Pharmacologic Class: Retinoid
ACTIONS AND USES: Vitamin A is essential for general growth and development, particularly of the bones, teeth, and epithelial membranes. It is necessary for proper wound healing, is essential for the biosynthesis of steroids, and is one of the pigments required for night vision. Wound healing
Vitamin A is indicated in deficiency states and during periods of increased need such as pregnancy, lactation, or undernutrition. Night blindness and slow wound healing can be effectively treated with as little as 30,000 units of vitamin A given daily over a week. It is also prescribed for GI disorders, when absorption in the small intestine is diminished or absent. Topical forms are available for acne, psoriasis, and other skin disorders. Doses of vitamin A are sometimes measured in retinoid equivalents (RE). In severe deficiency states, up to 500,000 units may be given per day for 3 days, gradually tapering off to 10,000–20,000 units/day.
ADMINISTRATION ALERTS: Pregnancy category A, at low doses. Pregnancy category X, at doses above the RDA. [Read about drug use in relation to pregnancy]
ADVERSE EFFECTS: Adverse effects are not observed with normal doses of vitamin A. Acute ingestion, however, produces serious central nervous system (CNS) toxicity, including headache, irritability, drowsiness, delirium, and possible coma. Long-term ingestion of high amounts causes drying and scaling of the skin, alopecia, fatigue, anorexia, vomiting, and leukopenia.
CONTRAINDICATIONS: Vitamin A in excess of the RDA is contraindicated in pregnant patients, or those who may become pregnant. Fetal harm may result.
INTERACTIONS: Drug–Drug: People who are taking vitamin A should avoid taking mineral oil and cholestyramine, because both may decrease the absorption of vitamin A. Concurrent use with isoretinoin may result in additive toxicity.
LAB TESTS: Vitamin A may increase serum calcium, serum cholesterol, and blood urea nitrogen (BUN).
RELATED;
1. VITAMIN C
2. BIOMOLECULES
4. BIOCHEMISTRY
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