Rebif® (interferon beta-1a)
Drug identification number (DIN):
Rebif 22 mcg 02237319
Rebif 44 mcg 02237320
Rebif Initiation Pk 02281708
Rebif 66 mcg Multi-dose 02318253
Rebif 132 mcg Multi-dose 02318261
EMD Serono Canada Inc.

Rebif (interferon beta-1a) is a beta-interferon that is produced from mammalian cells using recombinant DNA techniques (a series of procedures used to join together DNA segments). Beta-interferon is a protein that occurs naturally in the human body in response to initiating factors such as viruses.

Indications and use

Rebif is approved for the treatment of:

  1. relapsing forms of MS (in which persons still experience recurrent attacks, such as relapsing-remitting MS and secondary-progressive MS with relapses) to reduce the number and severity of attacks, slow the progression of physical disability, reduce the need for steroids and the number of hospitalizations due to MS, and to reduce the number of brain lesions seen on magnetic resonance imaging (MRI).
  2. clinically isolated syndrome (CIS): people at risk of developing clinically definite MS (CDMS) accompanied by at least two lesions on MRI to delay the progression to clinically definite MS. Before Rebif is initiated, alternative diagnoses must be ruled out.

Administration and dose

The usual dose of Rebif is 44 mcg three times per week. It is also available in a dose of 22 mcg three times per week. Rebif is self-injected three times per week under the skin (subcutaneously). Rebif is available in a pre-filled syringe and as an electronic auto-injector, RebiSmart®, for the self-administration of Rebif, using multidose cartridges, each of which contains one week of medicine.

Mechanism of action (MOA)

The main effects of Rebif 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.

Side effects*

The most common side effects of Rebif therapy include flu-like symptoms (fatigue, chills, fever, muscle aches, and sweating) and injection site reactions (swelling, redness, discolouration, and pain). Most of these symptoms tend to improve over time.

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

Neutralizing antibodies

Some people taking a beta-interferon therapy develop neutralizing anti- bodies (NAb). It is not known if NAbs completely “neutralize” the clinical benefits of therapy. Some research has found that a higher NAb level may be associated with a lesser treatment effect. Studies are continuing in this area, as is the development of a standardized NAb test.

Cost reimbursement

Rebif is set at approximately $24,000 per year. Much of the cost can 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.

Clinical trials

Clinical Trials in Relapsing-Remitting MS

PRISMS Study: Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis

The PRISMS study compared the effects of Rebif at two doses (44 mcg and 22 mcg, three times per week) with placebo (a treatment that has no active medication) in 560 persons with relapsing-remitting MS. At 2 years, both doses of Rebif were shown to be more effective than placebo in reducing the number and frequency of relapses. With the higher dose of Rebif, the number of relapses was reduced by about one-third. Rebif also delayed the progression of disability, and a larger proportion of people were relapse-free with treatment compared to placebo. 1 [PRISMS Study Group. Lancet 1998; 352: 1498-1504] A separate report on MRI results found that Rebif reduced the number of brain lesions compared to placebo. 2 [Li et al. Ann Neurol 1999; 46: 197-206]

Clinical Trials: Single Event Suggestive of MS

ETOMS Study: Effect of Early Treatment on Conversion to Definite MS

This study examined the effects of Rebif on the occurrence of MS attacks in 308 persons who were at risk of developing clinically definite MS, but who were not yet diagnosed with the disease. After 2 years of treatment, fewer persons in the Rebif group developed clinically definite MS (34%) compared to those in the placebo group (45%), which represents a 24% reduction in risk. Rebif was also found to have a positive effect on the relapse rate and MRI measures compared to placebo. 3 [Comi et al. Lancet 2001; 357: 1576-1582]

REFLEX (Rebif® Fexiible dosing in early MS)

REFLEXwas a two-year, double-blinded, placebo-controlled study that investigated the effects of interferon beta-1a (Rebif® 44mcg) in 517 individuals with CIS. Participants were chosen at random to receive one of the following treatments: Rebif® 44mcg three-times daily; Rebif® 44mcg once weekly and placebo. Researchers recorded relapse rates and MRI activity for participants in each group over a two year period, and measured the time to conversion to MS. Results from the study found that time to conversion to MS following a CIS was reduced by just over 50% for those treated with three-times weekly Rebif® 44mcg versus placebo. Rebif® (three times a week) was also found to significantly improve magnetic resonance imaging (MRI) outcomes and delayed relapses compared with placebo at two years.6 [REFLEX Study Group. Journal of Neurology 2014; 261:490–499]

Clinical Trials in Secondary-Progressive MS

SPECTRIMS Study: Secondary-Progressive Efficacy Clinical Trial of Recombinant Interferon beta-1a in MS

In the SPECTRIMS study, 618 persons with secondary-progressive MS were treated with either Rebif or placebo for 3 years. The study found that Rebif did not slow disease progression in people with secondary-progressive MS. Rebif treatment was associated with fewer relapses. 4 [SPECTRIMS Study Group. Neurology 2001; 56: 1496-1504] Rebif was also associated with fewer brain lesions as measured by MRI. 5 [Li et al. Neurology 2001; 56: 1505-1513]

Drug support program

Further information for persons with MS is available from the patient assistance program Adveva at 1-888-677-3243.


  1. PRISMS Study Group. Randomised double-blind placebo-controlled study of interferon beta-1a in relapsing/remitting multiple sclerosis. Lancet 1998; 352: 1498-1504.
  2. Li DKB, Paty DW, and the UBC MS/MRI Analysis Research Group and the PRISMS Study Group. Magnetic resonance imaging results of the PRISMS trial: a randomized, double-blind, placebo-controlled study of interferon-beta1a in relapsing-remitting multiple sclerosis. Ann Neurol 1999; 46: 197-206.
  3. Comi G, Filippi M, Barkhof F, et al. Effect of early interferon treatment on conversion to definite multiple sclerosis: a randomised study Lancet 2001; 357: 1576-1582.
  4. SPECTRIMS Study Group. Randomized controlled trial of interferon beta-1a in secondary progressive MS. Neurology 2001; 56: 1496-1504.
  5. Li DKB, Zhao GJ, Paty DW, et al. Randomized controlled trial of interferon beta-1a in secondary progressive MS: MRI results. Neurology 2001; 56: 1505-1513.
  6. Freedman, MS et al. (2014) Patient subgroup analyses of the treatment effect of subcutaneous interferon b-1a on development of multiple sclerosis in the randomized controlled REFLEX study. J Neurol 261:490–499.

Rebif® is a registered trademark of EMD Serono Canada Inc.