INTERFERON ALFA-2A

INTERFERON ALFA-2a

(in-ter-feer'on)

Roferon-A Injection
Classifications: antineoplastic; immunomodulator; interferon;
Therapeutic: antineoplastic; immunomodulator
Pregnancy Category: C

Availability

3 million IU/mL, 6 million IU/mL, 9 million IU/mL

Action

Interferon (IFN) alfa-2a, one of 4 types of alpha interferons, is a highly purified protein and natural product of human leukocytes within 4–6 h after viral stimulation. Also produced by recombinant DNA technology (rIFN-A). Antiviral action: Reprograms virus-infected cells to inhibit various stages of virus replication. Antitumor action: Suppresses cell proliferation. Immunomodulating action: Enhances phagocytic activity of macrophages and augments specific cytotoxicity of lymphocytes for target cells. IFN is species specific but not virus specific; it partially inhibits viral replication and is immediately produced at site of viral entry by any cell; thus, the immune system and the interferon system of defense are complementary.

Therapeutic Effect

Has a broad spectrum of antiviral, cytotoxic, and immunomodulating activity (i.e., favorably adjusts immune system to better combat foreign invasion of antigens, cancers, and viruses).

Uses

To induce hairy cell leukemia remission in splenectomized and non-splenectomized patients; treatment of hepatitis C, adjunct to surgery for malignant melanoma.

Unlabeled Uses

Chronic hepatitis B virus infection, solid tumors, human papillomavirus (HPV)-associated diseases, AIDS-associated Kaposi's sarcoma.

Contraindications

Hypersensitivity to alpha interferons or any component of product and to mouse immunoglobulin; E. coli protein hypersensitivity; history of autoimmune disease; infants and neonates; pregnancy (category C), lactation.

Cautious Use

Cardiac disease or history of cardiac illness, severe cardiac, renal, or hepatic disease; depression or severe psychiatric disorder, bipolar disorder; alcoholism; substance abuse; seizure disorders, compromised CNS function; myelosuppression; chickenpox (existing or recent, including recent exposure), herpes zoster.

Route & Dosage

Hairy Cell Leukemia
Adult: SC/IM 3 million U/d for 16–24 wk, may be reduced to 3 times/wk for maintenance therapy

AIDS-Related Kaposi's Sarcoma
Adult: SC/IM 36 million U/d for 10–12 wk, may then be reduced to 3 times/wk

Genital and Anal Warts
Adult: Intralesional 1 million U injected in each lesion 3 times/wk on alternate days for 3 wk

Chronic Viral Hepatitis
Adult: SC/IM 1–3 million U/d for 1 wk, then 3 times/wk for 48–52 wk

Administration

Note: IFN should be administered under the guidance of a qualified physician.

Subcutaneous/Intramuscular

Reconstitute by adding supplied diluent to the sterile powder vial.
Use reconstituted solutions within 30 d. Inspect solution for particulate matter and discoloration before administration.
Note: SC administration is recommended especially for patient who is at risk for bleeding (platelet count less than 50,000).
Store sterile powder and its accompanying diluent, reconstituted solution, and injectable solution in refrigerator at 2°–8° C (36°–46° F). Do not freeze or shake solution.

Adverse Effects (≥1%)

Body as a Whole: Flu-like syndrome (fever, chills, myalgia, headache). CNS: Fatigue, dizziness, confusion, paresthesias, lethargy, psychosis, depression, nervousness, forgetfulness. CV: Dyspnea, edema, hypertension, palpitations. GI: Nausea, vomiting, diarrhea, anorexia, abdominal pain, change in taste, mild to moderate hepatotoxicity. Hematologic: Leukopenia, neutropenia, thrombocytopenia, myelosuppression. Skin: Rash, dry skin, pruritus, partial alopecia (eyelash growth increases), urticaria, reactivation of herpes labialis. Respiratory: Dryness or inflammation of oropharynx, coughing. Other: Transient impotence, arthralgia.

Diagnostic Test Interference

Decreased Hgb, Hct; elevated fasting blood sugar, serum phosphorus, serum creatinine, AST, ALT, alkaline phosphatase, LDH; hypocalcemia.

Interactions

Drug: May increase theophylline levels; additive myelosuppression with antineoplastics, zidovudine may increase hematologic toxicity, increase doxorubicin toxicity, increase neurotoxicity with vinblastine. Aldesleukin (IL-2) may potentiate the risk of renal failure.

Pharmacokinetics

Absorption: Well absorbed after IM or SC injection. Peak: 15–60 min IV; 1–8 h IM. Distribution: Concentrating in spleen, kidney, liver, and lung. Metabolism: Principally in kidney. Half-Life: 5.1 h.

Nursing Implications

Assessment & Drug Effects

Lab tests: Establish baseline data for CBC and platelet count, peripheral and bone marrow hairy cells, liver and renal function. Monitor monthly during treatment.
Monitor I&O ratio and pattern. Patient should be well hydrated during early stages of treatment. Encourage increased intake to at least 2500 mL if tolerated.
Be aware of potential side effects. If detected early, most are reversible.
Note: Flu-like syndrome (fever, chills) occurs in most patients 2–6 h after a dose of IFN. Anorexia may persist after such an episode. Symptoms tend to lessen with continued therapy.
Monitor for ecchymoses, petechiae, unexplained bleeding.
Monitor BP, vital signs, and cardiac function. Older adults are particularly susceptible to cardiotoxicity.
Monitor for gait difficulty, dizziness, and hypotension. Advise against hazardous activity until response to drug is known.
Monitor for oral superinfection with Candida albicans. Alert physician if stomatitis (sore mouth with ulceration), gingivitis, or white patches on oropharyngeal membrane surfaces are evidenced.

Patient & Family Education

Understand the risks of severe and even fatal adverse reactions as well as the benefits from IFN therapy.
Learn to self-administer after therapy is well established. Read and keep handy patient information sheet about IFN.
Avoid exposure to infection during nadir period.
Follow up with careful periodic neuropsychiatric monitoring.
Notify physician promptly if symptoms of infection develop (sore throat, fever, vomiting, diarrhea).
Note: Fertile, nonpregnant women need to use effective contraception.
Do not change brands of interferon alfa without first consulting the physician (because of risk of dosage change).

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

(53)