Drug Interactions and Grapefruit Juice Study

Food-Drug Interactions

• Food and drugs can interact, altering how a drug acts in the body
• A drug-nutrient interaction is when a drug and a nutrient together cause a different effect than when they are given separately.
• A food-drug interaction is a broader term, including drug-nutrient interactions and how a medication affects nutritional status.
• Examples of drug-nutrient interactions include Zantac (ranitidine) decreasing vitamin B12 absorption and tetracycline decreasing drug absorption when taken with dairy.
• Patients with chronic diseases, elderly individuals, fetuses, infants, and pregnant women are at risk for food-nutrient interactions. Also, individuals with allergies or intolerances.

Food and Pharmacokinetics

• Absorption: Food can interfere with drug absorption if taken around the same time.

  • Iron absorption from supplements is reduced by 50% when taken with food.
  • Iron is best absorbed with 8 oz of water on an empty stomach.
  • Food can cause gastrointestinal upset.
  • Avoid bran, eggs, fiber supplements, tea, and coffee when taking drugs with food. Calcium supplements should also be avoided.
  • Ciprofloxacin and tetracycline form insoluble complexes with calcium in dairy products or foods
  • Also affects zinc, calcium or magnesium, zinc or iron, and aluminum in antacids.
  • Stop unnecessary supplements during drug therapy or give the drug either before or 6 hours after the mineral.

• Metabolism: Some food and nutritional supplements alter how the body processes drugs:

  • Fat-soluble compounds are metabolized by cytochrome P-450 enzymes.
  • Water-soluble compounds are excreted.
  • Grapefruit can affect the metabolism of certain drugs; leading to a rise in drug blood levels.

• Distribution:

  • Lower albumin levels in the body can increase the availability of drugs to tissues.
  • This makes drugs more potent.
  • Lower doses are generally recommended for persons with low albumin
    • Warfarin is highly protein-bound in the blood
    • Low albumin can result in poor activity
    • Phenytoin is highly protein-bound in the blood
    • Low albumin can result in poor activity
    • Obese or elderly individuals have more adipose tissue; fat-soluble drugs can accumulate in the body, increasing the risk of toxicity.

• Excretion:

  • For example, high sodium diets can increase the amount of lithium excreted.
  • This requires a higher dose of the product.

Grapefruit and Antibiotics

• A 2001 study in the "European Journal of Clinical Pharmacology" showed that grapefruit juice can amplify specific medication effects, such as erythromycin.
• A 2007 study in the "British Journal of Clinical Pharmacology" found that grapefruit juice can interact with clarithromycin, increasing blood glucose levels.
• Terfenadine (an antihistamine ), was removed from the market after unexpected deaths caused by interactions with grapefruit juice.
• The effects of grapefruit juice on medications can last for over 24 hours, meaning that grapefruit must be avoided during treatment even if medication is only taken once per day.
• Drugs listed below are known for interacting with grapefruit juice: alprazolam, amiodarone, atorvastatin, carbamazepine, cilostazol, clarithromycin, colchicine, dronedarone, erythromycin, felodipine, fentanyl.

Other Food-Drug Information

• List of foods with mucilage: line seeds, psyllium, aloe vera, okra, figs, agar-agar (algae), fenugreek, marshmallow root
• Mucilage should be accompanied by a sufficient intake of liquids (1.5-2 liters daily). Insufficient water intake can lead to flatulence.
• Linseed should not be used in cases of intestinal obstruction.
• It should not be used in children under the age of 12.
• Mucilage-containing products can inhibit the absorption of other drugs (iron, lithium, etc.) in the gastrointestinal tract, so there should be a gap between taking these.

Tea and Drug Interactions

• Different types of medications react to tea consumption, and individuals need to be cautious when mixing.
• Important note: Consult with a health professional for specific advice on tea and drug interactions as reactions vary widely.

Other Drug/Food Interactions

• Ginger should not be used by individuals with peptic ulcers.
• Excessive ginger intake may cause heartburn.
• Ginger may increase the effect of blood clotting medications such as warfarin, aspirin, and clopidogrel.
• Turmeric can have a similar effect to ginger, affecting blood clotting medications.
• Garlic can also increase effects on these same medications as ginger.

Food Sources of Specific Nutrients

• Seafood is a good source of selenium for white blood cell production.
  • Low selenium levels can be linked to an increased liver cancer risk in individuals with hepatitis B and/or C.
• Seafood is rich in zinc, which supports immune system function.
• Seafood is a good source of iron and vitamin B which are important for the immune system.
• Seafood includes omega-3 fatty acids (such as salmon, herring, and mackerel) that benefit the respiratory system.
• Chicken soup, with added garlic and onion, demonstrates immune-boosting effects.
• Cysteine, also included in chicken soup, can help the body combat viruses.

Other Interesting Points

• Eating yogurt with live bacteria can help improve health by stimulating the production of white blood cells, which ward off diseases.
• Green tea contains catechins, antioxidants that are more potent than vitamins C and E, and vitamin K, a nutrient that can decrease warfarin effects.

Specific Drug Categories

• Different categories—anti-infectives, antineoplastics, bronchodilators, cardiovascular drugs, stimulants—can affect appetite
• Psychotropics such as antipsychotics can increase appetite
• Some medications affect oral taste or smell
• Some medications may cause gastrointestinal effects

Specific Drug Interactions

• Some drugs, such as alendronate, need to be taken with a period of sitting upright to prevent esophagitis.
• Aspirin or other NSAIDs may cause gastrointestinal bleeding or gastritis
• Orlistat blocks fat absorption

Explore the interactions between grapefruit juice and various medications, particularly focusing on clarithromycin. This quiz covers the effects of grapefruit juice on drug metabolism and the implications for patients taking certain medications. Test your knowledge on the specifics of these interactions and their clinical relevance.