Vitamin A

Pronunciation

Class: Vitamin A
ATC Class: A11CA01
VA Class: VT050
CAS Number: 11103-57-4
Brands: Aquasol A

Introduction

Fat-soluble vitamin.a

Uses for Vitamin A

Vitamin A Deficiency

Used to treat and prevent symptoms of vitamin A deficiency such as xerophthalmia and night blindness.137 138 a

Used as a dietary supplement to prevent vitamin A deficiency in patients with GI diseases (e.g., malabsorption syndromes) and those with abnormal storage and transport of vitamin A (e.g., abetalipoproteinemia, protein deficiency, diabetes mellitus, hyperthyroidism, fever, liver disease, cystic fibrosis with hepatic involvement).a

Guidelines from WHO, the United Nations Children's Fund (UNICEF), and the International Vitamin A Consultative Group (IVACG, now the Micronutrient Forum) recommend high-dose vitamin A supplements in the prevention and treatment of severe vitamin A deficiency in certain populations.127 128 129 131 In developing countries where vitamin A deficiency is a public health problem, periodic supplementation with high-dose vitamin A (50,000–200,000 units, depending on age) has been recommended in certain high-risk populations (i.e., postpartum women, children), with reduced doses recommended for pregnant women.127 128 131 Such high doses of vitamin A generally are not used in the US except in individuals with vitamin A deficiency.135 137 138

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WHO and IVACG consider patients with active xerophthalmia (e.g., night blindness, conjunctival xerosis with Bitot's spots, corneal xerosis, corneal ulceration, keratomalacia) to be in imminent danger of corneal destruction and recommend immediate treatment with high dosages of vitamin A.127 129 131 (See Xerophthalmia under Dosage and Administration.)

Children with severe measles have been found to have low serum concentrations of vitamin A; WHO and AAP recommend that vitamin A supplements be given to all children with acute measles, regardless of their country of residence.115 127

Dietary Requirements

Adequate intake needed to prevent vitamin A deficiency and ocular complications (e.g., xerophthalmia) associated with vitamin A deficiency.126

Adequate intake of vitamin A usually can be accomplished through consumption of foodstuffs that contain preformed vitamin A (e.g., liver, dairy products, fish) and provitamin A carotenoids (e.g., darkly colored fruits and vegetables).126

Adequate intake (AI) established for infants ≤6 months of age based on observed mean vitamin A intake of infants fed principally human milk;126 AI for infants 7–12 months of age based on the AI for younger infants and the observed mean vitamin A intake from human milk and from solid food.126

The Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) for children 1–18 years of age based on data in adults.126

Other Uses

Because of the risk of hypervitaminosis A, some clinicians recommend against the use of vitamin A preparations except in vitamin A deficiency and in appropriate preventive situations.a

Vitamin A Dosage and Administration

General

  • Correct poor dietary habits and consider a multivitamin preparation containing vitamin A in patients with vitamin deficiencies since poor dietary habits often result in concurrent deficiencies.137 a

  • Risk of irreversible tissue damage from keratomalacia in patients with severe xerophthalmia; therefore, treat immediately.127 129 131 a

  • Requirements for vitamin A based on adequate liver stores of vitamin A.e Liver storage of vitamin A should be adequate before discontinuing therapy.137

Administration

Administer orally or by IM injection.127 133 137 a

Do not administer by IV injection.137

Oral Administration

Oral administration generally preferred over parenteral therapy.127

Oral vitamin A capsules containing high strengths (e.g., 50,000 units) no longer commercially available in the US but may be available from various organizations (e.g., UNICEF, the International Dispensary Association [IDA]) for treatment of deficiencies in developing countries.127

IM Administration

Administer by IM injection when oral administration is not feasible (e.g., anorexia, nausea, vomiting, pre- and postoperative conditions) or when malabsorption syndrome is present.127 137 a

