A Conversation for SEx - Science Explained
SEx: Grapefruit question
Orcus Started conversation Jun 7, 2007
My partner is currently on medication to reduce a bit of high blood pressure.
She's just swapped to a different course of tablets as the old ones gave her a nasty cough (a known side-effect it seems).
The new ones state categorically on the box - and the pharmacist has also stressed this - that she MUST NOT eat grapefruit when on this medication.
Sadly I can't remember the exact pills she is taking but my question is this.
(a) What is in grapefruit that can cause a reaction to anti-hypertension pills?
(b) Why grapefruit? Are oranges, lemons and lime OK?
SEx: Grapefruit question
Danny B Posted Jun 7, 2007
Grapefruits contain a number of 'furanocoumarins' that inhibit the cytochrome enzyme CYP3A4 - this is found in the small intestine and liver and is responsible for metabolism of a large number of drugs. If the enzyme is inhibited, the drug is not broken down as rapidly as normal, meaning that potentially harmful concentrations of the drug can build up. With some drugs, this doesn't matter so much, but other drugs with a 'narrow therapeutic window' (i.e. the dose needed for efficacy is almost high enough to be toxic) even a slight increase in concentration could be harmful.
Other citrus fruits don't contain the same compounds, or in anything like the same levels as in grapefruit (I think there's been some suggestion that limes also contain some of these compounds, but the danger of eating enough lime/lime juice to reach effective levels is very remote). Some herbal medicines may also block CYP3A4, so your partner should check with the pharmacist if she plans to take anything else.
If you're interested in more detail, I found this free-online literature review:
http://www.chinaphar.com/1671-4083/25/129.pdf
Hope that helps!
SEx: Grapefruit question
Orcus Posted Jun 7, 2007
Interesting.
Actually after I posted my question I decided to google it for myself (no idea why I didn't do this first) and that came up with a completely different answer.
Some antihypertensive drugs are calcium channel blockers and it seems there is a known group of compound specifically in grapefruit that also interact with calcium channels and so the combination of the two is potentially dangerous.
Anyway, whatever of the two is the answer - it's a good job we don't eat grapefruit anyway
SEx: Grapefruit question
Grapefriut keeps your cytochromes in shape. Gives them the exercise they need
Seriously, it's amazing how naive many people are concerning the so called herbal medicines. I've had a number of patients over the years with trouble livers due to ginseng teas, various asian remedies and unspecified pills bought at unlicensed pharmacies disguised as "natural health whatever".
"But it's just herbs, doc. Only natural stuff. No nasty chemicals"
Most of these "herbals" are the poisons plants execrete to defend themselves from being consumed.
OK, some compunds are effective but need to be handled in such a way that they're not dangerous.
SEx: Grapefruit question
Hati Posted Jun 7, 2007
I have this vague memory that grapefuits had something that helped against antritis. Well, a bit irrelevant..
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SEx: Grapefruit question
- 1: Orcus (Jun 7, 2007)
- 2: Danny B (Jun 7, 2007)
- 3: Orcus (Jun 7, 2007)
- 4: Danny B (Jun 7, 2007)
- 5: dragonqueen - eternally free and forever untamed - insomniac extraordinaire - proprietrix of a bullwhip, badger button and (partly) of a thoroughly used sub with a purple collar. Matron of Honour. (Jun 7, 2007)
- 6: Hati (Jun 7, 2007)
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