1990 Volume 5 Issue 3 Pages 353-364
Metabolism of 883-S (ceruletide diethylamine) was studied in rats after intravenous administration of 14C-883-S (alpha carbon of glycine residue was labeled with 14C).
The plasma level of unchanged 883-S rapidly decreased after injection. The level of unchanged 883-S was less than 10% of the total radioactivity present in the plasma 5min after injection. A major metabolite, present in plasma in the early phase, was a neutral peptide longer than tripeptide. One hour after injection, the radioactivity appeared in the plasma protein fraction, probably due to an extensive hydrolysis of 883-S and subsequent incorporation of 14C-glycine moiety into the protein via biosynthetic pathway. In the urine, unchanged 883-S was not detected. The major urinary metabolite was ceruletide-(1-6) peptide, Pyr-Gln-Asp-Tyr (SO3H)-Thr-Gly. The radioactive metabolites in the bile were separated into two fractions. The major fraction contained unchanged 883-S, and the minor one contained ceruletide-(1-6) peptide, the same metabolite found in the urine.