Dosage

Available as retinol, vitamin A palmitate, or vitamin A acetate; dosage expressed in terms of retinol (i.e., as retinol equivalents [RE] or retinol activity equivalents [RAE]) and in USP units or International Units (IU, units).137 a USP units and International Units are equivalent.137

One USP vitamin A unit is equivalent to 0.3 mcg of all-trans-retinol;137 a one RE is the specific biologic activity of 1 mcg of all-trans-retinol; one RAE is equal to 1 mcg of all-trans-retinol, 12 mcg of all trans-β-carotene, or 24 mcg of other provitamin A carotenoids.126 e

Dosage expressed in RAE is preferred when calculating and reporting the amount of total vitamin A in mixed foods or assessing the amount of dietary and supplemental vitamin A consumed.126

Consider the dietary intake of vitamin A when determining the dosage to avoid toxicity.a

Pediatric Patients

Vitamin A Deficiency
Treatment of Deficiency
Oral

Children >8 years of age: Some manufacturers have recommended a dosage of 100,000 units (30,000 RE) daily for 3 days, followed by 50,000 units (15,000 RE) daily for 2 weeks, then 10,000–20,000 units (3000–6000 RE) daily for 2 months.138 a

IM, then Oral

Low-birthweight infants: Manufacturer states dosage not established.137

Infants <1 year of age: Initially, 7500–15,000 units IM daily for 10 days, follow with 5000–10,000 units orally daily for 2 months.137

Children 1–8 years of age: Initially, 17,500–35,000 units IM daily for 10 days,137 follow with 5000–10,000 units orally daily for 2 months.137

Children >8 years of age: 100,000 units IM daily for 3 days, then 50,000 units IM daily for 2 weeks.137 Follow with 10,000–20,000 units of vitamin A orally daily for 2 months.137

Xerophthalmia
Oral

Infants <6 months of age: Initially, 50,000 units daily for 2 days; repeat with 50,000 units at least 2 weeks later (total of 3 doses).127

Children 6–12 months of age: Initially, 100,000 units daily for 2 days, then 100,000 units at least 2 weeks later (total of 3 doses).127

Children >12 months of age: Initially, 200,000 units daily for 2 days, then 200,000 units at least 2 weeks later (total of 3 doses).127

Prevention of Deficiency
Oral

Children living in underdeveloped countries where vitamin A deficiency resulting in keratomalacia and blindness is common: 50,000–200,000 units every 4–6 months have been given .127 128 a Consult guidelines from appropriate international organizations (e.g., WHO, IVACG) for additional information.127 128 129 131

Children with Measles
Oral or IM

Infants <6 months of age: 50,000 units once daily for 2 days; administer a third dose 2–4 weeks later if clinical manifestations of vitamin deficiency are present.115

Children 6–11 months of age: 100,000 units once daily for 2 days; administer a third dose 2–4 weeks later if clinical manifestations of vitamin deficiency are present.115

Children ≥12 months of age: 200,000 units once daily for 2 days; administer a third dose 2–4 weeks later if clinical manifestations of vitamin deficiency are present.115

Dietary Requirements
Oral

Infants ≤6 months of age: Recommended AI is 400 mcg of RAE (1320 units) daily.126 132 e

Infants 7–12 months of age: Recommended AI is 500 mcg of RAE (1650 units) daily.126 132 e

Children 1–3 years of age: RDA is 300 mcg of RAE (1000 units) daily.126 132 e

Children 4–8 years of age: RDA is 400 mcg of RAE (1320 units) daily.126 132 e

Children 9–13 years of age: RDA is 600 mcg of RAE (2000 units) daily.126 132 e

Girls 14–18 years of age: RDA is 700 mcg of RAE (2310 units) daily.126 132 e

Boys 14–18 years of age: RDA is 900 mcg of RAE (3000 units) daily.126 132 e

Adults

Vitamin A Deficiency
Treatment of Deficiency
Oral

Some manufacturers have recommended a dosage of 100,000 units (30,000 RE) daily for 3 days, followed by 50,000 units (15,000 RE) daily for 2 weeks, then 10,000–20,000 units (3000–6000 RE) daily for 2 months.138 a

