Comments on: Grapefruit juice might boost cancer drug’s effects

By: paula

paula — Fri, 01 Apr 2011 14:17:32 +0000

I found sucking a wedge of cold grapefruit was a brilliant cause for nausea while on chemo (FEC100 and Taxotere/ Docetaxel. It stopped me feeling yeuky literally seconds after ingesting it. My mum gave me this tip as it worked for her when she had chemo in the 1970s.(I know there are some chemo combinations + clinical trials of new anti-cancer drugs where is it not advised.)

By: Argon

Argon — Thu, 30 Apr 2009 21:52:32 +0000

“Grapefruit juice contains enzymes that break down common types of compounds of which pharmaceuticals are made. This means that if you drink grapefruit juice along with some drugs, the effect of the drug will be enhanced.”

???!!! It might be good to fix that info.

By: llewelly

llewelly — Thu, 30 Apr 2009 10:12:25 +0000

And how did you convince it to pee in the like bottle???

If an ape thinks you’ll be drinking out of the bottle, he’ll be more than happy to pee in it. Whether you want him to or not.

By: David

David — Thu, 30 Apr 2009 09:17:17 +0000

Nathan, I have no particular knowledge of why the authors of the cited study did what they did. I think adding intestinal CYP inhibitors to a drug regimen is probably a bad idea, potentially leading to erratic and unpredictable changes in pharmacokinetics. I’m currently working on several drug programs involving CYP 3A4, and I generally require trial participants to avoid potent inhibitors. It just seems safer that way.

That said, there have been some serious attempts at this approach, see Thisted et al Clin Ther 2006

By: Nathan Myers

Nathan Myers — Thu, 30 Apr 2009 01:44:51 +0000

David: Thank you for the education. Should we assume that the trials with grapefruit juice really are preliminary to putting the appropriate enzymes in the pill?

By: Kamel

Kamel — Wed, 29 Apr 2009 23:27:41 +0000

Greg, I’ve forwarded this post to the host for this month’s Cancer Research Blog Carnival (http://cancer-carnival.blogspot.com) that will be appearing on Friday. Hope you don’t mind.

By: samantha

samantha — Wed, 29 Apr 2009 20:30:38 +0000

I have several medications that say to avoid grapefruit juice (halcion, fentanyl).
For the life of me, I’ve never understood why we’re paying through the ass for ritanovir to boost other protease inhibitors by inhibiting CYP450 3A4 when 3A4 inhibitors have to be a dime a dozen. I like the ruby red + would greatly prefer to drink that than take a dinosour-sized Norvir twice a day.

By: Benjamin Geiger

Benjamin Geiger — Wed, 29 Apr 2009 20:16:52 +0000

I absolutely abhor grapefruit juice, and my body tends to agree (it gives me canker sores). But, if it’s to save thousands of dollars per month, I’d put up with some daily nastiness. In any case, it tastes infinitely better than MoviPrep.

What are the odds that someone will research and sell the enzymes in question in pill/gelcap form?

By: Greg Laden

Greg Laden — Wed, 29 Apr 2009 20:13:53 +0000

That is an un-copyrighted US government photograph of grapefruit. I labeled it with the purely mercenary hope that it would get picked up by Google Image for anyone searching for grapefruit pictures, who would then discover my blog. Like the chicken picture.

Ape piss is an Africanist archaeologist expression. Someday I’ll tell everyone the ape piss story.

By: David

David — Wed, 29 Apr 2009 20:12:43 +0000

I work for a pharma company, but not one that makes chemotherapy.

Cytochrome 3A4 is a notorious pain-in-the-a.., especially for drugs with serious toxicities, and hence, a narrow therapeutic index. Most chemo drugs are dosed within very narrow limits, and getting the dose right is the difference between life and death. There is huge population variability in the level of activity of Cyp3A4, but there is also huge variability in the responsiveness to 3A4 inhibitors. Grapefruit juice in general is a good inhibitor of gut cytochrome, not so much hepatic cytochrome. So the effect depends on the amount of grapefruit juice in the gut at the time the chemo drug is being absorbed. Consider that the level of grapefruit juice in the gut would go up and down during the course of the day, effected by variables like diet and activity, so the clearance rate of the chemo drug would become highly variable hour-by-hour. This is a nightmare. I can see how they can get impressive results in the setting of a phase 1 drug study, where all the variables are controlled. But in real life this is strikes me as a really really high-risk idea. For “really high-risk” you can substitute “stupid” (keep one of the reallys).

Nathan, hate to burst your pharma-bashing bubble, but if drug companies could get the same effect out of a lower dose, they would be lowering their cost-of-goods. If I had a cheap way of putting out pills that were equally effective at lower costs, my profit would go up.

Drugs aren’t priced by how much they cost to manufacture – that’s usually cheap, as proven by generics. Drugs are priced by the immense R&D costs, and by the putative savings they produce (either in improved health or reductions in other kinds of care).