FDA Warning: Don't Mix Meds With Grapefruit

FDA released a statement today saying that grapefruit juice can cause drug poisoning in certain circumstances.  Specifically, the FDA warns against taking any kind of medication with grapefruit juice, especially the following.
Chemical wan: what's in your gullet?*
  1. Some statin drugs to lower cholesterol, such as Zocor (simvastatin), Lipitor (atorvastatin) and Pravachol (pravastatin)
  2. Some blood pressure-lowering drugs, such as Nifediac and Afeditab (both nifedipine)
  3. Some organ transplant rejection drugs, such as Sandimmune and Neoral (both cyclosporine)
  4. Some anti-anxiety drugs, such as BuSpar (buspirone)
  5. Some anti-arrhythmia drugs, such as Cordarone and Nexterone (both amiodarone)
  6. Some antihistamines, such as Allegra (fexofenadine)
The science  Here's why.  Many drugs are metabolized in human intestines with the help of a vital enzyme called CYP3A4. Certain substances in grapefruit juice block the action of CYP3A4.  So, instead of being metabolized, more of the drug enters the bloodstream.  There, it stays in the body longer.  Since dosage is calculated assuming a certain amount of the drug, if not all of it, will be eliminated from the body in a certain time frame, the next dose adds onto the last, and the quantities accumulate in ways unintended.

The result: potentially dangerous levels of the drug in the body.  At a minimum it stresses the liver.

The amount of the CYP3A4 enzyme in the intestine varies from one person to another, says FDA. Some people have a lot, and others have just a little—so grapefruit juice may affect people differently when they take the same drug.  It's an experiment, of sorts.

Food for thought  There's more to this story, such as the fact that grapefruit juice reduces the effectiveness of fexofenadine, a key chemical in Allegra (among similar drugs).  Further: apple juice and orange juice also reduce the effectiveness of fexofenadine.  Eventually we'll talk about better chemical mixture labeling.  Allegra for instance bears a label that says, "Do not take with fruit juices."

For years, we've been hearing from pharma and chemical companies that "everything is made up of chemicals, anyway."  True, and it makes lab-created chemicals seem more benign if you consider that a grapefruit is also a chemical cocktail.  But these new studies complicate the matter.  Showing that indeed an innocent grapefruit is in fact a chemical mixture -- and so is the human digestive system -- and so is the pill we pop.  Suddenly it doesn't sit so well when we think about the crazy lab experiments going on inside our bellies.

Need some TUMS just thinking about it.

But then, what are the chemical ingredients in TUMS..?

Read more about grapefruit and medications on the FDA site:  

*couldn't resist that caption..

Kathleen Hurley