title: Pharmacokinetic study of a novel recombinant human granulocyte colony-stimulating factor in rats.
abstract: OBJECTIVE
  To study the pharmacokinetics of a novel recombinant human granulocyte colony-stimulating factor (rhG-CSFa) in rats and to determine the proteolytic rates of rhG-CSFa in the whole blood and serum of rats in vitro.
  
  
  METHODS
  The pharmacokinetics of rhG-CSFa and conventional (wild type, WT) granulocyte colony-stimulating factor (G-CSF) were investigated in Sprague-Dawley rats which received either intravenous or subcutaneous injection of rhG-CSFa or WT G-CSF at three different doses (20, 50, or 100 microg/kg). The blood samples of rats were collected at multiple time points (from 0.08 to 12 h) and the concentrations of rhG-CSFa and WT G-CSF in serum were determined with a sandwich enzyme-linked immunosorbent assay (ELISA). For the study of proteolytic rates in vitro, the concentrations of rhG-CSFa or WT G-CSF were determined at 3-minute intervals after addition of the respective drug to rat's whole blood or serum.
  
  
  RESULTS
  Pharmacokinetic analysis of serum rhG-CSFa or WT G-CSF levels indicated that, at each dose tested, for either route of drug administration, the area under concentration-time curve values and the maximum serum concentration of rhG-CSFa were higher than those of WT G-CSF, and the serum half life of rhG-CSFa was longer than that of WT G-CSF. Subsequent in vitro whole blood and serum stability study showed that the rates of drug degradation in WT G-CSF were 1.8 folds and 1.5 folds higher than those in rhG-CSFa, respectively.
  
  
  CONCLUSIONS
  rhG-CSFa has better serum and whole blood stability in vitro and higher bioavailability in vivo as compared to WT G-CSF.
authors.affiliation: Biopharmaceutical R&D Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou 215126, China.
authors.forename: Xiao-Xiao
authors.initials: XX
authors.lastname: Liu
authors.forename: Yong-Ping
authors.initials: YP
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000592:standards; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000097:blood* / Q000235:genetics / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins; D012680:Sensitivity and Specificity
chemical_list: D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor