Search
vitamin A
Dosage: RDA:
1) adults & children > 10 years: 5000 IU
2) children 7-10 years: 3300-3500 IU
3) children 4-6 years: 2500 IU
4) children 6 months-3 years: 1500-2000 IU
5) infants up to 6 months: 1500 IU
1 mg = 3333 units severe deficiency:
1) 100,000 IU/day for 3 days
2) followed by 50,000 IU daily for 2 weeks
3) then 10,000-20,000 IU daily for 2 months
Capsule: 25,000 units, 50,000 units
Pharmacokinetics:
- retinyl esters are storage forms of vitamin A
Adverse effects:
1) not common (1-10%)
-> irritability, vertigo, lethargy, malaise, fever, headache, drying or cracking of skin, hypercalcemia, weight loss, visual changes, hypervitaminosis
2) fracture
a) 2-fold increase risk of fractures in postmenopausal women not taking hormone replacement therapy with high intake of vitamin A
b) high serum levels of retinol (but not beta-carotene) associated with 1.6 fold increased risk of fracture in 50-75 year old men [4]
Drug interactions:
1) carbamazepine: increased clearance of carbamazepine
2) cholestyramine, mineral oil: decreased absorption of vit A
3) oral contraceptives: increased absorption of vit A
4) isotretinoin, etretinate: increased toxicity
5) vitamin A can antagonize the ability of vitamin D to enhance Ca+2 absorption [3]
Related
vitamin A deficiency (hyporetinemia)
Specific
alpha-carotene
beta-carotene
retinol; vitamin A1
General
vitamin
Properties
References
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Prescriber's Letter 9(2):8 2002
- Journal Watch 23(5):42, 2003
Micahaelsson K et al
Serum retinol levels and the risk of fracture.
N Engl J Med 348:287, 2003
PMID: 12540641
Lips P
Hypervitaminosis A and fractures.
N Engl J Med 348:347, 2003
PMID: 12540650
- Department of Veterans Affairs, VA National Formulary
Component-of
alpha tocopherol/ascorbate/biotin/biotin/cobalamin/ergocalciferol/folic acid/multivitamin/nicotinamide/panthenol/pyridoxine/riboflavin/thiamine/vitamin a/vitamin k
alpha tocopherol/ascorbate/biotin/cholecalciferol/cobalamin/folic acid/nicotinamide/panthenol/pyridoxine/riboflavin/thiamine/vitamin a/vitamin k
alpha tocopheryl acetate/ascorbate/cholecalciferol/cobalamin/nicotinamide/pyridoxine/riboflavin/thiamine/vitamin a
ascorbate/biotin/calcium carbonate/cobalamin/ferrous fumarate/folic acid/magnesium oxide/nicotinamide/pantothenate/pyridoxine/riboflavin/thiamine/vitamin a/vitamin e/zinc oxide
ascorbate/biotin/calcium carbonate/cobalamin/ferrous fumarate/folic acid/magnesium oxide/nicotinamide/pantothenate/pyridoxine/riboflavin/thiamine/vitamin a/vitamin e/zinc/zinc oxide
ascorbate/cholecalciferol/cobalamin/copper sulfate/ferrous fumarate/folic acid/kelp/magnesium oxide/magnesium sulfate/nicotinamide/pyridoxine/riboflavin/vitamin a/zinc sulfate
ascorbate/cholecalciferol/cobalamin/folic acid/magnesium oxide/nicotinic acid/polysaccharide iron complex/potassium iodide/pyridoxine/riboflavin/thiamine/vitamin a/vitamin e/zinc oxide
ascorbate/cholecalciferol/cobalamin/nicotinic acid/pyridoxine/riboflavin/sodium fluoride/thiamine/vitamin a/vitamin e
ascorbate/cholecalciferol/ferrous sulfate/sodium fluoride/vitamin a
ascorbate/cholecalciferol/sodium fluoride/vitamin a
ascorbate/cobalamin/folic acid/nicotinic acid/pyridoxine/riboflavin/sodium fluoride/thiamine/vitamin a/vitamin d/vitamin e
ascorbate/cobalamin/nicotinic acid/pyridoxine/riboflavin/thiamine/vitamin a/vitamin d/vitamin e
ascorbate/ferrous sulfate/nicotinic acid/pyridoxine/riboflavin/thiamine/vitamin a/vitamin d/vitamin e
ascorbate/ferrous sulfate/vitamin A
ascorbate/ferrous sulfate/vitamin A/vitamin D
ascorbate/vitamin a/vitamin d
cholecalciferol/vitamin a
ergocalciferol/vitamin a
kelp/vitamin a
vitamin a/vitamin d
vitamin a/vitamin e