interferon alfacon-1

interferon alfacon-1,

a recombinant type 1 interferon.

indications It is used to treat chronic hepatitis C infections. It is being used investigationally to treat hairy cell leukemia in combination with granulocyte colony-stimulating factor.

contraindications Hypersensitivity to alpha interferons or to products derived from Escherichia coli prohibit its use.

adverse effects Life-threatening effects include granulocytopenia, thrombocytopenia, and leukopenia. Other adverse effects include headache, rigors, insomnia, dizziness, nausea, diarrhea, anorexia, vomiting, constipation, hemorrhoids, decreased salivation, musculoskeletal pain, dysmenorrhea, vaginitis, menstrual disorders, alopecia, pruritus, rash, erythema, tinnitus, earache, conjunctivitis, eye pain, granulocytopenia, ecchymosis, hypertension, palpitations, nervousness, depression, anxiety, emotional lability, abnormal thinking, upper respiratory infection, respiratory tract congestion, and bronchitis.

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interferon alfacon-1

Infergen

Pharmacologic class: Biological response modifier

Therapeutic class: Antiviral

Pregnancy risk category C

FDA Boxed 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.

Action

Binds to membrane receptors on viral cells, inducing protein synthesis, inhibiting viral replication, and suppressing cell proliferation. Increases phagocytosis, enhances expression of human leukocyte antigen, and augments lymphocyte cytotoxicity.

Availability

Injection: 9-mcg/0.3-ml vials, 15-mcg/0.5-ml vials

⊘Indications and dosages

➣ Chronic hepatitis C

Adults: 9 mcg subcutaneously as a single dose three times weekly for 24 weeks. Wait at least 48 hours between doses.

Off-label uses

• Hairy cell leukemia

Contraindications

• Hypersensitivity to drug or Escherichia coli-derived products

Precautions

Use cautiously in:
• thyroid disorders, bone marrow depression, hepatic or cardiac disease, seizure disorders, compromised CNS function, severe psychiatric disorders
• pregnant or breastfeeding patients
• children age 18 and younger.

Administration

• Give by subcutaneous route only.
• Give antiemetics for nausea and vomiting, as needed and prescribed.

Route	Onset	Peak	Duration
Subcut.	Unknown	24-36 hr	Unknown

Adverse reactions

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

CV: chest pain, hypertension, palpitations, arrhythmias

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

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

GU: impaired fertility in women, gynecomastia, erectile dysfunction

Hematologic: anemia, leukopenia, thrombocytopenia, neutropenia

Metabolic: hyperglycemia, hypocalcemia

Musculoskeletal: joint pain, back pain, myalgia

Respiratory: cough, dyspnea

Skin: rash, dryness, pruritus, flushing, alopecia, candidiasis, dermatitis, diaphoresis

Other: gingivitis, flulike symptoms, edema, weight loss

Interactions

Drug-drug. Drugs metabolized by CYP450: altered blood levels of both drugs

Drug-diagnostic tests. Granulocytes, hemoglobin, platelets, white blood cells: decreased values

Alkaline phosphatase, aspartate aminotransferase, bilirubin, blood urea nitrogen, creatinine, International Normalized Ratio, lactate dehydrogenase, neutralizing antibodies, phosphorus, prothrombin time, triglycerides, uric acid: increased values

Patient monitoring

☞ Before and regularly during therapy, assess CBC with white cell differential and hepatitis C virus antibodies.
• Assess fluid intake and output. Keep patient well hydrated.
• Monitor for GI upset. Provide small, frequent meals and give antiemetics, as prescribed, to ease severe nausea and vomiting.
☞ Stay alert for depression, mental status changes, psychosis, and suicidal ideation (especially in patients with history of mental illness).
• Assess for bleeding and bruising.
• Institute infection-control measures. Monitor for signs and symptoms of infection.
• Watch for flulike symptoms.

Patient teaching

• Teach patient or caregiver how to administer drug subcutaneously, rotate injection sites, and track dosing schedule and injection sites on calendar.
• Advise patient to avoid sources of potential infection, such as crowds and people with known infections.
• Tell patient to eat small, frequent meals to combat nausea, vomiting, and appetite loss.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration, alertness, and vision.
• Tell female patient that drug is linked to fetal abnormalities. Advise her not to get pregnant during therapy, and to use barrier contraception.
☞ Instruct patient to immediately report symptoms of infection (fever, chills, sore throat), unusual bleeding or bruising, mental status changes, 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.