George K John
B. Pharm (India), M. Pharm Prac (South Africa), GCPE (South Africa) GCDM (South Africa), GCULT (Australia)
Senior Lecturer in Pharmacy Practice
School of Biomedical Sciences
Charles Sturt University
Wagga Wagga, Australia
Presentation to Dietitians Association Australia on 16/09/2013
1Objectives
2Introduction
3Definition of terms
4Relevance of topic
5Risk factors
6Absorption
7Distribution
8Metabolism
9Excretion
10Action
11Adverse effects
12Nutritional implications
13Management
14Resources
15Summary
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1

General Lecture ObjectivesPharmacists
This lecture addresses the following competencies of PSA 2010;
Domain 4Review and supply prescribed medicines
•
Standard 4.1-Undertake initial prescription assessment
•
Standard 4.2-Consider the appropriateness of prescribed medicines
Domain 7Promote and contribute to optimal use of medicines
•
Standard 7.1 Contribute to therapeutic decision-making
•
Standard 7.2 Provide ongoing medication management
•
Standard 7.3 Influence patterns of medicine use
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2

General Lecture ObjectivesDietitians & Nutritionist
This lecture addresses the following competencies of DAA 2009;
Unit 1Demonstrates knowledge sufficient to ensure safe practice
•
Elements 1.1
Applies current knowledge of the theory of human nutrition and dietetics and related practice to a level which supports safe practice
•
Elements 1.7
Applies the basic principles of education theory as it applies to nutrition and dietetic practice
Unit 4Manages client-centred nutrition care for individuals
•
Element 4.1
Undertakes screening and assessment to identify and prioritise those at nutritional risk
•
Element 4.2
Determines nutritional status using assessment data
•
Element 4.3
Makes appropriate nutrition diagnoses
•
Element 4.4
Prepares plan for achieving management goals in collaboration with client or carer and other members of health care team
1.
Outline the effects of nutrition on drug absorption, action, metabolism and excretion
2.
Discuss the effects of drugs on food intake, nutrient absorption, metabolism and excretion
3.
Evaluate the reasons why some drugs are more likely to have dietetic implications
4.
List the types of drugs which are likely to have nutritional implications
5.
Discuss the types of people who are at risk from drug-nutrient interactions
6.
Identify ways to manage some of these issues
7.
Have access to a few resources for future reading and professional practice.
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Background
It has been estimated that 76%-92% of elderly use at least one prescription or non prescription drug daily.
With increasing age, the body’s ability to metabolise medications decreases, therefore making it difficult for older adults to excrete multiple medications.
Older people take various medications for heart disease, and to treat respiratory problems, gastrointestinal disorders and arthritis.
Medications can help to enhance older people’s quality of life and good health; however, they can also contribute undesirable side-effects.
Adverse drug-nutrient interactions are more common in those who tend to be on multiple drugs, termed polypharmacy, for long periods of time.
Polypharmacy is a strong predictor of malnutrition.
Approximately 70% to 80% of older adults have been found to experience side effects of medications such as nausea and vomiting, suppressing appetite, changing oral environment (dry mouth), and altering the way food smells and tastes.
4

•
Well defined.
•
Predictable.
•
Reference tables.
•
Why?
–
Drug product always ±5% of stated content.
–
Taken in equal installments at regular intervals
•
•
Poorly defined.
•
Unpredictable.
Few reference tables.
•
Why Foodstuffs?
–
Content varies
–
Portion varies
–
Frequency varies
–
Storage
–
Processing
–
Incomplete consumption
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5

Mechanisms of Interaction
•
Drug in the body:
–
Absorption
–
Distribution
–
Metabolism
–
Action
–
Elimination
•
Interactions possible at all stages
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6

•
Drug-nutrient interaction: the result of the action between a drug and a nutrient that would not happen with the nutrient or the drug alone
•
Food-drug interaction: a broad term that includes drug-nutrient interactions and the effect of a medication on nutritional status
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•
Drug –Nutrient Interaction - Zantac (Ranitidine) &
Vitamin B12Decreases Nutrient absorption
•
Drug –Food Interaction -T etracycline's & Dairy products Decreases drug absorption
7

•
Bioavailability: degree to which a drug or other substance reaches the circulation and becomes available to the target organ or tissue
•
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
•
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.
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8

