Intron A

interferon alfa-2b, recombinant

Intron A, Viraferon (UK)

Pharmacologic class: Biological response modifier

Therapeutic class: Antineoplastic, antiviral

Pregnancy risk category C

FDA Box Warning

• Drug may cause or worsen fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Monitor patient closely with periodic clinical and laboratory evaluations. Discontinue drug in patients with persistently severe or worsening signs or symptoms of these conditions. In many cases, these disorders resolve after withdrawal.


Unknown. Antitumor and antiviral activity may stem from direct antiproliferative action against tumor or viral cells, inhibition of viral replication, and modulation of host immune response.


Injection: 3 million international units/0.5-ml vial, 5 million international units/0.5-ml vial, 10 million international units/1-ml vial; 18 million international units/3.2-ml vial, 25 million international units/3.2-ml vial

Powder for injection (vial with diluent): 3 million, 5 million, 10 million, 18 million, 25 million, and 50 million international units

Indications and dosages

Chronic hepatitis C

Adults: 3 million international units subcutaneously or I.M. three times weekly. If patient tolerates therapy and alanine aminotransferase (ALT) level is normal after 16 weeks, continue for 18 to 24 weeks. If ALT doesn't normalize, drug may be withdrawn.

Chronic hepatitis B

Adults: 30 to 35 million international units subcutaneously or I.M. weekly for 16 weeks, given as 5 million international units daily or 10 million international units three times weekly

Hairy cell leukemia

Adults: 2 million international units/m2 I.M. or subcutaneously three times weekly for 6 months or longer

AIDS-related Kaposi's sarcoma

Adults: 30 million international units/m2 subcutaneously or I.M. three times weekly. Continue dosage unless intolerance occurs or disease advances rapidly.

Malignant melanoma (as adjunct to surgery)

Adults: 20 million international units/m2 I.V. for 5 consecutive days per week for 4 weeks; then a maintenance dosage of 10 million international units/m2 subcutaneously three times weekly for 48 weeks. Withhold drug if adverse reactions occur; when reactions ease, resume at half of previous dosage. Withdraw if reactions persist.

Condyloma acuminatum (genital or venereal warts)

Adults: 1 million international units/lesion given intralesionally three times weekly for 3 weeks

Aggressive follicular non-Hodgkin's lymphoma

Adults: 5 million international units subcutaneously three times weekly for up to 18 months (given with chemotherapy regimen containing anthracycline)

Off-label uses

• Adjuvant treatment of malignant melanoma

• Hepatitis D


• Hypersensitivity to drug or its components

• Autoimmune disorders

• Female partners of males receiving drug


Use cautiously in:

• cardiac or pulmonary disease; bone marrow, autoimmune, seizure, or psychiatric disorders

• diabetic patients prone to ketoacidosis

• pregnant or breastfeeding patients

• children.


• Administer by subcutaneous, I.M., I.V., or intralesional route. For I.V. use, reconstitute with diluent provided by manufacturer (bacteriostatic water for injection), according to chart provided. Mix gently, draw drug up into sterile syringe, and inject into 100 ml of normal saline solution. Infuse slowly over 20 minutes.

• Give antiemetics, as needed and prescribed, for nausea and vomiting.

Adverse reactions

CNS: dizziness, confusion, paresthesia, rigors, lethargy, depression, difficulty thinking or concentrating, insomnia, anxiety, fatigue, asthenia, amnesia, malaise, nervousness, drowsiness, suicidal ideation

CV: chest pain, hypertension, palpitations, arrhythmias

EENT: visual disturbances, stye, hearing disorders, nasal congestion, sinusitis, rhinitis, pharyngitis

GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, flatulence, eructation, stomatitis, dry mouth, intestinal obstruction

GU: gynecomastia, impaired fertility in women, transient erectile dysfunction

Hematologic: anemia, leukopenia, thrombocytopenia, neutropenia

Metabolic: hyperglycemia, hypocalcemia

Musculoskeletal: joint pain, back pain, myalgia

Respiratory: cough, dyspnea

Skin: flushing, rash, dry skin, pruritus, alopecia, dermatitis, diaphoresis

Other: gingivitis, flulike symptoms, candidiasis, edema, weight loss


Drug-drug. Aminophylline, theophylline: reduced clearance of these drugs

CNS depressants: additive CNS effects

Live-virus vaccines: decreased antibody response to vaccine, increased risk of adverse reactions

Zidovudine: synergistic effects

Drug-diagnostic tests. Alkaline phosphatase, ALT, aspartate aminotransferase, bilirubin, blood urea nitrogen, calcium, creatinine, fasting glucose, lactate dehydrogenase, neutralizing antibodies, phosphate, uric acid: increased levels

Hemoglobin, platelets, white blood cells: decreased values

International Normalized Ratio, partial thromboplastin time, prothrombin time: increased values

Patient monitoring

Before therapy and monthly during therapy, assess CBC with white cell differential, bone marrow hairy cells, glucose and electrolyte levels, and liver and kidney function tests.