IM, then Oral

100,000 units IM daily for 3 days, follow with 50,000 units IM daily for 2 weeks, then 10,000–20,000 units orally daily for 2 months.137

Xerophthalmia
Oral

Initially, 200,000 units daily for 2 days, then 200,000 units at least 2 weeks later (total of 3 doses).127

Dietary Requirements
Oral

Women ≥19 years of age: RDA is 700 mcg of RAE (2310 units) daily.126 132 e

Men ≥19 years of age: RDA is 900 mcg of RAE (3000 units) daily.126 132 e

Prescribing Limits

Pediatric Patients

Vitamin A Deficiency
Oral

Infants 3–6 months of age: 18,500 units daily as water-miscible vitamin A for 1–3 months can cause hypervitaminosis A.137 a (See Hypervitaminosis A Syndrome under Cautions.)

Adults

Vitamin A Deficiency
Oral

Long-term (6–15 months) administration of large dosages (4000 units/kg daily) can cause hypervitaminosis A.137 a (See Hypervitaminosis A Syndrome under Cautions.)

Special Populations

Women of Childbearing Age

Xerophthalmia

Women of childbearing age with night blindness or Bitot's spots: 5000–10,000 units of oral vitamin A once daily for at least 4 weeks; alternatively, may give ≤25,000 units once weekly.127 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

High dosages of vitamin A may be required if acute corneal lesions are present since blindness occurs within 24–48 hours in most individuals with such severe symptoms; balance risk of teratogenicity against benefits of treatment (e.g., prevention of blindness).127 129 131 WHO recommends that women of childbearing age with active corneal lesions be treated with the same doses of vitamin A used in other groups for treatment of xerophthalmia.127

Pregnant Women

Dietary Requirements

Pregnant women 14–18 years of age: RDA is 750 mcg of RAE (2500 units) daily.126 132 e

Pregnant women 19–15 years of age: RDA is 770 mcg of RAE (2565 units) daily.126 132 e

See Fetal/Neonatal Morbidity and Mortality under Cautions.

Xerophthalmia

High dosages of vitamin A may be required if acute corneal lesions are present since blindness occurs within 24–48 hours in most individuals with such severe symptoms; balance risk of teratogenicity against benefits of treatment (e.g., prevention of blindness).127 129 131 WHO recommends that pregnant women with active corneal lesions be treated with the same doses of vitamin A used in other groups for treatment of xerophthalmia.127

Lactation

Lactating women 14–18 years of age: RDA is 1200 mcg of RAE (4000 units) daily.126 132 e

Lactating women 19–50 years of age: RDA is 1300 mcg of RAE (4300 units) daily, respectively.126 132 e

Cautions for Vitamin A

Contraindications

  • IV administration.137

  • Oral high-dose preparation of vitamin A (no longer commercially available in the US): Malabsorption syndromes.138

  • Hypervitaminosis A.137 a

  • Known sensitivity to vitamin A or any ingredient in the formulations.137 a

  • Dosages exceeding RDA contraindicated in women who are or may become pregnant.137 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Warnings/Precautions

Warnings

Fetal/Neonatal Morbidity and Mortality

May cause fetal harm in high dosages (i.e., dosages exceeding the RDA); teratogenicity demonstrated in animals.100 101 102 103 133 137

Human fetal malformations (e.g., cranial neural crest defects) reported following maternal ingestion of large dosages of vitamin A (≥10,000 units daily) shortly before and during pregnancy.103 104 105 106 107 108 113 e

If used during pregnancy or if patient becomes pregnant, apprise of potential fetal hazard.137

Use caution in women of childbearing age; intake of preformed vitamin A (obtained from animal products, fortified foods, and dietary supplement) generally should not exceed the RDA.103 133 137

Despite risks, dosages exceeding the RDA may be necessary in some women of childbearing age with vitamin A deficiency (e.g., active xerophthalmia, corneal lesions).127 129 (See Special Populations under Dosage and Administration.)

