Discussions that mention simvastatin

General Health board


Just a "heads-up" for all here that use grapefruit juice on their diets and take medications. Please check with your pharmacist to see if you should NOT be washing down your meds with grapefruit juice. Grapefruit juice alters the effect of some medications. Please read below:
A cold glass of grapefruit juice is part of the morning routine for a lot of people. What many do not realize, however, is that this same juice might interact with drugs they are taking.

The interaction between grapefruit and some medications was discovered by accident when researchers were looking for an interaction between a particular blood pressure medicine and alcohol. Grapefruit juice was used as a vehicle to mask the taste of the alcohol. While the alcohol did not affect the amount of the drug circulating in the body, the grapefruit juice greatly increased the levels of the medication.

It is thought that one or more of the chemicals (most likely flavonoids) in grapefruit juice alter the activity of specific enzymes (such as CYP3A4 and CYP1A2) in the intestinal tract. These enzymes decrease the amount of certain drugs which enter the systemic circulation. This could allow a larger amount of these drugs to reach the bloodstream, resulting in increased activity and possibly toxicity.

Some of the drugs which interact with grapefruit have a narrow therapeutic index. This means that the amount needed for the desired effects are not much lower than the amount that can cause toxicity. In this type of medication even a moderate increase in blood levels could cause harm.

Some other medications which may be affected by grapefruit juice include midazolam (Versed®), cyclosporin (Sandimmune®, Neoral®), lovastatin (Mevacor®), simvastatin (Zocor®), and caffeine. You should realize that this list is not a complete list just some examples of possible interacting drugs.

Certain prescription antihistamines could also be affected by grapefruit juice. Astemizole which is in Hismanal® and terfenadine which is in Seldane® and Seldane-D® are impacted by the CYP3A4 enzyme system. With these particular medications, increased drug levels could be associated with arrhythmias which could be fatal. In fact there has been a published report of a terfenadine related death where grapefruit juice was thought to have been a factor.

Erythromycin, itraconazole (Sporanox®), ketoconazole (Nizoral®), mibefradil (Posicor®), and some other drugs also inhibit CYP3A4. If you are taking a medication which should not be taken with one of these drugs, the safest course of action is to assume that it would interact with grapefruit juice, also. An example of this is cisapride (Propulsid®), which is used to treat certain gastrointestinal problems.

Some other medications which may be affected by grapefruit juice include midazolam (Versed®), cyclosporin (Sandimmune®, Neoral®), lovastatin (Mevacor®), pravastatin (Pravachol®), and caffeine. You should realize that this list is not a complete list just some examples of possible interacting drugs.

If you drink grapefruit juice regularly, it would be a good idea to inquire about its possible interaction with any medications you may be taking or any new drugs which are added. Some sources recommend not ingestion grapefruit juice within 2 hours before and 5 hours after a drug which may interact with it. A safer approach would be to substitute another citrus juice, such as orange juice, which has the same vitamins but has not demonstrated the drug interactions. Remember that eating grapefruit or taking grapefruit supplements may also interact with the same medications since the flavonoids could be present in these, as well. You should also be aware that some drinks which are flavored with fruit juice could be flavored with grapefruit juice even if grapefruit is not part of the name of the drink. Check the label for the ingredients, if you are not sure.