Movement of drugs through the body by
•
Absorption
•
Distribution
•
Metabolism
•
Excretion
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•
Movement of the drug from the site of administration to the bloodstream; depends on
–
The route of administration
–
The chemistry of the drug and its ability to cross membranes
–
The rate of gastric emptying (for oral drugs) and GI movement
–
The quality of the product formulation
•
Food, food components and nutritional supplements can interfere with absorption, especially if the drug is taken orally
9

When the drug leaves the systemic circulation and moves to various parts of the body
•
Drugs in the bloodstream are often bound to plasma proteins; only unbound drugs can leave the blood and affect target organs
•
Low serum albumin can increase availability of drugs and potentiate their effects
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•
Primarily in the liver; cytochrome P-450 enzyme system facilitates drug metabolism; metabolism generally changes fat soluble compounds to water soluble compounds that can be excreted
•
Foods or dietary supplements that increase or inhibit these enzyme systems can change the rate or extent of drug metabolism
10

•
Drugs are eliminated from the body as an unchanged drug or metabolite
–
Renal excretion the major route of elimination; affected by renal function and urinary pH
–
Some drugs eliminated in bile and other body fluids
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•
Physiologic and biochemical effects of a drug or combination of drugs
•
The mechanism of action, e.g. how a drug works
•
Often the drug molecule binds to a receptor, enzyme, or ion channel, producing a physiological response
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Benefits of Minimizing Food Drug Interactions
•
•
Medications achieve their intended effects
Improved compliance with medications
•
Less need for additional medication or higher dosages
•
Fewer caloric or nutrient supplements are required
•
•
Adverse side effects are avoided
Optimal nutritional status is preserved
•
Accidents and injuries are avoided
•
Disease complications are minimized
•
•
The cost of health care services is reduced
There is less professional liability
•
Licensing agency requirements are met
12

Therapeutically important interactions are those that:
•
Alter the intended response to the medication
•
Cause drug toxicity
•
Alter normal nutritional status
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13

Patients at Risk for Food-Nutrient Interactions
•
Patient with chronic disease
•
Elderly
•
Foetus
•
Infant
•
Pregnant woman
•
•
Malnourished patient
Allergies or intolerances
Food and Drug-Related Risk Factors
•
Special diets
•
Nutritional supplements
•
Tube feeding
•
Herbal or phytonutrient products
•
Alcohol intake
•
Polypharmacy
•
Drugs of abuse
•
Non-nutrients in foods
•
Excipients in drugs or food
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Food/Nutrient Effects on Drugs
Absorption
Presence of food and nutrients in intestinal tract may affect absorption of drug
•
Antiosteoporosis drugs Fosamax or Actonel: absorption negligible if given with food; ↓ 60% with coffee or orange juice
•
Absorption of iron from supplements ↓↓ 50% when taken with food.
It is best absorbed when taken with 8 oz of water on empty stomach
Food may ↓↓ GI upset
•
If GI upset is present take with food, avoid bran, eggs, fiber supplements, tea, coffee, dairy products, calcium supplements as they enhance GI upset. Eg. Ibuprofen or Diclofenac Sodium.
15

Food/Nutrient Effects on Drugs
Absorption
Ciprofloxacin and Tetracycline form insoluble complexes with calcium in dairy products or fortified foods; also zinc, calcium, magnesium, zinc or iron supplements; aluminum in antacids
–
Stop unnecessary supplements during drug therapy or give drug 2 hours before or 6 hours after the mineral
Presence of food enhances the absorption of some medications
–
Bioavailability of Axetil (Ceftin), an antibiotic, is 52% after a meal vs
37% in the fasting state
–
Absorption of the antiretroviral drug saquinavir is increased twofold by food
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Food/Nutrient Effects on Drugs
Absorption:
•
•
GI pH can affect drug absorption
Achlorhydria or hypochlorhydria can reduce absorption of ketoconozole and delavirdine
•
•
Antacid medications can result in reduced acidity in the stomach
Taking these medicines with orange or cranberry juice can reduce stomach pH and increase absorption
16

