Assessment of the debrisoquin and dextromethorphan phenotyping tests by gaussian mixture distributions analysis.

From a sample of 149 unrelated Spaniards, individuals were phenotyped for their ability to hydroxylate debrisoquin and O-demethylate dextromethorphan. The distribution of urinary metabolic ratios for each test was analyzed by univariate gaussian mixture distributions analysis to determine the number of populations, the mean and standard deviation of the metabolic ratios for each population, and the proportion belonging to each population. For the 124 subjects phenotyped with both the debrisoquin and dextromethorphan tests a bivariate analysis was performed. The results demonstrate that both tests similarly separated this sample into two populations, with 10% belonging to poor metabolizer phenotypes. In addition, the correlation between the metabolic ratios from each test is significant, indicating that they are measuring the same biologic trait and the certainty of correctly identifying the debrisoquin oxidation phenotype of an individual is improved by using the results of both tests.