Unimodal distribution of the metabolic ratio for debrisoquine in Cuna Amerindians of Panama.

1. The metabolic oxidation of debrisoquine (DB) was studied in 89 non-related Cuna Amerindian subjects. 2. Means and standard deviations for urinary recoveries of the intact drug and its 4-hydroxy metabolite (4-HD) were: %DB: 6.8 +/- 4.5; %4-HD: 16.0 +/- 9.1; %sum: 22.8 +/- 12.0. The log10 metabolic ratios for DB (LMRDB) were distributed within a single mode of insignificant skewness (-0.01, P greater than 0.10), which was unimodal (log kernel density and maximum likelihood methods) and normal (chi 2 = 22.5; d.f. = 15; P greater than 0.09; power of the test greater than 80%). 3. Therefore, no poor metabolizers (95% C.I.: 0.1%, 5.2%) were detected in the population sample studied.