ACIDIC DEGRADATION OF CEPHALOGLYCIN AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF DEACETYLCEPHALOGLYCIN IN HUMAN URINE

Abstract

In order to provide fundamental knowledge about the determination of deacetylcephaloglycin excreted in human urine as an active metabolite of cephaloglycin, the degradation of cephaloglycin in acidic media has been investigated with varying reaction temperature between 30°and 50°C and pH between 1.2 and 2.8. The degradation pathway observed under these conditions was the elimination of the 3-acetyl group yielding deacetylcephaloglycin followed by formation of deacetylcephaloglycin lactone. Estimation of first order rate constants revealed that deacetylation is the rate-determining step for the degradation of cephaloglycin to the lactone. It is found from the kinetic results that reproducible assays of deacetylcephaloglycin excreted in urine can be achieved by a quantitative conversion to deacetylcephaloglycin lactone in a medium of pH 1.4 at 37°C for 2 hours, followed by a reversed-phase ion-pair high-performance liquid chromatography. The utility of the present method is demonstrated by determining the time course of urinary excretion of deacetylcephaloglycin after oral administration of cephaloglycin capsule.