Grapefruit Juice

Factual Questions
1

I’ve been reading quite a bit lately about the dire consequences of taking meds with grapefruit juice. I don’t understand the dynamics though and am hoping someone can answer a pointed question here.

Sometimes I have nasty bouts of sciatica. For this pain, I’ve been prescribed the catch-all goodie - Vicodin.

How does grapefruit juice interact with hydrocodone? Would I be (in theory) able to reduce actual dosage if ingested with grapefruit juice? Or, on the other hand, would I have to take more medication than indicated to relieve a level 7 pain?

I understand that it works in a bad way with some medications. It would be great though, if I could reduce the amount of script being taken if the juice would accelerate the pain relief.

As always, TIA!

2

First, I’m not a pharmacist, and this is not medical advice in any way. However, I do work in a pharmacy, so I know a “little” about this. I’ll respond now till someone more knowledgable comes around.

I have not heard of grapefruit having any effect on Hydrocodone/APAP. There are some medications where having grapefruit at the same time would be very bad, but they are a totally diffrent class of medications. In the pharmacy I work at, we have those nice little yellow stickers we put on the drug vials to warn you, and there is not one on Hydrocodone.

3

From what I’ve heard, if your medication does interact with grapefruit juice, you should never be deliberately using that effect to get more or faster effects from your medication, any more than you should take more of your medication than you were prescribed. You can end up with some fairly nasty side effects from doing that.

4

Grapefruit inhibits the action of liver cytochrome p-450 3A4, while hydrocodone is metabolised primarily by liver cytochrome p-450 2D6. CYP 3A4 does play a lesser role though, so there might be some effect from drinking grapefruit juice.

5

This thread has some helpful links.

Here is a link to a concise overview of grapefruit interactions with medicines.

6

Nice cites, Doc. :cool:

7

I have been prescribed Cyclosporin and was told at the time that grapefruit juice would cause large and random fluctuations in the amount of the drug that would reach my bloodstream. Grapefruit juice doesn’t sound like something you could use with any consistent effect.

BTW, what exactly is it in grapefruit juice that causes these problems? Is there any risk from eating other citrus fruit?

8

Grapfruit juice, but not other citrus fruits, contains substances called furanocoumarins. It is these that screw up the enzymes involved in breaking down certain drugs (see prvious link). Actually, they cause a lot of their mischief by increasing the absorption of certain drugs from the intestine, rather than preventing the drugs from being broken down, and thence building up in the blood stream.

That being said, there is some evidence that other citrus juices other than grapefruit, may possess similar activity. Here is a recent, albeit jargon-filled, abstract on the question. But, again, AFAIK, there are no clinically relevant reports of any citrus fruit or juice causing meaningful problems.