1. Inhibition of cytochrome P450 2D6 modifies codeine abuse liability.
- Author
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Kathiramalainathan K, Kaplan HL, Romach MK, Busto UE, Li NY, Säwe J, Tyndale RF, and Sellers EM
- Subjects
- Adult, Codeine pharmacokinetics, Cytochrome P-450 CYP2D6 genetics, Dealkylation, Dose-Response Relationship, Drug, Female, Humans, Male, Narcotics pharmacokinetics, Polymorphism, Genetic genetics, Pupil drug effects, Reproducibility of Results, Single-Blind Method, Time Factors, Codeine adverse effects, Cytochrome P-450 CYP2D6 Inhibitors, Enzyme Inhibitors therapeutic use, Narcotics adverse effects, Opioid-Related Disorders prevention & control, Quinidine therapeutic use
- Abstract
Oral codeine preparations, widely used for analgesia and cough suppression, are abused by some individuals for their mood-altering properties. The enzymatic O-demethylation of codeine is catalyzed by cytochrome P450 2D6 (CYP2D6), leading to the production of metabolites (morphine, morphine-6-glucuronide) that are pharmacologically more potent than codeine. A placebo-controlled, single-blind study was conducted to characterize the subjective effects of codeine associated with abuse liability and to determine the importance of metabolic O-demethylation to codeine abuse liability. Twelve non-drug-dependent subjects received oral administration of placebo and codeine 60, 120, and 180 mg, and a favorite dose (FD) was determined for each subject. The FD was readministered after pretreatment with placebo, 50 mg of quinidine (a specific, selective CYP2D6 inhibitor) once, or 50 mg of quinidine given four times a day for 4 days. Single-dose quinidine pretreatment significantly decreased the recovery of O-demethylated metabolites in plasma (p < 0.01) and resulted in a decrease in the positive (e.g., "high," p < 0.05) and negative (e.g., nausea, p < 0.05) subjective effects of codeine in both the FD120 and FD180 groups. Short-term quinidine pretreatment inhibited codeine O-demethylation more than did single-dose quinidine pretreatment (p < 0.01), and it decreased positive codeine effects in the FD120 group (N = 7), but unexpectedly not in the FD180 group (N = 5). These results suggest that the O-demethylated metabolites contribute substantially to the subjective effects and abuse liability of codeine.
- Published
- 2000
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