Antiviral Interferons

Question 1

Antiviral Interferons

Answer 1

Pegylated interferon-α 2a, 2b
Interferon-α 2a, 2b

Interferons are normal human cytokines that are used by the immune system to activate cells when infection is present, fight cancerous cells and perform other functions

Given for many diseases (like MS, cancer, viral hepatitis)

This class has been used for viral hepatitis B and C; now only pegylated forms recommended

Question 2

Antiviral Interferons MOA

Answer 2

Have multiple MOA
Have direct antiviral effects, change cellular differentiation, inhibit cell growth, activate macrophages, increase lymphocyte cytotoxicity

Pegylated forms have PEG attached to the interferons; improve their PK by increasing half lives (allowing for decreased administration frequency)

Question 3

Antiviral Interferons Spectrum

Answer 3

Alpha interferons used for HBV and HCV infections

Question 4

Antiviral Interferons Adverse Effects

Answer 4

Very common; lead to noncompliance, dropout, and avoidance of use

Flu-like symptoms (most common): HA, fatigue, weakness, fever, myalgia

Depression is common; requires pharmacologic treatment
Do not give if patient has suicidal ideation
Anxiety can occur

Hematologic effects (notably cytopenias): neutropenia, anemia, thrombocytopenia
In treatment of HCV, ribavirin usually primary cause of anemia

Can worsen decompensated cirrhosis; generally not recommended to these patients

Question 5

Antiviral Interferons Important Facts

Answer 5

Pegylated: once weekly, less adverse effects, efficacy is similar or somewhat higher
Non-pegylated: three times weekly

Dosing varies significantly by agent and indication
For HCV, ribavirin differs for each form as well

For HCV: the two pegylated forms are equivalent but dosing differs

2a: fixed dose
2b: doses by weight

For HBV: only 2a has FDA indication but 2b has been studied

Interferons commonly cause it exacerbate depression; contraindicated in severe depression and suicidal patients
No rush for chronic HCV, so make sure depression is controlled before starting
For HBV, other drugs are better options for depressed patients

Question 6

Antiviral Interferons Good For

Answer 6

Use for HCV has declined due to advent of new direct acting antiviral agents

For chronic HBV, nucleoside/tide analogs preferred due to better adverse effect profile but are taken indefinitely compared to finite regimen for interferon