Antioxidant Formula (beta-carotene/ascorbic acid/vitE ac/selenium yeast)

Vitamin E activity is generally expressed in USP or International Units which are equivalent; the International Unit of vitamin E is no longer officially recognized but continues to be used in the labeling of some preparations. It should be noted that vitamin E preparations are historically and incorrectly labeled as d- or dl-alpha-tocopherol and their respective esters. Vitamin E compounds include the all racemic (all rac)-alpha-tocopherol (dl-alpha-tocopherol (RRR-, RRS-, RSR-, RSS-, SSS-, SRS-, SSR-, and SRR-) or synthetic) form and its esters and the RRR-alpha-tocopherol (d-alpha-tocopherol or natural) form and its esters, and any of these compounds may be present in fortified foods and vitamin preparations.

One unit of vitamin E equals the biologic activity of 1 mg of all rac-alpha-tocopheryl acetate (dl-alpha-tocopheryl acetate), 1.12 mg of all rac-alpha-tocopheryl succinate (dl-alpha-tocopheryl acid succinate), 910 mcg of all rac-alpha-tocopherol (dl-alpha-tocopherol), 735 mcg of RRR-alpha-tocopheryl acetate (d-alpha-tocopheryl acetate), 830 mcg of RRR-alpha-tocopheryl succinate (d-alpha-tocopheryl acid succinate), and 670 mcg of RRR-alpha-tocopherol (d-alpha-tocopherol). However, because the USP potency unit for vitamin E was defined before studies showed a lack of human activity for the 2S-stereoisomers, the National Academy of Sciences (NAS) Food and Nutrition Board recommended in 2000 that the current equivalency defined in the USP standard be redefined based on the R-stereoisomeric forms of alpha-tocopherol, which are the forms that are active in humans. According to the NAS definition, each USP unit of vitamin E is equivalent to the biologic activity of 450 mcg of the synthetic all rac-alpha-forms of tocopherol and its esters or 670 mcg of the RRR-alpha-forms of tocopherol and its esters.

To avoid toxicity, dietary intake of vitamin A should be estimated and considered when determining the dosage of the vitamin. Vitamin A activity is expressed in terms of the equivalent amount of retinol (i.e., as retinol equivalents (RE) or retinol activity equivalents (RAE)) and is expressed also in USP units or International Units (IU, units). USP units and International Units are equivalent. One USP vitamin A unit is the specific biologic activity of 0.3 mcg of all-trans-retinol; one retinol equivalent (RE) is the specific biologic activity of 1 mcg of all-trans-retinol; one retinol activity equivalent (RAE) is equal to 1 mcg of all-trans-retinol, 12 mcg of all trans-beta-carotene, or 24 mcg of other provitamin A carotenoids. The use of 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.

Ascorbic acid is usually administered orally. When oral administration is not feasible or when malabsorption is suspected, the drug may be administered IM, IV, or subcutaneously. When given parenterally, utilization of the vitamin reportedly is best after IM administration and that is the preferred parenteral route.

Vitamin E is usually administered orally. When oral administration is not feasible or when malabsorption is suspected, the drug may be given parenterally as a component of a multivitamin injection. Some clinicians use water-miscible oral vitamin E preparations in patients with malabsorption syndromes.

Vitamin A usually is administered orally. 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., United Nations Children's Fund (UNICEF), the International Dispensary Association (IDA)) for treatment of deficiencies in developing countries. When oral administration is not feasible or when malabsorption is present, the drug may be given IM.

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Concurrent administration of more than 200 mg of ascorbic acid per 30 mg of elemental iron increases absorption of iron from the GI tract; however, most individuals are able to absorb orally ingested iron adequately without concurrent administration of ascorbic acid.

Increased urinary excretion of ascorbic acid and decreased excretion of aspirin occur when the drugs are administered concurrently.

