Peginterferon Alfa-2a

Pegylated recombinant human interferon alfa-2a is an inducer of the innate antiviral immune response [see Microbiology (12.4) ] .

• PEGASYS is an inducer of the innate immune response indicated for the treatment of Chronic Hepatitis C (CHC) ( 1.1 ) Adult Patients: In combination therapy with other hepatitis C virus drugs for adults with compensated liver disease. PEGASYS monotherapy is indicated only if patient has contraindication or significant intolerance to other HCV drugs.ICD-10: B18.2

• PEGASYS is contraindicated in patients with: Known hypersensitivity reactions such as urticaria, angioedema, bronchoconstriction, anaphylaxis, or Stevens-Johnson syndrome to alpha interferons, including PEGASYS, or any of its components. Autoimmune hepatitis Hepatic decompensation (Child-Pugh score greater than 6 [class B and C]) in cirrhotic patients before treatment Hepatic decompensation with Child-Pugh score greater than or equal to 6 in cirrhotic CHC patients coinfected with HIV before treatment PEGASYS is contraindicated in neonates and infants because it contains benzyl alcohol.contraindicated

PEGASYS is administered by subcutaneous injection ( 2 ) In adult patients with CHC, PEGASYS is dosed as 180 mcg per week and the duration of treatment depends on indication, genotype, and whether it is administered with other HCV antiviral drugs ( 2.2 ). In adult patients with CHB, PEGASYS is dosed as 180 mcg per week for 48 weeks ( 2.4 ). In pediatric patients with CHC, PEGASYS is dosed as 180 mcg/1.73 m 2 × BSA per week, in combination with ribavirin, and the duration of treatment depends on genotype ( 2.3 ) In pediatric patients with CHB, PEGASYS is dosed as 180 mcg/1.73 m 2 × BSA per week for 48 weeks ( 2.5 ): Dosage modification is recommended in patients experiencing certain laboratory abnormalities, adverse reactions or renal impairment ( 2.6 , 12.3 ) 2.1 Dosage Overview Administer PEGASYS by subcutaneous injection once weekly in the abdomen or thigh for the treatment of: Adult patients with CHC without or with HIV coinfection [see Dosage and Administration (2.2) ]; Pediatric patients with CHC [see Dosage and Administration (2.3) ] ; Adult patients with CHB [see Dosage and Administration (2.4) ] ; and Pediatric patients with CHB [see Dosage and Administration (2.5) ]. For treatment of CHC, use PEGASYS in combination with other HCV antiviral drugs. For information about the recommended dosage and administration and the safe and effective use of these other HCV antiviral drugs, refer to their prescribing information. PEGASYS monotherapy is only indicated in the treatment of CHC if there are contraindications to or significant intolerance to other HCV antiviral drugs.

Refer to the prescribing information of the other HCV antiviral drugs, including ribavirin, for their Warnings and Precautions. Use with ribavirin Birth defects and fetal death: patients must have a negative pregnancy test prior to therapy, use 2 forms of effective contraception, and have monthly pregnancy tests ( 5.1 ) PEGASYS Clinically Significant Adverse Reactions or Risks Patients exhibiting the following events should be closely monitored and may require dose reduction or discontinuation of therapy: Neuropsychiatric reactions ( 5.2 ) Cardiovascular disorders ( 5.3 ) Bone marrow suppression ( 5.4 ) Autoimmune and endocrine disorders (including thyroid disorders; hyperglycemia) ( 5.5 , 5.6 ) Ophthalmologic disorders ( 5.7 ) Cerebrovascular disorders ( 5.8 ) Hepatic decompensation in cirrhotic patients. Exacerbation of hepatitis during hepatitis B treatment ( 5.9 ) Pulmonary disorders ( 5.10 ) Infections (bacterial, viral, fungal) ( 5.11 ) Colitis and pancreatitis ( 5.12 , 5.13 ) Hypersensitivity and serious skin reactions including Stevens-Johnson syndrome ( 5.14 ) Growth impairment with combination therapy in pediatric patients ( 5.15 ) Peripheral neuropathy when used in combination with telbivudine ( 5.16 ) 5.1 Pregnancy: Use with ribavirin Ribavirin may cause birth defects and/or death of the exposed fetus. Patients must avoid pregnancy (female patients or female partners of male patients) while taking PEGASYS and ribavirin combination therapy.

