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Ascorbic Acid

Class: Vitamin C
ATC Class: A11GA01
VA Class: VT400
Chemical Name: l-ascorbic acid
CAS Number: 50-81-7
Brands: Ascor

Medically reviewed by Drugs.com on Apr 4, 2022. Written by ASHP.

Introduction

An essential water-soluble vitamin; ascorbic acid is the in vivo form of vitamin C.

Uses for Ascorbic Acid

Scurvy

Prevention and treatment of scurvy.

Dietary Requirements

Adequate intake needed to prevent scurvy and provide antioxidant protection.

Adequate vitamin C intake can be accomplished through consumption of foodstuffs. Citrus fruits, tomatoes, and potatoes are the major contributors of vitamin C in the diet of US adults and children.

Recommended Dietary Allowances (RDA) in adults based on near maximal neutrophil concentrations with minimal urinary excretion of ascorbate.

Requirements slightly lower in women than men based on water-soluble nature of the vitamin and the larger lean body mass and total body water in males relative to females.

Adequate intake (AI) established for infants ≤6 months of age based on observed mean vitamin C intake of infants fed principally human milk; AI for infants 7–12 months of age based on vitamin C intake from human milk and solid food.

RDA for children 1–18 years of age based on data in adults.

Macular Degeneration

Suggested as a component of high-dose antioxidant supplements with zinc to reduce risk of developing advanced age-related macular degeneration in high-risk patients (i.e., those with intermediate stage age-related macular degeneration or advanced stage macular degeneration in only one eye).

Respiratory Infections

Large doses have been advocated for lessening severity of and for preventing the common cold. Routine supplementation modestly decreases duration of symptoms; also appears to decrease incidence in individuals under heavy physical stress but not in the overall population. No consistent effect on duration or severity of symptoms when initiated following symptom onset.

Limited study data available regarding effects in the prevention or treatment of pneumonia; available studies were conducted under specific circumstances and may not be applicable to the general population.

Studies required to establish efficacy of adjunctive ascorbic acid therapy in the treatment of severe viral respiratory infections.

Sepsis

High-dose IV ascorbic acid has been evaluated in patients with sepsis; efficacy remains to be established.

Meta-analysis of several small studies suggested beneficial effects from adjunctive IV ascorbic acid in patients with sepsis, but primary efficacy end points were not improved in 2 subsequent multicenter, randomized studies (CITRIS-ALI, VITAMINS). Additional studies under way.

Methemoglobinemia

Has been used in the treatment of idiopathic methemoglobinemia.

Ascorbic Acid Dosage and Administration

Administration

Usually administered orally. May be administered by IM, IV, or sub-Q injection when oral administration is not feasible or when malabsorption is suspected.

Parenteral Administration

Preferred parenteral method of administration is IM.

Pressure may build within the vial during storage. Exercise care when withdrawing a dose and/or insert a vent needle (e.g., empty sterile syringe) into the vial to release the pressure.

IV Administration

Dilution

For solution and drug compatibility, see Compatibility under Stability.

Dilute with large volume of compatible parenteral fluid to minimize adverse reactions. Avoid rapid infusion.

Dosage

Available as ascorbic acid, calcium ascorbate, and sodium ascorbate; dosage expressed in terms of ascorbic acid.

Pediatric Patients

Scurvy
Treatment
Oral or IV

100–300 mg daily for 1 month or until full recovery.

Dietary and Replacement Requirements
Oral

Infants ≤6 months of age: Recommended AI is 40 mg (about 6 mg/kg) daily.

Infants 7–12 months of age: Recommended AI is 50 mg (about 6 mg/kg) daily.

Children 1–3 years of age: RDA is 15 mg daily.

Children 4–8 years of age: RDA is 25 mg daily.

Children 9–13 years of age: RDA is 45 mg daily.

Boys 14–18 years of age: RDA is 75 mg daily.

Girls 14–18 years of age: RDA is 65 mg daily.

Adults

Scurvy
Treatment
Oral or IV

300 mg–1 g daily for 1 month or until full recovery.

Dietary and Replacement Requirements
Oral

Men ≥19 years of age: RDA is 90 mg daily.

Women ≥19 years of age: RDA is 75 mg daily.

Macular Degeneration†
Oral

500 mg in combination with beta carotene 15 mg, vitamin E 400 units, and zinc (as zinc oxide) 80 mg, with copper (as cupric oxide) 2 mg (to prevent anemia) daily has been used.

Respiratory Infections†
Common Cold†
Oral

1–3 g or greater per day has been recommended for prevention and treatment.

Idiopathic Methemoglobinemia†
Oral

300–600 mg daily in divided doses has been used.

Special Populations

Pregnant Women

RDA for pregnant women 14–18 years of age is 80 mg daily.

RDA for pregnant women 19–50 years of age is 85 mg daily.

Requirements increased in pregnant women to ensure transfer of adequate amounts of the vitamin to the fetus.

Lactating Women

RDA for lactating women 14–18 or 19–50 years of age is 115 or 120 mg daily, respectively.

Requirements increased in lactating women to ensure adequate concentration of the vitamin in milk.

Smokers

RDA increased by 35 mg daily.

Smoking increases oxidative stress and metabolic turnover of vitamin C.

Cautions for Ascorbic Acid

Contraindications

  • Manufacturer states no known contraindications.

Warnings/Precautions

General Precautions

Sodium Content

Each 1 gram of sodium ascorbate contains approximately 5 mEq of sodium; consider sodium content in patients on sodium-restricted diets.

Kidney Stone Formation

Kidney stone (renal calculus) formation reported in individuals with renal disease receiving large dosages of ascorbic acid; excess ascorbic acid intake not associated with kidney stone formation in healthy individuals.