Food/Nutrient Effects on Drugs
•
Adsorption: adhesion to a food or food component
–
High fiber diet may decrease the absorption of tricyclic antidepressants such as amitriptyline
(Elavil)
–
Digoxin (Lanoxin) should not be taken with high phytate foods such as wheat bran or oatmeal
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Drug Effects on Nutrition: Absorption
•
Drug-nutrient complexes: example, ciprofloxacin and tetracycline will complex with calcium, supplemental magnesium, iron, or zinc
–
Take minerals 2 to 6 hours apart from the drug
•
Decreased transit time: cathartic agents, laxatives, drugs containing sorbitol, drugs that increase peristalsis
17

Drug Effects on Nutrition; Absorption
Change GI environment
–
Proton pump inhibitors, H2 receptor antagonists inhibit gastric acid secretion, raise gastric pH; cimetidine reduces intrinsic factor secretion; this impairs B12 absorption;
↑ pH may impair absorpon of calcium, iron, zinc, folic acid, and B -carotene
Damage GI Mucosa
•
•
Chemotherapeutic agents, NSAIDs, antibiotic therapy
•
Alters ability to absorb minerals, especially iron and calcium
Affect Intestinal Transport
Cochicine (gout), paraaminosalicylic acid (TB), sulfasalazine (ulcerative colitis), trimethoprim (antibiotic) and pyrimethamine (antiprotozoal)
•
•
– Impair absorption of B12 or folate
Fat absorption
Cholestyramine (antihyperlipidemic bile acid sequestrant) also adsorbs fat-soluble vitamins A, D, E, K, possibly folic acid; may need supplements for long term therapy, especially if dosed several times a day
Mineral oil: (>2 tbsp/day) ↓ absorpon of fat soluble vitamins
– take vitamins at least 2 hours after mineral oil
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18

Malnutrition Effect on Drugs
•
Low albumin levels can make drugs more potent by increasing availability to tissues
–
Lower doses often recommended for persons with low albumin
–
Warfarin and phenytoin are highly protein bound in blood;
↓ albumin can result in poor seizure control (phenytoin) or hemorrhage (warfarin)
•
Body composition: obese or elderly persons have a higher ratio of adipose tissue; fat soluble drugs may accumulate in the body ↑ risk of toxicity
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19

Food/Nutrient Effects on Drugs
Metabolism
Changes in diet may alter drug action
•
Theophylline: a high protein, low CHO diet can enhance clearance of this and other drugs
•
Grapefruit/juice: inhibits the intestinal metabolism
(cytochrome P-450 3A4 enzyme) of numerous drugs
(calcium channel blockers, HMG CoA inhibitors, antianxiety agents) enhancing their effects and increasing risk of toxicity; may interfere with the absorption of other drugs
Drug Effects on Nutrition: Metabolism
•
Phenobarbital and phenytoin increase metabolism of vitamin D, vitamin K, and folic acid
–
Patients on chronic tx may need supplements
•
Carbamazepine may affect metabolism of biotin, vitamin D, and folic acid, leading to possible depletion
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20

Drug Effects on Nutrition: Metabolism
•
INH (anti-tuberculosis) blocks conversion of pyridoxine to active form
–
Patients with low intake at higher risk
–
May cause deficiency and peripheral neuropathy
–
Pts on long term tx may need supplements
•
Hydralazine, penacillamine, levodopa and cycloserine are also pyridoxine antagonists
•
Methotrexate (cancer and rheumatoid arthritis) and pyrimethamine (malaria, toxoplasmosis) are folic acid antagonists
–
May treat with folinic acid (reduced form of folic acid, does not need conversion to active form) or folic acid supplements
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Grapefruit Inhibits Metabolism of Many Drugs
•
Inactivates metabolizing intestinal enzyme resulting in enhanced activity and possible toxicity
•
Effect persists for 72 hours so it is not helpful to separate the drug and the grapefruit
•
Many hospitals and health care centers have taken grapefruit products off the menu entirely
21

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Food/Nutrient Effects on Drugs
•
Excretion
—Patients on low sodium diets will reabsorb more lithium along with sodium; patients on high sodium diets will excrete more lithium and need higher doses
—Urinary pH: some diets, particularly extreme diets, may affect urinary pH, which affects reabsorption of acidic and basic medications http://www.nrv.gov.au/nutrients/index.htm
22

