Prediction of drug oxidation rates in man: lack of correlation with serum gamma-glutamyl transpeptidase and urinary excretion of D-glucaric acid and 6 beta-hydroxycortisol.

Abstract

The plasma half-lives and clearances of antipyrine, phenylbutazone and warfarin, the 24 h urinary excretion of D-glucaric acid and 6β-hydroxycortisol, and serum gamma-glutamyl transpeptidase activity were measured in a group of healthy young volunteer subjects who were not taking other drugs. The half-lives of antipyrine and phenylbutazone were positively correlated (r=0.581), and so were the clearances of phenylbutazone and warfarin (r=0.796), but there were no concordances between any of the other test parameters. The results indicate that, in the absence of overt microsomal enzyme induction or inhibition, none of the tests would be of predictive value in the assessment of drug oxidation in clinical practice.