Grapefruit and Kidney Disease, and Medications

Posted on Nov 29, 2012 | 0 comments

This image was selected as a picture of the we...

This image was selected as a picture of the week on the Farsi Wikipedia for the 22nd week, 2011. (Photo credit: Wikipedia)

I got a question this week about grapefruit and kidney disease. Recently in the news, a lot of information has come out about how medications and grapefruit juice or grapefruits interact. Some news even suggesting that they cause kidney damage or sudden death.

As a registered dietitian, I have known for many years that certain medications interact with grapefruit juice and it’s recommended to not consume grapefruit juice with these medications. That’s one of the reasons I know that many hospitals do not even place grapefruit juice on their menus, because of the myriad of medications that can be affected by it.

But let me take a moment and explain to you what the new research is showing and help you understand what it’s trying to say so that you can make a good decision about grapefruit and kidney disease.

The research shows that over the past four years since 2008, the number of medications with the potential to interact with grapefruits and cause serious adverse effects increased to 43 medications. Those serious adverse effects can include sudden death, acute kidney failure, respiratory failure, gastrointestinal bleeding, bone marrow suppression in people with compromised immune systems, kidney toxicity and other serious side effects. Here is the research article: http://www.cmaj.ca/site/misc/pr/26nov12_pr.xhtml

First of all, you should not take anything I say in this article as medical advice. You should discuss any medications you take with your Dr. What’s important to be aware of is that even a small amount of grapefruit juice or grapefruit can affect these medications. You may think that drinking a glass of grapefruit juice in the morning which is only about 4 ounces may not affect you. But the research has shown that the interaction can occur even if the grapefruit is taken in many hours before you take your medication. Even a small amount of grapefruit juice can affect how much of the medication is absorbed.

So what is happening with the grapefruit and your kidneys in this case?

Normally, these medications and the chemicals that are in them are only absorbed at about a 50% rate. So if it’s 100 mg of active ingredient, your body normally only absorbs about 50 mg of that medication or less. These drugs interact with an enzyme called CYP3A4 in the intestinal tract for absorption. The grapefruit juice you drink interacts with that enzyme and causes it not to be effective.

So suddenly, your body is able to absorb over 50% of that medication. So you’re getting more of the active ingredient then normal person would who didn’t drink grapefruit juice or eat a grapefruit. That’s where the damage can occur because your body has a higher concentration of that medication.  That medication in the higher concentration can affect your kidneys. Your kidneys process some of the drugs you take and make them inactive in your body so a larger amount of that drug may damage your kidneys by overwhelming the capacity that they have to inactivate medications.

Basically you took 100 mg pill and you absorbed over 50 mg (which is what your doctor expected you to absorb), and that amount can cause damage over time or if it’s a significant increase can cause damage fairly quickly. That is where the damage from grapefruit juice or grapefruits can occur – not with the juice itself, but with the interaction and increased absorption of the active ingredients of the medications.

A large amount of medications on the list that are affected by grapefruit or grapefruit juice ingestion and can affect your kidneys. The link to that list is here. Go there and check and see if you take any medications that are on the list.

The list contains medications that are anti-cancer agents, anti-diabetic agents, anti-infective agents, anti-inflammatory agents, anti-lipemic agents, cardiovascular agents, central nervous system agents, estrogens, gastrointestinal agents, immunosuppressant agents, and urinary tract agents.

As always, I recommend that if you feel you have concerns about this, to talk to your doctor immediately. I would recommend calling your doctor’s office and letting them know that you’ve heard about this and that you do drink grapefruit juice and you take one of these medications that is on the list, and you’re concerned. I hope this has been helpful to you and explained a little bit about what’s going on.

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