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    Old 07-13-2006, 06:42 PM   #1
    starship
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    Grapefruit

    I was wondering why grapefruit is not recommended to be taken at the same time as statins. Thanks.

     
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    Old 07-13-2006, 07:54 PM   #2
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    Re: Grapefruit

    not sure why, but I heard no grape fruit at all.

     
    Old 07-14-2006, 04:41 AM   #3
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    Re: Grapefruit

    I'm not sure of the mechanism, but it greatly enhances absorption, so more of the drug hits your blood stream more quickly. It also apparently slows the normal metabolism and clearance of the drug from the blood stream (it inhibits the action of at least one enzyme, CYP3A4, involved in the breakdown of some statins). Too rapid absorption, and prolonged elevation of levels in the blood stream has been indicated as increasing the risk of muscle side effects, or outright rhabdomyolysis (muscle wasting).

     
    Old 07-14-2006, 05:52 AM   #4
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    Re: Grapefruit

    starship,

    It takes LOTS of grapefruit to cause the interaction and it's very unlikely that a half grapefruit at breakfast would have any effect at all...a quart of juice during the day <yeccch> might though.

     
    Old 07-14-2006, 06:15 AM   #5
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    Re: Grapefruit

    It seems the frequency of eating grapefruit is key too. A case study in Neurology (2004, vol. 62(4)) reported on a woman, who went from healthy and exercising regularly, to true rhabdomyolysis in just 2 weeks (only aggressive treatment by the hospital avoided renal failure). She was on zocor, and had started, 2 weeks prior to the crisis, to eat a daily whole grapefruit with breakfast. So, the effects of frequent consumption seem to be cumulative.

    Also, the particular statin seems significant. Zocor (simvastatin) seems to be affected by grapefruit more then others (at least according to the UK's Medical products department, or whatever "MHRA" stands for).

    Last edited by Fathersson; 07-14-2006 at 06:16 AM.

     
    Old 07-14-2006, 08:24 AM   #6
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    Re: Grapefruit

    To put it simply if you are on meds AVOID grapefruit. The meds actually become supercharged, I think to the effect of 3 times the prescribed dose.

     
    Old 07-14-2006, 11:36 AM   #7
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    Re: Grapefruit

    Grapefruit juice is a cytochrome 450 3a4 inhibitor. Statins are a cytochrome 450 3A4 substrate/inhibitor. The 450 3A4 is the pathway by whch they are metabolized (broken down by the body for use). The 450 3A4 pathway is primarily by the liver. An inhibitor slows down the metabolism and breakdown of substrates. When you get too may things (medications) on the same pathway, they will not be able to broken down as completely and efficiently (time wise). If you have cars on a highway all wanting to get off at the same exit a backup will occur. The inhibitor creates more cars wanting to get off at that exit, with an even bigger backup. Each new dose provides even more cars on the highway which want to get off at that certain exit. With a resulting even larger backup. For an example Dilitiazem (a calcium channel blocker) is a 450 3A4 inhibitor as is the grapefruit juice. It cause sthe serum concentration of Lipitor to be increased by app. 3.9 times. Since there is a backup, its removal is slowed down, and also not completed by the time the next dose is to be taken. Therefore causing a builup of the statin in the blood. This is the same for the other statins. (or close). Some statins use mutiple pathways, (to some extent). There are also other 450 3A4 inhibitors... you can search, (cytochrome 450 3A4 inhibitors), to get the additional medications that can cause this problem. Blood oranges (not regular) are also in the same class as the grapefruit juice. I have seen where it takes a liter of grapefruit juice to cause this problem...but then, I also see different reports to avoid grapefruit juice. If you do eat a small amount of grapefruit each day, it might be wise to at least space it before your statin.

    Last edited by NHone; 07-14-2006 at 11:37 AM.

     
    Old 07-18-2006, 07:37 PM   #8
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    Re: Grapefruit

    I note that the manufacturer's literature on Pravachol does NOT proscribe consumption of grapefruit .

     
    Old 07-18-2006, 10:12 PM   #9
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    Re: Grapefruit

    Maybe this sounds dumb, but would grapefruit be a substitute for the statins- possibly without the side effects? Or would you have to consume so much it would leave you swimming in it? How about coming up with a med that compliments the grapefruit and let nature cleanse the cholesterol with minimal intervention?

    Ok - just thinking out loud here...

     
    Old 07-19-2006, 05:26 AM   #10
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    Re: Grapefruit

    I was thinking the same thing. Perhaps, since grapefruit POTENTIATES statins maybe a persone taking 20 mg. Lipitor could get by with 10 mg. if he has a pint of grapefruit juice every day.
    Who knows??...I'm sure the effect has never been quantified!

    Fran,
    As far as grapefruit alone though; just because both substances are broken down by the same route doesn't mean that both work in the same way.
    So I doubt that grapefruit alone has any antipilidemic qualities. Possible though!
    IF there was any evidence, I'm sure the Florida Grapefruit campaign would be shouting it from the rooftops and pictures of grapefreet would adorn every billboard the world over (even more than it is now! )

    Last edited by Lenin; 07-19-2006 at 05:31 AM.

     
    Old 07-19-2006, 06:30 AM   #11
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    Re: Grapefruit

    Lenin, I agree that it should not be a replacement for prescribed medications. I did look up studies on grapefruit however, and found a couple of small very recent studies that were done indicating the are benefits in grapefruit juice for lowering cholesterol.

    In one study they isolated the substance that causes increased absorption of statins - furanocoumarins. Apparently there is an intesinal enzyme (CYP3A,) which destroys the drug causing inadequate absorption, which leads to requiring an increased the amount of the active ingredient in the statin to maintain proper levels. They removed the furanocoumarins from the grapefruit juice and measured the amount of drug absorbed. It showed that there was no increase or interaction with the furanocoumarins-free grapefruit. There are going to be additional studies to see if furanocoumarins can be combined with the statins to reduce the dosage required. They are also going to consider the possibility of marketing grapefruit without the furanocoumarins.

    In the other study they looked at the effects of lowering cholesterol in patients who didn't respond significantly to statins. They found red and white grapefruit significantly reduced the lipids, with red being the most effective.

    These were very small studies, but it looks like there will be more coming soon.

     
    Old 07-19-2006, 06:35 AM   #12
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    Re: Grapefruit

    Quote:
    Originally Posted by Granny Fran
    Maybe this sounds dumb, but would grapefruit be a substitute for the statins- possibly without the side effects? Or would you have to consume so much it would leave you swimming in it? How about coming up with a med that compliments the grapefruit and let nature cleanse the cholesterol with minimal intervention?

    Ok - just thinking out loud here...
    I think you have to be very careful too, about considering all statins as equals.

    The various statins available have some very profound differences in how they are transported to their sites of action, how they are transported to their sites of elimination, and the actualy metabolic pathway(s) involved in their elimination. Also, Some are taken in their active form, some are converted to their active form after being absorbed into the blood stream.

    This web site - [url]http://www.pharmgkb.org/search/[/url] is highly technical, but also will clearly show what I mean. Enter "statin" in the search box, and then you will get a page with links to schematics of their pathways of action and pathways of elimination.

    *sorry, can't just paste a link to the pathway schematics, since they are java script generated.

    Crestor, for example, is not metabolised at all by the pathway which includes the enzyme CYP3A4, so presumably, grapefruit should have no adverse affect for crestor users (I can't say - I take crestor, but I don't like grapefruit ).

     
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