Pharmacokinetics of tolbutamide: Prediction by concentration in saliva

Abstract

The excretion of tolbutamide in saliva of diabetic patients receiving single intravenous doses of 1 gm tolbutamide is described. Gas chromatography with electron capture was used for analysis. Pharmacokinetic parameters could be obtained from either salivary or plasma tolbutamide levels. There was a good linear relationship between tolbutamide concentration in saliva and in plasma; salivary levels were 1.2% of plasma levels. Equations are presented that account for the excretion in saliva based on extent of protein binding and degree of ionization of tolbutamide in plasma and saliva. Correlation of the saliva to plasma concentration ratio was extended to data in the literature on two other drugs.