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FILGIA is a medicine containing Filgrastim (Recombinant Human Granulocyte Colony Stimulating Factor) that used to reduce the duration of neutropenia in patients treated with established cytotoxic chemotherapy for non-myeloid malignancy.
Pharmacology: Filgrastim (Recombinant Human Granulocyte Colony Stimulating Factor/rHu G-CSF) is a 175 amino acid protein manufactured by recombinant DNA technology. It is produced by Escherichia coli (E.coli) bacteria into which the human granulocyte colony stimulating factor gene has been inserted. G-CSF is a colony stimulating factor which produced by monocyte, fibroblast, and endothelial cell. 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).
In patients with various non-myeloid malignancies, Filgrastim administration results in a dose dependent increase in circulating neutrophil counts. In general, neutrophil counts returns to baseline, in most cases within 4 days, when Filgrastim therapy discontinued. The absolute monocyte count is reported to increase in a dose dependent manner inmost patients receiving Filgrastim. However, the percentage of monocytes in the differential count remains within the normal range. Absolute counts of both eosinophils and basophils do not change and are within the normal range following administration of Filgrastim. Increases in lymphocyte counts following Filgrastim administrations have been reported in some normal subjects and cancer patients.
Pharmacokinetics: Filgrastim can be administered intravenously or subcutaneously. A positive linear correlation occurred between the parenteral dose and both the serum concentration and area under the concentration-time curves. Continuous IV infusion with Filgrastim 20 μg/kg body weight resulted in mean serum concentration approximately 48 ng/mL. Subcutaneous administration of 3.45 μg/kg body weight and 11.5 μg/kg body weight resulted in maximum concentration (Cmax) of 4 and 49 ng/mL respectively, within 2 to 8 hours.
The volume of distribution in blood is approximately 150 mL/kg. Half-life for IV and SC administration following doses of 1 μg/kgBW/day are 1.4 hours and 2.15 hours. Filgrastim undergoes extensive renal and hepatic metabolism. Clearance rate depends on neutrophil counts, where elimination half-life decreases from 4.7 to 2 hours with higher neutrophil count. About 94% of administered drug is excreted in urine and 4% in faeces.