Salicylates inhibit uptake of ascorbic acid by leukocytes and platelets. As a result, leukocyte and plasma concentrations of ascorbic acid are decreased to concentrations slightly higher than those associated with tissue depletion of the vitamin; however, there is no evidence to date that salicylate therapy precipitates ascorbic acid deficiency. Although concomitant administration of ascorbic acid supplements in patients receiving salicylates increases plasma ascorbic acid concentrations, leukocyte ascorbic acid concentrations are not increased and tissue stores of the vitamin may not be increased. Therefore, routine administration of ascorbic acid supplements to patients receiving salicylates is not warranted; however, patients receiving high dosages of salicylates who exhibit any signs or symptoms of ascorbic acid deficiency should be evaluated for such a deficiency.

Ascorbic acid has reportedly decreased the anticoagulant effect of warfarin; however, other investigators have failed to show this effect. Concurrent administration of ascorbic acid and fluphenazine reportedly resulted in decreased fluphenazine plasma concentration. Acidification of the urine following administration of ascorbic acid may result in altered excretion of other drugs.

Vitamin E may increase the absorption, utilization, and storage of vitamin A and may protect against hypervitaminosis A; however, these effects are controversial.

Vitamin E in dosages of greater than 10 units/kg daily may delay the response to iron therapy in children with iron-deficiency anemia, and low-birthweight infants treated with iron supplements may develop vitamin E-deficiency hemolytic anemia.

Vitamin E or one of its metabolites reportedly may have anti-vitamin K effects; patients receiving oral anticoagulants may be at risk of hemorrhage after large doses of vitamin E. In normal healthy individuals, vitamin E caused no change in blood clotting.

Excessive use of mineral oil may decrease the absorption of vitamin E.

Orlistat may result in decreased GI absorption of fat-soluble vitamins such as vitamin E. At least 2 hours should elapse between (before or after) any orlistat dose and vitamin E administration; administering fat-soluble vitamins at bedtime may be a convenient time. Although the manufacturer of orlistat recommends that a vitamin supplement containing fat-soluble vitamins (A, D, E and K) be used during orlistat therapy, such vitamin concentrations in clinical studies with the drug remained within the normal range for most patients despite decreases, and vitamin supplementation was only occasionally needed.

Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

Vitamin A/Selected Retinoids

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: The retinoids are structurally related to vitamin A. (1-6)

CLINICAL EFFECTS: Concurrent use of retinoids with vitamin A supplements may result in signs of vitamin A toxicity.(1-6) Symptoms of vitamin A toxicity include nausea, vomiting, loss of appetite, weakness, dry or itchy skin or lips, irritability, and hair loss.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of acitretin states that concomitant use of vitamin A supplements should be avoided.(1) The manufacturer of bexarotene states that patients should be advised to limit vitamin A supplements. In clinical studies, patients were advised to limit their vitamin A intake to less than or equal to 15,000 International Units/day.(2) The manufacturer of isotretinoin states that patients should be advised against taking vitamin A supplements.(3) The manufacturer of palovarotene states that concomitant use of vitamin A must be avoided.(4) The manufacturer of tretinoin states that tretinoin must not be administered in combination with vitamin A.(5) The UK manufacturer of alitretinoin states that tretinoin must not be administered in combination with vitamin A.(6)

DISCUSSION: The retinoids are structurally related to vitamin A. The concurrent use of retinoids with vitamin A may result in signs and symptoms of vitamin A toxicity.(1-6)

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Ascorbic Acid (Vitamin C)/Bortezomib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Vitamin C can form a complex with the boronic acid moiety of the bortezomib molecule, preventing its absorption into cells.(1-4) This may protect normal tissue in the body, which may have higher levels of Vitamin C.(5)

CLINICAL EFFECTS: Concurrent administration of Vitamin C may result in decreased bortezomib activity.(1-4)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Instruct patients receiving bortezomib therapy not to begin taking vitamin C supplements without consulting their oncologist first. Patients who are instructed to take vitamin C should follow their oncologist's instructions on how to separate dosages and should be carefully monitored for bortezomib efficacy.

