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31 May 2020 

When Fruit & Medicine Don’t Mix


Issue 4 –Feb 2013

When a medicine enters the body, regardless of how it has been administrated, via its absorption, distribution and final elimination, it closely interacts with many elements and physiological systems within the body. Orally administered medications have the most interactions as they should be absorbed by the gastro-intestinal (GI) system. The physiologic condition of the stomach and intestine in addition to other medications, foods and beverages that are eaten before, con - current with, or after the administration are important factors affecting the level of medication absorbed. Some foods also influence the level of drug metabolism, by activating or deactivating the breaking down process. Lots of drug to drug, and food to drug interactions are known today and a lot more are discovered every day. One of the well known food to drug interac - tions is made by citrus juice and grapefruit in particular. Grapefruit juice interferes with the way the body absorbs and breaks medications. Citrus fruits contain molecules called furanocoumarins which affect drug metabolism by inhibiting the enzyme that breaks down almost half of all drugs. Furanocoumarins are present in grapefruit, Seville oranges, limes and pomelos, but sweet citrus fruits like naval and Valencia oranges do not have furanocoumarins. This enzyme is present in the lining of the gut and in liver. The furanocoumarins in grapefruit mainly inhibits the gut enzyme so the amount of absorbed drugs broken by this enzyme before absorption, will increase. On the other hand inhibition of the liver enzyme decreases the amount of metabolism and breaking down. These processes result in the presence of a more ac - tive drug in the body than necessary, which in some cases can be lethal. David Bailey, a clinical pharmacologist at the Lawson Health Research Institute in London, Ontario, discovered the interaction between grapfruit and medications 20 years ago. In November 2012 he said: “what I’ve noticed over the last four years is really quite a disturbing trend, and that is the increase in the number of drugs that can produce not only adverse reactions but extraordinarily serious adverse drug reactions. Between 2008 and 2012, the number of drugs in the list has gone from 17 to now 44.” He believes taking one tablet of some medications with a glass of grapefruit can be similar to take 20 tablets at a time. Popular prescription drugs which interfere with grapefruit are: cholesterol lowering medications, such as Atorvastatin; heart and blood pressure medications such as Diltiazem, Nicardipine, Losartan, Carvedilol, Digoxin; antidepressants such as Sertraline; benzodiazepines such as Diazepam and Triazolam. The amount of interaction depends on the kind of grapefruit (pink or white) and may continue up to three days from grapefruit ingestion. The impor - tant point to remember is that having grapefruit together with a regimen of any of the above medications is totally forbidden. Some other juices may interact with drugs too. Apple juice may reduce the amount of medication absorbed so contrary to grapefruit, apple juice will decrease the effects of the medication. Although studies are inconclusive, it is known that apple juice reduces absorption of some drugs, noticeably: fexofenadine, itraconazole, levofloxacin, ciprofloxacin, cyclosporine, atenolol and etoposide. It is advised to consume apple juice 4 hours before or after any of the above medications. People over 45 buy the most fruit juices and take the most prescription medications, so they are most at risk and should be careful. ... read more