Posted by SLS on October 18, 2002, at 15:44:26
In reply to Re: lexapro and grapefruit, posted by Mystia on October 13, 2002, at 11:49:23
Hi.
Grapefruit interactions do not extend to all of the SSRIs. Such a generalization is not justified.
Prozac, Zoloft, and Paxil do not react with grapefruit juice. The only SSRI I know of for which this is a problem is Luvox (fluvoxamine), whose main metabolic pathway uses CYP3A4. The culprit substance in grapefruit that affects the levels of many drugs is a cytochrome enzyme known as CYP3A4. Lexapro (escitalopram) does not use this enzyme exclusively for its metabolism.
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"After normalization for hepatic abundance, relative contributions to net intrinsic clearance were 37% for CYP2C19, 28% for CYP2D6, and 35% for CYP3A4"
[Escitalopram (S-citalopram) and its metabolites in vitro: cytochromes mediating biotransformation, inhibitory effects, and comparison to R-citalopram.]
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I think it would be a good idea to investigate this matter further by perhaps calling Forest Labs to get accurate information. From what I see, though, I don't think there should be a problem with combining Lexapro and grapefruit juice.
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"These findings suggest that there is a low potential for interactions between escitalopram and other agents that inhibit CYP3A4."http://www.nimh.nih.gov/ncdeu/abstracts2001/ncdeu3021.cfm
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"We investigated the inhibitory activity of the furanocoumarin derivatives from grapefruit juice to the drug metabolizing enzyme, cytochrome P450 (CYP) 3A4. Although two known furanocoumarin dimers GF-I-1 (1) and GF-I-4 (2) showed potent CYP3A4 inhibition with IC50 value of 0.07 microM, a semi-synthetic dihydroxybergamottin caproate (11), which was more stable and more simple than the dimers, exhibited comparable activity against CYP3A4."
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"Grapefruit juice, a beverage consumed in large quantities by the general population, is an inhibitor of the intestinal cytochrome P-450 3A4 system, which is responsible for the first-pass metabolism of many medications. Through the inhibition of this enzyme system, grapefruit juice interacts with a variety of medications, leading to elevation of their serum concentrations."
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poster:SLS
thread:123438
URL: http://www.dr-bob.org/babble/20021012/msgs/124143.html