Debrisoquin oxidation polymorphism in a Spanish population

Area of Science:

• Pharmacogenetics
• Drug Metabolism
• Clinical Pharmacology

Background:

• Debrisoquin is a substrate for the cytochrome P450 enzyme CYP2D6.
• CYP2D6 activity exhibits significant inter-individual variability, leading to distinct metabolic phenotypes.
• Understanding debrisoquin metabolism is essential for predicting drug response and potential adverse effects.

Purpose of the Study:

• To investigate the genetic polymorphism of debrisoquin metabolism in a healthy Spanish volunteer population.
• To phenotype individuals as poor metabolizers (PMs) or extensive metabolizers (EMs) based on debrisoquin and its metabolite excretion.
• To determine the frequency of debrisoquin metabolic phenotypes in this specific ethnic group.

Main Methods:

• A cohort of 377 healthy Spanish volunteers received an oral dose of debrisoquin.
• Urinary concentrations of debrisoquin and its primary metabolite, 4-hydroxydebrisoquin, were measured over a 6-hour period.
• The metabolic ratio (MR) of debrisoquin to 4-hydroxydebrisoquin was calculated to classify individuals into metabolic phenotypes.

Main Results:

• Debrisoquin oxidation was found to be polymorphic, consistent with CYP2D6 activity.
• 25 volunteers (6.6%) were classified as poor metabolizers (PMs).
• 352 volunteers (93.4%) were classified as extensive metabolizers (EMs), with metabolic ratios ranging from 0.03 to 93.5.

Conclusions:

• The observed frequency of poor debrisoquin metabolizers (6.6%) in the Spanish population falls within the range reported for other Caucasian populations.
• This study confirms the polymorphic nature of debrisoquin metabolism in Spaniards.
• Findings have implications for personalized medicine and optimizing drug therapy involving CYP2D6 substrates.