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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS. Meshes: Adult, Analgesics, Opioid, Cytochrome P-450 CYP2D6, Dealkylation, Female, Humans, Male, Middle Aged, Polymorphism, Genetic, Sparteine, Tramadol.
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Does polymorphic CYP2D6 mediate O-demethylation of the opioid analgesic tramadol? Context: This study was designed to investigate whether the in vivo metabolism of tramadol was influenced by CYP2D6 polymorphism. The extent of tramadol O- and N-demethylation was calculated by determining the amounts of tramadol and O- and N-desmethyltramadol in 24 h urine after ingestion of a test dose of tramadol. The O- and N-demethylation rates were calculated by dividing the 24-h urinary excretion amount of tramadol by that of O- and N-desmethyltramadol. Volunteers were phenotyped for CYP2D6 polymorphism using sparteine as an in vivo probe.
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High correlation was found between tramadol-O-demethylation and sparteine oxidation in 71 extensive metabolizers of sparteine (rs = 0.544). The mean metabolic ratio of tramadol O-demethylation was significantly higher in poor metabolizers of sparteine than in extensive metabolizers (4.4 vs 0.8). These in vivo results confirm that tramadol O-demethylation is carried out to a large extent by the polymorphic CYP2D6. Final Decision: yes