fjrigjwwe9r0Board:Content
(1) Drug-Nutrient Interactions
¨Í Drug-Vitamin Interaction
¨Î Drug-Mineral Interaction
¨Ï Test your NDI knowledge level
¨Ð Incidence of ADRs in Hospitalized Patients
(2) Antioxidant vitamins & nuclear opacities (3) Nutrition Abstracts
(4) Aeterna Liquid Extracts
Drug- Vitamin Interactions
Poor vitamin absorption is a common problem with drug adminis-tration. The effectiveness of vitamins ingested not only from supplements, but also from food, can often be deterred by drug ingestion.
One of the most common DNIs occurs with the frequent prescription of antibiotics and the way they can affect the bioavailability of the fat-soluble vitamins (A, D, E, K). Cholestyramine, a drug that is classified as a bile acid sequestrate, can retard the absorption of vitamins A, D and K and bind essential fatty acids as well. Other interactions between drugs and fat-soluble vitamins include:
Vitamin A, Beta-Carotene
- Neomycin can retard absorption.
- Ethanol can cause hepatotoxicity resulting in hypervitaminosis A.
- Tetracycline may cause hypertension.
Vitamin D
- Cathartics can retard absorption of vitamin D.
- Glutethimide produces vitamin D deficiency.
Vitamin E
- Dicumarol enhances anticoagulant action.
- Digoxin causes hypercalcemia and arrythmias.
Vitamin K
- Anticonvulsants induce enzymatic inactivation.
- Dicumarol inhibits hypoprothrombin action.
Water-soluble vitamins may also be depleted by medication use. Sometimes it is recommended to ingest the nutrients two hours apart from the prescribed medication to avoid any interaction. However, this rule of thumb may depend on the drug.
Vitamin B 12
- Colchicine impairs B 12 absorption.
Vitamin B 6
- Oral contraceptives, Hydralazine, Isoniazid and Penicillamine increase the requirement for B 6.
Folate
- Aspirin competes with folate for serum protein binding.
- Barbiturates cause malabsorption.
- Primadone interferes with folate metabolism.
- Oral contraceptives cause malabsorption of polyglutamate.
- Cycloserine is secondary to vitamin B6 antagonism.
- Methotrexate inhibits dihydrofolate reductase.
Vitamin C
- Salicylates decrease uptake of vitamin C.
- Tetracyclines deplete vitamin C.
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