Disease modifying drug therapy, what you need to know Beta interferon and glatiramer acetate
Who is eligible for treatment?
The prescribing criteria for the beta interferon drugs and glatiramer acetate are based on guidelines from the Association of British Neurologists (ABN). People who meet the criteria are entitled to treatment on the NHS.
- a maximum Expanded Disability Status Scale (EDSS) score 6.5 - that is, able to walk (with or without walking aids) about 20 metres without resting
- have experienced at least two clinically significant relapses in the last two years OR a single major relapse in the preceding two years, with MRI scan suggesting active MS
- normally be aged 18 or above.
Assessment before treatment
Blood tests will be taken before treatment is started to check for problems that might affect how well a person will do on the drugs. The neurologist needs to be made aware of any pre-existing conditions or reactions to previous treatments. Whilst treatment may still be an option, it may need to be started in a different way.
Interferons are proteins produced naturally in the body which alter how the immune system responds to infection. Beta interferon reduces both the immune response and inflammation. In MS, the immune system attacks the body's own myelin; beta interferon can help to reduce this immune response.There are two forms of beta interferon used for the treatment of MS:
- interferon beta 1a (Avonex)
- interferon beta 1a (Rebif)
- interferon beta 1b (Betaferon)
- interferon beta 1b (Extavia)
The differences between these forms lie in the way they are manufactured.
Glatiramer acetate (Copaxone) produces similar results to beta interferon but acts in a different way. Glatiramer acetate is a synthetic combination of four amino acids, resembling the myelin protein surrounding nerve fibres. It is thought to lessen the immune reaction that attacks myelin.
These are injected, either under the skin (subcutaneous) or into a muscle (intramuscular).
|Avonex (interferon beta 1a)||once a week||into a muscle|
|Betaferon (interferon beta 1b)||every other day||under the skin|
|Extavia (interferon beta 1b)||every other day||under the skin|
|Rebif (interferon beta 1a)||three times a week||under the skin|
|Copaxone (glatiramer acetate)||every day||under the skin|
All of these drugs come with devices to make injection easier. Many people may feel nervous about filling or holding a needle and seeing the needle going into the skin. Some devices help with this.
The first dose of the drug is usually given in the presence of a nurse, who will give instructions on the injection technique. The nurse will discuss the practicalities and offer advice or training and ongoing support if necessary.
Drug companies provide homecare support allowing drugs to be delivered direct to an individual's home, so they do not need to be obtained from a pharmacist. They also give advice on drug storage, travelling with the drug, safety issues of medicines in the home and disposal of sharp needles.
Beta interferon and glatiramer acetate have been used to treat MS since the 1990s. In clinical trials these drugs reduced the frequency of relapses by around one third. MRI scans showed most people were found to have fewer, smaller or no new areas of damage within the central nervous system. Beta interferon may also reduce the severity of relapses.
By limiting lesion formation, beta interferon may also delay or slow disability, particularly when treatment is started early in the disease course. However, there is a lack of clarity about the extent of the effect on disability.
In addition, beta interferon and glatiramer acetate have been shown, in clinical trials, to delay the conversion from clinically isolated syndrome to clinically definite MS in the two to five years following the start of treatment.
For most people, any side effects of these drugs are relatively mild and manageable.
One of the more common side effects of beta interferon is flu-like symptoms, such as headache, muscle ache and stiffness, chills or fever, which may occur following injection and may lessen over time. Injection into a muscle may also produce discomfort and stiffness.
An MS specialist nurse will provide support and ensure any side effects experienced are managed as effectively as possible. There are various strategies that may be recommended to reduce the risk of experiencing side effects. For example:
- a lower dose may be given at the start of treatment and the dose will be slowly increased over time to allow the body to adjust to the drug
- to help with flu-like symptoms, it may be helpful to change the time of day of injection in order to sleep through the worst of the side effects
- to help reduce body temperature, paracetamol or ibuprofen can be taken before the injection and at four to six hour intervals after the injection, as required.
Some people may experience a reaction, known as the Immediate Post-Injection Reaction (IPIR), which can occur immediately after injection. This may involve one or more of the following: flushing, tightness of the chest, shortness of breath and palpitations. This reaction can last 15-30 minutes and will ease without any treatment.
|Treatment||Common (affect more than 1 person in 100)||Less common (affect fewer than 1 person in 100)|
Further information concerning administration and possible side effects can be found within the patient information leaflet that comes with the treatment package and drug company support helplines.
If the neurologist prescribes one of the beta interferon drugs, blood tests will be performed regularly throughout treatment to check that the body is tolerating the drug. Regular blood tests may be taken during the first year of treatment and, assuming a person responds well, may be reduced to once a year, although this may vary between centres. Treatment with glatiramer acetate does not require regular blood tests.
Assessments will be made to monitor how the person's MS is responding to treatment. This may involve checking body functions such as vision, strength, sensation, thinking and activity performance.
Antibodies are proteins produced by the immune system to fight foreign substances, such as infection. Sometimes the body's natural defences will develop antibodies against drugs entering the body, 'neutralising' their effect.
Treatment with beta interferon drugs can lead to the development of neutralising antibodies (NAbs), which can reduce their effectiveness. The person may experience a similar number of relapses as they would have done before taking the drug, or develop new MS lesions that are detected using MRI. Neutralising antibodies are not associated with any new side effects or long-term safety issues.
The majority of people will not develop significant levels of neutralising antibodies and in some people they may reduce again over time. A test may be performed if the presence of neutralising antibodies is suspected. Depending on the results, the neurologist may then discuss whether to continue with treatment, or suggest switching to a disease modifying treatment that is not beta interferon.