Peginterferon alfa-2b is a long-acting PEGylated recombinant interferon protein. It is produced by covalently conjugating recombinant human interferon alfa-2b with monomethoxy polyethylene glycol (PEG). The commonly documented PegIntron form contains approximately 12 kDa PEG attached to the approximately 19.3 kDa interferon alfa-2b protein, giving an average molecular mass of approximately 31.3 kDa.
The FDA Global Substance Registration System identifies peginterferon alfa-2b with CAS 215647-85-1, an estimated average molecular weight of 31,000 Da, and an estimated molecular formula of C860H1355O250N233S9.
Peginterferon alfa-2b belongs to the interferon immunostimulant class and is assigned ATC code L03AB10.
Important: Do not confuse peginterferon alfa-2b with ropeginterferon alfa-2b. They are different PEGylated interferon products. Ropeginterferon alfa-2b has CAS 1335098-50-4 and an estimated average molecular weight of approximately 60 kDa.
Peginterferon alfa-2b is a PEGylated recombinant protein, not a conventional small-molecule API. The interferon alfa-2b component is a recombinant protein produced using E. coli. The protein moiety has an approximate molecular weight of 19,300 Da, while the PEG component averages approximately 12,000 Da.
The PEG modification increases the effective molecular size and changes the pharmacokinetic characteristics of interferon alfa-2b. The biological activity of the product is derived from its interferon alfa-2b component.
Peginterferon alfa-2b has historically been used in the treatment of chronic hepatitis C, including in combination with other antiviral medicines. The EU marketing authorisation for PegIntron was withdrawn in 2021 for commercial reasons, so the product should not be described as a currently EU-authorized marketed medicine.
| 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% |
| pH (1% Solution) | 6.5–7.1 |