Grapefruit / MAOI effects on PCM?

[0utrider]

hi
SWIM was thinking about using codein with a CWE and using a lil less but combining it with grapefruit -juice in order to potentiate it a lil bit. now he worries about any effects of the MAOI on the (remaining) PCM.

[0utrider]

oh acutally i found something on this

Grapefruit juice is an inhibitor of CYP3A4, which is a minor
metabolizer of hydrocodone and a major
metabolizer of acetaminophen. What this means is that degree to
which plasma concentrations of acetaminophen increase would be much
greater than the degree to which plasma levels of hydrocodone would
increase; thus the risk of liver toxicity is actually higher.



The OTC antihistimine chlorpheniramine is an inhibitor of CYP2D6 and
may help you accomplish what you seek. Warning though, high doses
would potentiate the "narcotic's constipation" that is often seen with
excessive opiod use.
by: McDiggy

would be grateful for other opinions though

[Tortoise]

That information is somewhat inaccurate and very misleading. Liver damage from paracetamol overdose is not caused by increased plasma concentrations of the drug, rather by toxic metabolites that can be formed when a person has taken too much.

Let me explain; Paracetamol is primarily metabolised safely in the liver by a system other than the cytochrome P450 enzyme system (CYP2D6, CYP3A4, etc). Only when this primary metabolic pathway is saturated (ie, paracetamol overdose) is the paracetamol metabolised by the Cytochrome P450 enzyme system. This secondary metabolic pathway results in toxic metabolites which subsequently cause liver damage.

Theoretically, if one were to take too much paracetamol, a CYP2D6 and/or CYP3A4 inhibitor would actually be of benefit.

Hope this makes sense.

[0utrider]

ok, so what does this conclude to the question of using grapefruit juice while pcm might be present?

[Tortoise]

The conclusion is that grapefruit juice does not make it any more likely to suffer from paracetamol (acetaminophen, APAP, PCM, whatever you want to call it) toxicity. If anything, it makes it less likely.

In other words, it's totally safe.