Plegridy® (interferon beta-1a)
Drug Identification Number (DIN); 02444399 (pre-filled syringe or pre-filled pen)
Biogen Canada Inc.

Plegridy™ (peginterferon beta-1a) is a pegylated form of interferon beta-1a. The pegylation process allows for a longer half-life of the drug and therefore less frequent dosing. Beta interferon occurs naturally in the human body as part of the immune response against foreign agents.

Indications and use

Plegridy is indicated for the treatment of people with relapsing-remitting MS to reduce the risk of further disability arising from relapses and decrease the frequency of MS attacks.The safety and efficacy of Plegridy has not been established in people with primary and secondary progressive multiple sclerosis.

It is not known if Plegridy is safe and effective in children under age 18 or adults over 65.

There are no adequate and well-controlled studies of Plegridy in pregnant women and it is not known whether Plegridy is excreted in human milk.

Administration and dosage

Plegridy is injected once every two weeks under the skin (subcutaneously). The medication is available as a pre-filled syringe (Plegridy PS) and pre-filled auto-injector (Plegridy Pen). The recommended dose of Plegridy is 125mcg once every two weeks.

Mechanism of action (MOA)

Although the exact mechanism of action is not known, it is thought that the main effects of Plegridy are to block the activity of certain immune system cells and to reduce the passage of these immune cells into the central nervous system, where they cause inflammation and damage to myelin (the insulating material that protects nerves and helps them work properly).

Side effects*

The most common side effects of Plegridy therapy include flu-like symptoms (fever, chills, sweating, muscle aches and tiredness) and injection site reactions (redness or itching).

This is not a comprehensive list of all possible side effects of Plegridy. Please see the Plegridy product monograph for a list of other potentially serious side effects. It is important that those with MS discuss side effects of any medication they are considering with their physician. (*Health Canada, product monograph for Plegridy.)

Clinical trials

Clinical Trials in Relapsing-Remitting MS

Patients were randomly selected to receive either Plegridy (taken at a dose of 125mcg via under-the-skin injection once every two or four weeks) or placebo. Data from the first year showed that Plegridy, dosed once every two weeks, significantly reduced annualized relapse rate (ARR) by 36% compared to placebo. Treatment with Plegridy also significantly reduced the risk of further disability arising from relapses – as measured by the Expanded Disability Status Scale (EDSS) – by 38%, and the number of new or active lesions observed on MRI, compared to placebo. In year two of the ADVANCE trial, all patients received Plegridy (placebo patients were randomized to Plegridy every two or four weeks). Results after two years were consistent with what was observed after one year.

The 2-year extension trial included 1,468 people with MS who continued to take Plegridy for up to a total of three years. Results of the trial showed that treatment with Plegridy at a dose of 125mcg via under-the-skin injection once every two weeks maintained positive efficacy on outcomes including ARR, the proportion of individuals who experienced a relapse, the proportion of individuals with 24-week confirmed disability progression, and MRI measures over a three year period. The results demonstrates sustained long-term safety and efficacy of Plegridy.

Cost reimbursement

The price of Plegridy is $22,000 per year. Much of the cost may be reimbursed through private and group health plans for people who meet the prescribing criteria and through provincial drug programs for individuals who meet the prescribing criteria. For more information, speak to your healthcare provider.

Drug support program

Further information for persons with MS is available from Biogen ONETM program at 1-855-MSONE-00 or 1-855-676-6300.

Switching therapies

Individuals are encouraged to discuss their disease management plans with their neurologist, keeping in mind their disease history and treatment goals, to determine whether changing therapies are a suitable option for them. Due to the large number of different MS therapies currently available people with MS should discuss their disease management plans with their MS health care team.


Calabresi PA et al. Pegylated interferon beta-1a for relapsing-remitting multiple sclerosis (ADVANCE): a randomised, phase 3, double-blind study. The Lancet. 2014; 13: 657-665.

Arnold DL et al. Effect of peginterferon beta-1a on MRI measures and achieving no evidence of disease activity: results from a randomized controlled trial in relapsing-remitting multiple sclerosis. BMC Neurology. 2014; 14: 240.

Plegridy® is a registered trademark of Biogen Canada Inc.