Avonex - National Multiple Sclerosis Society

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About this Medication
  • Brand Name: Avonex (U.S. and Canada)
  • Chemical Name: interferon (in-ter-feer-on) beta-1a
  • Usage in MS: Disease-Modifying Agent
  • Generic Available: No

This medication is taken by injection.

The information in this medication sheet has been adapted from the FDA-approved prescribing information for Avonex.


Avonex is a medication manufactured by a biotechnological process from one of the naturally-occurring interferons (a type of protein). It is made up of exactly the same amino acids (major components of proteins) as the interferon beta found in the human body. In controlled clinical trials in relapsing MS, those taking the medication had a reduced risk of disability progression, experienced fewer exacerbations, and showed a reduction in number and size of active lesions in the brain (as shown on MRI) when compared with the group taking a placebo. In a subsequent study of patients who had experienced a single demyelinating event in the optic nerve, spinal cord, or brainstem, and had lesions typical of MS on brain MRI, Avonex significantly delayed the time to a second exacerbation, and thus to a clinically definite diagnosis of MS.

Approval by the U.S. Food and Drug Administration (FDA)

Avonex is approved by the U.S. Food and Drug Administration (FDA) for the treatment of patients with relapsing forms of MS to slow the accumulation of physical disability and decrease the frequency of clinical exacerbations. Patients with MS in whom efficacy has been demonstrated include those who have experienced a first clinical episode and have MRI features consistent with MS.

In February, 2012, the FDA approved the AVONEX PEN single-use prefilled autoinjector. It contains the same dose of medication (30 micrograms) as the prefilled syringe and the powder vial. The PEN is made up of a prefilled glass syringe surrounded by an autoinjector. Like other forms of this medication, the autoinjector should be stored in the refrigerator until 30 minutes prior to use.

The FDA also approved a gradually-increasing dosing schedule for people starting the medication, which is designed to reduce the incidence and severity of flu-like symptoms that sometimes occur. The schedule for dose titration is as follows: 

Week 1                          7.5 micrograms (1/4 dose)

Week 2                          15 micrograms (1/2 dose)

Week 3                           22.5 micrograms (3/4 dose)

Week 4 and following         full dose

The AVOSTARTGRIP titration kit is available for use with the prefilled syringe (see below) to deliver the titrated doses over the first three weeks.

Proper Usage

  • Avonex is given as a once-a-week intramuscular (IM) injection. For the pre-filled syringe and powdered formulations, the best intramuscular injection sites are the thigh and upper arm. The autoinjector can only be used in the upper or outer thigh.
  • You and your care partner will be instructed in safe and proper IM injection procedures. If you are unable to self-inject, and have no family member or friend available to do the injections, your physician or nurse will administer the injections. Do not attempt to inject yourself until you are sure that you understand the procedures.
  • In addition to the AVONEX PEN autoinjector approved in 2012, the medication comes in two other forms—as a liquid in a pre-filled syringe and as a powder in a single-use vial.
    • Prefilled syringe: AVONEX prefilled syringes should be refrigerated at 36-46°F (2-8°C). About 30 minutes before taking Avonex, it is recommended that you remove your syringe from the refrigerator and allow it to warm to room temperature. Do not use external heat sources such as hot water to warm your AVONEX in a prefilled syringe. Should refrigeration be unavailable, AVONEX in a prefilled syringe can be stored up to 77°F (25°C) for up to 7 days. Note that after the product is removed from the refrigerator, it must not be stored above 77°F (25°C). If your Avonex prefilled syringe has been exposed to conditions other than those recommended, do not use the product. Instead, discard your prefilled syringe and call your pharmacist.
    • Powder: Vials of AVONEX should be refrigerated at 36-46°F (2-8°C). Should refrigeration be unavailable, vials of AVONEX can be stored up to 77°F (25°C) for up to 7 days. Do not expose the vials of AVONEX to high or freezing temperatures. After mixing the powder, AVONEX solution should be used immediately or within 6 hours if stored in the refrigerator.
  • Flu-like symptoms are a fairly common side effect during the initial weeks of Avonex treatment. It is recommended that you take your Avonex injection before bedtime. Immediately before your injection, and for the 24 hours that follow the injection, patients have found that use of over the counter pain and fever reducing medications can help with this common side effect.

Warnings and Precautions

  • In response to post-marketing findings (events that have been reported by patients and doctors since Avonex was approved for use), the FDA has added warnings and precautions to the prescribing information for this medication:
    • Depression and suicide
      It is recommended that individuals with a history of severe depressive disorder or other mental disorder be closely monitored while taking Avonex. The people receiving Avonex in the original clinical trial did not report an increase in depression. However, depression and suicidal thoughts are known to occur with some frequency in MS, and depression and suicidal thoughts have been reported with high doses of various interferon products. In addition, there have been post-marketing reports of depression, suicidal thoughts and/or development of new or worsening of other pre-existing psychiatric disorders, including psychosis. Some of these patients improved when they stopped the medication.
    • Seizures
      Avonex should be used with caution in individuals with a seizure disorder. A few individuals with no prior history of seizures have experienced seizures while on Avonex. Since seizures are known to occur somewhat more frequently in people with MS than in the general population, it is not known whether these seizures were related to the MS, to the medication, or to some combination of the two.
    • Heart problems
      People with cardiac disease should be closely monitored for a worsening of their condition. While Avonex is not known to cause cardiac problems, there have been infrequent post-marketing reports of congestive heart failure and other cardiac problems in people with no prior history and no other factors predisposing them to heart problems.
    • Liver problems
      Avonex, like other interferon medications, can affect liver functions. In post-marketing studies, a few people have developed severe liver injury. Periodic blood tests to measure liver functions are recommended for any person taking an interferon medication.
    • Allergic reactions
      Some people taking Avonex have developed a severe allergic reaction that interferes with breathing. An allergic reaction can occur after the first dose, or not until after several doses. Less severe reactions—including itching, skin bumps, a rash, or swelling of the mouth and tongue can also occur. Anyone who develops any kind of allergic reaction should stop the medication immediately and contact his or her physician.
    • Blood problems
      Avonex can cause a reduction in levels of infection-fighting blood cells, red blood cells, or cells that help to form blood clots. Severe changes of this kind can lessen a person’s ability to fight infections and cause tiredness. Periodic blood tests can identify changes in levels of these important types of cells.
  • Prior to taking Avonex, be sure to tell your physician if you have ever had any of the following medical problems:
    • Depression, anxiety, or trouble sleeping
    • Problems with your thyroid gland
    • Blood problems such as bleeding or bruising easily, anemia, low white cell count
    • Seizures
    • Heart problems
    • Liver disease
  • Avonex should not be used during pregnancy or by any woman who is trying to become pregnant. Women taking Avonex should use birth control measures at all times. If you want to become pregnant while being treated with Avonex, discuss the matter with your physician. If you become pregnant while using Avonex, stop the treatment and contact your physician.

Possible Side Effects

  • Common side effects include flu-like symptoms (fatigue, chills, fever, muscle aches, and sweating). Most of these symptoms will tend to disappear after the initial few weeks of treatment. If they continue, become more severe, or cause you significant discomfort, be sure to talk them over with your physician.
  • Symptoms of depression, including ongoing sadness, anxiety, loss of interest in daily activities, irritability, low self-esteem, guilt, poor concentration, indecisiveness, confusion, and eating and sleep disturbances, should be reported promptly to your doctor.


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