposure to light; slight coloration reportedly does not affect its therapeutic action.
Intravenous

Verify correct IV concentration and rate of infusion for children with physician.

PREPARE: Direct/Continuous/Intermittent: ??Give undiluted or diluted (preferred) in solutions such as NS, D5W, D5/NS, RL.??Be aware that parenteral vitamin C is incompatible with many drugs. ??Consult pharmacist for compatibility information. 

ADMINISTER: Direct: Give undiluted at a rate of 100 mg or a fraction thereof over 1 min.  Continuous/Intermittent (preferred): Give at ordered rate determined by volume of solution to be infused.  

INCOMPATIBILITIES Solution/additive: Aminophylline, bleomycin, erythromycin, nafcillin, sodium bicarbonate, theophylline. Y-site: Etomidate, thiopental.

  • Store in airtight, light-resistant, nonmetallic containers, away from heat and sunlight, preferably at 15°–30° C (59°–86° F), unless otherwise specified by manufacturer.

Adverse Effects (≥1%)

GI: Nausea, vomiting, heartburn, diarrhea, or abdominal cramps (high doses). Hematologic: Acute hemolytic anemia (patients with deficiency of G6PD); sickle cell crisis. CNS: Headache or insomnia (high doses). Urogenital: Urethritis, dysuria, crystalluria, hyperoxaluria, or hyperuricemia (high doses). Other: Mild soreness at injection site; dizziness and temporary faintness with rapid IV administration.

Diagnostic Test Interference

High doses of ascorbic acid can produce false-negative results for urine glucose with glucose oxidase methods (e.g., Clinitest, TesTape, Diastix); false-positive results with copper reduction methods (e.g., Benedict's solution, Clinitest); and false increases in serum uric acid determinations (by enzymatic methods). Interferes with urinary steroid (17-OHCS) determinations (by modified Reddy, Jenkins, Thorn procedure), decreases in serum bilirubin, and may cause increases in serum cholesterol, creatinine, and uric acid (methodologic inferences). May produce false-negative tests for occult blood in stools if taken within 48–72 h of test.

Interactions

Drug: Large doses may attenuate hypoprothrombinemic effects of oral anticoagulants; salicylates may inhibit ascorbic acid uptake by leukocytes and tissues, and ascorbic acid may decrease elimination of salicylates; chronic high doses of ascorbic acid may diminish the effects of disulfiram.

Pharmacokinetics

Absorption: Readily absorbed PO; however, absorption may be limited with large doses. Distribution: Widely distributed to body tissues; crosses placenta; distributed into breast milk. Metabolism: In liver. Elimination: Rapidly in urine when plasma level exceeds renal threshold of 1.4 mg/dL.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Periodic Hct & Hgb, serum electrolytes.
  • Monitor for S&S of acute hemolytic anemia, sickle cell crisis.

Patient & Family Education

  • High doses of vitamin C are not recommended during pregnancy.
  • Take large doses of vitamin C in divided amounts because the body uses only what is needed at a particular time and excretes the rest in urine.
  • Megadoses can interfere with absorption of vitamin B12.
  • Note: Vitamin C increases the absorption of iron when taken at the same time as iron-rich foods.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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