Simvastatin and Grapefruit

Simvastatin Grapefruit Juice: There is a great deal the literature about the widely known effects of grapefruit juice on many medications.  Simvastatin and grapefruit juice is among the more common drug interactions in this category.  Grapefruit juice alters the bioavailability of simvastatin by inhibition of the CYP 3A4 in the small intestine which normally breaks down a percent of the simvastatin making it less bioavailable.  This inhibition of the CYP 3A4 enzyme in the small intestine by grapefruit juice is irreversible and its affect may last up to 72 hours.  The consequence of this is that a person cannot take grapefruit juice at one time during the day and safely take the simvastatin at a separate time of the day.  This is especially important to know because many people during grapefruit juice with breakfast in most physicians recommend taking the Staton medications like simvastatin at the evening meal or at bedtime.

Fortunately simvastatin is available as a generic medication making it an affordable option for most patients.  It is also among the more potent of the Staton medications and it’s unfortunate that patients taking simvastatin should avoid drinking grapefruit juice.

There’s a lot of misunderstanding about the simvastatin grapefruit juice interaction.  This misunderstanding is largely related to not recognize the irreversible nature of the CYP 3A4 inhibition by grapefruit juice.  Advice that is separation in timing of ingestion of simvastatin grapefruit juice alleviates the concern is not felt to be valid advice.  Simvastatin side effects may be significantly increased in patients who drink grapefruit juice.  Alternative Staton medications like Crestor and pravastatin are not metabolized by the CYP 3A4 enzyme and so are not affected by grapefruit juice.  Lipitor on the other hand is metabolized by the CYP 3A4 enzyme and so should not be taken with grapefruit juice.  If you have any experience with simvastatin and grapefruit, please share in the comments with the other readers.