Pegfilgrastim
PEGylated filgrastim with extended half-life for single-dose chemotherapy-induced neutropenia prevention.
Chemical Identity
| Property | Value |
|---|---|
| Molecular Weight | ~38.8 kDa |
| PEG Size | 20 kDa (single PEG chain) |
| CAS Number | 208265-92-3 |
| Protein | Filgrastim (G-CSF) |
| Route | SC (single injection per cycle) |
Structure
Pegfilgrastim (Neulasta) is filgrastim conjugated to a single 20 kDa polyethylene glycol (PEG) chain at the N-terminus. The PEG moiety reduces renal clearance and proteolytic degradation, extending the half-life from 3.5 hours (filgrastim) to 15-80 hours, enabling once-per-chemotherapy-cycle dosing.
Mechanism of Action
Like filgrastim, pegfilgrastim binds G-CSF receptors to stimulate neutrophil production and mobilization. The extended half-life provides sustained neutrophil recovery after chemotherapy. Neutrophil-mediated clearance (via G-CSF receptors on neutrophils) creates self-regulating pharmacokinetics.
Clinical Applications
- Chemotherapy-induced neutropenia: Single SC injection per chemotherapy cycle
- Febrile neutropenia prevention: 6 mg fixed dose 24 hours after chemotherapy
- Stem cell mobilization: Investigational
- Convenience advantage: Single dose vs daily filgrastim
Pharmacokinetics
- Half-life: 15-80 hours (neutrophil-mediated clearance)
- Tmax: 16-120 hours
- Dosing: 6 mg SC once per chemotherapy cycle
- Clearance: Neutrophil-mediated (self-regulating)
- Route: SC injection
Safety and Side Effects
Bone pain (26%), headache (10%), nausea (6%), and splenomegaly. Similar safety profile to filgrastim. Fixed dose in adults >45 kg; weight-based dosing in pediatric patients.
References
- Holmes, F.A., et al. (2002). Pegfilgrastim vs filgrastim for neutropenia. Journal of Clinical Oncology, 20, 727-731.
- Green, M.D., et al. (2003). Pegfilgrastim: once-per-cycle G-CSF. Annals of Pharmacotherapy, 37, 1182-1189.
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