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    Xenobiotica. 1991 Nov;21(11):1501-9.

    Thebaine O-demethylation to oripavine: genetic differences between two rat strains.

    Mikus G, Somogyi AA, Bochner F, Eichelbaum M.

    Department of Clinical and Experimental Pharmacology, University of Adelaide, Australia.

    1. Codeine O-demethylation to morphine is mediated by cytochrome P450 IID1 (rat), or P450 IID6 (man), and exhibits genetic polymorphism. Thebaine is a precursor in the formation of endogenous morphine and codeine in man, being O-demethylated to oripavine. 2. The objective of the present study was to ascertain whether the O-demethylation of thebaine to oripavine was mediated by cytochrome P450 IID1 in rat liver microsomes. 3. Thebaine O-demethylation showed strain differences in female Sprague-Dawley (SD) and female Dark-Agouti (DA) rats, which serve as a model for the human debrisoquine/sparteine metabolism phenotypes. 4. The total intrinsic clearance of thebaine to oripavine was high (19.7 ml/h per mg protein) in SD rats, indicating that oripavine is a major metabolite of thebaine. A 3-fold lower intrinsic clearance was observed in DA rats (6.7 ml/h per mg protein). 5. Thebaine O-demethylation was inhibited by quinine and known substrates of cytochrome P450 IID1/P450 IID6, supporting the major involvement of cytochrome P450 IID1 in oripavine formation in rats.

    PMID: 1763524 [PubMed - indexed for MEDLINE]

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    • Quinine (Qualaquin®)

      Quinine is used alone or with other medications to treat malaria (a serious or life-threatening illness that is spread by mosquitos in certain parts of the world). Quinine should not be used to prevent malaria or to prev...

    • Codeine (Brontex®, Capital and Codeine®, Cheracol® with Codeine Syrup, ...)

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