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Avonex (interferon beta-1a)

Avonex is a form of interferon beta administered by intramuscular (IM) injection indicated for the treatment of patients with relapsing forms of multiple sclerosis (MS). Use of Avonex is intended to slow the progression of physical disability. Avonex is prescribed for people with MRI results that contain features consistent with multiple sclerosis lesions.

What are the ingredients in Avonex?

The active ingredient in Avonex is interferon beta-1a, a 186 amino acid glycoprotein.

How does Avonex work?

Avonex is an interferon, a group of glycoproteins produced by the body to fight viral infections and other foreign matter. Avonex contains all of the same basic components as the interferon beta that occurs naturally in the human body.

Interferons help control immune system activities. Avonex helps to inhibit inflammation that can cause MS flare-ups.

What are possible side effects of Avonex?

Many clinical trials evaluated the safety and efficacy of Avonex. The most common side effects experienced by those taking Avonex include:

  • Headache
  • Chills
  • Fever
  • Pain
  • Depression
  • Injection site reactions
  • Nausea
  • Fatigue
  • Backache
  • Muscle aches

These symptoms generally last for a day or two after the injection and lessen over time. The flu-like symptoms can generally be treated with over-the-counter pain relief medications.

This is not an exhaustive list of all potential side effects of Avonex. For more information, consult your doctor or healthcare provider. If you notice any new or worsening conditions, contact your doctor or healthcare provider immediately.

Things to note about Avonex

Avonex is administered by IM injection and comes in several forms:

  • Powder form of Avonex which is reconstituted in a single-use vial
  • Single-use prefilled syringe with 30 micrograms solution
  • Single-use prefilled auto-injector containing 30 micrograms solution
  • Avostart Grip Titration kit to use with prefilled syringes to build dose up gradually to decrease flu-like symptoms

In addition to routine MS lab tests, complete blood and differential white blood cell counts, platelet counts and blood chemistries as well as liver function tests are recommended during Avonex therapy.

Before starting Avonex talk to your doctor if you:

  • Have a history of hypersensitivity or allergic reaction to natural or recombinant interferon beta, albumin or any other component of the formulation
  • Have a history of anaphylaxis
  • Are pregnant or planning to get pregnant, as there is limited information on the use of Avonex in pregnancy. Avonex should be used only if the potential benefit of Avonex therapy exceeds the risk to the fetus
  • Have a history of depression, suicide, and/or psychotic disorders. Any new symptoms of depression, suicidal ideation, and/or psychosis should be reported to your doctor. Consider discontinuation of Avonex if depression occurs
  • Have hepatic (liver) injury
  • Are a congestive heart failure patient, who should be monitored for worsening symptoms
  • Have Thrombotic Microangiopathy (damage to small blood vessels in vital organs)
  • Experience development of new autoimmune disorders
  • Experience seizures

Individuals with the above conditions should be monitored closely while taking Avonex.

Dosing information

Avonex is administered by IM injection. It is recommended that the first dosage be administered under clinical supervision before ongoing shots are done independently or given at home. Injection sites should be rotated to minimize the chance of injection site reactions. IM injections should not be administered where the skin is bruised, irritated or red, infected, or scarred.

The recommended dose is 30 micrograms, once a week. Avonex may be titrated, starting with 7.5 micrograms (1/4 dose) for the first week, to reduce the chance of developing flu-like symptoms. Dosage can be increased by 7.5 micrograms each week for the next 3 weeks until recommended dose of 30 micrograms, a full dose, is reached. Injection sites should be examined for redness, swelling or tenderness 2 hours after a shot is given.

Avonex should be stored in the refrigerator. It should be allowed to come to room temperature before use. Safe disposal practices should be used for needles and syringes. Do not reuse needles, syringes, pre-filled syringes or auto-injectors. Following the administration of each titrated dose, throw away any remaining product.

For more details, read the full prescribing information of Avonex.

Written by Linda Saxl Minton | Last review date: July 2019.
Avonex (interferon beta-1a) Prescribing Information. Biogen Idec Inc; Cambridge, MA: 2012.