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ALIMENTARY TRACT AND METABOLISM › VITAMINS › VITAMIN A AND D, INCL. COMBINATIONS OF THE TWO › Vitamin A, plain
retinol (vit A)
A11CA01
Forms & Strengths
- Oral capsules: 10,000 IU, 25,000 IU, 50,000 IU
- Oral drops: 5,000 IU/drop
- Injectable solution: 50,000 IU/mL
Adult Dosing
- Vitamin A deficiency with xerophthalmia: 500,000 IU PO daily for 3 days, then 50,000 IU daily for 2 weeks
- Dietary supplementation: 4,000 to 5,000 IU PO daily
- Measles treatment (WHO guideline): 200,000 IU PO once daily for 2 consecutive days
Pediatric Dosing
- Severe vitamin A deficiency with xerophthalmia (>1 year): 200,000 IU PO daily for 3 days, then 50,000 IU daily for 2 weeks
- Infants 6-11 months: 100,000 IU PO single dose
- Measles treatment (6 months-2 years): 200,000 IU PO daily for 2 days
Indications
- Treatment and prevention of vitamin A deficiency
- Adjunctive treatment of measles in pediatric patients in developing areas
- Management of xerophthalmia and keratomalacia
Mechanism of Action
- Essential for normal cellular growth and differentiation
- Critical for visual pigment formation (rhodopsin in retinal photoreceptors)
- Supports maintenance of epithelial tissue integrity and immune function
Contraindications
- Hypersensitivity to vitamin A or retinoids
- Hypervitaminosis A
- Pregnancy (high-dose systemic use due to teratogenicity)
Adverse Reactions
- Hypervitaminosis A (chronic): dry skin, alopecia, hepatotoxicity, intracranial hypertension, bone pain
- Acute toxicity: nausea, vomiting, dizziness, blurred vision
- Local irritation or erythema (topical formulations)
Drug Interactions
- Retinoids (isotretinoin, acitretin): additive toxicity and risk of hypervitaminosis A
- Anticoagulants (warfarin): high-dose vitamin A may impair clotting factor synthesis, increasing bleeding risk
- Tetracyclines: co-administration increases risk of pseudotumor cerebri (benign intracranial hypertension)
Curated Content: Needs Vetting Before Put to Clinical Use