Pegfilgrastim API is a long-acting, PEGylated recombinant human granulocyte colony-stimulating factor (G-CSF) used as a hematopoietic growth factor. It is produced by covalently attaching an approximately 20 kDa monomethoxypolyethylene glycol (PEG) molecule to the N-terminal methionyl residue of recombinant human G-CSF (filgrastim). The resulting pegfilgrastim molecule has an average molecular weight of approximately 39 kDa.
Pegfilgrastim is a 175-amino-acid recombinant protein derived from Escherichia coli. The protein component has a molecular weight of approximately 18.8–19 kDa, while the attached PEG moiety contributes approximately 20 kDa. PEGylation extends the exposure of G-CSF and reduces renal clearance compared with filgrastim.
The CAS Number of Pegfilgrastim is 208265-92-3. FDA records identify pegfilgrastim as a leukocyte growth factor, while its WHO ATC classification is L03AA13.
Pegfilgrastim acts by binding to the granulocyte colony-stimulating factor receptor on hematopoietic cells, stimulating proliferation, differentiation, and functional activation of cells in the neutrophil lineage. Pegfilgrastim products are primarily used to reduce the duration of chemotherapy-induced neutropenia and the incidence of febrile neutropenia in appropriate patients receiving cytotoxic chemotherapy.
Because pegfilgrastim is a biological/biotechnological product rather than a conventional small-molecule API, its characterization requires a combination of physicochemical and biological analytical techniques. Regulatory assessments describe the use of peptide mapping, mass spectrometry, RP-HPLC, SEC-HPLC, ion-exchange chromatography, SDS-PAGE, structural characterization and cell-based potency assays.
The pegfilgrastim molecule contains the expected disulfide-bond structure of recombinant G-CSF, with PEG attached to the N-terminal methionyl residue. Regulatory characterization confirms the molecular structure and evaluates molecular-mass distribution, PEGylation, higher-order structure, purity, aggregates and biological activity.
Unlike a conventional small-molecule API, HPLC assay alone is not an appropriate universal release specification for pegfilgrastim. Biological potency is evaluated using validated cell-based assays, including M-NFS-60 cell proliferation assays, with relative potency compared against an appropriate reference standard.
Approved pegfilgrastim products are supplied as sterile, clear, colorless, preservative-free aqueous solutions. The reference Neulasta formulation has a reported pH of 4.0.
It is important to distinguish this finished-product pH from the CMS field labelled “pH (1% Solution)”. A pH of 4.0 should not be incorrectly entered as the pH of a 1% API solution; the FDA value refers specifically to the approved drug-product formulation.
Manufacturing Pegfilgrastim API requires specialized recombinant protein and PEGylation capabilities, together with extensive purification and analytical characterization. The manufacturing process must control critical quality attributes such as identity, PEGylation, molecular-mass distribution, aggregates, charge variants, product-related impurities, host-cell impurities and biological potency.
A qualified Pegfilgrastim API manufacturer in India should therefore use validated analytical methods and appropriate quality systems for biological products. Regulatory assessments emphasize orthogonal characterization and controls for physicochemical attributes, purity, potency and product-related variants.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.5% |
| Individual Impurity | NMT 0.5% |
| Total Impurities | ≤ 1.5% |