Drug Effects on Nutrition: Excretion
•
Loop diuretics (furosemide, bumetanice) increase excretion of potassium, magnesium, sodium, chloride, calcium
–
Patients may need supplements with long term use, high dosages, poor diets
–
Electrolytes should be monitored
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Drug Effects on Nutrition: Excretion
•
Thiazide diuretics (hydrochlorthiazide) increase the excretion of potassium and magnesium, but reduce excretion of calcium
–
High doses plus calcium supplementation may result in hypercalcemia
•
Potassium-sparing diuretics (spironolactone) increase excretion of sodium, chloride, calcium
–
Potassium levels can rise to dangerous levels if pt takes K+ supplements or has renal insufficiency
23

Drug Effects on Nutrition: Excretion
•
Corticosteroids (prednisone) decrease sodium excretion, resulting in sodium and water retention; increase excretion of potassium and calcium
–
Low sodium, high potassium diet is recommended
–
Calcium and vitamin D supplements are recommended with long term steroid use (lupus,
RA) to prevent osteoporosis
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Drug Effects on Nutrition: Excretion
•
Phenothiazine antipsychotic drugs (chlorpromazine) increase excretion of riboflavin
–
Can lead to riboflavin deficiency in those with poor intakes
•
Cisplatin causes nephrotoxicity and renal magnesium wasting resulting in acute hypomagnesemia in 90% of patients (also hypocalcemia, hypokalemia, hypophosphatemia)
–
May require intravenous mg supplementation or post-treatment hydration and oral mg supplementation
–
May persist for months or years after therapy is finished
24

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Food/Nutrient Effects on Drug Action : MAOIs
•
Monoamine oxidase inhibitors (MAOI) interact with pressor agents in foods (tyramine, dopamine, histamine)
•
Pressors are generally deaminated rapidly by MAO; MAOIs prevent the breakdown of tyramine and other pressors
•
Significant intake of high-tyramine foods (aged cheeses, cured meats) by pts on MAOIs can precipitate hypertensive crisis
25

Food/Nutrient Effects on Drug Action: Caffeine
•
Increases adverse effects of stimulants such as amphetamines, methylphenidate, theophylline, causing nervousness, tremor, insomnia
•
Counters the anti-anxiety effect of tranquilizers
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Food/Nutrient Effects on Drug Action: Warfarin
•
Warfarin (anticoagulant) acts by preventing the conversion of vitamin K to a usable form
•
Ingestion of vitamin K in usable form will allow production of more clotting factors, making the drug less effective
•
Pts must achieve a balance or steady state between dose of drug and consumption of vitamin K; recommend steady intake of K
•
Other foods with anticlotting qualities may also have an effect
(garlic, onions, vitamin E in large amounts, and ginseng)
26

Food/Nutrient Effects on Drug Action: Alcohol
•
In combination with some drugs will produce additive toxicity
•
With CNS-suppressant drugs may produce excessive drowsiness, and lack of coordination
•
Acts as gastric irritant; in combination with other irritants such as NSAIDs may increase chance of GI bleed
•
Should not be combined with other hepatotoxic drugs such as acetominophen, amiodarone, methotrexate
•
Can inhibit gluconeogenesis when consumed in a fasting state; can prolong hypoglycemic episode caused by insulin or other diabetes meds
•
Can produce life-threatening reaction when combined with disulfiram (Antabuse) which prevents the catabolism of ethanol by the liver
–
Causes nausea, headache, flushing, increased blood pressure
•
Metronidazole, Cefoperazone, chlorpropamide (Diabenese) and procarbacine cause similar symptoms
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Drugs known to interact with grapefruit juice
•
Anti-hypertensives
(filodipine, nifedipine, nimodipine, nicardipine, isradipine)
•
•
•
Immunosuppressants
(cyclosporine, tacrolimus)
Antihistamines (astemizole)
Protease inhibitors
(saquinavir)
•
•
Lipid-Lowering Drugs
(atorvastatin, lovastatin, simvastatin)
Anti-anxiety, antidepressants (buspirone, diazepam, midazolam, triazolam, zaleplon, carbamazepine, clomipramine, trazodone
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Drug Side Effects that Affect Nutritional Status
•
Appetite changes
•
Oral taste and smell
•
Nausea
•
Dry mouth
•
Gastrointestinal effects
•
Organ system toxicity
•
Glucose levels
28

