Quick question regarding Codeine.

[shady4091]

Okay, so Codeine is converted into Morphine in your body via some Cxxxx enzyme, at a ratio of about 10% and the other 90% into the inactive Norcodeine, correct?

So what I was curious about is, is this 10% also subject to further degradation by your liver or does the 10% end up in your blood stream?

Let's say someone takes 100mg of Codeine. This would be converted into 10mg Morphine. Would this then be metabolized by another 70% (~30% oral BA of Morphine) resulting in only 2.5mg of Morphine in your blood stream?

If not, would I be correct in saying that 100mg Codeine is equivalent to approximately 40mg Morphine taken orally? That doesn't really sound right to me...

Just something I've been curious about for a little while.

 

[sekio]

That 10% figure is for conversion of codeine to morphine in the blood. So if you take 100mg codeine, 10mg of it will be converted to morphine circulating around in your blood. That means 10mg codeine really is equivalent to 30-40mg oral morphine. It does not mean that 100mg codeine will be equivalent to 10mg oral morphine (2.5mg blood morphine), though eventually the morphine that is metabolically made will be destroyed in the liver too.

Morphine is poorly absorbed when given orally, it makes dosages seem a lot higher than they actually are. And do keep in mind that different people have different reactions. Some are much better at converting codeine to active drugs.

Mind you, there are more metabolites than just morphine and norcodeine that are generated, codeine-6-glucuronide is another active metabolite that is purported to be the major active one (more c-6-g is made relative to morphine). I don't think 90% of a codeine dose is turned to norcodeine.

 

[debaser]

No, 10% of 100mg of oral codeine is like if you injected 10mg of morphine. Directly goes into your bloodstream. If I correctly understood your question, of course.

 

[shady4091]

Perfect answers, thanks guys.