What You Should Know About Avonex vs. Rebif

Medically reviewed by Alan Carter, PharmD on January 15, 2016Written by Susan J. Bliss, RPh, MBA on January 15, 2016

Avonex vs. Rebif

Avonex and Rebif are both injectable drugs used to treat relapsing and remitting multiple sclerosis (RRMS). They both contain interferon beta-1a. Interferons are chemical messengers that help regulate your immune response.

Multiple sclerosis (MS) is an autoimmune disease. It causes inflammation of the insulating membranes, or myelin, that surrounds nerves within the central nervous system. Avonex and Rebif help prevent damage to the central nervous system as a result of MS flare-ups.

Main differences between Avonex and Rebif

Avonex dosing, use, and storage

Avonex is injected deep into a major muscle. The full dose is 30 micrograms. You should take it once per week.

Avonex is available in a dried powder form. You must dissolve this powder in liquid before injection. There’s also a premixed injectable liquid form that’s packaged either in a prefilled syringe or in a single use, auto-injector pen.

Your doctor may start you on a lower dose of Avonex. For example, you may start with a dose of 7.5 micrograms the first week and gradually increase the dose by 7.5 micrograms each week until you reach the full dose the fourth week. This helps minimize the flu-like side effects common with Avonex. A special starter kit is available that allows you to gradually increase the dose.

You should inject Avonex on the same day each week. Inject it in a different place each time to minimize irritation, redness, or skin damage from the injection.

Many doctors recommend taking an over-the-counter medication, such as acetaminophen or ibuprofen, before each dose. That can also help reduce flu-like side effects. Injecting Avonex late in the day or in the evening helps minimize side effects.

Avonex prefilled syringes or the auto-injector should be stored at 36 to 46°F (2 to 8°C). Keep it from freezing, and allow the medication to warm to room temperature before using.

The dried powder should be stored at 36 to 46°F (2 to 8°C). It can also be stored at 77°F (25°C) for up to 30 days. After mixing, you can also store it up to 6 hours at 36 to 46°F (2 to 8°C).

Rebif dosing, use, and storage

Rebif is injected subcutaneously, or under the skin. The full dose is 22 or 44 micrograms, three times per week. The drug is given on the same three days each week, 48 hours apart. For example, Monday, Wednesday, and Friday could be your dosing schedule. It’s usually recommended to inject it in the late afternoon or evening. Your doctor may also advise you to start with a smaller dose and slowly increase it. Both of these approaches help minimize the flu-like side effects, such as headaches, fatigue, and chills, which commonly occur with this drug.

Rebif comes in prefilled syringes and also in a starter kit, which makes it easier to start Rebif gradually. You’ll likely start with 20 percent of the full dose three times for the first week, and increase the dose gradually over four weeks to the prescribed dose. Rebif should be stored between 36 and 46°F (2 to 8°C). Allow it to warm to room temperature before using. If needed, it may be stored between 36 and 77°F (2 to 25°C) for up to 30 days.

Cost, availability, and insurance

Both Avonex and Rebif are expensive drugs. Each drug costs about $6,000 per month of treatment. Both require prior authorization before insurance companies will pay for them, and both are almost exclusively dispensed by specialty pharmacies and shipped directly to you.

Most manufacturers also have assistance programs. These programs may pay for most or all of the cost of the drug if you qualify for assistance. Talk to your doctor if you need help paying for your injectable MS drug.

Side effects of Avonex and Rebif

Avonex and Rebif are both interferons. This group of medications has some side effects in common.

Side effects of Avonex

Avonex is given once each week, so the side effects will tend to be most noticeable the first few hours after treatment. Frequent side effects can include:

  • a headache
  • flu-like symptoms, such as fatigue, chills, or dizziness
  • pain at the injection site
  • a skin reaction at the injection site
  • low blood pressure
  • an increased heart rate
  • stomach pain
  • low white blood cell count
  • reduced thyroid function, which can be found through blood tests

See your doctor right away if you experience any of these more serious side effects:

  • Avonex contains proteins, and you could develop antibodies to them. Sometimes, there are no symptoms, but it’s possible that you could have a reaction like hives, rash, or trouble breathing. These symptoms indicate you may be having an immune reaction. See your doctor right away if this happens.
  • There’s a higher risk of depression if you’ve had depression before, and you could have an increased risk of suicide.
  • Signs of liver injury can include increasing fatigue, yellowing of eyes or skin, or swollen or painful abdomen.
  • Your risk of a seizure is increased if you have a history of seizures.
  • If you have a history of heart disease, you are at higher risk of heart failure.

Side effects of Rebif

Rebif is given three times per week. Milder side effects can include:

  • a headache
  • flu-like symptoms, such as fatigue, chills or dizziness
  • pain at the injection site
  • a skin reaction at the injection site
  • chest pain
  • stomach pain

See your doctor right away if you experience any of the more serious side effects. These more serious side effects include:

  • Rebif also contains proteins and you could develop antibodies to them. The symptoms can include hives, a rash, or trouble breathing. These symptoms indicate you may be having an immune reaction. See your doctor right away if this happens.
  • There’s a higher risk of having depression if you’ve had depression before, and you could have an increased risk of suicide.
  • Signs of liver injury can include increasing fatigue, yellowing of the eyes or skin, or swollen or painful abdomen.
  • You have an increased risk of seizures if you have a seizure disorder and start taking Rebif.
  • Reduced red and white blood cell counts and platelet counts could lead to increased risk of infection, or problems with bleeding and bruising.

Which drug is right for you?

The FDA label for Rebif includes results of a study directly comparing the effects of Rebif versus Avonex. People were randomly chosen to receive either 44 micrograms of Rebif subcutaneous injections three times per week or 30 microgram of Avonex intramuscular injections once per week. The study lasted 48 weeks.

Results were evaluated based on the proportion of people who didn’t have flare-ups after 24 weeks and the number of active lesions each person had as found by MRI. The study showed that those treated with 44 micrograms of Rebif three times per week were more likely to not have relapses after 24 and 48 weeks compared to those treated with 30 micrograms of Avonex per week.

Only the highest FDA-approved dose of Rebif was used in this study. The doses of the drugs were different, but it’s not possible to exactly compare them since they’re given in different ways. Additionally, according to their FDA labels, the way both Avonex and Rebif are absorbed and processed in your body isn’t completely understood.

Pharmacist’s takeaway

Although Avonex and Rebif are similar and both contain interferon beta-1a, they aren’t interchangeable. They’re injected differently, dosed differently, and they have a different frequency or pattern of dosing.

Treatments for MS are individualized and based on your personal health history, other diseases you may have, and other treatments you currently take. The best way for you to decide which drug is for you is to talk to your doctor who has experience treating people who have RRMS. They can help you find a treatment regimen that is best for you based on your symptoms, lifestyle, and health history.

CMS Id: 97133