DISCUSSION: An in vitro study with human plasma and multiple myeloma cells found that high levels of vitamin C (following 1 gram/day of ascorbic acid for 4 days) decreased bortezomib effectiveness by 26%. An in vivo study in mice found that vitamin C administration with bortezomib completely blocked the response of bortezomib.(6) An in vitro study in rat Schwann cells and myeloma cells(4) and an in vivo study in mice(7) found that delayed administration of vitamin C had no effect on bortezomib effects. In an in vivo study in multiple myeloma patients, concurrent ascorbic acid, arsenic trioxide, bortezomib, and high-dose melphalan in which ascorbic acid was administered close to bortezomib, the combination was safe and well tolerated, but produced no changes in response rates.(8) In another in vivo study in multiple myeloma patients, a regimen of ascorbic acid, bortezomib, and melphalan in which bortezomib was administered in the morning and ascorbic acid in the evening was found to be safe and efficacious, with 74% of patients responding to therapy.(9)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Ascorbic Acid (Vitamin C)/Deferoxamine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: It is believed that ascorbic acid increases the iron available for chelation from an labile intracellular iron pool. Ascorbic acid may then facilitate iron-induced oxidative tissue damage.(1)

CLINICAL EFFECTS: Dietary ascorbic acid may increase the absorption of dietary iron. Supplemental ascorbic acid therapy given during chelation therapy may improve iron output;(1-9) however, excessive dosages may result in cardiac toxicity from iron-induced oxidative tissue damage.(1,2,11-13)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Ascorbic acid intake is often restricted in patients with iron overload; however, it has been used in conjunction with deferoxamine to increase iron excretion.(2) Supplemental ascorbic acid therapy should only be initiated after one month of deferoxamine therapy. Ascorbic acid therapy should only be given in patients receiving deferoxamine regularly and the dose should be given after the infusion has started. The dosage of ascorbic acid should be limited to 50 mg daily in children under 10 years of age; 100 mg daily in older children; and 200 mg daily, in divided doses, in adults.(2) Cardiac function should be monitored in patients receiving concurrent therapy. Discontinue ascorbic acid therapy in patients who develop cardiac dysfunction.(2)

DISCUSSION: Supplemental ascorbic acid therapy given during chelation therapy has been shown to improve iron output,(1-9) possibly by increasing iron available for chelation from an labile intracellular iron pool.(1) However, dosages in excess of 500 mg daily have been associated with cardiac dysfunction.(1,2,11-13)

Fat Soluble Vitamins/Colesevelam

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Colesevelam may decrease the absorption of fat-soluble vitamins A, D, E, and K.(1)

CLINICAL EFFECTS: Colesevelam may reduce absorption of fat soluble vitamins, leading to a deficiency state.

PREDISPOSING FACTORS: A pre-existing deficiency of fat soluble vitamins (A,D,E and K) or chronic malabsorption syndrome.

PATIENT MANAGEMENT: The inhibition of fat soluble vitamin absorption by colesevelam should be borne in mind during implementation of a vitamin supplementation strategy. Oral multivitamin supplements should be taken at least four hours before the dose of colesevelam.(1)

DISCUSSION: Colesevelam may decrease the absorption of fat-soluble vitamins A, D, E, and K.(1)

Fat Soluble Vitamins/Orlistat

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: The acetate ester forms of vitamin A and vitamin E must undergo hydrolysis for absorption from the gastrointestinal tract.(1) The enzyme responsible for this hydrolysis is inhibited by orlistat.(2)

CLINICAL EFFECTS: Orlistat may reduce absorption of fat soluble vitamins, leading to a deficiency state.

PREDISPOSING FACTORS: A pre-existing deficiency of fat soluble vitamins (A,D,E and K) or chronic malabsorption syndrome.

