Drug-Nutrient Interactions PDF

1  Interactions usually occur due to  Continuous use of prescription medications  Drugs that form part of the food chain ○ Naturally present as contaminants (few) ○ Introduction (majority)  Drugs introduced to food chain:  Pesticides  Hormones and antibiotics for livestock...

1  Interactions usually occur due to  Continuous use of prescription medications  Drugs that form part of the food chain ○ Naturally present as contaminants (few) ○ Introduction (majority)  Drugs introduced to food chain:  Pesticides  Hormones and antibiotics for livestock production  Serious in developing countries due to lack of efficient control systems 2 Some effects of contaminants  Residues in agricultural products  Metabolites can persist and still be found in the human diet  E.g. estrogen metabolites, suggested to be carcinogenic Development Increased Antibiotic of resistant risk of contaminants strains infection 3  Interaction between non-nutritional chemicals and nutrients is bi-directional  Interactions can lead to malnutrition  Deficient nutritional status enhances toxicity of contaminants e.g. pesticides  May reduce efficacy of prescribed drugs, increase possible adverse side effects  Interactions occur at various levels in humans 4  Any condition that impairs drug metabolism and clearance enhances the possibility of a drug-nutrient interaction  Liver diseases  Kidney diseases  PEM patients may have problems with detoxification following drug administration  Lack of enzymes 5 Elderly Persons at Higher Risk  Likely to be taking more drugs for longer periods to control chronic diseases  Bodies have less capability to handle drugs efficiently – wear and tear of tissues with age  Nutritional status more likely to be deficient  Inappropriate application of medications likely to occur, especially in the absence of adequate care  Mental confusion, illness 6 7  Intake Effect of drugs on nutrition Absorption Metabolism 8 1. Increasing appetite  Antihistamines:  E.g. Periactin, a serotonin antagonist can cause sharp increase in appetite  Psychotropic drugs:  E.g. Valium, Elavil (anti-depressant)  Steroids:  E.g. testosterone, glucocortinoids 9 2. Decreasing appetite  Amphetamine  Stimulants of CNS for treating attention deficit hyperactivity disorder  Depresses desire to eat  Insulin  Insulin-induced drop in blood sugar level may cause nausea and aversion to food 10 3. Taste changes  D-penicillamine  Chelating agent for treating heavy metal poisoning Binds to Zinc Loss of Zinc deficiency taste  Other groups of drugs that induce taste loss  Anti-cancer drugs e.g. methotrexate  Drugs for treating Parkinson’s disease 11  4. Nausea  E.g. drugs for treating/managing cancer  5. Bulking effect  Bulking agents e.g. methyl cellulose (laxative) can create sense of fullness and decrease desire for food 12 13 1. Increasing absorption  Use of some drugs increase the absorption of some nutrients in the body  E.g. Cimetidine (Tagamet, for ulcer) increases CHO and protein absorption 14 2. Decreasing absorption  Usually achieved using two pathways  By decreasing availability in intestinal lumen ○ E.g. bulking agents bind to nutrients and interferes with absorption  By inhibiting transport across intestines ○ E.g. drugs that inhibit protein synthesis  Interactions are observed mostly when the drug and nutrient are taken concurrently 15  Drugs that cause malabsorption of nutrients Drug Use Action Nutrients affected Cholestyramine Control of Binding agent for bile Fat, fat-soluble cholesterol level salts vitamins Methyldopa Anti-hypertensive Unclear B12, folic acid, iron, agent Mineral oil Laxative Nutrients dissolve in Fat-soluble vitamins oil and are lost in feces Neomycin Antibiotic Binds bile salts, Fat-soluble lowers pancreatic vitamins, lactose, lipase Na, K, iron, Ca Para- Anti-TB agent Blocks mucosal B12 aminosalicyclic acid uptake of B12 Phenolphthalein Laxative Rapid intestinal Ca, K, vitamin D transit Potassium chloride Potassium Lowers ileal pH B12 replacement Azulfidine Anti-inflammatory Blocks mucosal Folic acid uptake of folic acid 16 3. Mineral depletion  Intake of some drugs lead to depletion of certain minerals  Induced GIT losses  Increased renal excretion  Diuretics  Used to reduce water and sodium levels  May also result in loss of potassium, magnesium and Zinc  Antacids produce phosphate deficiency  Aluminium-containing ones reduce phosphate absorption  Magnesium depletion associated 17 4. Vitamin antagonists  Some drugs have therapeutic effect due to their antagonistic interactions with certain vitamins Target vitamin Drugs Vitamin K Coumarin anticoagulants Folic acid Methotrexate Pyrimethamine Trimethoprim Vitamin B6 Cycloserine Isoniazide Levodopa 18 19 Examples  Dietary protein may compete with drugs that are amino acid derivatives  Dietary amino acids may compete with some drugs in entering the brain at the blood-brain barrier  Absorption of tetracycline is impaired when taken with milk  Presence of fat in diet increases activity of valium  Citrus juices increase absorption of Nifedipine (anti-hypertensive drug) 20 Examples  Food components that affect GIT transit time influence absorption and bacterial metabolism of some drugs  Drug metabolizing enzymes can be influenced by food components that are favorable substrates  E.g. indoles in cabbage and cytochrome P450 enzymes 21 Nutrients  Drugs 22