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Linda asked...

Statins and grapefruit

I understand that when taking statins you should avoid grapefruit juice. Does this also apply to the actual grapefruit? The atorvastatin leafleft says 2no more than two small glasses of grapefruit juice a day", wheras the simvastatin leafleft says "avoid grapefruit juice." Can you clear up this point please. Haveing eaten grapefruit daily for most of my life, I would like to be able to continue, even though I am on statins.

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The answer

I agree that on the surface the information on Atorvastatin and Simvastatin patient information leaflet can be confusing and seem conflicting.

However, as you may be aware the statins are metabolized by the liver. Any changes in the liver enzymes can affect the exposure to the statins. Grapefruit juice is a potent inhibitor of the liver enzyme cytochrome P450 3A4.This action stops certain drugs including statins from breaking down. This action increases the exposure of the statins and other drugs. This means that the body behaves as if you have taken a much bigger dose than you have so increases the risk of side effects such as muscular aches and weakness.

Grapefruit juice mainly inhibits intestinal enzyme CYP3A4 with only minimal effects on liver enzyme CYP3A4.  Grapefruit juice is thought to inhibit some drug transporter proteins. Grapefruit contains naringin, which degrades during processing to naringenin a substance known to inhibit CYP3A4 enzyme. Naringin is not present in any other citrus fruits. This fact has led to the assumption that the whole fruit will not interact but processed grapefruit juice will.

However, in practice some reports have suggested both the whole fruit and grapefruit juice will interact.

The current information is that when taken at the same time, large amounts of grapefruit juice markedly to very markedly increase simvastatin exposure, and also moderately increase atorvastatin exposure. This accounts for the differing advice on the patient information leaflet for atorvastatin and simvastatin.

Greater exposure means that Simvastatin and Lovastatin are in the body at much higher level and for longer period of time when grapefruit juice is consumed at the same time as taking simvastatin and lovastatin than when grapefruit juice is not consumed.

Having smaller amounts of grapefruit juice and separating it from simvastatin by 12 hours have lesser effect. 

Pitavastatin and pravastatin seem not to be affected by grapefruit juice, but orange juice appears to slightly increase the absorption of pravastatin. 

An isolated case describes rhabdomyolysis in a patient taking simvastatin after starting to eat grapefruit, and another case occurred in a patient taking rosuvastatin after starting to drink pomegranate juice.

In summary the information available suggested it is better to avoid the whole grapefruit and grapefruit juice or minimise the amount you consume, as indicated in the patient information leaflet no more than two glasses of grapefruit juice. There is no evidence based data about how much of the whole fruit can be consumed before interaction becomes a problem.

Answered by the Health at Hand nurses  

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