Hypervitaminosis A Syndrome

Toxic manifestations from excess vitamin A intake include fatigue, malaise, lethargy, irritability, psychiatric changes mimicking severe depression or schizophrenic disorder, anorexia, abdominal discomfort, nausea and vomiting, mild fever, and excessive sweating.137 a If vitamin A toxicity occurs, withdraw the vitamin and provide symptomatic and supportive treatment.137 a

Sensitivity Reactions

Anaphylactic shock and death have been reported following IV administration.137 (See Contraindications.)

Allergic reactions and anaphylactoid type reaction have been reported rarely.137

General Precautions

Patient Monitoring

Carefully supervise patients receiving prolonged daily dosages >25,000 units.137 a

Specific Populations

Pregnancy

Category X.137 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Lactation

Distributed into milk.103

Unless the maternal diet is grossly inadequate, infants can usually obtain sufficient vitamin A from nursing;103 127 however, the effect of large maternal dosages of vitamin A on nursing infants is not known.103

Pediatric Use

Vitamin A is a well-established and effective treatment of deficiency states in the pediatric population.115 116 127 137

Polysorbates found in the vitamin A injection have been associated with E-Ferol syndrome (thrombocytopenia, renal dysfunction, hepatomegaly, cholestasis, ascites, hypotension, and metabolic acidosis) in low birth-weight infants.137

Common Adverse Effects

Usually nontoxic at therapeutic doses.a

Interactions for Vitamin A

Specific Drugs and Laboratory Tests

Drug or Test

Interaction

Comments

Cholestyramine

May result in decreased absorption of vitamin Aa

Consider daily supplements of water-miscible preparations of vitamin A during long-term cholestyramine administrationa

Mineral oil

May impair absorption of vitamin Aa

Avoid concomitant usea

Neomycin

May result in decreased absorption of vitamin Aa

Oral contraceptives

Possible increase in vitamin A concentrations137

Orlistat

May result in decreased GI absorption of vitamin A117

Allow ≥ 2 hours to elapse between (before or after) an orlistat dose and vitamin A administration117 119 123 125

Retinoids (e.g., etretinate, isotretinoin)

Possible additive adverse effectsa

Avoid concomitant use of preparations containing vitamin A or its derivativesa

Tests, bilirubin (Ehrlich’s reagent)

May falsely elevate bilirubin determinationsa

Warfarin

Possible increased hypoprothrombinemic effect from large doses of vitamin Aa

Vitamin A Pharmacokinetics

Absorption

Bioavailability

Readily and completely absorbed from the GI tract.137 a

Water-miscible preparations of retinol or its esters are absorbed more rapidly from the GI tract than oil solutions.a

Following oral administration of retinol in an oil solution, peak plasma concentrations of retinol esters are attained in about 4–5 hours.a

Following oral administration of water-miscible retinol, peak plasma concentrations of retinol esters are attained in about 3–4 hours.a

Higher plasma concentrations are obtained after administration of a water-miscible preparation of vitamin A than after an oil solution.a

Onset

Ocular symptoms of vitamin A deficiency usually respond quickly and recovery occurs in a few days.131 a

Special Populations

Absorption is incomplete following administration of large doses and in patients with fat malabsorption, low protein intake, or hepatic or pancreatic disease.a

Distribution

Extent

Stored mainly in the liver as retinyl palmitate and small amounts of retinol and retinal.137 a Also stored in the kidneys, lungs, adrenals, retinas, and intraperitoneal fat in lesser amounts as retinyl palmitate.a Normal adult body stores of vitamin A are sufficient to meet the body’s requirements for several months to 2 years.137 a

Does not readily cross the placenta; distributed into milk.a (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Released from the liver bound to a specific α1-globulin, retinol-binding protein (RBP).a

