The metabolism of (ureyl-14C)tolbutamide in vitro and in vivo in man

Hepatic microsomal kinetic constants and plasma half-lives and plasma clearances for the metabolism of tolbutamine were measured in the same patients. No significant correlations were found for the seven experiments performed. There was a trend to an inverse correlation between hepatic microsomal cytochrome P-450 content and the plasma clearance. The negative findings suggest a lack of variation in the hepatic drug-metabolizing activities of normal humans.