vitamin A
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Dosage
RDA:
- adults & children > 10 years: 5000 IU
- children 7-10 years: 3300-3500 IU
- children 4-6 years: 2500 IU
- children 6 months-3 years: 1500-2000 IU
- infants up to 6 months: 1500 IU
1 mg = 3333 units severe deficiency:
- 100,000 IU/day for 3 days
- followed by 50,000 IU daily for 2 weeks
- 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
- not common (1-10%)
- irritability, vertigo, lethargy, malaise, fever, headache, drying or cracking of skin, hypercalcemia, weight loss, visual changes, hypervitaminosis
- fracture
- 2-fold increase risk of fractures in postmenopausal women not taking hormone replacement therapy with high intake of vitamin A
- 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
- carbamazepine: increased clearance of carbamazepine
- cholestyramine, mineral oil: decreased absorption of vit A
- oral contraceptives: increased absorption of vit A
- isotretinoin, etretinate: increased toxicity
- vitamin A can antagonize the ability of vitamin D to enhance Ca+2 absorption[3]
More general terms
More specific terms
Additional terms
Component of
- phosphatidylcholine/vitamin a/vitamin e
- ascorbate/cholecalciferol/vitamin a
- ascorbate/cholecalciferol/palmitate/sodium fluoride/vitamin a
- ascorbate/cholecalciferol/ferrous sulfate/palmitate/sodium fluoride/vitamin a
- ascorbate/cholecalciferol/ferrous sulfate/nicotinic acid/pyridoxine/riboflavin/thiamine/vitamin a/vitamin e
- ascorbate/cholecalciferol/cobalamin/nicotinic acid/pyridoxine/riboflavin/thiamine/vitamin a/vitamin e
- ascorbate/cholecalciferol/cobalamin/folic acid/nicotinic acid/pyridoxine/riboflavin/sodium fluoride/thiamine/vitamin a/vitamin e
- alpha tocopherol/cholecalciferol/vitamin a
- alpha tocopherol/ascorbate/biotin/cobalamin/ergocalciferol/folic acid/multivitamin/nicotinamide/panthenol/phytonadione/pyridoxine/riboflavin/thiamine/vitamin a
- alpha tocopherol/ascorbate/biotin/cholecalciferol/cobalamin/folic acid/nicotinamide/palmitate/panthenol/phytonadione/pyridoxine/riboflavin/thiamine/vitamin a
- vitamin a/vitamin e
- kelp/vitamin a
- ergocalciferol/vitamin a
- cholecalciferol/vitamin a
- ascorbate/cobalamin/folic acid/nicotinic acid/pyridoxine/riboflavin/sodium fluoride/thiamine/vitamin a/vitamin d/vitamin e
- ascorbate/cholecalciferol/ferrous sulfate/sodium fluoride/vitamin a
- ascorbate/cholecalciferol/cobalamin/nicotinic acid/pyridoxine/riboflavin/sodium fluoride/thiamine/vitamin a/vitamin e
- 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/copper sulfate/ferrous fumarate/folic acid/kelp/magnesium oxide/magnesium sulfate/nicotinamide/pyridoxine/riboflavin/vitamin a/zinc sulfate
- 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
- alpha tocopheryl acetate/ascorbate/cholecalciferol/cobalamin/nicotinamide/pyridoxine/riboflavin/thiamine/vitamin a
- alpha tocopherol/ascorbate/biotin/cholecalciferol/cobalamin/folic acid/nicotinamide/panthenol/pyridoxine/riboflavin/thiamine/vitamin a/vitamin k
- alpha tocopherol/ascorbate/biotin/biotin/cobalamin/ergocalciferol/folic acid/multivitamin/nicotinamide/panthenol/pyridoxine/riboflavin/thiamine/vitamin a/vitamin k
- ascorbate/cholecalciferol/sodium fluoride/vitamin a
- vitamin a/vitamin d
- ascorbate/vitamin a/vitamin d
- ascorbate/cobalamin/nicotinic acid/pyridoxine/riboflavin/thiamine/vitamin a/vitamin d/vitamin e
- ascorbate/ferrous sulfate/vitamin A/vitamin D
- ascorbate/ferrous sulfate/vitamin A
- ascorbate/ferrous sulfate/nicotinic acid/pyridoxine/riboflavin/thiamine/vitamin a/vitamin d/vitamin e
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
- ↑ 3.0 3.1 Prescriber's Letter 9(2):8 2002
- ↑ 4.0 4.1 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: https://www.ncbi.nlm.nih.gov/pubmed/12540641 Lips P Hypervitaminosis A and fractures. N Engl J Med 348:347, 2003 PMID: https://www.ncbi.nlm.nih.gov/pubmed/12540650
- ↑ Department of Veterans Affairs, VA National Formulary