Home Drug Guide Interferon Alfa-2b

Drug Guide

Generic Name

Interferon Alfa-2b

Brand Names Intron A

Classification

Therapeutic: Antiviral and Antineoplastic agent

Pharmacological: Interferon (cytokine)

FDA Approved Indications

Hairy cell leukemia
Chronic hepatitis B
Chronic hepatitis C (in combination with other agents)
Malignant melanoma (adjuvant therapy)
Kaposi's sarcoma

Mechanism of Action

Interferon Alfa-2b exerts antiviral, antiproliferative, and immunomodulatory effects by inducing the expression of enzymes that inhibit viral replication, activating immune cells, and modulating the immune response.

Dosage and Administration

Adult: Dosing varies by indication; for hepatitis C, typically 3 million IU thrice weekly via subcutaneous injection for 24-48 weeks.

Pediatric: Dosing is weight-based and varies by condition. Specific protocols should be followed.

Geriatric: Use caution; start at lower doses and titrate as tolerated.

Renal Impairment: Dose adjustment may be necessary based on renal function.

Hepatic Impairment: No specific dose adjustment, but monitoring is recommended.

Pharmacokinetics

Absorption: Subcutaneous injection with peak plasma levels in approximately 3-24 hours.

Distribution: Distributed broadly; crosses the blood-brain barrier to some extent.

Metabolism: Largely metabolized intracellularly by proteolytic enzymes.

Excretion: Renal excretion of unchanged drug is minimal.

Half Life: Approximately 4-8 hours.

Contraindications

Hypersensitivity to interferons or any component of the formulation

Precautions

Pre-existing psychiatric disorders, autoimmune diseases, cardiovascular diseases, hepatic diseases, known hypersensitivity, and in pregnant or breastfeeding women. Monitoring for depression, neurotoxicity, and bone marrow suppression is essential.

Adverse Reactions - Common

Flu-like symptoms (fever, chills, myalgia, fatigue) (Common)
Bone marrow suppression (neutropenia, thrombocytopenia) (Common)
Hepatotoxicity (Common)

Adverse Reactions - Serious

Psychosis, depression, suicidal ideation (Serious but less common)
Severe hematologic toxicity (aplastic anemia, pancytopenia) (Rare)
Autoimmune disorders (thyroiditis, autoimmune hepatitis) (Rare)

Drug-Drug Interactions

May enhance myelosuppressive effects when combined with other myelosuppressants or chemotherapy agents.
Caution with drugs affecting the immune system.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor hepatic function, blood counts, mental health status, and infusion site for reactions.

Diagnoses:

Risk for infection, activity intolerance, risk for depression.

Implementation: Administer subcutaneously as prescribed, preferably at the same time three times weekly. Educate patient on signs of adverse effects.

Evaluation: Assess for therapeutic response and adverse effects regularly.

Patient/Family Teaching

Report flu-like symptoms, mood changes, bleeding, or signs of infection.
Use contraception as interferons may affect pregnancy.
Avoid pregnancy during treatment and for some time after cessation (consult specific guidelines).

Special Considerations

Black Box Warnings:

Serious depression, behavioral changes, neurotoxicity, and potentially fatal neuropsychiatric reactions.
Combination with other hepatotoxic agents increases risk.

Genetic Factors: Response may vary based on genetic factors affecting cytokine pathways.

Lab Test Interference: May cause transient changes in hematologic and hepatic function tests.

Overdose Management

Signs/Symptoms: Flu-like symptoms may be exacerbated; neurotoxicity, neuropsychiatric symptoms, or severe hematologic abnormalities could occur.

Treatment: Supportive care; there is no specific antidote. Discontinue therapy and provide symptomatic treatment.

Storage and Handling

Storage: Store in a refrigerator (2°C to 8°C); protect from light.

Stability: Stable until expiration date when stored properly.