In clinical trials, a broad variety of serious adverse reactions were observed in 1,010 subjects who received PEGASYS at doses of 180 mcg for 48 weeks, alone or in combination with ribavirin [see Boxed Warning and Warnings and Precautions (5) ] . The most common life-threatening or fatal events induced or aggravated by PEGASYS and ribavirin include depression, suicide, relapse of drug abuse/overdose, and bacterial infections, each occurring at a frequency of less than 1%. Hepatic decompensation occurred in 2% (10/574) of CHC/HIV subjects [see Warnings and Precautions (5.9) ] . Adult subjects: The most common adverse reactions (incidence greater than 40%) are fatigue/asthenia, pyrexia, myalgia, and headache ( 6.1 ) Pediatric subjects: The most common adverse reactions are similar to those seen in adults ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact pharma& agent at 1-888-814-7734 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying and controlled conditions, adverse reaction rates observed in clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug, and may not reflect the rates observed in clinical practice. Chronic Hepatitis C Adult Subjects In all hepatitis C studies, one or more serious adverse reactions occurred in 10% of CHC monoinfected subjects and in 19% of CHC/HIV subjects receiving PEGASYS alone or in combination with ribavirin.

Pediatric patients: Safety and efficacy in CHC pediatric patients less than 5 years old and CHB pediatric patients less than 3 years old have not been established ( 8.4 ) Geriatric patients: Neuropsychiatric, cardiac, and systemic (flu-like) adverse reactions may be more severe ( 8.5 ) Patients with hepatic impairment: Clinical status and hepatic function should be closely monitored and treatment should be immediately discontinued if decompensation occurs ( 8.6 ) Patients with renal impairment: PEGASYS dose should be reduced in patients with creatinine clearance less than 30 mL/min ( 2.6 , 8.7 ) CHB: Safety and efficacy have not been established in hepatitis B patients coinfected with HCV or HIV ( 8.9 ) 8.1 Pregnancy Pregnancy Exposure Registry – Use with ribavirin A ribavirin Pregnancy Registry has been established to monitor maternal and fetal outcomes of pregnancies of female patients and female partners of male patients exposed to ribavirin during pregnancy or who become pregnant within 6 months following cessation of treatment with ribavirin. Healthcare providers and patients are encouraged to report such cases by calling 1-800-593-2214. Risk Summary There are no adequate and well-controlled studies of PEGASYS in pregnant women to inform a drug-associated risk.

Metabolism

Maximal serum concentrations (C max ) and AUC increased in a nonlinear dose related manner following administration of 90 to 270 mcg of PEGASYS. Maximal serum concentrations (C max ) occur between 72 to 96 hours post-dose.

There is limited experience with overdosage. The maximum dose received by any patient was 7 times the intended dose of PEGASYS (180 mcg/day for 7 days). There were no serious reactions attributed to overdosages. Weekly doses of up to 630 mcg have been administered to patients with cancer. Dose-limiting toxicities were fatigue, elevated liver enzymes, neutropenia, and thrombocytopenia. There is no specific antidote for PEGASYS. Hemodialysis and peritoneal dialysis are not effective.

• Oct 16, 2002BLABLA103964Pharmaand Gmbh

Reference statistics from the openFDA drug-shortage dataset. For a live view, consult the FDA database directly. Not clinical guidance.

• Pegasys, Injection, 180 ug/.5 mL (NDC 82154-0451-4)Active
  Sponsor: pharmaand GmbH (pharma&)
  Updated Jun 1, 2026
• Pegasys, Injection, 180 ug/1 mL (NDC 82154-0449-1)Active
  Sponsor: pharmaand GmbH (pharma&) · Reason: Regulatory delay
  Updated Jun 1, 2026

1. 1Fatigue9,25817%
2. 2Nausea7,16413%
3. 3Anaemia6,62412%
4. 4Rash4,8769.1%
5. 5Headache4,4548.3%
6. 6White Blood Cell Count Decreased4,2297.9%
7. 7Pruritus4,2247.9%
8. 8Pyrexia3,4736.5%
9. 9Diarrhoea3,3846.3%
10. 10Vomiting3,3346.2%
11. 11Asthenia3,1495.9%
12. 12Insomnia3,0785.7%
13. 13Dyspnoea3,0495.7%
14. 14Decreased Appetite2,9175.4%
15. 15Influenza Like Illness2,7375.1%

