indication

Increases leukocyte production, for treatment in non-myeloid cancer, neutropenia and bone marrow transplant

pharmacology

Used in the treatment of chemotherapy-induced neutropenia by enhancing the production of neutrophils. Pegfilgrastim acts on hematopoietic cells by binding to specific cell surface receptors thereby stimulating proliferation, differentiation, commitment, and end cell functional activation. Pegfilgrastim has reduced renal clearance and prolonged persistence in vivo as compared to Filgrastim.

mechanism of action

Pegfilgrastim binds to the G-CSF receptor. As a G-CSF analog, it controls proliferation of committed progenitor cells and influences their maturation into mature neutrophils. Pegfilgrastim also stimulates the release of neutrophils from bone marrow storage pools and reduces their maturation time. Pegfilgrastim acts to increase the phagocytic activity of mature neutrophils. In patients receiving cytotoxic chemotherapy, pegfilgrastim can accelerate neutrophil recovery, leading to a reduction in duration of the neutropenic phase

half life

15-80 hrs

route of elimination

Filgrastim is primarily eliminated by the kidney and neutrophils/neutrophil precursors; the latter presumably involves binding of the growth factor to the G-CSF receptor on the cell surface, internalization of the growth factor-receptor complexes via endocytosis, and subsequent degradation inside the cells. Pegylation of filgrastim renders renal clearance insignificant, which was demonstrated in bilaterally nephrectomized rats and confirmed in subjects with renal impairment. As a result, the neutrophil-mediated clearance is the predominant elimination pathway for pegfilgrastim. During chemotherapy-induced neutropenia, the clearance of pegfilgrastim is significantly reduced and the concentration of pegfilgrastim is sustained until onset of neutrophil recovery.