Pegylated Interferon Alfa-2a is a long-acting, covalent conjugate of recombinant interferon alfa-2a with a branched 40 kDa polyethylene glycol (PEG) chain. This pegylation significantly prolongs its half-life, allowing for once-weekly subcutaneous administration. It is a potent immunomodulator and antiviral agent, primarily used in the treatment of chronic hepatitis B and C infections in the Indian context. It exerts its effects by binding to specific cell surface receptors, activating the JAK-STAT signaling pathway, leading to the transcription of interferon-stimulated genes (ISGs) that mediate antiviral, antiproliferative, and immunomodulatory activities.
Adult: 180 mcg administered subcutaneously once weekly. For HCV: Duration is 24-48 weeks based on genotype and response (Genotype 1 & 4: 48 weeks; Genotype 2 & 3: 24 weeks with ribavirin). For HBV: 48 weeks.
Note: For subcutaneous use only. Administer in the abdomen or thigh. Rotate injection sites. Prefilled syringes should be allowed to reach room temperature before use. Do not shake. Inspect for particulate matter or discoloration before administration. Dispose of syringe in a sharps container.
Peginterferon alfa-2a binds to specific, high-affinity cell surface receptors (IFNAR1 and IFNAR2) present on most human cells. This binding activates the receptor-associated Janus tyrosine kinases (JAK1 and TYK2), which phosphorylate signal transducers and activators of transcription (STAT) proteins. Phosphorylated STATs form heterodimers, translocate to the nucleus, and bind to interferon-stimulated response elements (ISREs), promoting the transcription of over 300 interferon-stimulated genes (ISGs). The net effects include: 1) Inhibition of viral entry, uncoating, replication, and assembly. 2) Upregulation of Major Histocompatibility Complex (MHC) class I expression, enhancing cytotoxic T-cell recognition of infected cells. 3) Activation of natural killer (NK) cells. 4) Antiproliferative effects on certain cell types.
Pregnancy: Pregnancy Category C (US FDA). Animal studies show abortifacient effects. When used in combination with ribavirin (Category X), pregnancy is absolutely contraindicated. Women of childbearing potential and their male partners must use two effective forms of contraception during and for at least 6 months after therapy.
Driving: May cause fatigue, dizziness, and somnolence. Patients should be cautioned against driving or operating machinery if they experience these effects.
| Ribavirin | Additive myelosuppression (anemia, neutropenia) and teratogenicity risk. Used therapeutically in combination for HCV. | Major |
| Telbivudine | Increased risk of peripheral neuropathy. | Major |
| Zidovudine (AZT) | Additive risk of neutropenia and anemia. | Major |
| Theophylline | Peginterferon reduces the clearance of theophylline, increasing its plasma levels and risk of toxicity. | Moderate |
| Methadone | May increase methadone plasma levels; monitor for sedation and respiratory depression. | Moderate |
| Warfarin | May alter INR; increased monitoring required. | Moderate |
| Live Attenuated Vaccines | Risk of disseminated vaccine-related infection due to immunosuppression. Avoid. | Major |
| Clozapine | Increased risk of agranulocytosis. | Major |