Vitamin E (vitamin E acetate)

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.

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.

No dosing information is available for this tab.

No dosing information is available for this tab.

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.

There are no contraindication interactions for this drug.

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

Vitamin E (Alpha Tocopherol) >=800 Unit/Slt Anticoag (Vit K)

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

MECHANISM OF ACTION: Vitamin E may decrease vitamin K-dependent clotting factors, resulting in additive effects with vitamin K antagonists.(1)

CLINICAL EFFECTS: Dose of vitamin E of 800 units/day or more may increase the pharmacologic effects of vitamin K antagonists.(1-7)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving vitamin E supplements of 800 units/day or more may require lower dosages of vitamin K antagonists. In patients maintained on warfarin who initiate vitamin E supplements in dosages of 800 units/day or more, measured INR one to two weeks after initiation of vitamin E and also every two to four weeks during the first two months.(2)

DISCUSSION: Vitamin E doses up to 400 units/day is believed not to affect the prothrombin time in patients concomitantly receiving warfarin.(2) Vitamin E doses of 800 International Units/day and more have been reported to increase the hypoprothrombinemic effect of warfarin. However, in a double blind clinical trial, with only 13 subjects completing the study, patients who had received chronic warfarin therapy with the addition of vitamin E dose as high as 1,200 IU/day for 1 month saw negligible change in the INR or prothrombin time.(3) Selumetinib capsules contain a significant amount of vitamin E. Each 10 mg capsule contains 32 mg (48 units) and each 25 mg capsule contains (54 units) of vitamin E. The daily dose of selumetinib may contain up to 256 mg (384 units) of vitamin E. Vitamin E supplementation is not recommended if it will result in a daily vitamin E intake exceeding recommended or safe amounts.(4) Agenerase brand of amprenavir capsules and oral solution contain a significant amount of vitamin E. Each 150 mg capsule contains 109 International Units vitamin E, with a total of 1,744 International Units of vitamin E in the recommended daily adult dose. Each mL of oral solution contains 46 International Units of vitamin E.(5) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.

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

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)

There is no enhanced messaging for this drug.

There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

• Increased risk of bleeding due to coagulation disorder
• Vitamin K deficiency induced hypoprothrombinemia

There is no enhanced messaging for this drug.

Rare or Very Rare

• Hemorrhage

Rare or Very Rare

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

No enhanced messaging available.

No enhanced messaging available.

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.)

No enhanced messaging available.

No enhanced messaging available.