Food-Drug Interactions Chapter 19. © 2004, 2002 Elsevier Inc. All rights reserved. Key Terms n...

Food-Drug InteractionsFood-Drug Interactions

Chapter 19Chapter 19

© 2004, 2002 Elsevier Inc. All rights reserved.

Key TermsKey Terms

Bioavailability: degree to which a drug or other substance reaches the circulation and becomes available to the target organ or tissue

Drug-nutrient interactions: the results of the action between a drug and a nutrient that would not happen with the nutrient or drug alone

Bioavailability: degree to which a drug or other substance reaches the circulation and becomes available to the target organ or tissue

Drug-nutrient interactions: the results of the action between a drug and a nutrient that would not happen with the nutrient or drug alone


Key Terms—cont’dKey Terms—cont’d

Half-life: amount of time it takes for the blood concentration of a drug to decrease by one half of its steady state level

Side effect: adverse effect/reaction or any undesirable effect of a drug

Half-life: amount of time it takes for the blood concentration of a drug to decrease by one half of its steady state level

Side effect: adverse effect/reaction or any undesirable effect of a drug


Pharmacology TermsPharmacology Terms

Stages of Drug Action

Pharmacokinetics: movement of a drug through the body by absorption, distribution, metabolism, and excretion

Pharmacodynamics: physiologic and biochemical effects of a drug or combination of drugs

Stages of Drug Action

Pharmacokinetics: movement of a drug through the body by absorption, distribution, metabolism, and excretion

Pharmacodynamics: physiologic and biochemical effects of a drug or combination of drugs


Pharmacology Terms—cont’dPharmacology Terms—cont’d

Pharmacogenomics: genetically determined variations that are revealed solely by the effects of drugs

Pharmacogenomics: genetically determined variations that are revealed solely by the effects of drugs


Therapeutic ImportanceTherapeutic Importance

Therapeutically important interactions are those that:

—Alter the intended response to the medication

—Cause drug toxicity

—Alter normal nutritional status

Therapeutically important interactions are those that:

—Alter the intended response to the medication

—Cause drug toxicity

—Alter normal nutritional status


Other TermsOther Terms

Bioavailability: % free to function

Absorption rate: % absorbed and time for absorption

Transported: amount in blood (free or bound)

Metabolized: altered by enzymes in tissues

Mixed-function oxidase system (MFOS): enzyme system that metabolizes drugs, carcinogens, compounds in foods, etc.

Bioavailability: % free to function

Absorption rate: % absorbed and time for absorption

Transported: amount in blood (free or bound)

Metabolized: altered by enzymes in tissues

Mixed-function oxidase system (MFOS): enzyme system that metabolizes drugs, carcinogens, compounds in foods, etc.


Patients at Risk for Food-Nutrient InteractionsPatients at Risk for Food-Nutrient Interactions

Patient with chronic disease

Elderly

Fetus

Infant

Pregnant woman

Malnourished patient

Patient with chronic disease

Elderly

Fetus

Infant

Pregnant woman

Malnourished patient


Drug Effects on NutritionDrug Effects on Nutrition

Decreased or increased intake

—Appetite

—Taste

—Nausea

—Dry mouth

Alter metabolism

—Anti-vitamins

—Monoamine oxidase inhibitors

Decreased or increased intake

—Appetite

—Taste

—Nausea

—Dry mouth

Alter metabolism

—Anti-vitamins

—Monoamine oxidase inhibitors


Drug Effects on Nutrition—cont’dDrug Effects on Nutrition—cont’d

Change absorption

—GI pH

—Transit time or motility

—Bile acid secretion or activity

—Drug-nutrient complexes

—Muscosal damage

Change excretion

Change absorption

—GI pH

—Transit time or motility

—Bile acid secretion or activity

—Drug-nutrient complexes

—Muscosal damage

Change excretion


Nutrient Effects on DrugsNutrient Effects on Drugs

Absorption

—Note if drug is taken with or without food

—Note which foods to avoid

Metabolism

—Changes in diet may alter drug action

—Malnutrition alters albumin level (blood binding) and MFOS enzyme activity

level

Absorption

—Note if drug is taken with or without food

—Note which foods to avoid

Metabolism

—Changes in diet may alter drug action

—Malnutrition alters albumin level (blood binding) and MFOS enzyme activity

level


Nutrient Effects on Drugs—cont’dNutrient Effects on Drugs—cont’d

Excretion

—Fluid status

—Urinary pH

Excretion

—Fluid status

—Urinary pH


Important InteractionsImportant Interactions

Oral contraceptives

—Folate Antihypertensives

—Ca

—K

—Mg MAOIs

—Tyramine in foods

Oral contraceptives

—Folate Antihypertensives

—Ca

—K

—Mg MAOIs

—Tyramine in foods


Key InformationKey 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


Examples of Drug Categories That May Cause Loss of AppetiteExamples of Drug Categories That May Cause Loss of Appetite

Antiinfectives

Antineoplastics

Bronchodilators

Cardiovascular drugs

Stimulants

Antiinfectives

Antineoplastics

Bronchodilators

Cardiovascular drugs

Stimulants


Examples of Drug Classes That Cause DiarrheaExamples of Drug Classes That Cause Diarrhea

Laxatives

Antiretrovirals

Antibiotics

Antineoplastics

Laxatives

Antiretrovirals

Antibiotics

Antineoplastics


Drugs That May Increase AppetiteDrugs That May Increase Appetite

Anticonvulsants

Hormones

Psychotropic drugs

—Antipsychotics

—Antidepressants, tricyclics, MAOIs

Anticonvulsants

Hormones

Psychotropic drugs

—Antipsychotics

—Antidepressants, tricyclics, MAOIs


Drugs That May Affect Glucose LevelsDrugs That May Affect Glucose Levels

Antidiabetic drugs

Drugs that can cause hypoglycemia

Antiretrovirals, protease inhibitors

Diuretics, antihypertensives

Hormones

Antidiabetic drugs

Drugs that can cause hypoglycemia

Antiretrovirals, protease inhibitors

Diuretics, antihypertensives

Hormones


Medical Nutrition Therapy for Food-Drug InteractionsMedical Nutrition Therapy for Food-Drug Interactions

Prospective: all MNT offered when the patient first starts a drug

Retrospective: evaluation of symptoms to determine if medical problems might be the result of food-drug interactions

Prospective: all MNT offered when the patient first starts a drug

Retrospective: evaluation of symptoms to determine if medical problems might be the result of food-drug interactions


Enteral Nutrition and DrugsEnteral Nutrition and Drugs

Drugs put in feeding tubes may cause:

—Diarrhea

—Drug-nutrient binding

—Blocked tube Avoid adding drug to formula When drugs must be given through tube:

—Stop feeding, flush tube, give drug, flush

—Use liquid form of drug

—Avoid crushing tablets

Drugs put in feeding tubes may cause:

—Diarrhea

—Drug-nutrient binding

—Blocked tube Avoid adding drug to formula When drugs must be given through tube:

—Stop feeding, flush tube, give drug, flush

—Use liquid form of drug

—Avoid crushing tablets


SummarySummary

All drugs are metabolized ahead of nutrients.

Most drugs have nutritional status side effects.

Always look for potential interactions.

Watch for use of multiple drugs (polypharmacy) especially among the elderly!

All drugs are metabolized ahead of nutrients.

Most drugs have nutritional status side effects.

Always look for potential interactions.

Watch for use of multiple drugs (polypharmacy) especially among the elderly!

Food-Drug Interactions Chapter 19. © 2004, 2002 Elsevier Inc. All rights reserved. Key Terms n...

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