Grastigen Mechanism of Action

Pharmacology: Colony-stimulating factors are glycoproteins which act on hematopoietic cells by binding to specific cell surface receptors. Endogenous G-CSF is a lineage specific colony-stimulating factor which is produced by monocytes, fibroblasts, and endothelial cells. G-CSF regulates the production of neutrophils within the bone marrow and affects neutrophil progenitor proliferation, differentiation, and selected end-cell functional activation (including enhanced phagocytic ability, priming of the cellular metabolism associated with respiratory burst, antibody dependent killing, and the increased expression of some functions associated with cell surface antigens). G-CSF is not species specific and has been shown to have minimal direct in vivo or in vitro effects on the production of hematopoietic cell types other than the neutrophil lineage.
Pharmacokinetics: There is a positive linear correlation between the dose and the serum concentration of Filgrastim, whether administered intravenously or subcutaneously. Peak serum concentrations following subcutaneous injection are generally attained within 4-5 hours. The volume of distribution averaged 150 mL/kg. Clearance of Filgrastim has been shown to follow first-order pharmacokinetics after both subcutaneous and intravenous administration. The mean serum elimination half-life of Filgrastim is approximately 3.5 hours, with a clearance rate of approximately 0.6 mL/min/kg.