• Select Your Topic Then Scroll Down
    Alcohol Bupe Benzos
    Cocaine Heroin Opioids
    RCs Stimulants Misc
    Harm Reduction All Topics Gabapentinoids
    Tired of your habit? Struggling to cope?
    Want to regain control or get sober?
    Visit our Recovery Support Forums

Grapefruit Juice and Codeine

neurotoxic

Ex-Bluelighter
Joined
Sep 27, 2003
Messages
555
Does grapefruit juice increase or decrease the effects of codeine?

Codeine is converted into morphine in the brain, so wouldn't it make sense that liver enzymes have no effect on the conversion?
 
I can remeber one time eating half an OC 80 which usually will give me a good buzz but not make me nod, and I drank a lot off grapefruit juice just to see what happened and I could defenatly tell a difference in a good way.
 
neurotoxic said:
Does grapefruit juice increase or decrease the effects of codeine?

Codeine is converted into morphine in the brain, so wouldn't it make sense that liver enzymes have no effect on the conversion?

As far as I know Codeine is not converted to morphine in the brain - that takes place in the liver. And yes - the tagament (sp?) in grapfruit juice apparently potentiates the effects of opiates and benzos.

--- G.
 
QUOTE]It supposedly increases the effects. [/QUOTE]

You guys couldnt be more wrong. Cytochrome p450 inhibitors like grapegruit juice do not work on codeine, in fact it only weakens the effect. Grapefruit juice and cimetidine both negatively effect the conversion of codeine into morphine, therefore reducing the high. Cp450 inhibitors do work on drugs like oxycodone, and other opiates, but NOT codeine. If you take grapefruit juice with codeine, your simply wasting the drug. Dont base your actions on what myths other people propagate, research it for yourself. And dont trinity dont spread misinformation........

The way you get high from codeine, is when the cytochrome P450 enzyme CYP2D6 converts the codeine into morphine, in your liver. Codeine itself does not cross the blood brain barrier.

From this website: codeine
i found the following;

Tagamet should not be taken with codeine because it impairs the metabolism into morphine necessary for it to have any real effect.Tagamet and grapefruit juice will weaken codeine substantially.
 
Last edited:
Thats interesting negro, since the following site comes to the opposite conclusion:

http://www.globalrph.com/gfruit.htm

Codeine is on the list of drugs which may exhibit increased serum concentrations based on this interaction. The site has plenty of references as well.
 
Negro, how did I spread mis-information.
I said I took OXYCODONE and it increased the effect.
You just said the same thing in your post that OC and Hydro are potenated by grapefruit juice but not codeine, so next time read the post correctly and put down the neddle, it's rotting your brain.

No offence, read the post next time.
 
Besides, trinity simply posted a subjective experience. How can that be called misinformation?
 
Trinity, your first responce to his question was, "It supposedly increases the effects". This is simply wrong. He was asking if grapefruit juice potentiates codeine, and you implied that it did. Then you posted again saying it worked with oxycontin, which is besides the point. The question was about codeine, and grapefruit juice does not potentiate codeine. If the needle is "rotting my brain", despite that I was correct, what is your excuse?

Im not trying to start a flame war, but you did make a cheap shot with the needle thing, which has nothing to do with this thread, and you were incorrect in saying it supposedly increases the effects. Supposedly is a loaded word, and doesnt mean your statement was necessarily subjective. If you werent sure if it potentiated codeine, then why post at all?

Also that globalrph thing is just an error, codeine theoretically would be potentiated by grapefruit juice, being that it is an opiate, but in practice it does the opposite. There are many other references that support that codeine is not potentiated by grapefruit juice or tagamet and decreases its conversion into morphine, it is simply a fact. CYP2D6 activation to morphine is central to codeine's effects, so its inhibition by substances such as grapefruit juice or tagamet would without a doubt weaken codeine's high.

So if you think grapefruit juice potentiates codeine go ahead, but your simply wasting it, becauses it doesnt.
 
Last edited:
Presently many questions remain, as there is also been some conjecture made that administration of grapefruit juice might interfere with the conversion of codeine to morphine due to its lesser inhibition of some CYP subfamilies. This does not seem to be the case; Caraco et al. 1996 reported (in animals) that if codeine was coadministered with selective inhibitors of CYP3A4 this could result in increased morphine production and enhanced effects due to “shunting into the CYP2D6 pathway” (as CYP2D6 would NOT be affected).

source: http://opioids.com/proglumide/
 
Well after testing the effects of codeine + grapefruit juice subjectively, I'd say there was a noticeable decrease in euphoria. I also didn't experience as much flushing and itchiness as usual.

So maybe grapefruit juice does inhibit the conversion to morphine...
 
Well it as was eluded to in an above post it all depends on which enymes are the main detoxifiers of codiene. I know grapefruit juice increases blood levels and prolongs half-lives in many frugs. I work in a psych hospital and I know it potentiates a lot of anti-psychotics. I'm not sure about opiates . It is a topic worthy of investigation though. I will see if i can get some info at work. May only be able to gather general effects on opioids and not specific drugs. I realize different drugs will behave a little differently but I cannot arouse suspicion by getting too specific.

And not to be a nit-picker but all (or at least most) drugs are detoxified through the liver in a 2 step process. The first is the P450 enzyme system, which sometimes produces metabolites more potent than the parent compound in some cases. The next is to change said metabolites to a water soluble excretable form through gluconation or methylation. Everthing passes through the liver eventually. Either directly by the portal vein ( oral ingestion) or through more circuitive means.
 
Grapefruit juice and cimetidine work on most opiates/opiods, but since codeine relies on the enzymes activation to accomplish the conversion into its most important metabolite, morphine, the enzymes inhibition by inhibitors such as grapefruit juice/cimetidine will only result in a lesser amount of codeine being metabolized into morphine, translating into a definately less pronounced high. In this case, most of the codeine (when taken with a large amount of grapefruit juice) would be excreted in ones urine, instead of being converted into its active metabolite, morphine. These inhibitors works for a good number of benzos too. Codeine is simply an exception.
 
negrogesic said:
CYP2D6 activation to morphine is central to codeine's effects, so its inhibition by substances such as grapefruit juice or tagamet would without a doubt weaken codeine's high.

Here's the straight dope:

It's true that 2d6 is essential to codeine's effects, but grapefruit actually inhibits CYP3A4. This is the enzyme responsible for metabolizing codeine into its other (inferior) pro-drug, norcodeine. By inhibiting 3A4 you force 2d6 to do more of the metabolizing work, and thus more codeine is converted to morphine.
 
tagamet, on the other hand, does inhibit 2d6 and will decrease codeine's analgesic effects. Unfortunately, 2d6 cannot be induced. So the best you can do is avoid 2d6 inhibitors and try inhibiting 3a4.
 
this is some of the most interesting opiate talk ever, i tried the grapefruit the other day just from what i read and i can't stand the taste of the shit but i noticed the differnence
 
Top