by Sudesh Samuel

Created on: January 06, 2009

A drug-food interaction occurs most commonly when the consumption of a specific food or beverage affects the activity of a drug or consumption of the drug affects the activity of the food or overall nutritional status.

When a food alters a drug's activity or vice versa, the affected compound is changed in aspects of how quickly or how much of it gets absorbed into the body, how much of it distributes to it's site of action, and how quickly it gets broken down or passed out from the body. Such drug-food interactions may result in the individual experiencing side effects, toxicity or not getting full benefit from the drug or food.

In altering the absorption of drugs, foods may bind with the drug, change the acidity of the stomach, moderate the contractions of stomach muscles or change the speed at which stomach contents move through the body. Dietary fibre in the form of pectin and other soluble fibres can slow down the absorption of Tylenol (acetaminophen). Almost half of a single dose of the antibiotic Zithromax (azithromycin) does not get absorbed when it is taken with food. When another antibiotic ciprofloxacin is taken with iron, a complex is formed and about half of a single dose also becomes unavailable for absorption. One of the most significantly food-affected drugs is Fosamax (alendronate) where up to 99.9% of an oral tablet can become unavailable for absorption if taken with food, coffee or orange juice. Sometimes increased benefit is derived from taking certain medicines with food. Taking the statin Mevacor (lovastatin) with food enhances it's absorption while taking non-steroidal anti-inflammatory drugs like aspirin with food can help to reduce stomach irritation.

Different drinks can alter the breakdown of a drug in the body. Components of grapefruit juice can inhibit enzymes in the liver from breaking down a variety of drugs. Taking grapefruit juice while on the heart drug felodipine results in much less of the drug broken down and this can cause lower blood pressure and faster heart rates than otherwise expected. The heart drug Inderal (propranolol) can escape early breakdown in the liver when it is taken with food hence it's effectiveness could be increased.

One important class of drugs known as monoamine oxidase inhibitors (MAOIs) can inhibit body enzymes from breaking down a compound known as tyramine. This compound can be found in aged cheese, pickled fish, yeast extracts, red wine, fava beans and fermented products, and can accumulate in the

• 1
• 2
• Next Page >>