Food-Drug Interactions

1. Drug-Nutrient Interactions Nutrient-Drug Interactions Food-Drug Interactions

2. Types of Interactions • Drug-Nutrient Interactions • Effect of a medication (Both prescription and OTC medications ) on food or a nutrient in food • Nutrient-Drug Interactions • Effect of food or a nutrient in food on a medication Drug Nutrient Nutrient Drug

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

4. 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

5. Benefits of Minimizing Food Drug Interactions • 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

6. Nutrition Implications • Little chance taking a medication for a short time will affect your nutritional status • However, using some medications for months or years may affect your nutritional health • Changing diet to include more foods rich in vitamins and minerals is preferred to taking vitamin or mineral supplements

7. Drug-Nutrient Interactions • Medications, can affect nutrients by: • Decreasing food intake • Decreasing nutrient absorption • Slowing down nutrient production • Interfering with nutrient metabolism • Increasing nutrient excretion

8. Drug-Nutrient Interactions:Food Intake • Some medications can affect nutritional health by causing poor food intake due to: • Decreased appetite • Nausea or vomiting • Unpleasant taste or dry mouth • Gastrointestinal sores or inflammation However, nutritional health can be affected if decreased food intake persists

9. Drug-Nutrient Interactions:Food Intake • Examples: • Appetite suppressants are medications which affect food intake by depressing appetite • Several cancer medications and treatments may dramatically reduce food intake by causing: • Loss of appetite • Changes in taste perception • Nausea, vomiting • Dry mouth • Mouth and intestinal sores or inflammation

10. 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

11. Chemotherapy-Induced Oral Mucositis Oral complications of Radiotherapy

12. 2- Drug-Nutrient Interactions:Nutrient Absorption • Some medications can affect nutritional health by decreasing nutrient absorption due to: • Decreasing time in intestine • Altering stomach acidity • Damaging intestinal lining • Competing for absorption • Binding nutrients

13. 2- Drug-Nutrient Interactions:Nutrient Absorption • Examples: • Laxatives can cause food to move rapidly through the intestinal track which can decrease nutrient absorption • Antacids can lower stomach acidity which can may interfere with iron, folate and vitamin B12 absorption • Many cancer medications and treatments can damage the intestinal lining which can decrease nutrient absorption

14. 2- Drug-Nutrient Interactions:Nutrient Absorption (cont.) • Examples: • Some anticonvulsants can compete for absorption with folate resulting in decreased folate absorption • Some cholesterol lowering medications reduce cholesterol by removing bile acids • Bile acids are needed to absorb essential fatty acids and fat-soluble vitamins • As a result some cholesterol lowering medications can reduce absorption of fat-soluble nutrients

15. 3- Drug-Nutrient Interactions:Nutrient Production • Some medications can affect nutritional health by slowing down nutrient production • Vitamin K produced by bacteria in the intestine • Antibiotics kill harmful bacteria, but they can also kill helpful bacteria , Killing helpful vitamin K producing bacteria can result in decreased vitamin K production

16. 4- Drug-Nutrient Interactions:Nutrient Metabolism • Some medications can affect nutritional health by interfering with body’s ability to metabolize nutrients due to: • Affecting enzyme systems • Competing with enzyme systems

17. 4- Drug-Nutrient Interactions:Nutrient Metabolism • Examples: • Some anticonvulsants alter liver enzyme activity causing increased metabolism of folate, vitamin D, and vitamin K • Methotrexate resembles folate in structure and competes with enzymes that converts folate to its active form, this can result in folate deficiency

18. 5- Drug-Nutrient Interactions:Nutrient Excretion • Some medications can affect nutritional health by increasing nutrient excretion due to: • Decreased kidney reabsorption • Increased urinary excretion

19. 5- Drug-Nutrient Interactions:Nutrient Excretion • Diuretics remove excess fluid from the body • Some diuretics may also increase loss of potassium along with fluids • Large amounts of aspirin can cause increased loss of folate • Isoniazid, an antituberculosis medication, is similar in structure to vitamin B6 and induces vitamin B6 excretion • Since treatment is for 6 months, B6 supplements are routinely given to prevent deficiency

20. Food-Drug Interactions • Some foods or nutrients in food can also alter a medication’s effectiveness by: • Decreasing medication absorption • Interfering with medication metabolism • Interfering with medication removal

21. Absorption • 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

22. Nutrient Interactions:Medication Absorption • Some foods or nutrients in food can increase or decrease medication absorption by: • Decreasing stomach emptying • Binding to medications • Competing for absorption • Altering acidity Effectivness overdose effect the intended dose