PATIENT MANAGEMENT: The inhibition of fat soluble vitamin absorption by orlistat should be borne in mind during implementation of a vitamin supplementation strategy. Patients should be strongly encouraged to take a multivitamin supplement which contains fat soluble vitamins, particularly Vitamin D as it appears most susceptible to this interaction.(4,5) Multivitamin supplements should be taken at least two hours before or after the dose of orlistat, or at bedtime.(4) Patients with chronic malabsorption syndromes should not receive orlistat.(4)

DISCUSSION: Adult patients taking orlistat without supplementation showed a greater reduction in vitamin A,D,E and beta-carotene levels compared to placebo during two or more consecutive visits in studies of 1-2 years duration; these patients had normal baseline values prior to orlistat therapy. Low vitamin values in orlistat patients were as follows: low Vitamin D 12%, low beta-carotene 6.1%, low Vitamin E 5.8%, low Vitamin A 2.2%.(4) A pharmacokinetic interaction study showed a 30% reduction in beta-carotene supplement absorption and a 60% decreased in vitamin E acetate absorption with concomitant orlistat.(4) In a study, orlistat produced the vitamin net concentration by approximately 43%.(1) In a study, no statistically significant decrease in vitamin A absorption was observed with concurrent orlistat.(2) In a study, mean vitamin D levels were significantly reduced compared with baseline after one month of orlistat therapy despite multivitamin supplementation.(5)

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• Hypervitaminosis A

• Pregnancy

• Disease of liver
• Increased risk of bleeding due to coagulation disorder
• Malabsorption states
• Vitamin K deficiency induced hypoprothrombinemia

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Rare or Very Rare

• Hemorrhage

More Frequent

• Carotenodermia

Rare or Very Rare

• Abdominal pain with cramps
• Arthralgia
• Blurred vision
• Diarrhea
• Diarrhea
• Dizziness
• Ecchymosis
• Fatigue
• General weakness
• Headache disorder
• Mastalgia
• Nausea
• Skin rash
• Thrombophlebitis

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Vitamin E has not been shown to be teratogenic. There is no evidence that vitamin E requirements in pregnant women differ from women who are not pregnant. (See Dosage: Dietary and Replacement Requirements, under Dosage and Administration.)

Vitamin A is teratogenic in animals; malformations of the CNS, eye, palate, and urogenital tract have been described in several species. Adequate and well-controlled studies in humans are not available. A limited number of reports of human fetal malformations (e.g., cranial neural crest defects) following maternal ingestion of large dosages of vitamin A (10,000 units or more daily) during or both before and during pregnancy suggest potential teratogenicity, at least at high dosages. The use of vitamin A in excess of the US RDA generally is contraindicated in women who are or may become pregnant. (See Dietary and Replacement Requirements in Dosage and Administration: Dosage.)If vitamin A is used during pregnancy or if the patient becomes pregnant while receiving the drug, the patient should be apprised of the potential fetal hazard. It also has been suggested that women of reproductive age should limit their intake of dietary sources (e.g., liver) containing high concentrations of vitamin A; beta-carotene, a precursor of vitamin A, has not been shown to be teratogenic and may be considered as a source of vitamin A supplementation in such women. Dosages exceeding the RDA may be necessary in women of childbearing age with vitamin A deficiency. There is some evidence suggesting that dosages up to 10,000 units daily or up to 25,000 units weekly may be used safely in women of childbearing age (13-49 years of age), and such dosages are recommended in those with active xerophthalmia. Even higher dosages may be necessary if active corneal lesions are present. (See Vitamin A Deficiency under Dosage and Administration: Dosage.)

Vitamin A is distributed into milk. Unless the maternal diet is inadequate, infants can usually obtain sufficient vitamin A from nursing, at least for the first 6 months of life. The effect of large maternal dosages of vitamin A on nursing infants is not known.

For information on the currently recommended RDAs of vitamin A for pregnant and lactating women, see Dietary and Replacement Requirements, under Dosage and Administration: Dosage.

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