Interferon alfa-2b

Antineoplastic; biological response modifier.

Interferon alfa-2b (Intron A) is a recombinant DNA product derived from the interferon alfa-2b gene of human white blood cells. Its mechanism of antitumor action involves binding to a plasma membrane receptor but is otherwise poorly understood. Its serum half-life is 2 to 3 hours after parenteral administration.

Intron A (Schering); Intron A HSA-free (Schering).

Interferon alfa-2b, Intron A, a water-soluble protein of165 amino acids and an approximate molecular mass of19,200 Da, is expressed from a recombinant strain of E. coli.This interferon molecule possesses an arginine at position23 and a histidine at position 34.Interferon alfa-2b is a broad-spectrum agent. It is indicatedfor hairy cell leukemia, condyloma acuminata (genital or venereal warts), AIDS-related Kaposi sarcoma, and chronichepatitis B and C infections.Intron A can be administered by the SC, IM, or IV routes,by infusion or by intralesional routes. The dose is 1 to 35 millionIU/day, depending on the application. The drug is suppliedas a solution or as a powder for solution, and both formscontain albumin, glycine, and sodium phosphate buffer.Hence, they should not be shaken. Vials of solution should bestored at 2°C to 8°C without freezing. The powder is stablefor 18 months at room temperature or 7 days at 45°C.

Interferon alfa-2b is useful in the treatment of a rare form of chronic leukemia, hairy cell leukemia, in which it produces remissions in 60 to 80% of patients. However, it has minimal antitumor activity in most human cancers.Remissions lasting a few months have been observed in 10 to 20% of patients with lymphomas, multiple myeloma, melanoma, renal cell carcinoma, and ovarian carcinoma.

The adverse effects of interferon alfa-2b include fever and a flulike syndrome of muscle ache, fatigue, headache, anorexia, and nausea. Other less common side effects include leukopenia, diarrhea, dizziness, and skin rash.

Potentially hazardous interactions with other drugs
Aminophylline and theophylline: metabolism of aminophylline and theophylline reduced, consider reducing dose of aminophylline and theophylline
. Antivirals: increased risk of peripheral neuropathy with telbivudine
. Immunosuppressants, e.g. ciclosporin, tacrolimus, sirolimus may have an antagonistic effect.
Administration of interferon in combination with other chemotherapeutic agents, e.g. cytarabine, cyclophosphamide, doxorubicin may lead to increased risk of severe toxicity.

Alpha-interferons are totally filtered through the glomeruli and undergo rapid proteolytic degradation during tubular reabsorption, rendering a negligible reappearance of intact alfa interferon in the systemic circulation.