Debrisoquine oxidation in an Australian population

Area of Science:

• Pharmacogenetics
• Drug Metabolism Studies

Background:

• The debrisoquine metabolic ratio (MR) is a standard measure for phenotyping drug metabolism.
• Traditional methods require extended sample collection times, limiting same-day analysis.

Purpose of the Study:

• To modify and shorten the standard laboratory method for debrisoquine phenotyping.
• To assess the feasibility of same-day debrisoquine phenotyping.
• To investigate the association between debrisoquine phenotype and sulphadimidine acetylation status.

Main Methods:

• A modified, shortened laboratory procedure for debrisoquine phenotyping.
• Collection of debrisoquine metabolic ratios (MR) at 4 and 8 hours.
• Phenotyping of 100 Caucasian Australian subjects for debrisoquine metabolism.
• Acetylation phenotyping of 50 subjects using sulphadimidine.

Main Results:

• The modified method showed no loss of sensitivity compared to the standard procedure.
• Excellent correlation between 4-hour and 8-hour MR indicated shortened collection times are possible.
• Same-day phenotyping of debrisoquine is feasible.
• 6% of the 100 subjects were identified as poor metabolisers (PM) of debrisoquine.
• Among 50 subjects, 34% were fast and 66% were slow acetylators.
• No significant association was found between debrisoquine poor metaboliser status and sulphadimidine acetylation phenotype.

Conclusions:

• A rapid, same-day debrisoquine phenotyping method is effective and validated.
• The prevalence of debrisoquine poor metabolisers in this population is 6%.
• Debrisoquine metabolism phenotype is not significantly associated with sulphadimidine acetylation status in this cohort.