Generic Name

Peginterferon Alfa-2a

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Classification

FDA Approved Indications

• Chronic hepatitis B virus infection
• Chronic hepatitis C virus infection (in combination with other agents)

Mechanism of Action

Peginterferon Alfa-2a enhances the immune response against viral-infected cells and inhibits viral replication by modulating the immune system and interfering with viral gene expression and replication.

Dosage and Administration

Adult: Usually 180 mcg once weekly by subcutaneous injection. Dosage may vary based on condition and patient response.

Pediatric: Not typically recommended for children.

Geriatric: Use with caution; adjust dose based on tolerability and response.

Renal Impairment: Adjust dose if necessary; monitor renal function.

Hepatic Impairment: Use with caution; hepatic function should be monitored.

Pharmacokinetics

Absorption: Once weekly subcutaneous injection with peak levels in 24-48 hours.

Distribution: Distributed into tissues; large volume of distribution.

Metabolism: Metabolized by proteolytic enzymes; not extensively processed by liver enzymes.

Excretion: Primarily excreted via kidneys.

Half Life: Approximately 40-60 hours.

Contraindications

• Hypersensitivity to peginterferon alfa-2a or any component of the formulation.
• Autoimmune hepatitis.
• Decompensated liver disease.

Precautions

• Monitor for autoimmune disorders.
• Use with caution in patients with psychiatric disorders, cardiac disease, or hematologic abnormalities.
• Pregnancy category C; should only be used if clearly needed during pregnancy; effective contraception recommended during therapy and for 6 months after.

Adverse Reactions - Common

• Flu-like symptoms (fever, chills, myalgia) (Very common)
• Fatigue (Common)
• Headache (Common)
• Nausea and vomiting (Common)
• Bone marrow suppression (neutropenia, thrombocytopenia, anemia) (Common)

Adverse Reactions - Serious

• Neuropsychiatric effects (depression, suicidal ideation) (Uncommon)
• Autoimmune disorders (thyroiditis, autoimmune hepatitis) (Uncommon)
• Severe neuropsychiatric symptoms or depression leading to discontinuation (Uncommon)
• Allergic reactions including anaphylaxis (Rare)

Drug-Drug Interactions

• Ribavirin, other myelosuppressants, other immunomodulators.

Drug-Food Interactions

• Limited data; generally no significant food interactions.

Drug-Herb Interactions

• Potential interactions with herbal supplements affecting immune function; consult with healthcare provider.

Nursing Implications

Patient/Family Teaching

• Report flu-like symptoms, depression, suicidal thoughts, or unusual bleeding.
• Use contraceptives during treatment and for 6 months after.
• Adherence to injection schedule is essential for effectiveness.
• Avoid pregnancy during therapy and for 6 months afterward.

Special Considerations

Black Box Warnings:

• Neuropsychiatric effects, including depression and suicidality.
• Hepatitis B reactivation in patients with HBV infection undergoing treatment for hepatitis C.

Genetic Factors: Genetic polymorphisms can influence response to therapy.

Lab Test Interference: Can cause transient decreases in blood counts and liver enzymes, monitor regularly.

Overdose Management

Signs/Symptoms: Flu-like symptoms, hematologic abnormalities, neuropsychiatric symptoms.

Treatment: Supportive care; no specific antidote. Discontinue drug and provide symptomatic treatment as needed.

Storage and Handling

Storage: Store refrigerated at 2-8°C (36-46°F). Do not freeze.

Stability: Stable until the expiration date on the label when stored properly.