1. Food-Drug Interactions Chapter 19

2. © 2004, 2002 Elsevier Inc. All rights reserved. Key Terms n Bioavailability: degree to which a drug or other substance reaches the circulation and becomes available to the target organ or tissue n Drug-nutrient interactions: the results of the action between a drug and a nutrient that would not happen with the nutrient or drug alone n Bioavailability: degree to which a drug or other substance reaches the circulation and becomes available to the target organ or tissue n Drug-nutrient interactions: the results of the action between a drug and a nutrient that would not happen with the nutrient or drug alone

3. © 2004, 2002 Elsevier Inc. All rights reserved. Key Terms—cont’d n Half-life: amount of time it takes for the blood concentration of a drug to decrease by one half of its steady state level n Side effect: adverse effect/reaction or any undesirable effect of a drug n Half-life: amount of time it takes for the blood concentration of a drug to decrease by one half of its steady state level n Side effect: adverse effect/reaction or any undesirable effect of a drug

4. © 2004, 2002 Elsevier Inc. All rights reserved. Pharmacology Terms Stages of Drug Action n Pharmacokinetics: movement of a drug through the body by absorption, distribution, metabolism, and excretion n Pharmacodynamics: physiologic and biochemical effects of a drug or combination of drugs Stages of Drug Action n Pharmacokinetics: movement of a drug through the body by absorption, distribution, metabolism, and excretion n Pharmacodynamics: physiologic and biochemical effects of a drug or combination of drugs

5. © 2004, 2002 Elsevier Inc. All rights reserved. Pharmacology Terms—cont’d n Pharmacogenomics: genetically determined variations that are revealed solely by the effects of drugs

6. © 2004, 2002 Elsevier Inc. All rights reserved. Therapeutic Importance n Therapeutically important interactions are those that: —Alter the intended response to the medication —Cause drug toxicity —Alter normal nutritional status n Therapeutically important interactions are those that: —Alter the intended response to the medication —Cause drug toxicity —Alter normal nutritional status

7. © 2004, 2002 Elsevier Inc. All rights reserved. Other Terms n Bioavailability: % free to function n Absorption rate: % absorbed and time for absorption n Transported: amount in blood (free or bound) n Metabolized: altered by enzymes in tissues n Mixed-function oxidase system (MFOS): enzyme system that metabolizes drugs, carcinogens, compounds in foods, etc. n Bioavailability: % free to function n Absorption rate: % absorbed and time for absorption n Transported: amount in blood (free or bound) n Metabolized: altered by enzymes in tissues n Mixed-function oxidase system (MFOS): enzyme system that metabolizes drugs, carcinogens, compounds in foods, etc.

8. © 2004, 2002 Elsevier Inc. All rights reserved. Patients at Risk for Food-Nutrient Interactions n Patient with chronic disease n Elderly n Fetus n Infant n Pregnant woman n Malnourished patient n Patient with chronic disease n Elderly n Fetus n Infant n Pregnant woman n Malnourished patient

9. © 2004, 2002 Elsevier Inc. All rights reserved. Drug Effects on Nutrition n Decreased or increased intake —Appetite —Taste —Nausea —Dry mouth n Alter metabolism —Anti-vitamins —Monoamine oxidase inhibitors n Decreased or increased intake —Appetite —Taste —Nausea —Dry mouth n Alter metabolism —Anti-vitamins —Monoamine oxidase inhibitors

10. © 2004, 2002 Elsevier Inc. All rights reserved. Drug Effects on Nutrition—cont’d n Change absorption —GI pH —Transit time or motility —Bile acid secretion or activity —Drug-nutrient complexes —Muscosal damage n Change excretion n Change absorption —GI pH —Transit time or motility —Bile acid secretion or activity —Drug-nutrient complexes —Muscosal damage n Change excretion

11. © 2004, 2002 Elsevier Inc. All rights reserved. Nutrient Effects on Drugs n Absorption —Note if drug is taken with or without food —Note which foods to avoid n Metabolism —Changes in diet may alter drug action —Malnutrition alters albumin level (blood binding) and MFOS enzyme activity level n Absorption —Note if drug is taken with or without food —Note which foods to avoid n Metabolism —Changes in diet may alter drug action —Malnutrition alters albumin level (blood binding) and MFOS enzyme activity level