Examples of Drug Categories that may affect Appetite
Decrease Appetite
•
Antiinfectives
•
Antineoplastics
•
Bronchodilators
•
Cardiovascular drugs
•
Stimulants
Increase Appetite
•
Anticonvulsants
•
Hormones
•
Psychotropic drugs
—Antipsychotics
—Antidepressants, tricyclics, MAOIs
Drugs Affecting Oral Cavity, Taste and Smell
•
•
Taste changes: cisplatin, captopril (anti-hypertensive) amprenavir (antiviral) phenytoin (anti-convulsive), clarithromycin (antibiotic)
Mucositis: antineoplastic drugs such as interleukin-2, paclitaxel, carboplatin
•
Dry mouth: Anticholinergic drugs (tricyclic antidepressants such as amytriptyline, antihistamines such as diphenhydramine, antispasmodics such as oxybutynin
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29

Drugs that Affect the GI Tract
•
Alendronate (Fosamax) anti-osteoporosis drug—patients must sit upright 30 minutes after taking it to avoid esophagitis
•
•
Aspirin or other NASAIDs –can cause GI bleeding, gastritis
Orlistat – blocks fat absorption, can cause oily spotting, fecal urgency, incontinence
•
Narcotic agents cause constipation
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Examples of Drug Classes That Cause Diarrhea
•
Laxatives
•
•
•
•
Antiretrovirals
Antibiotics
Antineoplastics
+ liquid medications in elixirs containing sugar alcohols
30

Drugs That May effect Glucose Levels
Decrease glucose levels
•
Antidiabetic drugs (acarbose, glimepiride, glipizide, glyburide, insulin, metformin, miglitol, neteglinide, pioglitizone, repaglinide, roiglitizone
•
Drugs that can cause hypoglycemia: ethanol, quinine, disopyramide
(antiarrhythmic) and pentamidine isethionate (antiprotozoal)
Increase glucose levels
•
Antiretrovirals, protease inhibitors (amprenavir, nelfinavir, ritonavir, saquinavir)
•
Diuretics, antihypertensives (furosemide, hydrochlorothiazide, indapamide)
•
Hormones (corticosteroids, danazol, estrogen or estrogen/progesterone replacement therapy, megestrol acetate, oral contraceptives)
•
Niacin (antihyperlipidemic) baclofen, caffeine, olanzapine, cyclosporine, interferon alfa-2a
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Nutrition Implications of Excipients in Drugs
•
Excipients: are inactive ingredients added to drugs as fillers, buffers, binders, disintegrant, flavoring, dye, preservative, suspending agent, coating
•
Approved by TGA for use in pharmaceuticals
•
Vary widely from brand to brand and formulation strengths of the same drug
•
Excipients may cause allergic or health reactions in persons with celiac disease, dye sensitivity, other allergies, inborn errors of metabolism
•
Examples of excipients that might cause reactions are albumin, wheat products, alcohol, aspartame, lactose, sugar alcohols, starch, sulfites, tartrazine, vegetable oil
•
Some meds may contain sufficient CHO or protein to put a patient on a ketogenic diet out of ketosis http://www.tga.gov.au/industry/cm-ingredients.htm#.UzClr84VeAo
Nutrition Implications of Excipients in Drugs
•
Some drugs at usual dosages may contain enough excipients to be nutritionally significant
–
Agenerase: 1744 IU vitamin E
–
Accupril: 50-200 mg magnesium
–
Fibercon/Fiberlax: 600 mg ca+ in 6 tabs
–
Propofol (Diprivan) contains 10% soybean emulsion; may provide 1663 kcals/day for 70 kg person
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Food/Nutrient Effects on Drugs – Enteral Feedings
•
Most medications should not be mixed with enteral feedings; physical incompatibilities can occur including granulation, gel formation, separation of the feeding leading to clogged tubes
•
Enteral feedings interfere with phenytoin absorption; window the feeding around drug dose (2 hours before and after)
33

Enteral Nutrition and Drugs
•
Drugs put in feeding tubes may cause:
—Diarrhea
—Drug-nutrient binding
—Blocked tube
•
If patient does not receive total volume of enteral feeding, he/she will not receive the full dose of the drug
•
Avoid adding drug to formula
•
When drugs must be given through tube:
–
Stop feeding, flush tube, give drug, flush
–
Use liquid form of drug (but be aware of effects of elixirs on bowel function)
–
Avoid crushing tablets (There is a detailed section in the Australian
Pharmaceutical Formulary- APF 22 , about drugs not to crush)
•
Be aware of potential interactions between enteral feedings and drugs
–
Phenytoin
–
Ciprofloxacin
Medicines not to be Crushed-APF 22 #
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# Australian Pharmaceutical Formulary and Handbook. 2012. Pharmaceutical Society of Australia.
34

