Interferon Alfa
Type I interferon glycoprotein with antiviral, antiproliferative, and immunomodulatory effects for hepatitis and cancer.
Chemical Identity
| Property | Value |
|---|---|
| Molecular Weight | ~19 kDa |
| Amino Acids | 165-166 (varies by subtype) |
| Gene Family | IFNA (13 subtypes) |
| Receptor | IFNAR1/IFNAR2 |
| Route | SC, IM |
Structure
Interferon alfa (IFN-alpha) is a family of type I interferons consisting of 13 subtypes (IFN-alpha1, 2a, 2b, etc.) with 165-166 amino acids and two disulfide bonds. All subtypes share the same receptor (IFNAR1/IFNAR2) and have similar biological activities, though potencies differ.
Mechanism of Action
IFN-alpha binds IFNAR1/IFNAR2, activating JAK1/TYK2 and STAT1/STAT2 signaling. This induces hundreds of interferon-stimulated genes (ISGs) that establish an antiviral state (PKR, OAS, Mx proteins), enhance MHC class I expression, activate NK cells and cytotoxic T cells, and inhibit cell proliferation.
Clinical Applications
- Hepatitis B: Pegylated IFN-alpha (peginterferon alfa)
- Hepatitis C: With ribavirin (now replaced by DAAs)
- Hairy cell leukemia: First-line therapy
- Melanoma: Adjuvant high-dose therapy
- Kaposi sarcoma: AIDS-related KS
Pharmacokinetics
- Half-life: 2-4 hours (native), 40-80 hours (pegylated)
- Tmax: 4-8 hours (SC)
- Bioavailability: 80% (SC)
- Metabolism: Renal and hepatic
- Route: SC, IM (pegylated: SC weekly)
Safety and Side Effects
Flu-like symptoms (90%), fatigue (70%), depression (30%), neutropenia, thrombocytopenia, autoimmune thyroiditis, and hepatotoxicity. Dose-limiting toxicity for many patients.
References
- Isaacs, A., & Lindenmann, J. (1957). Virus interference: the interferon. Proceedings of the Royal Society B, 147, 258-267.
- Lindsay, K.L. (1997). Therapy of hepatitis C: overview. Hepatology, 26, 71S-77S.
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