ascorbic acid

Therapeutic Classification: vitamins

Pharmacologic Classification: water soluble vitamins

Indications ⬆ ⬇

REMS

Treatment of ascorbic acid deficiency.
Supplemental therapy in some GI diseases during long-term parenteral nutrition or chronic hemodialysis.
Treatment and prevention of scurvy.

Action ⬆ ⬇

Necessary for collagen formation and tissue repair.
Involved in oxidation reduction reactions; tyrosine, folic acid, iron, and carbohydrate metabolism; lipid and protein synthesis; cellular respiration; and resistance to infection.

Therapeutic effects:

Replacement in deficiency states.
Supplementation during increased requirements.

Pharmacokinetics ⬆ ⬇

Absorption: Actively absorbed after oral administration by a saturable process. IV administration results in complete bioavailability.

Distribution: Widely distributed. Crosses the placenta; enters breast milk.

Metabolism/Excretion: Converted to compounds that are excreted by the kidneys.

Half-Life: 7.4 hr.

Time/Action Profile ⬆ ⬇

(response to skeletal and hemorrhagic changes in scurvy)

ROUTE	ONSET	PEAK	DURATION
PO, IM, IV, SUBQ	2 days–3 wk	unknown	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Tartrazine hypersensitivity (some oral products contain tartrazine—FDC yellow dye #5).

Use Cautiously in:

Renal impairment (↑ risk for nephrolithiasis);
Recurrent kidney stones (↑ risk for nephrolithiasis);
Glucose 6–phosphate dehydrogenase deficiency (↑ risk for hemolysis; avoid exceeding US recommended daily allowance);
OB: Avoid exceeding US recommended daily allowance;
Pedi: Children 2 yr ( risk for nephrolithiasis); children 5 mo (safety and effectiveness of IV formulation not established)
Geri: risk for nephrolithiasis.

Adv. Reactions/Side Effects ⬆ ⬇

Derm: flushing

GI: vomiting, cramps, diarrhea, heartburn, nausea

GU: nephrolithiasis, oxalate nephropathy

Hemat: hemolysis (in G6PD deficiency), deep vein thrombosis

Local: pain at SUBQ, IM, or IV sites

Neuro: fatigue, drowsiness, headache, insomnia

Interactions ⬆ ⬇

Drug-drug:

If urinary acidification occurs, may ↑ excretion and ↓ effects of mexiletine,amphetamine, fluphenazine, or tricyclic antidepressants.
Large doses (>10 g/day) may ↓ response to warfarin.
↑iron toxicity when given concurrently with deferoxamine.
May ↓ effects of erythromycin, streptomycin, doxycycline, and bleomycin.

Route/Dosage ⬆ ⬇

PO (Adults ): Scurvy: 500 mg/day for at least 14 days. Prevention of deficiency: 50–100 mg/day.
PO (Children ): Scurvy: 100–300 mg/day for at least 14 days. Prevention of deficiency: 30–45 mg/day.
IM (Adults ): Scurvy: 100–500 mg/day for at least 14 days.
IM (Children ): Scurvy: 100–300 mg/day for at least 14 days.
IV (Adults and Children ≥11 yr): Scurvy (treatment): 200 mg once daily for up to 7 days; if no improvement in symptoms, retreat until symptoms resolve.
IV (Children 1–10 yr): 100 mg once daily for up to 7 days. Retreatment is not recommended.
IV (Children 5 mo-<1 yr): 50 mg once daily for up to 7 days. Retreatment is not recommended.

Availability ⬆ ⬇

(Generic available)

Chewable tablets: 60 mg^OTC; 100 mg^OTC; 250 mg^OTC; 500 mg^OTC; 1 g^OTC
Extended-release capsules: 500 mg^OTC
Extended-release tablets: 500 mg^OTC; 1 g^OTC; 1.5 g^OTC
Oral solution: 50 mg/0.6 mL^OTC; 100 mg/mL^OTC
Syrup: 250 mg/5 mL^OTC
Solution for injection: 222 mg/mL; 250 mg/mL; 500 mg/mL
Tablets: 25 mg^OTC; 50 mg^OTC; 100 mg^OTC; 125 mg^OTC; 250 mg^OTC; 500 mg^OTC; 1 g^OTC; 1.5 g^OTC
In combination with: other vitamins and minerals in multivitamin preparations.

Assessment ⬆ ⬇

Vitamin C Deficiency: Assess for signs and symptoms of vitamin C deficiency (faulty bone and tooth development, gingivitis, bleeding gums, loosened teeth) before and during therapy.

Lab Test Considerations:

Megadoses of ascorbic acid (>10 times the RDA requirement) may cause false-negative results for occult blood in the stool.
- May interfere with blood and urine glucose tests for up to 24 hr after infusion.
- May cause ↓ serum bilirubin and ↑ urine oxalate, urate, and cysteine levels.

Implementation ⬆ ⬇

Often ordered as a part of multivitamin supplementation, because inadequate diet often results in multiple-vitamin deficiency.
PO: Extended-release tablets and capsules should be swallowed whole without crushing, breaking, or chewing; contents of capsules may be mixed with jelly or jam. Chewable tablets should be chewed well or crushed before swallowing. Oral solution may be taken directly by mouth or mixed with fruit juice, cereal, or other food.
IM: IM is usually the preferred parenteral route.

IV Administration:

Diluent: Dilute dose in 1000 mL D5W, D10W, 0.9% NaCl, 0.45% NaCl, LR or Ringer’s solution, dextrose/saline or dextrose/Ringer’s combinations.
Rate: Infuse slowly.

Patient/Family Teaching ⬆ ⬇

Advise patient to take medication as directed and not to exceed dose prescribed. Excess doses may lead to diarrhea and urinary stone formation. If a dose is missed, skip dose and return to dose schedule.
Vitamin C Deficiency: Encourage patient to comply with diet recommendations of health care professional. Explain that the best source of vitamins is a well-balanced diet.
- Foods high in ascorbic acid include citrus fruits, tomatoes, strawberries, cantaloupe, and raw peppers. Gradual loss of ascorbic acid occurs when fresh food is stored, but not when it is frozen. Rapid loss is caused by drying, salting, and cooking.
- Patients self-medicating with vitamin supplements should be cautioned not to exceed RDA. The effectiveness of megadoses of vitamins for treatment of various medical conditions is unproven and may cause side effects. Abrupt withdrawal of megadoses of ascorbic acid may cause rebound deficiency.

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Pronunciation ⬇

Classifications ⬆ ⬇