Should you avoid drinking grapefruit juice while taking azithromycin?

Answer 1

Grapefruit has a lot of Vitamin C plus some enzymes that seem to speed up things . (For a while back in the 60's- grapefruit was thought to be a fat burner. )

Some antibiotics i.e. Erythromycin and other drugs which are in this class (the Not Pencillins) do not mix well at all, especially with Garpefruit. So those of you who take Erythromycin because of your pencillin Allergies should be careful; especially when taking megadoses of Vitamin C or eating grapefruit.

The end result is your liver gets a big buildup of drugs it cannot handle - you are actually poisoning your self because the drugs are not working properly.

Here is the science: Erythromycin competes - It does the exact same thing as Vitamin C: it inhibits the cytochrome P450 system, particularly the CYP3A4 isozyme, which can cause it to affect the metabolism of many different drugs, not just Vitamin C.

I am not the pharmacist- just a smart nutritionist student who knows biochemistry. When I graduate I will sign this. In the meantime you are provided with the following

quoted directly from a professional source D.McAuley,

with references GlobalRPH.com

His site is a great study guide as well. Just always give him credit because he has copyrighted the site.

" Grapefruit juice is a potent inhibitor of the intestinal cytochrome P-450 3A4 system (specifically: CYP3A4 - mediated drug metabolism) which is responsible for the first-pass metabolism of many medications. This interaction can lead to increases in bioavailability and corresponding increases in serum drug levels.

In many cases, the increased serum drug levels can produce some readily observable symptoms. Here are a few examples of adverse effects that are possible when the following medications are taken concurrently with grapefruit.

(1) Excessive sedation: benzodiazepines.

(2) Increased risk of rhabdomyolyis: HMG-CoA reductase inhibitors (statins)-- there are some exceptions.

(3) Symptomatic hypotension: dihydropyridine calcium antagonists (some exceptions exist). (4) QT interval prolongation: astemizole, cisapride, pimozide, terfenadine. "Drug interactions may be most apparent when patients are stabilized on the affected drug and the CYP3A4 inhibitor is then added to the regimen." 5

CONVERSELY THE VITAMIN C THAT IS FACILITATED BY THE ENZYMES IN GRAPEFRUIT IS NOT ALL BAD>>>> the problem is that the drugs you take work on the same enzyme activation sites or pathways and only one thing can work well at a time or in the case of some drugs like the heart medicines the heartbeat is sped up or slowed down which is NOT what the doctor ordered when he put you on the medication.

There may be some pharmacological advantages to this interaction. If the interaction is taken into account during the initialization of drug therapy it is possible to decrease drug dosages. This concept can be applied to cyclosporine therapy. If a patient regularly consumes grapefruit, lower dosages of cyclosporine will be required, which will lead to lower drug costs.

IN CONCLUSION

Grapefruit juice is not the only inhibitor of this enzyme system. Other drugs which have a similar effect include: clarithromycin (Biaxin ®), erythromycin (E-Mycin ®, others), itraconazole (Sporonox ®), ketoconazole (Nizoril ®), nefazodone (Serzone ®), and ritonavir (Norvir ®). "

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Lilja JJ, Kivisto KT, Neuvonen PJ. Duration of effect of grapefruit juice on the pharmacokinetics of the CYP3A4 substrate simvastatin. Clin Pharmacol Ther. 2000 Oct;68(4):384-90.19.

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© D.McAuley, GlobalRPH.com 2001

Answer 2

Grapefruit interrupts some of the important enzymes in the liver from metabolizing several medications.