Aluminum Content

Some ascorbic acid injection preparations contain aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired. Premature neonates are particularly at risk because their kidneys are immature, and they require large amounts of calcium and phosphate solutions, which contain aluminum.

Research indicates that patients with impaired kidney function, including premature neonates, who receive parenteral levels of aluminum >4–5 mcg/kg daily accumulate aluminum at levels associated with CNS and bone toxicity. Tissue loading may occur at even lower rates of administration.

Specific Populations

Pregnancy

Category C.

Lactation

Distributed into milk. Caution if parenteral preparation is used in nursing women.

Common Adverse Effects

Relatively nontoxic; nausea, vomiting, heartburn, fatigue, flushing, headache, insomnia, sleepiness, and other GI disturbances (diarrhea, transient colic, abdominal cramps, flatulent distention) reported.

Interactions for Ascorbic Acid

Laboratory Tests

Interferes with numerous laboratory tests based on oxidation-reduction reactions. Degree of interference depends on several factors (e.g., ascorbic acid concentration, resulting pH, specific reagents). Consult specialized references.

Specific Drugs and Laboratory Tests

Drug or Test

Interaction

Comments

Aspirin

Increased urinary excretion of ascorbic acid and decreased excretion of aspirin reported with concomitant administration

Fluphenazine

Decreased fluphenazine concentrations

Iron, oral

Increased GI absorption of iron

Tests for detection of occult blood in stool

Possible false-negative results

Manufacturer of parenteral ascorbic acid recommends discontinuing vitamin C supplements 48–72 hours before test

Tests for glucose in urine

Possible false-positive with tests based on cupric sulfate reagent and false-negative with tests that use glucose oxidase method

Warfarin

Decreased anticoagulant effect reported; other investigators did not observe this effect

Ascorbic Acid Pharmacokinetics

Absorption

Bioavailability

Readily absorbed by an active process that may be limited after very large doses.

Distribution

Extent

Widely distributed in body tissues.

Crosses the placenta; cord blood concentration 2–4 times maternal blood concentrations. Distributed into human milk.

Plasma Protein Binding

About 25%.

Elimination

Metabolism

Reversibly oxidized to dehydroascorbic acid.

Elimination Route

Excreted in urine.

Removed by hemodialysis.

Stability

Storage

Oral

Capsules and Tablets

Cool dry place.

Parenteral

Solution

Store in carton until time of use at room temperature (≤25°C). Protect from light.

Compatibility

For information on systemic interactions resulting from concomitant use, see Interactions.

Parenteral

Solution CompatibilityHID

Compatible

Dextran 6% in dextrose 5%

Dextran 6% in sodium chloride 0.9%

Dextrose-Ringer’s injection combinations

Dextrose-Ringer’s injection, lactated, combinations

Dextrose-saline combinations

Dextrose 2½, 5, or 10% in water

Fructose 10% in sodium chloride 0.9%

Fructose 10% in water

Invert sugar 5 and 10% in sodium chloride 0.9%

Invert sugar 5 and 10% in water

Ionosol products

Ringer’s injection

Ringer’s injection, lactated

Sodium chloride 0.45 or 0.9%

Sodium lactate 1/6 M

Variable

Fat emulsion 10%, IV

Drug Compatibility
Admixture CompatibilityHID

Compatible

Amikacin sulfate

Calcium chloride

Calcium gluconate

Chloramphenicol sodium succinate

Chlorpromazine HCl

Colistimethate sodium

Cyanocobalamin

Dimenhydrinate HCl

Heparin sodium

Kanamycin sulfate

Methyldopate HCl

Penicillin G potassium

Polymyxin B sulfate

Procaine HCl

Prochlorperazine edisylate

Promethazine HCl

Verapamil HCl

Incompatible

Bleomycin sulfate

Nafcillin sodium

Sodium bicarbonate

Theophylline

Variable

Aminophylline

Erythromycin lactobionate

Y-Site CompatibilityHID

Compatible

Warfarin sodium

Incompatible

Etomidate

Thiopental sodium

Actions

  • An essential water-soluble vitamin present in fresh fruits and vegetables. Vitamin C refers to both ascorbic acid and dehydroascorbic acid (DHA); both compounds exhibit antiscorbutic activity.

  • An antioxidant and a cofactor in enzymatic and metabolic processes.

  • Required for collagen formation and tissue repair.

Advice to Patients

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs as well as any concomitant illnesses.

  • Importance of proper dietary habits, including taking appropriate AI or RDA of vitamin C.

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

  • Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Ascorbic Acid (as Ascorbic Acid or Sodium Ascorbate)

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Bulk

Powder*

Oral

Capsules, extended-release

250 mg*

500 mg*

Lozenges

60 mg*

Solution

25 mg/drop

100 mg/mL

500 mg/5 mL*

Tablets

100 mg*

250 mg*

500 mg*

1 g*

Tablets, chewable

100 mg*

250 mg*

500 mg*

1 g*

Tablets, extended-release

500 mg*

1 g*

1.5 g*

Parenteral

Injection

500 mg/mL*

Ascor

McGuff

Ascorbic acid and sodium ascorbate are also commercially available in combination with other vitamins, minerals, amino acids, analgesic-antipyretics, antihistamines, anti-inflammatory agents, cough suppressants, expectorants, infant formulas, protein supplements, and herbal supplements. For IV infusion, ascorbic acid or sodium ascorbate is also commercially available in combination with other vitamins in caloric and electrolyte solutions.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Calcium Ascorbate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Bulk

Powder*

Oral

Tablets

610 mg (500 mg of ascorbic acid)*

Calcium ascorbate is also commercially available in combination with other vitamins.

AHFS DI Essentials™. © Copyright 2022, Selected Revisions April 13, 2020. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

† Use is not currently included in the labeling approved by the US Food and Drug Administration.

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