The 10 most recently updated of 587 ClinicalTrials.gov registrations naming Peginterferon Alfa-2a as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• A Study of Bomedemstat (IMG-7289/MK-3543) Compared to Best Available Therapy (BAT) in Participants With Essential Thrombocythemia and an Inadequate Response or Intolerance of Hydroxyurea (MK-3543-006)
  Recruiting · Phase 3 · Interventional · 340 enrolled · Merck Sharp & Dohme LLC
  NCT06079879updated 2026-06-12
• A Phase 3 Study of INCA033989 Versus Best Available Therapy in Participants With Essential Thrombocythemia
  Not yet recruiting · Phase 3 · Interventional · 426 enrolled · Incyte Corporation
  NCT07623200updated 2026-06-09
• AlloHCT With PegINFa for Myelofibrosis
  Recruiting · Phase 1 · Interventional · 18 enrolled · University of Utah
  NCT05535764updated 2026-06-04
• VIR-2218 and Peginterferon Alfa-2a for Chronic Hepatitis B
  Recruiting · Phase 2 · Interventional · 50 enrolled · National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
  NCT06092333updated 2026-05-29
• Treatment of Chronic Hepatitis C With PEG Interferon alfa2a and Ribavirin in HIV-infected Patients
  Completed · Phase 2 · Interventional · 17 enrolled · University Hospital, Bordeaux
  NCT00221650updated 2026-05-15
• Open-Label Study of AB-729, Nucleos(t)Ide Analogue and Pegylated Interferon Alfa-2a in Subjects With Chronic Hepatitis B Infection
  Completed · Phase 2 · Interventional · 43 enrolled · Arbutus Biopharma Corporation
  NCT04980482updated 2026-04-29
• Study of VIR-2218 With or Without Pegylated Interferon Alpha-2a for Treatment of Chronic Hepatitis B Virus Infection
  Completed · Phase 2 · Interventional · 84 enrolled · Vir Biotechnology, Inc.
  NCT04412863updated 2026-04-16
• DOC1021 Dendritic Cell Immunotherapy for Refractory Melanoma
  Recruiting · Phase 1 · Phase 2 · Interventional · 35 enrolled · Diakonos Oncology Corporation
  NCT07288112updated 2026-04-14
• Therapy With Asunaprevir, Daclatasvir, Ribavirin and Pegylated Interferon Alpha-2a in HCV Genotype 4-infected Patients Who Have Failed to a Previous Therapy With Peg-Interferon/Ribavirin (ANRS HC32 QUATTRO)
  Completed · Phase 2 · Interventional · 60 enrolled · ANRS, Emerging Infectious Diseases
  NCT02107365updated 2026-04-13
• Study of the Bria-IMT Regimen and CPI vs Physicians' Choice in Advanced Metastatic Breast Cancer.
  Recruiting · Phase 3 · Interventional · 404 enrolled · BriaCell Therapeutics Corporation
  NCT06072612updated 2026-04-07

CPIC-curated drug–gene pairs for Peginterferon Alfa-2a. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

• IFNL3CPIC RetiredClinPGx 1B
  IFNL3 and Peginterferon-alpha-based Regimens
• IFNL4CPIC RetiredClinPGx 1B
  IFNL3 and Peginterferon-alpha-based Regimens

Frequently asked questions

How does Peginterferon Alfa-2a work?

Pegylated recombinant human interferon alfa-2a is an inducer of the innate antiviral immune response [see Microbiology (12.4) ] .

What is Peginterferon Alfa-2a used for?

According to FDA labeling, Peginterferon Alfa-2a carries indications including: PEGASYS is an inducer of the innate immune response indicated for the treatment of Chronic Hepatitis C (CHC) ( 1.1 ) Adult Patients: In combination therapy with other hepatitis C virus drugs for adults with compensated liver disease. PEGASYS monotherapy is indicated only if patient has contraindication or significant intolerance to other HCV drugs.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Peginterferon Alfa-2a?

Peginterferon Alfa-2a is classified as Interferons, Interferon alpha, Biological Response Modifiers, RNA Replicase Inhibitors, Cellular Growth Phase Arrest, Increased Cytokine Activity, RNA Replication Alteration.

What are the brand names for Peginterferon Alfa-2a?

Peginterferon Alfa-2a is marketed under brand names including Pegasys.

What are the contraindications for Peginterferon Alfa-2a?

Peginterferon Alfa-2a labeling lists contraindications including: PEGASYS is contraindicated in patients with: Known hypersensitivity reactions such as urticaria, angioedema, bronchoconstriction, anaphylaxis, or Stevens-Johnson syndrome to alpha interferons, including PEGASYS, or any of its components. Autoimmune hepatitis Hepatic decompensation (Child-Pugh score greater than 6 [class B and C]) in cirrhotic patients before treatment Hepatic decompensation with Child-Pugh score greater than or equal to 6 in cirrhotic CHC patients coinfected with HIV before treatment PEGASYS is contraindicated in neonates and infants because it contains benzyl alcohol.. Always consult the full prescribing information and a clinician.