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Table: Commonly Used Herbs and Spices and their Potential Drug Interactions. Gall, A., & Shenkute, Z.2009. Ethnomed.
Herb/Spice
Herb/Spice
Basil
Ocimum basilicum
Black Mustard
Brassica nigra
1.
Common Uses
Common Uses
Mostly culinary
2.
Medicinal: headache, insect repellent, malaria
1. Culinary use
2. Medicinal use: stomach ache, constipation, bloating, amoebic dysentery and abortifacient
3. Also used for wound dressing.
Drugs Affected
Drugs Affected
1.
Anticoagulants
2.
Hypoglycemic agents
Mechanism
Mechanism
1.
Oil extract has been found to increase clotting time
2.
Synergistic interaction with insulin and oral hypoglycemic agents
1.
2.
Consequences
Consequences
Increased chance of bleeding
May further lower blood glucose
1.
Proton Pump Inhibitors
1)
2.
H
2 receptor antagonists
2)
3.
Anticoagulants
4.
May interact with aspirin
3)
Mustard seeds and oil may increase production of stomach acid 1)
Allyl thiocyanate is an irritant that can cause severe burns and tissue necrosis (Fullas 2003) 2)
Interferes with antacid treatment
Antagonizes effects of
Warfarin
High concentration of Vitamin K
Black seed
Nigella sativa
1)
2)
Culinary uses
Medicinal: headache, stomachache, abortifacient
1)
2)
3)
Anti-coagulants
Anti-hypertensives
Insulin and oral hypoglycemic drugs
Capsicum pepper
Cayenne pepper
1)
2)
Capsicum annum
Mostly culinary
Medicinal: stomach ache,
1)
2) antimicrobial
3)
Anti-coagulants
Anti-hypertensives
ACE inhibitors
1)
2)
3)
4)
1)
2)
Platelet aggregation inhibition
Increases pancreatic insulin secretion
Evidence in animal studies of reduced arterial
1) blood pressure by increasing vasodilation and
2) inhibiting contraction.
Evidence of pregnancy inhibitor in rats
(Fullas, 2003)
Increased risk of bleeding
Synergistic action with medication that lowers blood pressure and blood glucose
Capsaicin may inhibit platelet aggregation
Increases production of catecholamines
1)
2)
Increased risk of bleeding
May counteract mechanism of anti-hypertensives
3) Decreases blood glucose levels and stimulates insulin release
3) Recorded incidences of increased cough when combined with ACE inhibitors
35

