Pharmacogenetic covariation of defective N-oxidation of sparteine and 4-hydroxylation of debrisoquine.

Two subjects from each of the three groups of homozygous rapid, heterozygous, and homozygous non-metabolizers (N-oxidation) of sparteine received a single oral dose of debrisoquine. The urinary ratio of debrisoquine/4-hydroxy-debrisoquine, reflecting the individual's capacity to C-hydroxylate debrisoquine, was closely related to his phenotype for sparteine metabolism. This indicates that the two metabolic reactions are controlled by similar if not identical genetic factors.