12. © 2004, 2002 Elsevier Inc. All rights reserved. Nutrient Effects on Drugs—cont’d n Excretion —Fluid status —Urinary pH n Excretion —Fluid status —Urinary pH

13. © 2004, 2002 Elsevier Inc. All rights reserved. Important Interactions n Oral contraceptives —Folate n Antihypertensives —Ca —K —Mg n MAOIs —Tyramine in foods n Oral contraceptives —Folate n Antihypertensives —Ca —K —Mg n MAOIs —Tyramine in foods

14. © 2004, 2002 Elsevier Inc. All rights reserved. Key Information 1. Physician’s Desk Reference – food and drug interactions—there are other drug indexes 2. Generic or chemical name differs from brand name 3. Drugs are classified by action, manufacturer, class, brand name, and generic name 4. Over-the-counter drugs may be bought without prescription 1. Physician’s Desk Reference – food and drug interactions—there are other drug indexes 2. Generic or chemical name differs from brand name 3. Drugs are classified by action, manufacturer, class, brand name, and generic name 4. Over-the-counter drugs may be bought without prescription

15. © 2004, 2002 Elsevier Inc. All rights reserved. Examples of Drug Categories That May Cause Loss of Appetite n Antiinfectives n Antineoplastics n Bronchodilators n Cardiovascular drugs n Stimulants n Antiinfectives n Antineoplastics n Bronchodilators n Cardiovascular drugs n Stimulants

16. © 2004, 2002 Elsevier Inc. All rights reserved. Examples of Drug Classes That Cause Diarrhea n Laxatives n Antiretrovirals n Antibiotics n Antineoplastics n Laxatives n Antiretrovirals n Antibiotics n Antineoplastics

17. © 2004, 2002 Elsevier Inc. All rights reserved. Drugs That May Increase Appetite n Anticonvulsants n Hormones n Psychotropic drugs —Antipsychotics —Antidepressants, tricyclics, MAOIs n Anticonvulsants n Hormones n Psychotropic drugs —Antipsychotics —Antidepressants, tricyclics, MAOIs

18. © 2004, 2002 Elsevier Inc. All rights reserved. Drugs That May Affect Glucose Levels n Antidiabetic drugs n Drugs that can cause hypoglycemia n Antiretrovirals, protease inhibitors n Diuretics, antihypertensives n Hormones n Antidiabetic drugs n Drugs that can cause hypoglycemia n Antiretrovirals, protease inhibitors n Diuretics, antihypertensives n Hormones

19. © 2004, 2002 Elsevier Inc. All rights reserved. Medical Nutrition Therapy for Food-Drug Interactions n Prospective: all MNT offered when the patient first starts a drug n Retrospective: evaluation of symptoms to determine if medical problems might be the result of food-drug interactions n Prospective: all MNT offered when the patient first starts a drug n Retrospective: evaluation of symptoms to determine if medical problems might be the result of food-drug interactions

20. © 2004, 2002 Elsevier Inc. All rights reserved. Enteral Nutrition and Drugs n Drugs put in feeding tubes may cause: —Diarrhea —Drug-nutrient binding —Blocked tube n Avoid adding drug to formula n When drugs must be given through tube: —Stop feeding, flush tube, give drug, flush —Use liquid form of drug —Avoid crushing tablets n Drugs put in feeding tubes may cause: —Diarrhea —Drug-nutrient binding —Blocked tube n Avoid adding drug to formula n When drugs must be given through tube: —Stop feeding, flush tube, give drug, flush —Use liquid form of drug —Avoid crushing tablets

21. © 2004, 2002 Elsevier Inc. All rights reserved. Summary n All drugs are metabolized ahead of nutrients. n Most drugs have nutritional status side effects. n Always look for potential interactions. n Watch for use of multiple drugs (polypharmacy) especially among the elderly! n All drugs are metabolized ahead of nutrients. n Most drugs have nutritional status side effects. n Always look for potential interactions. n Watch for use of multiple drugs (polypharmacy) especially among the elderly!