Peginterferon alfa

How it works

It binds type I interferon receptors to activate intracellular signalling that induces antiviral, antiproliferative and immunomodulatory gene expression; pegylation prolongs its half-life to allow less frequent administration.

Prescribing in practice

• Can precipitate or worsen severe psychiatric effects including depression and suicidal ideation, as well as serious bone-marrow suppression and autoimmune or ischaemic complications, so it is contraindicated in decompensated hepatic disease and severe psychiatric illness and requires careful baseline assessment.
• Administered by subcutaneous injection on an intermittent (typically weekly) schedule.
• Dose adjustment is required in renal impairment and according to haematological and biochemical tolerance per current prescribing references.

Monitoring

Monitor full blood count, liver function, thyroid function, mood and signs of autoimmune or ophthalmological complications throughout treatment.

Counselling the patient

• Flu-like symptoms are common, especially after the first injections, and can be eased with paracetamol.
• Report any low mood, thoughts of self-harm, marked fatigue, breathlessness or visual changes promptly.
• Effective contraception is needed during treatment for relevant patients.

Evidence & guidelines

Pegylated interferon-based regimens are long-established in chronic viral hepatitis, though direct-acting antivirals have largely superseded them for hepatitis C in current NICE guidance.