• Discontinue therapy if neutrophil count drops below 500 cells/mm2.

• Monitor fluid intake and output. Keep patient well hydrated.

• Assess for GI upset. Provide small, frequent meals and antiemetics to ease severe nausea and vomiting.

Monitor for mental status changes, depression, and suicidal ideation.

• Assess for bleeding and bruising.

• Institute infection-control measures. Monitor for signs and symptoms of infection.

Patient teaching

• Teach patient or caregiver how to prepare and give drug subcutaneously or I.M., rotate injection sites, and track dosing schedule and injection sites on calendar.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration, alertness, and vision.

• Inform female patient that drug is linked to fetal abnormalities. Advise her not to get pregnant during therapy, and to use barrier contraception.

• Tell female patient not to breastfeed.

• Advise patient to avoid potential infection sources, such as crowds and people with known infections.

• Tell patient to eat small, frequent meals to combat nausea, vomiting, and loss of appetite.

• Inform male patient that drug may cause transient erectile dysfunction.

Instruct patient to immediately report depression, suicidal thoughts, mental status changes, signs or symptoms of infection (such as fever, chills, sore throat), unusual bleeding or bruising, dizziness, palpitations, or chest pain.

• Tell patient he'll need regular follow-up examinations and blood tests to gauge drug effects.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved


A purified human interferon (IFN), IFN-alfa-n3, which has been used to treat various cancers (leukaemia, melanoma, Kaposi’s sarcoma) and viral infections, including genital warts, hepatitis B and hepatitis C.

Adverse effects
Injection site reactions, diarrhoea, upset stomach, loss of appetite, dry mouth, nausea, flu-like symptoms, vomiting, and occasionally hair loss.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

Intron A

A brand name for INTERFERON ALFA-2 b.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
Distribution of PZ intron F G79A polymorphism in control and stroke patients Intron n GG GA AA F G79A n (%) n (%) n (%) Controls 70 41 (58.5) 28 (40.0) 1 (1.4) Patients 91 52 (57.1) 34 (37.4) 5 (5.5) * Intron A allele p OR (95%CI) F G79A frequency Controls 0.214 0.57 1 Patients 0.242 0.57 1.16 (0.68-1.98) * p=0.62; OR: 3.94 (0.44-35.1) Table 2.
Specific primers for 4 predicted introns were designed, but only those specific for histone 3 intron A (H3-iA) produced clear one or two-banded phenotypes, and only in the Manila clam (Fig.
Important Safety Information Regarding United States Labeling for PEGINTRON Alpha interferons, including PEGINTRON and INTRON A, may cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders.
Significantly more patients infected with genotype 1 or 4 hepatitis C virus (HCV) developed a sustained virologic response (SVR) with peginterferon alfa-2b (Peg-Intron) plus ribavirin (Rebetol) than with interferon alfa-2b (Intron A) plus ribavirin (17% of 125 patients vs.
In July, the FDA approved a stand-alone package of Rebetol, which was previously available only in a package with Intron A (marketed as Rebetron).
The safety and efficacy of REBETOL Capsules with interferons other than INTRON A have not been established.
Schering-Plough markets Ribapharm's ribavirin in the United States, Europe and Japan under the brand name Rebetol for use in combination with its Intron A or Peg-Intron to treat chronic hepatitis C in adult patients with compensated liver disease.
REBETOL had been previously approved in the United States for use in combination with INTRON A (interferon alfa-2b, recombinant) Injection for the treatment of chronic hepatitis C in patients with compensated liver disease previously untreated with alpha interferon or who have relapsed following alpha interferon therapy.
A long-acting formulation of Intron A (interferon alfa-2b) for once-weekly monotherapy in patients with chronic hepatitis C who were not previously treated with alpha-interferon, have compensated liver disease, and are at least age 18 years.
Schering-Plough's United States alpha interferon products include INTRON A (interferon alfa-2b, recombinant) Injection; PEG-INTRON (peginterferon alfa-2b) Powder for Injection; and REBETRON Combination Therapy containing REBETOL (ribavirin, USP) Capsules and INTRON A.
Patients were randomized to receive subcutaneous injections of INTRON A 3 million international units (MIU) three times per week and either oral REBETOL 1,000-1,200 mg or a matched placebo daily for 24 or 48 weeks followed by 24 weeks of off-therapy follow up.
PEG-INTRON is a longer-acting form of INTRON A (interferon alfa-2b, recombinant) Injection that uses proprietary PEG technology developed by Enzon, Inc.