What is the recommended dose of filgrastim (granulocyte-colony stimulating factor)?

Recommended Dose of Filgrastim

The recommended dose of filgrastim is 5 mcg/kg/day subcutaneously for all clinical settings except peripheral blood progenitor cell (PBPC) mobilization, where 10 mcg/kg/day may be preferable. 1

Standard Dosing for Chemotherapy-Induced Neutropenia

• Administer 5 mcg/kg/day subcutaneously starting 1-3 days (24-72 hours) after completion of myelotoxic chemotherapy 1, 2
• Continue daily dosing until the absolute neutrophil count (ANC) recovers to 2-3 × 10⁹/L 1
• The dose may be rounded to the nearest vial size according to institution-defined weight limits 1
• The subcutaneous route is strongly preferred over intravenous administration 1, 3

Critical Timing Considerations

Never administer filgrastim on the same day as chemotherapy 2. This is a critical contraindication because:

• Administering filgrastim during active chemotherapy pushes cells into the cell cycle precisely when they are most susceptible to chemotherapeutic killing 2
• Phase II studies demonstrate increased incidence of febrile neutropenia and adverse events when given same-day versus next-day in breast cancer and lymphoma patients 1

Special Clinical Settings

High-Dose Therapy and Stem Cell Rescue

• Filgrastim can be started 1-5 days after administration of high-dose therapy 1
• Continue until ANC recovery to normal or near-normal levels 1

PBPC Mobilization

• Use 10 mcg/kg/day subcutaneously (higher than standard dose) 1
• Start 4 days before the first leukapheresis procedure 1
• Continue through the last leukapheresis 1
• Evidence from a randomized trial of 131 patients showed that 10 mcg/kg tended to yield higher CD34+ cell collection (12.0 vs 7.2 × 10⁶/kg) compared to 5 mcg/kg, though engraftment times were similar 4

Severe Chronic Neutropenia

• Idiopathic neutropenia: Start at 3.6 mcg/kg/day subcutaneously 5
• Cyclic neutropenia: Start at 6 mcg/kg/day subcutaneously 5
• Congenital neutropenia: Start at 6 mcg/kg/day divided twice daily, may increase incrementally to 12 mcg/kg/day divided twice daily if no response 5
• Adjust doses to maintain blood neutrophil levels in the normal or low-normal range 1

Acute Radiation Syndrome

• Use 10 mcg/kg/day subcutaneously starting as soon as possible after suspected or confirmed exposure to myelosuppressive doses of radiation 5
• Continue daily until ANC remains ≥1,000/mm³ for 3 consecutive days 5

Duration of Therapy

• Continue filgrastim until post-nadir ANC recovery to normal or near-normal levels by laboratory standards 1
• Specific targets: ANC ≥1.0 × 10⁹/L for 3 consecutive days or ≥10.0 × 10⁹/L for 1 day 2
• For severe chronic neutropenia, continue long-term with dose adjustments to maintain target ANC 1

Important Caveats

• Prophylaxis must continue through all chemotherapy cycles, not just the first few cycles—women receiving pegfilgrastim only during the first two cycles had 36% febrile neutropenia versus 10% when given all six cycles 1
• Do not use prophylactic filgrastim during concurrent chemotherapy and radiation therapy, particularly involving the mediastinum, due to increased complications and mortality risk 2
• Rotate injection sites when administering multiple doses over several days to prevent local tissue irritation 3
• For patients already receiving prophylactic filgrastim who develop febrile neutropenia, continue the filgrastim 1