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Dose - How much Codeine metabolizes into Morpine?

Discussion in 'Codeine' started by fleeman, Jun 22, 2013.

  1. fleeman

    fleeman Newbie

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    24 y/o from Canada
    Hey first post here.

    I have looked up and down this forum for an answer but couldn't find anything.

    A Buddy of mine was wondering how much codeine actually metabolizes into Morphine?

    For example if he were to take 50mg of codeine, how much of that would metabolize into morphine?

    thanks in advance for any replies!
     
  2. Millie Platt

    Millie Platt Newbie

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    i'm sure this has been covered about a million times but the rule of thumb is roughly 10% - give or take depending on metabolism.

    some can't metabolise it at all.
     
  3. Mindless

    Mindless Gold Member

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    The amount of codeine metabolised into morphine can vary. Some individuals appear to be extensive metabolisers, while others may be poor metabolisers. 6%-10% Caucasians, 2%-5% African Americans, and 1% Asians are poor metabolisers of CYP2D6 substrates such as codeine
    Ten percent seems to be the usual overall dose of morphine from codeine. Perhaps members of this group occupy points around the middle of a poor metaboliser-extensive metaboliser continuum.

    Drug Interactions: insights and observations. Understanding an Important Variable in Patient Response. John R. Horn, PharmD, FCCP, and Philip D. Hansten, PharmD, Pharmacy Times 2006.

    It has been suggested that extensive metabolisers may convert codeine into morphine at an 'ultra-rapid' rate. CYP3AF inhibitors and renal insufficiency may lead to an increased risk of codeine toxicity for extensive metabolisers.

    Codeine Intoxication Associated With Ultrarapid CYP2D6 Metabolism.

    Chen et al (1991) make similar comments:
    Disposition and metabolism of codeine after single and chronic doses in one poor and seven extensive metabolisers.
     
    Last edited: Jul 20, 2013