Table: Commonly Used Herbs and Spices and their Potential Drug Interactions. Gall, A., & Shenkute, Z.2009. Ethnomed.
Herb/Spice Common Uses Drugs Affected Mechanism
Consequences
C innamon
Cinnamomum zelanicum
Coriander
Coriandrum sativum
Cumin
Cuminum cyminum
Dingetegna
Taverniera abyssinica
Culinary
Medicinal: treatment for cold symptoms
Antacids
Tetracyclines
Mostly culinary
Medicinal: stomach ache and colic
Insulin and oral hypoglycemic agents
Claimed to increase stomach acid
Experimental evidence of tetracycline dissolution rate interference
May counteract antacids
May inhibit tetracycline action
Unknown, but has been shown to be effective in treating stomach upset (Fullas 2003)
*Lowers blood sugar levels;
Mostly culinary
Hypoglycemic agents
Anticoagulants
May have hypoglycemic properties
May have anticoagulating properties
*Hypoglycemia
*Increased risk of bleeding
Medicinal only for stomach upset
Fever reduction
No specific class
Antispasmodic properties may affect absorption of medication
Decreased absorption of medication
Fenugreek
•
Trigonella foenumgraceum
•
Mostly culinary
•
Medicinal: stomach ache, antispasmodic, powder used for wound dressing
•
•
•
Antidiabetic drugs
Lipid lowering drugs
Thyroid Replacement
Therapy
Warfarin
•
•
•
•
Studies have shown that fenugreek acts synergistically with blood glucose lowering drugs
•
•
• Decreases total cholesterol and LDLs
Alters T
3 and T
4 levels
Anticoagulating properties
•
*Hypoglycemia
*Lower cholesterol
*Reduced intestinal absorbance of medication
*Increased risk of bleeding
20/11/2014
Table: Commonly Used Herbs and Spices and their Potential Drug Interactions. Gall, A., & Shenkute, Z.2009. Ethnomed.
Herb/Spice
Herb/Spice
Flaxseed and flaxseed oil
Linum usitatissimum
•
Ginger
Zingiber officinale
•
•
Common Uses
Common Uses
•
•
Medicinal: purgative, diuretic, laxative
•
•
Culinary
Medicinal: stomachache, cough, fever, influenza
•
•
•
•
Drugs Affected
Drugs Affected
•
Anti-coagulants
Cardiac glycosides
Laxatives
Insulin and oral hypoglycemic agents
Hormonal drugs
Lipid lowering agents
•
•
•
Antacids
Anticoagulants
•
•
Mechanism
Mechanism
Flaxseed and oil decrease platelet aggregation, increase effects of lipid lowering and hypoglycemic agents
Consequences
Consequences
•
*Increased risk of bleeding
Reduced intestinal absorbance of oral medication; as any fiber source
Lignans (phyto-estrogens) from flaxseed (not oil) possess hormonal effects
•
Increased risk of hypoglycemia
As a bulk forming laxative, flaxseed may bind to cardiac glycosides and other
• orally administered medications and prevent absorption
Flaxseed enhances laxative effects of stool softeners
Irritates gastric mucosa
Decreases platelet aggregation
Possible dehydration from increased laxative effects of flaxseed (Due to absorption of liquid by fiber. It is important for patient to drink enough water.)
•
*Inhibits antacid therapy
*Increased risk of bleeding
Khat
Catha edulis
•
•
Mostly recreational
Medicinal: stimulant,
• mental illness, gonorrhea, common cold
•
Amphetamines
Amoxicillin and ampicillin, PCN others
•
•
•
Cathinone (active ingredient) may act synergistically with amphetamines
•
Tannins (component of Khat) complexes • with ß-lactam antibiotics
•
Possible additive effect with amphetamines
Decreases absorbability of b-lactam antibiotics
Lowers seizure threshold,
Increases b.p and heart rate and induces cardiac arrythmias.
36

Table: Commonly Used Herbs and Spices and their Potential Drug Interactions. Gall, A., & Shenkute, Z.2009. Ethnomed.
Herb/Spice
Herb/Spice
Peppermint
Mentha piperita
•
Rue
Ruta chalepensis
•
•
Turmeric
Curcuma longa
•
Garlic
Allium sativum
•
•
Common Uses
Common Uses
•
Medicinal: common cold, headache
•
•
•
Medicinal: common cold, stomachache, diarrhea, influenza
•
•
Mostly culinary
•
Medicinal: used topically for “crying eyes” in children
•
Culinary
Medicinal: common cold, malaria, cough,
• pulmonary TB, hypertension, wounds,
•
STDs, asthma, parasitic infections, toothache, diabetes, hemorrhoids
•
•
•
Drugs Affected
Drugs Affected
Felodipine and simvastatin
Warfarin
•
Iron
•
Warfarin
Acid Suppression therapy
•
(antacids)
Psoraien Ultraviolet
(PUVA) therapy
•
•
•
•
Antiplatelets and anticoagulants
Insulin and oral hypoglycemics
Antiplatelets
Anticoagulants
Insulin and oral hypoglycemic agents
Cholesterol lowering drugs
Thyroid replacement therapy
•
•
•
•
•
Mechanism
Mechanism
•
Inhibits gut wall metabolism of felodipine and simvastatin •
Decreases absorption of non-heme iron
Reduces Warfarin internal normalized ratio to sub-therapeutic levels
•
No major interactions reported
5-methoxy psoralen content of rue may increase phototoxic response
•
May interact with Warfarin
Has been shown to inhibit platelet aggregation in vitro
•
Curcuminoids and sesquiterpene components of turmeric have hypoglycemic
•
May be additive with cholesterollowering drugs
Hypertensive activity but it is not known
• if this effect is antihypertensive drug additive
•
Decreases T
3 and T
4 levels
May have blood thinning properties
Consequences
Consequences
Increased risk of clots if patient is in a hypercoagulable state
Non-absorption of felodipine, simvostatin and iron
Increases GERD symptoms unless taken as enteric-coated capsules
Anticoagulant effects maybe additive
Increased risk of bleeding
(theoretical risk; has not been demonstrated)
Reduces blood sugar levels
*Possible increased risk of bleeding;
*Reverses effects of orally administered thyroxine
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Management for Food-Drug Interactions
•
Prospective: 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
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Avoiding Food-Drug Interactions: Prospective
•
When medications are initiated, patients should be provided with complete written and verbal drug education at an appropriate reading level including food-drug interaction information
•
Patients should be encouraged to ask specific questions about their medications and whether they might interact with each other or with foods
•
Patients should read the drug label and accompanying materials provided by the pharmacist
•
In acute-care settings, patients receiving high risk medications should be identified and evaluated
•
Nurses should have information regarding drug-food interactions and drug administration guidelines available at the bedside
•
Med pass times should be evaluated in light of potential food-drug interactions
•
Systems should be established so that pharmacists can communicate with food and nutrition staff regarding high risk patients
38

