I am not going to tell you why you should be on disease-modifying therapy for MS. Instead, I want to provide some information to help you decide if Avonex is the right choice for you as you consider the various existing disease-modifying therapies (DMT).
I know that the decision-making process around MS treatment can be confusing and stressful, with the drug companies presenting information on colorful websites with testimonials from smiling patients who “swear by” their drug of choice.
My goal is to give you the practical information that I was interested in when I was trying to make a decision about which MS treatment to start.
Avonex: The Bottom Line
Avonex (Interferon beta-1a) provides the lowest dose of all the interferons (30mcg/week, while Rebif is 44mcg 3 times/week). There is some evidence that higher-dose interferons may be more effective in some patients, and many doctors switch their patients to Rebif if they have several relapses on Avonex.
That said, it is still true that all of the CRAB drugs (Copaxone, Rebif, Avonex, Betaseron) are pretty much equally effective overall, offering about one-third reduction in relapses when compared to a placebo over two years in people with relapsing-remitting MS (RRMS).
People with RRMS usually make their treatment decisions based on their doctor’s advice and experience with similar patients, as well as concerns about convenience, side effects and cost. Avonex is also FDA-approved for use in people who have had one attack, which is suspected to be MS, but does not meet all diagnostic criteria.
Many people choose Avonex as their first disease-modifying therapy because they will only need one injection per week, as opposed to 3 to 7 injections per week that are required for some of the other drugs. The once-a-week dosing schedule also reduces flu-like side effects commonly associated with these drugs (many people take their injections on Friday night, giving them the weekend to recover).
These factors make Avonex a convenient choice for people who are working full-time, caring for small children, or have other concerns that make limiting "down time" due to side effects a necessity.
The dosing schedule also appeals to many people who are uncomfortable with injecting themselves, although Avonex injections are intramuscular (usually injected into the muscle of the thigh), whereas all of the other CRAB drugs are given subcutaneously (injected into the fat right under the skin).
If people are very nervous about injecting themselves -- and don’t have family members or friends willing to do it -- arrangements can usually be made for a technician at a doctor's office to give the injections. However, most people eventually become “comfortable” enough with the process to do it themselves.
More Details on Avonex
Type of MS and Severity
Avonex is for people with RRMS. It is also approved for use in people who have experienced one “MS event,” but do not yet meet all criteria for MS.
Similar to all the CRAB drugs, Avonex was found to decrease relapses by 32% in an initial trial of patients with mild to moderate RRMS over 2 years (18 to 38% decrease in subsequent studies, depending on type of patient and length of treatment time). Avonex does not seem to become less effective over time.
Blood tests need to be done every 3 months for the first year to check white blood cell count and liver function. After a year, these checks can be reduced to once every four months.
Avonex is given once a week as an intramuscular injection into the thigh, which is usually done by the patient or a nurse. The needle is 1.25 inches long, and is 23-gauge (however, a 25-gauge (thinner), 1-inch (shorter) needle can be substituted if a doctor gives the okay). Red spots at the injection sites, as seen with the other interferon treatments, do not usually occur since Avonex is injected into the muscle. Avonex should be given on the same day every week, but injections can be as close as 5 days or as long as 10 days apart.
The side effects of Avonex are similar to those of other interferon-based therapies, however Avonex does not cause as many injection-site reactions as the others.
- Flu-like Symptoms
The most important side effect is flu-like symptoms, which are experienced by about 61% of patients. These include: fever, chills, sweating, muscle aches and fatigue (but not nausea or stomach upset), and they last for 24 to 36 hours. This side effect is usually the worst after the first dose and progressively lessens with each injection. Most people still experience these symptoms after 6 months, though they're usually more tolerable. This reaction can be reduced by starting with a low dose and increasing to a full dose gradually over several weeks. Taking ibuprofen or acetaminophen a couple hours before and after an injection can help with some of these side effects, too.
- Liver Damage
Hepatitis and elevated levels of liver enzymes, which can cause liver damage, have been reported. Regular monitoring is required to prevent liver damage from occurring or progressing (see "Necessary Monitoring" above).
- Blood Counts
Avonex can cause a decrease in the numbers of red and white blood cells, as well as a reduction in the number of platelets in the blood.
Avonex should be used with caution in patients with depression.