Polymorphism of dextromethorphan oxidation in a French population.

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Abstract
Genetically‐controlled drug oxidation capacity was studied using dextromethorphan, an anti‐tussive drug, as the test compound in 103 healthy white French subjects (61 males and 42 females). Phenotyping was performed using the metabolic ratio (MR) calculated as MR = 0‐10 h urinary output of dextromethorphan/0‐10 h urinary output of dextrorphan, after oral administration of 40 mg (113.6 mumol) of dextromethorphan hydrobromide. The log MR was bimodally distributed: 99 subjects (96.1%) were phenotyped as extensive metabolizers; they had a log MR between −3.1 and −1.1, a urinary output of dextromethorphan below 5 mumol 10 h‐1 and a urinary output of dextrorphan above 20 mumol 10 h‐1. Four subjects (3.9%) were phenotyped as poor metabolizers; they had a log MR between −0.5 and +0.7, a urinary output of dextromethorphan above 5 mumol 10 h‐1 and a urinary out of dextrorphan below 20 mumol 10 h‐1.