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News Severe Co-Codamol Shortage in the UK

4DQSAR said:
Well, technically there are two classes of compound in grapefruit juice (and orange peel - so Seville marmalade will also work) that blocks the action of CYP3A4.

So It stops N-demethylation. But the result is the same - more morphine (the active metabolite of codeine).

It certainly does make things like codeine act for longer as N-demethylation is an important pathway.

If anyone finds a CYP-2D6 inducer (the enzyme that performs the O-demethylation) which is safe and well-tolerated, that would likely win a Nobel Prize.
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I read so many conflicting opinions about whether white or pink grapefruit juice must be used, and whether it should be taken before, with, or after codeine. The same also applies to other things that block the action of the relevant enzymes. Things like cimetidine-tagamet, which I guess is mainly theoretical now, since it's no longer incredibly easy to import a vast range of POMs like this from online pharmacies based in India.

Perhaps now it's long since defunct I can mention 4NRX (or something like that). What an amazing website that was for ordering a vast array of POMs from India. Never any bother from UK Border Force either. How much things have changed! :(

Perhaps @4DQSAR could comment on my first sentence?
 
@Bleaney - I'm sorry but I don't know. I just drink pink grapefruit juice because that's all that's available in the two shops that sell it that I can physcally get to.

I can go look into it for you if it matters.

Always happy to help a friend.
 
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Temperature (°C) Approximate Solubility (g/L) Parts of Water required per 1 part Codeine Phosphate
0°C ~230 – 250 g/L ~1 in 4 to 4.3 parts
5°C ~270 g/L ~1 in 3.7 parts
10°C ~310 g/L ~1 in 3.2 parts
15°C ~350 g/L ~1 in 2.8 parts
20°C 400 g/L (Official Standard Point) 1 in 2.5 parts
25°C ~430 – 450 g/L ~1 in 2.2 parts
30°C ~480 – 500 g/L ~1 in 2.0 parts

I don't know how to make neat tables on BL. I spaced it all out but I'm sure people can manage that for themselves.

The KEY part is that codeine phosphate is VASTLY more water-soluble than paracetamol in dH2O. If a buffer is added e.g. soluble tablet formulations, the solubility of paracetamol goes up a lot hence should be avoided and one of the above references just shows how shifting the pH a little to the basic can result in vast changes to underline why soluble formulations are verboten.
 
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4DQSAR said:
@Bleaney - I'm sorry but I don't know. I just drink pink grapefruit juice because that's all that's available in the two shops that sell it that I can physcally get to.

I can go look into it for you if it matters.

Always happy to help a friend.
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No it doesn't matter very much right at this moment, as I'm using quite a lot of kratom r/n anyway, and that completely blocks all good effects from lighter opiates such as codeine for a week or more, in my experience.

I just wondered if you knew off the top of your head. No need to look into it if not, as I probably wont be using codeine for some time.

(Barring any unforseen hospital admissions and enforced kratom abstinence, or any other injuries or pain conditions etc.)
 
Bleaney said:
No it doesn't matter very much right at this moment,
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As far as I know, in all of the human experiments I've read, no mention of the specific type of grapefruit juice is given (which on reflection it possibly should have been) but both contain furanocoumarins and be it 4 x 100mL in the elderly of 3 x 200mL in adults, the results were almost total inhibition of N-demethylation. Probably less would work but the experiments were aimed at real-world cases.

Do people drink grapefruit juice in smaller quantities than 100mL? I don't know...
 
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