filgrastim
Brand: Neupogen, Zarxio (biosimilar), Nivestym (biosimilar)
Prototype Drug
Drug Class: granulocyte colony-stimulating factor (G-CSF)
Drug Family: hematopoietic agent
Subclass: recombinant human G-CSF
Organ Systems: hematology-oncology
Mechanism of Action
Recombinant human G-CSF produced in E. coli; binds G-CSF receptor on myeloid progenitors, stimulating proliferation, differentiation, and activation of neutrophil precursors; reduces duration and severity of chemotherapy-induced neutropenia and febrile neutropenia.
G-CSF receptor (G-CSFR) on neutrophil precursors
Indications
- chemotherapy-induced neutropenia (primary and secondary prophylaxis)
- mobilization of peripheral blood progenitor cells for hematopoietic stem cell transplantation
- severe chronic neutropenia (congenital, cyclic, idiopathic)
- post-autologous/allogeneic HSCT recovery
Contraindications
- filgrastim hypersensitivity
- concurrent administration with chemotherapy (do not give within 24 hours before or after cytotoxic chemotherapy)
Adverse Effects
Common
- bone pain (very common — from marrow expansion)
- headache
- fatigue
- injection site reactions
Serious
- splenic rupture (rare but potentially fatal — instruct patients to report left upper quadrant pain)
- acute respiratory distress syndrome (rare)
- sickle cell crisis (in sickle cell disease)
- capillary leak syndrome (rare)
Pharmacokinetics (ADME)
| Absorption | SC or IV; SC bioavailability ~60–70% |
| Distribution | distributes to bone marrow |
| Metabolism | receptor-mediated endocytosis and neutrophil uptake; minimal renal elimination |
| Excretion | primarily by neutrophil internalization and receptor-mediated catabolism |
| Half-life | 3.5 hours (SC); 1–7 hours (IV) |
| Onset | hours (ANC rise within 24 hours) |
| Peak | 2–8 hours (SC) |
| Duration | daily dosing until ANC recovery |
| Protein Binding | minimal |
| Vd | limited (0.15 L/kg) |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| chemotherapy | concurrent administration increases myelotoxicity; administer 24 hours after chemotherapy and discontinue 24 hours before next cycle | major |
Nursing Considerations
- Do NOT administer within 24 hours before or 24 hours after cytotoxic chemotherapy administration.
- Teach subcutaneous self-injection technique; rotate sites; refrigerate and allow to reach room temperature before injection.
- Counsel patients to report left-sided shoulder or abdominal pain — may indicate splenic rupture, which requires immediate evaluation.
- Bone pain is expected and can be severe; acetaminophen usually provides adequate relief; avoid NSAIDs if patient is thrombocytopenic.
Clinical Pearls
- Primary prophylaxis with G-CSF is recommended when the risk of febrile neutropenia from a chemotherapy regimen exceeds 20% (per ASCO guidelines); secondary prophylaxis is used after a prior febrile neutropenic episode to allow continued chemotherapy delivery.
- Pegfilgrastim (Neulasta) — pegylated long-acting G-CSF — is administered as a single dose per chemotherapy cycle rather than daily; its prolonged half-life results from reduced renal clearance and neutrophil-mediated clearance that decreases as neutrophil counts rise.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.
Chemotherapy-induced Neutropenia (primary And Secondary Prophylaxis) Granulocyte Colony-stimulating Factor (G-CSF) Mobilization Of Peripheral Blood Progenitor Cells For Hematopoietic Stem Cell Transplantation Post-autologous/allogeneic HSCT Recovery Severe Chronic Neutropenia (congenital, Cyclic, Idiopathic)