Avoiding Food-Drug Interactions: Retrospective
•
Clinicians including dietitians should obtain a full drug and diet history including the use of OTC and dietary supplements and review potential drug-food interactions
•
A plan should be developed for dealing with potential drug-food interactions for short and long term drug therapy
•
When therapeutic goals are not met, clinicians should ask questions about how and when drugs are being taken in relation to foods and nutritional supplements
•
Clinicians should evaluate whether medical problems could be the result of drug-food interactions
•
Often it may be the dietitian who is most aware of these issues
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Avoiding Food-Drug Interactions: Example
•
A 20-year-old disabled patient who was a long term resident of a nursing home was admitted to an acute care hospital for a workup to determine the cause of chronic diarrhea
•
The enteral feeding had been changed numerous times in an effort to normalize the patient’s bowel function
•
The patient was currently receiving a defined formula feeding at a slow rate
•
The workup revealed no apparent medical reason for the impaired bowel function.
•
After reviewing the pts medications, the dietitian suggested that the patient’s medications (given in liquid elixir forms containing sugar alcohols) might be causing the diarrhea .
•
The patient’s medications were changed, and the diarrhea resolved.
•
The patient returned to the nursing home on a standard enteral feeding formula
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20/11/2014
Further reading & resources
1.
http://www.nutritionaustralia.org/national/resource/nutritionist-or-dietitian
2.
http://www.foodstandards.gov.au/
3.
http://www.nps.org.au/conditions-and-topics/topics/how-to-be-medicinewise/side-effects-interactions/understandinginteractions
4.
http://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2012/07/WC500129606.pdf
5.
http://www.healthychildren.org/English/healthy-living/nutrition/pages/Food-and-Medication-
Interactions.aspx?nfstatus=401&nftoken=00000000-0000-0000-0000-
000000000000&nfstatusdescription=ERROR%3a+No+local+token
6.
http://www.australianprescriber.com/magazine/29/2/40/2
7.
http://www.fda.gov/downloads/Drugs/ResourcesForYou/Consumers/BuyingUsingMedicineSafely/EnsuringSafeUseofMedicin e/GeneralUseo fMedicine/UCM229033.pdf
8.
http://www.healthyfoodguide.com.au/articles/2008/april/dangerous-cocktail-how-food-and-drugs-interact
9.
http://www.tga.gov.au/pdf/euguide/ewp056095en.pdf
10.
http://www.guild.org.au/iwov-resources/documents/The_Guild/tab-News_and_events/Guild_News_Centre/Article%20-
%20Drug%20nutritient%20interactions%20Yvonne%20Coleman.pdf
11.
http://www.nevdgp.org.au/files/programsupport/HMR/2011/DrugInteractions%20in%20Aged%20Care%20Homes.pdf
12.
http://www.foodanddruginteractions.co.uk/
13.
http://daa.asn.au/wp-content/uploads/2011/11/Enteral-nutrition-manual-Oct-2011.pdf
40

Summary
•
Most drugs have nutritional status and side effects.
•
Always look for therapeutically significant interactions between food and drugs
•
Identify and monitor high risk patients, those on multiple medications and marginal diets
•
Be vigilant in your professional practice and empower your patient with the best health outcomes
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