Can I eat grapefruit when taking levothyroxine, warfarin, cyclobenzeprine, and sertraline?
Question posted by sueannfisher on 7 March 2010
Last updated on 29 September 2011
The only one drug I found that could go eith way depending on the article was Warfarin. Here is a list below written by different people and companies. I hope this helps.
Grape fruit juice is known to change the absorption or metabolism of many different drugs. Although ingestion of grape fruit juice produces small changes in the absorption of thyroid hormone, it does not seem likely that regular ingestion of grapefruit juice will significantly affect the absorption or metabolism of thyroid hormone in patients taking L-thyroxine
Avoid grapefruit as well. Grapefruit can slow down metabolism of a wide variety of drugs by the liver.
Grapefruit has the potential to interact with warfarin by inhibiting its metabolism.8 Warfarin contains two racemic mixtures, S-enantiomers and R-enantiomers.9 CYP450 isozymes 1A2 and 3A4 are the principal isozymes for metabolizing the R-enantiomer.10 Isozyme 2C9 is the principal isozyme for metabolizing the more potent S-enantiomer.11,12 Other metabolic pathways include CYP2C8, CYP2C18, and CYP2C19.9
Grapefruit has been found to inhibit the 1A2 and 3A4 isozymes, thus repressing warfarin metabolism.13-15 Literature suggests that grapefruit's components naringin, naringenin, and bergapten are responsible for this inhibition.
Preliminary evidence suggests that grapefruit juice may inhibit cytochrome P450 1A2. Currently, this interaction has not been reported in humans. Drugs metabolized by cytochrome P450 1A2 include amitriptyline, clomipramine, clozapine, cyclobenzaprine, haloperidol, naproxen, ondansetron, propranolol, theophylline, and verapamil.
Sertraline (Zoloft) is increased by 50% by a single glass of juice. The significance is unclear for sertraline, and could be helpful in terms of the effects, but could also increase side effects.
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