[Study on pharmacokinetics of human granulocyte-macrophage colony stimulating factor (hGM-CSF) in rats using a...

A sensitive and reliable sandwich enzyme linked immunosorbent assay (ELISA) has been developed for determination of concentration of recombinant human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The assay is quantitative between 0.39-12.5 ng.ml-1 for bacterially synthesized hGM-CSF in rat serum and urine. The method was shown to be highly specific and did not significantly alter the determination when adding some potential interfering substances. After single sc injection of hGM-CSF 50, 100 or 200 micrograms.kg-1, a high hGM-CSF level was detected about 15 min in rat serum, the highest level of hGM-CSF was two apparent phases with half-lives T1/20 of 0.72, 0.70, 0.80 h and T1/28 of 8.77, 8.87 and 5.58 h. A detectable urinary excretion occured after sc injection of hGM-CSF 200 micrograms.kg-1, but the total urinary excretion of unchanged hGM-CSF was very low.