AVONEX

What it is

AVONEX is a sterile solution for injection containing interferon beta-1a (rch) for intramuscular injection. Each 0.5 mL solution contains 30 µg of interferon beta-1a with 6 million IU of antiviral activity. AVONEX is available as a pre-filled syringe and as a pen delivery device. Interferon beta-1a is a 166 amino acid glycoprotein produced by mammalian cells, and the amino acid sequence of AVONEX is identical to that of natural human interferon beta.

Approved indications

— Treatment of relapsing forms of multiple sclerosis (MS). — Treatment of patients who have experienced a single demyelinating event and are at risk of developing clinically definite MS based on the presence of brain MRI abnormalities characteristic of MS. — Treatment of secondary progressive MS in patients in whom relapse is still a feature of the disease.

Dosing overview

The recommended dosage of AVONEX is 30 µg (6 million IU) injected intramuscularly once a week. For secondary progressive MS of moderate severity (EDSS 3.5–6.5) with recent or continuing relapses, the recommended dosage is 60 µg (12 million IU) injected intramuscularly once a week. A significant reduction in the severity and incidence of flu-like symptoms has been demonstrated by titration at the initiation of treatment, achieved by incremental quarter-dose increases each week, reaching the full dose by the fourth week.

Key safety warnings

Flu-like symptoms are the most common adverse events associated with AVONEX administration and are most prominent at the initiation of therapy but decrease in frequency with continued treatment. Titrating at initiation of therapy has demonstrated a significant reduction in the severity and incidence of these symptoms. Caution should be exercised when administering AVONEX to patients with a history of seizures or those receiving treatment with antiepileptics, particularly if their epilepsy is not adequately controlled. Patients who newly develop seizures with AVONEX therapy should be discontinued and an aetiological basis established, with appropriate anti-convulsant therapy instituted prior to resuming AVONEX therapy. Rare post-marketing cases of serious hepatic injury including autoimmune hepatitis, hepatitis and hepatic failure have been reported with beta-interferon treatment for MS, including very rare cases with AVONEX. In some patients, a recurrence of elevated serum levels of hepatic enzymes has occurred upon AVONEX re-challenge. It is recommended that liver function tests be undertaken prior to initiation of treatment with AVONEX and monitored periodically thereafter. Withdrawal of treatment should be considered if hepatic transaminase levels significantly increase or if they are associated with clinical symptoms such as jaundice. Cases of pulmonary arterial hypertension (PAH) have been reported with AVONEX. PAH has occurred in patients treated with interferon beta products in the absence of other contributory factors and may occur several years after starting treatment. Patients who develop unexplained symptoms such as dyspnoea or new or increasing fatigue should be assessed for PAH. If a diagnosis of PAH is confirmed, discontinue treatment and manage as clinically indicated. AVONEX should be administered with caution to patients with previous or current depressive disorders, in particular to those with antecedents of suicidal ideation. Depression and suicidal ideation are known to occur in increased frequency in the MS population and in association with interferon use. Patients treated with AVONEX should be advised to report immediately any symptoms of depression and/or suicidal ideation to their prescribing physician.

Contraindications

AVONEX is contraindicated in patients with a history of hypersensitivity to natural or recombinant interferon beta, or to any excipients. AVONEX is contraindicated in patients with current severe depression and/or suicidal ideation and in women who are or plan to become pregnant while on therapy.

Regulatory history

AVONEX interferon beta-1a 30 µg/0.5 mL injection pre-filled syringe was first listed on the Australian Register of Therapeutic Goods on 4 May 2004. AVONEX PEN—interferon beta-1a 30 µg/0.5 mL solution for injection pre-filled pen was first listed on 22 November 2011.