food drug interactions

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FOOD-DRUG INTERACTIONS

PAA KWESI HACKMAN

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OutlineDefinitionEffects of FDIsRisk factorsFactors Affecting the Impact of

FDIsEffects of Drugs on Foods Effects of Foods on Drugs OthersConclusion

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What are FDIs? FDIs are alterations of kinetics or dynamics of a drug or a nutrient/food.

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Effects of FDIs Alter the intended response to the medication

Cause drug toxicity

Alter normal nutritional status

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Risk Factors Polypharmacy Older patients Nutritional status Genetics Underlying illness Special diets Nutrition

supplements EN or PN Herbal or

phytonutrient products

OH intake

Non-nutrients in foodExcipients in drugs or

foodAllergies, or

intolerancesPoor patient

compliancePhysicians' prescribingpatternsLong-term treatmentfor chronic diseaseDrugs of abuse

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Factors Affecting the Impact of FDIs

Dosage of the drugPerson's ageSize State of healthThe time interval between the intake of drugs and foods

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Effects of Drugs on

Foods

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Nutrient Ingestion Metformin anorexia.

Potassium, iron preparations, antibiotics, ARVs nausea & vomiting.

ACE Inhibitor (Captopril) dysgeusia

Corticosteroids (prednisone) increased appetite.

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Nutrient Absorption /1 Quinolones & tetracycline chelates Ca2+

Zn2+, Mg2+ in dairy products and other supplements.

Bile acid sequestrants hinder the absorption of fat-soluble vitamins. e.g. colestipol, cholestyramine

Metformin reduces vitamin B12 absorption.

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Nutrient Absorption /I1

Reduction of GITT of food:o Furosemide, lactulose & other laxatives,

antigout (colchicine) diarrhoea losses of K+, Ca2+ etc.

Damage to the Intestinal Absorptive Surface:

o NSAIDs (like ibuprofen, aspirin) may hinder the absorption of Fe2+ & Ca2+ .

o OH inhibits folate, vitamins B1 and B12 absorption.

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Nutrient Absorption /III

Changing the GI environment:o H2-receptor antagonists (Famotidine)

& PPIs (omeprazole) inhibit gastric acid secretion, gastric pH & impairing vitamin Bl2 absorption;

o Cimetidine also reduces IF secretion.

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Nutrient Metabolism

Inhibiting synthesis of some biomolecules.

o E.g. HMGCoA reductase inhibitors (statins) hinder CHOL & CoQ10 synthesis.

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Nutrient Excretion

or the urinary excretion of nutrients:

o Loop & thiazide diuretics results in excretion of Na+, K+, HCO3

-, Mg2+ PO43- , I-,

Cl- etc.

o ACE inhibitors K+ excretion, leading to increased K+ serum levels.

o Corticosteroids (like prednisone) excretion, resulting in K+ and H2O retention.

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Effects of Foods on Drugs

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Drug Absorption /I Altering GITT for effective absorptiono Some drugs like amprenavir, ketoconazole are

acid dependent and thus are favoured by foods that enhance GITT.

Chelationo Fe from Fe preparations, quinolones may be

hindered by bran, eggs, high-phytate foods, fiber supplements, tea, coffee, dairy products, or calcium supplements.

Food Restrictionso ACE inhibitors are taken on empty stomach.

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Drug Absorption /II Changing gastric pHo Amprenavir, ketoconazole are reliably

absorbed in low pH, so it is taken with food. They may also be taken with sugary drinks.

Bile acid or fat-enhaced drug dissolutiono Saquinavir is properly absorbed with bile, so is

taken with food, especially fatty.

Physical bindingo Digoxin for HF may bind with fibre reducing

absorption

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Drug Distribution Hypoalbuminaemia (<3g/l)

are at increased risk of adverse effects of drugs.o Warfarin, which is 99.9% serum

protein-bound. With warfarin, higher levels of free drug lead to risk of excessive anticoagulation and bleeding.

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Drug Metabolism Inhibition of Cytochrome P-450 3A4 Enzyme o Furanocoumarins in grapefruit or juice increase

the effect of statins & calcium channel blockers.

Competition For Metabolising Enzymeso Foods especially meat may increase the

pharmacological effect of beta blockers (propranolol) which can cause low BP & dizziness.

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Others /IThe Phylloquinone-Warfarin War

Ingestion of vitamin K in the usable form oppose the action of warfarin & allow the production of more clotting factors.

To achieve an optimal level of anticoagulation, a consistent dietary vitamin K intake rather than prohibiting all high-vitamin K foods, such as dark green leafy vegetables. (Johnson, 2005)

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Others /IISalt & Na+ vs ACE Inhibitors

Excessive Na+ intake hampers the effects of ACE inhibitors by elevating BP.

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Medication and EN Interactions Use of feeding tube to administer medication can

be a problem. When liquid medications are mixed with enteral formulas, incompatibilities like granulation, gel formation, & separation of the enteral product may occur.

These frequently clog feeding tubes and interrupt delivery of nutrition to the patient.

Examples of drugs that can cause granulation and gel formation are ciprofloxacin & ferrous sulfate elixir.

(Wohlt et al., 2009)

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Conclusion FDIs are a major challenge even in the

hospital because food consumption is not always documented.

FDI’s are critical in therapy mgt. and must be considered and monitored in patients.

It is imperative that the medical team including the Dietician effectively review all medications of clients, especially critically-ill and old folk before nourishment.

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ReferencesHarvard Health Publications.

http://www.health.harvard.edu/hearthealth/grapefruit-juice-and-statins

Krause’s Food and Nutrition Care Process. 12th Edition. Elsevier Ltd.

Pronsky & Crowe JP: Food-medication interactions, ed 16, Birchrunville, Pa, Food-Medication Interactions.

Johnson MA: Influence of vitamin K on anticoagulant therapy depends on vitamin K status and the source and forms of vitamin K, Nutr Rev 63:91, 2005.

Wohlt PD, et al: Recommendations for use of medications with continuous enteral nutrition, Am J Health-Syst Pharm 66:1458, 2009.

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