23. 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

24. Food/Nutrient Effects on Drugs Absorption • Absorption of iron from supplements ↓↓ 50% when taken with food • Best absorbed when taken with 8 oz of water on empty stomach • Food may ↓↓ GI upset • If take with food, avoid bran, eggs, fiber supplements, tea, coffee, dairy products, calcium supplements

25. Nutrient Interactions:Medication Absorption • Medications are typically absorbed more quickly when the stomach is empty (1 hour before or 2 hours after eating) • Having food in the stomach typically will slow down a medications absorption

26. 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

27. Nutrient Interactions:Medication Absorption • Examples: • Dietarycalcium can bind to the antibiotic tetracycline making it unavailable for absorption • Amino acids compete for absorption with levodopa

28. Food/Nutrient Effects on Drugs • Absorption • 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

29. 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

30. Food/Nutrient Effects on Drugs • 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 meds with orange or cranberry juice can reduce stomach pH and increase absorption

31. Nutrient Interactions:Medication Absorption • Examples: • Acidity of food or beverage consumed with a medication can affect absorption • Some medications are better absorbed in an acidic environment • Other medications can be damaged by an acid environment, these types of medications are often available in coated forms to resist stomach acidity

32. 2. Distribution 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

33. 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

34. 3. Food-Drug Interactions:Medication Metabolism • Some foods or nutrients in foods may interfere with a medication’s metabolism or action in the body by: • Affecting enzyme systems • Interacting with medications • Having a similar chemical structure resulting in competition

35. Metabolism (biotransformation) • 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

36. 3. Food-Drug Interactions:Medication Metabolism • Examples: • Components in grapefruit juice • Inactivate enzymes that metabolize many medications which can result in increased medication levels • inhibits the intestinal metabolism (cytochrome P-450 3A4 enzyme) of numerous drugs (calcium channel blockers, HMG CoA inhibitors, anti-anxiety agents) enhancing their effects and increasing risk of toxicity; may interfere with the absorption of other drugs

37. 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

38. 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 • Aged and fermented foods • Contain a chemical called tyramine that interacts with a medication, monoamine oxidase inhibitor, which can result in dangerously high blood pressure

39. Vitamin KStructurally similar to the anticoagulant warfarin which can decrease the effectiveness of warfarin

40. 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

41. 4. Food-Drug Interactions:Medication Removal • Some food or nutrients in foods may interfere with removal of a medication from the body by: • Affecting enzymes involved in preparing medications for removal • Altering urine pH

42. Excretion • 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

43. Food-Drug Interactions:Medication Removal • Examples • Liver enzymes prepare medications for removal from the body • These enzymes require nutrients to work properly • If nutrients are not present the medication may stay active in the body longer than intended • Quinidine is excreted more readily in an acidic urine • Foods that cause the urine to be more basic, such as sodium bicarbonate, may reduce quinidine excretion

44. Drug Effects on Nutrition: Metabolism • 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

45. Drug Effects on Nutrition: Excretion • 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 Mg Ca K Ph

46. Pharmacogenomics • Genetically determined variations that are revealed solely by the effects of drugs • Affect only a subset of people • Examples include G6PD enzyme deficiency, warfarin resistance, and slow inactivation of isoniazid (IHN) or phenelzine

47. Slow CYP2D6 Metabolizers • CYP2D6 and CYP2C19 metabolize 25% of drugs including many antidepressants, antipsychotics, and narcotics • Slow metabolizers at risk for toxicity and adverse drug effects • Fast metabolizers have unpredictable response • Drug genotyping in future will help determine most effective meds for individuals

48. Many Medications • These are just a few examples to understand how medications and nutrients can interact, this is not indented to be a complete list of possible interactions • There are thousands of medications on the market and numerous new medications that come out ever year

49. Alcohol Interacts With Medications • Alcohol can adversely affect medications • Alcohol can slow down or speed up how the body metabolizes a medication • Medication action can be either intensified or reduced • In combination with some drugs will produce additive toxicity • In some cases, mixing alcohol and medications can be fatal • With CNS-suppressant drugs may produce excessive drowsiness, incoordination • Acts as gastric irritant; in combination with other irritants such as NSAIDs may increase chance of GI bleed

50. Nutrient Supplements • Nutrient supplements themselves can result in drug-nutrient interactions • In excessive amounts, vitamin and mineral supplements can act like drugs instead of nutrients • Nutrients in excessive amounts may: • Compete with other nutrients for absorption, transport or metabolism • Have a direct overdose effect