METABOLISM OF PANTETHINE IN THE RAT

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The consecutive changes in blood concentrations and the urinary excretion of free and bound pantothenic acid were studied after oral and intravenous administration of pantethine (21.6 μmoles/kg) to rats. The results were compared with those obtained after administration of Ca-pantothenate (21.6 μmoles/kg).
The concentration of total pantothenic acid in blood was significantly higher in the pantethine group than in the Ca-pantothenate group after oral administration of vitamins. The maximal concentrations were observed at 2-4.5 hr after ingestion in both groups. The excretion rates of total pantothenic acid in 24-hr urines were 29±3 % of the dose and 18±2% in the pantethine and the Ca-pantothenate groups, respectively. These findings indicate that pantethine was more absorbable through the gastrointestinal wall of the rat than Ca-pantothenate. No significant difference was, however, found in the amounts of bound pantothenic acid in blood between these two groups. Pantethine was found to be hydrolyzed, to some extent, to pantothenic acid by an enzyme during passing the intestinal mucosa. After an intravenous injection of pantethine, about 50% of total pantothenic acid in blood was pantethine and the rest was free pantothenic acid, while little bound pantothenic acid was detected after injection of Ca-pantothenate. The decrease in total pantothenic acid in blood was significantly delayed in the early period after injection in the pantethine group when compared with that of the Ca-pantothenate group, although both the vitamins were almost completely eliminated in 24-hr urines after injection.