Elimination

Metabolism

Retinol esters are hydrolyzed in the GI lumen by pancreatic enzymes.a

Retinol is conjugated with glucuronic acid; the β-glucuronide undergoes enterohepatic circulation and oxidation to retinal and retinoic acid.a Retinoic acid undergoes decarboxylation and further conjugation with glucuronic acid.a

Retinol is reesterified, mainly to retinyl palmitate.a

Elimination Route

Retinoic acid is excreted in feces via biliary elimination.a Retinal, retinoic acid, and other water-soluble metabolites are excreted in urine and feces.a Generally, unchanged retinol is not excreted in the urine.a

Special Populations

In patients with pneumonia or chronic nephritis, unchanged retinol may be excreted in the urine.a

Stability

Storage

Oral

Capsules and Tablets

Tight, light-resistant containers.127 139 a

Parenteral

Injection

2–8°C;137 do not freeze.137 a Protect from air and light.127 137 a

Actions

  • A fat-soluble vitamin required for human growth and bone development, vision, reproduction, and the integrity of mucosal and epithelial surfaces.133 137 a

  • Retinal combines with the rod pigment, opsin, in the retina to form rhodopsin, necessary for visual dark adaptation.137 a

  • Cofactor in various biochemical reactions including mucopolysaccharide synthesis, cholesterol synthesis, and hydroxysteroid metabolism.a

Advice to Patients

  • Advise women of child-bearing age to limit their intake of dietary sources (e.g., liver) containing high concentrations of vitamin A to avoid possible teratogenic effects.114 133 Inform these patients to choose fortified foods that contain vitamin A in the form of beta-carotene (e.g., fruits and vegetables) rather than preformed vitamin A.

  • Keep out of reach of children.137

  • Importance of proper dietary habits, including taking appropriate AI or RDA of vitamin A.137 a

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.137

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.137 a (See Fetal/Neonatal Morbidity and Mortality under Cautions.) Advise lactating women that their vitamin A requirements increase to ensure adequate concentration of the vitamin in milk.a

  • Importance of informing patients of other important precautionary information.137 (See Cautions.)

Preparations

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

Vitamin A also is commercially available in various dietary supplement preparations, as well as in combination with other vitamins, minerals, protein supplements, and infant formulas. Oral vitamin A capsules containing high strengths (e.g., 50,000 units) no longer are commercially available in the US; however, high-strength oral capsules and solutions may be available from various organizations (e.g., UNICEF, IDA) for treatment of deficiencies in developing countries.127

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

Vitamin A (as Retinol, Retinyl Palmitate, or Retinyl Acetate)

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Capsules

8,000 units (2400 RE)*

10,000 units (3000 RE)*

25,000 units (7500 RE)*

Capsules, water-miscible

10,000 units (3000 RE)*

Tablets

5,000 units (1500 RE)*

10,000 units (3000 RE)*

15,000 units (4500 RE)*

Parenteral

Injection

50,000 units (15,000 RE) per mL

Aquasol A (water-miscible)

Hospira

AHFS DI Essentials. © Copyright, 2004-2014, Selected Revisions January 22, 2014. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

References

Only references cited for selected revisions after 1984 are available electronically.

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127. WHO/UNICEF/IVACG Task Force. Vitamin A supplements: a guide to their use in the treatment and prevention of vitamin A deficiency and xerophthalmia (2nd edition.). Geneva: World Health Organization; 1997.

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137. Hospira. Aquasol A Parenteral (water-miscible vitamin A palmitate) prescribing information. Lake Forest, IL; 2007 Sep.

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a. AHFS Drug Information 2007. McEvoy GK, ed. Vitamin A. Bethesda, MD: American Society of Health-System Pharmacists; 2007.

e. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Otten JJ, Hellwig JP, Meyers LD, eds. Vitamin A. Washington, DC: National Academy Press; 2006: 170-81.

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