Filgrastim is a human granulocyte colony stimulating factor (G-CSF) produced by recombinant DNA technology. G-CSF regulates the production of neutrophils within the bone marrow and affects neutrophil progenitor proliferation, differentiation and enhances phagocytic activity.

Pharmacology

Filgrastim is a granulocyte-colony stimulating factor which binds to cell surface receptors on haemetopoietic cells thus stimulating the development of granulocytes to increase their migration and cytotoxicity.

Filgrastim is a glycoprotein which regulates the production and release of functional neutrophils from the bone marrow. Filgrastim causes marked increases in peripheral blood neutrophil counts within 24 hours, with minor increases in monocytes. Elevations of neutrophil counts are dose-dependent at recommended doses. Following termination of Filgrastim therapy, circulating neutrophil counts decrease by 50% within 1 to 2 days, and to normal levels within 1 to 7 days.

Filgrastim is indicated to those:

• Cancer patients receiving myelosuppressive chemotherapy
• Patients with Acute Myeloid Leukemia receiving induction or consolidation chemotherapy
• Cancer patients receiving bone marrow transplant
• Patients with severe neutropenia
• Peripheral blood progenitor cell collection and therapy

Parenteral-

Chemotherapy-induced neutropenia: 5 mcg/kg daily as a single daily SC inj, as a continuous IV or SC infusion, or as a daily IV infusion over 15-30 minutes, starting not

Bone marrow transplantation: 10 mcg/kg daily by IV infusion over 30 min or 4 hr or continuous IV or SC infusion over 24 hr. Adjust according to response.

Subcutaneous-

Mobilisation of peripheral blood progenitor cells for autologous peripheral blood stem cell transplantation: 10 mcg/kg daily, as a single inj or by continuous infusion, for 4-7 days until the last leucapheresis procedure. If it is given after myelosuppressive chemotherapy: 5 mcg/kg daily by inj; given from the 1st day after chemotherapy completion until expected neutrophil nadir is passed and neutrophil count has returned to normal range, so that leucapheresis can be performed.

Congenital neutropenia: 12 mcg/kg daily in single or divided doses. Adjust according to response. In patients with cyclic or idiopathic neutropenia: 5 mcg/kg daily in single or divided doses. Adjust according to response.

HIV infection and persistent neutropenia: Initially, 1 mcg/kg daily. Dose may be increased to 4 mcg/kg daily until normal neutrophil count is achieved. Maintenance: 300 mcg daily. Max: 4 mcg/kg daily.

Filgrastim is contraindicated in patients hypersensitive to the drug, any ingredient in the formulation, or proteins derived from Escherichia coli.

Musculoskeletal pain, bone pain, hypersensitivity reactions, splenic enlargement, hepatomegaly, thrombocytopaenia, anaemia, epistaxis, headache, nausea, vomiting, diarrhoea, urinary abnormalities (dysuria, proteinuria, haematuria), osteoporosis, exacerbation of rheumatoid arthritis, transient decrease in blood glucose, raised uric acid, cutaneous vasculitis, transient hypotension.

Overdose Effects

The possibility of Filgrastim acting as a growth factor for any tumor type and adverse effects of excessive neutrophils may occur in overdose of Filgrastim.

Filgrastim should not be administered within 24 hours before and after chemotherapy The possibility of Filgrastim acting as a growth factor for any tumor type cannot be excluded. To avoid adverse effects of excessive neutrophils complete blood count is recommended twice per week during treatment. Filgrastim is given by subcutaneous or intravenous infusion as required

Use in Special Populations

Pediatric precautions: Filgrastim has been used in children 3 months to 18 years of age without unusual adverse effect. However, safety and efficacy of the drug in neonates or patients with autoimmune neutropenia of infancy have not been established.

Pregnancy & Lactation

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.