Interferon alfa

Summary

Interferon alfa is a family of recombinant or natural type I interferons used therapeutically for chronic viral hepatitis (HBV, HCV), certain hematologic malignancies (hairy cell leukemia, chronic myelogenous leukemia, follicular lymphoma), melanoma, renal cell carcinoma, and Kaposi's sarcoma. Multiple subtypes (alfa-2a, alfa-2b, alfa-n1, alfa-n3) and pegylated formulations exist. Pegylated forms (peginterferon alfa-2a, alfa-2b) have largely replaced standard interferon alfa due to improved pharmacokinetics and dosing convenience.

Mechanism of Action

Binds to the type I interferon receptor (IFNAR1/IFNAR2) on cell surfaces, activating the JAK-STAT signaling pathway (JAK1/TYK2), which induces transcription of interferon-stimulated genes (ISGs). This results in antiviral, antiproliferative, and immunomodulatory effects including enhanced NK cell activity, upregulation of MHC class I expression, and inhibition of viral replication and tumor cell proliferation.

Routes of Administration

Goals & Uses

• Chronic Hepatitis C treatmentAntiviralHigh
• Chronic Hepatitis B treatmentAntiviralHigh
• Melanoma adjuvant therapyOncologyHigh
• Hairy cell leukemia treatmentOncologyHigh
• Kaposi's sarcoma treatmentOncologyModerate
• Follicular lymphoma treatmentOncologyModerate

Contraindications

• Decompensated liver disease (Child-Pugh B/C)HepaticHigh
• Severe psychiatric disorder (untreated)PsychiatricHigh
• Neonates (formulations with benzyl alcohol)PediatricHigh
• PregnancyPopulationHighPotential fetal risk or insufficient safety data
• Hypersensitivity to interferon alfaImmunologicHigh
• Autoimmune hepatitisHepatic / AutoimmuneHigh

Adverse Effects

• Neutropenia and thrombocytopeniaHematologicCommon
• Injection site reactionsLocalCommon
• Thyroid dysfunction (hyper- or hypothyroidism)EndocrineUncommon
• Flu-like syndrome (fever, chills, myalgia, fatigue)SystemicCommon
• Depression and suicidal ideationPsychiatricCommon
• RetinopathyOphthalmologicUncommon

Drug Interactions

• Zidovudine (AZT)Moderate
• Immunosuppressants (e.g., tacrolimus, cyclosporine)Moderate
• RibavirinModerate
• ClozapineHigh
• TheophyllineHigh
• MethadoneModerate

Population Constraints

• Patients with severe renal impairment (CrCl <50 mL/min)RenalRelative
• Elderly (>65 years)AgeRelative
• Patients with pre-existing autoimmune disordersImmunologicRelative
• Pediatric patients (<1 year)AgeAbsolute
• Pregnant womenReproductiveRelative
• Patients with pre-existing cardiac diseaseCardiovascularRelative

Regulatory Status

• European UnionApprovedApproved: Chronic hepatitis B, Chronic hepatitis C, Hairy cell leukemia, Follicular lymphoma, Kaposi's sarcoma, Renal cell carcinoma, Chronic myeloid leukemiaEMA-approved products include peginterferon alfa-2a (Pegasys) and alfa-2b (PegIntron). Standard interferon products largely superseded.
• United StatesApprovedApproved: Chronic hepatitis B, Chronic hepatitis C (pegylated preferred), Hairy cell leukemia, Melanoma (adjuvant, high-dose), AIDS-related Kaposi's sarcoma, Follicular non-Hodgkin lymphoma, Chronic myelogenous leukemiaMultiple formulations approved (alfa-2a, alfa-2b). HCV use markedly reduced due to DAA availability. Pegylated formulations are FDA-approved and generally preferred.
• United KingdomApprovedApproved: Chronic hepatitis B, Chronic hepatitis C, Hairy cell leukemia, Follicular lymphoma, Kaposi's sarcomaMHRA-approved; pegylated formulations preferred. HCV indications largely historical due to DAA therapies.

Multiple approved formulations exist: Interferon alfa-2b (Intron A) and alfa-2a (Roferon-A) approved by FDA. Pegylated versions (Pegasys, PegIntron) are preferred for hepatitis C. Use in HCV has been largely superseded by direct-acting antivirals (DAAs). Biosimilar interferons available in some jurisdictions.

Evidence & Sources

No sources recorded yet.