Class: Hematopoietic growth factor – PEGylated recombinant human G-CSF (granulocyte colony-stimulating factor).
Mechanism of Action:
- Stimulates proliferation, differentiation, and activation of neutrophil precursors in the bone marrow.
- PEGylation prolongs its half-life → allows once-per-cycle dosing instead of daily filgrastim.
Clinical Uses
- Primary prophylaxis of chemotherapy-induced neutropenia.
- Reduces febrile neutropenia risk in patients receiving myelosuppressive chemotherapy.
- Occasionally used in stem cell mobilization (off-label).
Dosing
- Fixed dose: 6 mg subcutaneously once per chemotherapy cycle, typically 24–72 hours after chemotherapy.
- Adjustments: Not usually weight-based due to PEGylation; contraindicated in hypersensitivity to filgrastim or PEG.
Toxicities
- Bone pain – most common, due to marrow expansion.
- Splenic enlargement / rupture – rare but serious.
- Leukocytosis – usually mild and transient.
- Injection site reactions – erythema, pain, swelling.
- Rare: acute respiratory distress, capillary leak syndrome.
Monitoring
- Baseline CBC before each cycle.
- Monitor for severe bone pain or abdominal pain (spleen-related).
- Not routinely monitored with WBC counts unless clinically indicated.
Summary
Pegfilgrastim is a long-acting G-CSF used to prevent chemotherapy-induced neutropenia. Its once-per-cycle dosing improves convenience over filgrastim. Bone pain is the most common adverse effect, while rare events like splenic rupture warrant immediate attention.