Drug Food Interactions

I’ve had a request to explain a couple of the most common drug/food interactions I see. There were two that immediately popped into my mind:

1. Statins(Zocor-simvastatin, Lipitor-atorvastatin, etc.) are some of the most widely used drugs in the US and there is an interaction with grapefruit juice. Different clinicians tend to manage this in different ways, and really management of this interaction should be done on a case by case basis. If a patient is adamant that they have grapefruit juice (I have seen them) – what do you do? Should a statin be stopped because of this? I don’t believe so unless strong evidence exists that indicates potential for harm. The result from this interaction is that it increases the amount of the statin in the body. Lexi-comp essentially states that if grapefruit juice will not be avoided, the patient should limit their intake to less than 7-10 ounces per day (about a cup). In my opinion, if you do decide to continue to take grapefruit juice with the guidance of your pharmacist/doctor, small quantities are the way to go.

2. Vitamin K is essential for the formation of clotting factors and in the end, essential for the formation of clots. It is widely found in various foods (i.e. green leafy vegetables etc.) I’ve heard individuals say that vitamin K should be avoided if you are taking Coumadin (warfarin). This is simply not true. A variance in vitamin K intake can affect your INR however. It’s important that you be consistent in your vitamin K intake if you are on Coumadin. More than your usual intake and your INR will be low. Take in less vitamin K than normal for a few days/weeks, your INR will be higher.


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Written By Eric Christianson

January 8, 2014

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