Interferon Beta-1a
Avonex, Rebif · ATC code L03AB07
Also known as: İnterferon beta-1a
- Key facts
- Active substance
- Interferon Beta-1a
- Drug class
- Interferon
- ATC code
- L03AB07
- Authorisation
- centrally authorised across the EU (EMA)
- Dosage forms
- AVONEX 30 micrograms/0.5 ml solution for injection. · AVONEX 30 micrograms/0.5ml solution for injection in pre-filled pen. · Rebif 22 micrograms solution for injection in pre-filled syringe · Rebif 44 micrograms solution for injection in pre-filled syringe · Rebif 22 micrograms/0.5 mL solution for injection in cartridge · Rebif 44 micrograms/0.5 mL solution for injection in cartridge · Rebif 22 micrograms solution for injection in pre-filled pen · Rebif 44 micrograms solution for injection in pre-filled pen
- Marketing authorisation holder
- Biogen Netherlands B.V., Merck Europe B.V.
- Information as of
- 2026-10-29
Key facts
Interferon beta-1a (Avonex, Rebif) is an immunomodulating interferon given by injection to treat relapsing multiple sclerosis.
What it is used for
- Relapsing multiple sclerosis (Avonex and Rebif).
- Single demyelinating event with an active inflammatory process and high risk of clinically definite MS (Avonex; Rebif 44 micrograms).
- Avonex should be discontinued if progressive MS develops; Rebif efficacy has not been shown in secondary progressive MS without ongoing relapses.
Dosing
- Avonex: 30 micrograms (0.5 ml) once a week by intramuscular injection; a higher dose (60 micrograms) shows no additional benefit. Treatment can be titrated in quarter- or half-dose steps, reaching the full dose by the fourth week.
- Rebif: 44 micrograms three times per week by subcutaneous injection; 22 micrograms three times per week for patients who cannot tolerate the higher dose.
- Rebif titration: weeks 1-2 8.8 micrograms, weeks 3-4 22 micrograms, then 44 micrograms three times per week.
- An antipyretic analgesic is advised before and for 24 hours after each injection to reduce flu-like symptoms; injection sites should be varied.
- Regular re-evaluation (Avonex after two years; Rebif at least every second year in the first 4 years).
Contraindications
- Hypersensitivity to natural or recombinant interferon beta or any excipient.
- Current severe depression and/or suicidal ideation.
Important warnings
- Depression and suicidal ideation: caution with a history of depressive disorders; symptoms should be reported immediately and stopping considered.
- Thrombotic microangiopathy (TMA): prompt treatment and immediate discontinuation if diagnosed.
- Nephrotic syndrome, possibly after several years; monitor for oedema, proteinuria and renal function.
- Hepatic injury including hepatitis and hepatic failure has been reported; patients should be monitored for signs of liver injury.
- Caution with a history of seizures, severe renal or hepatic failure, severe myelosuppression and cardiac disease.
Side effects
- Most common are flu-like symptoms (myalgia, fever, chills, sweating, asthenia, headache, nausea), mainly at the start of treatment; with Rebif in approximately 70% within the first six months.
- Rebif: injection site reactions in approximately 30%; asymptomatic liver test increases and decreased white blood cells are common.
- Rare: nephrotic syndrome; transient neurological symptoms may follow injections.
Interactions
- Interferons can reduce hepatic CYP450-dependent enzyme activity; caution with narrow-therapeutic-index medicines cleared by CYP450 (e.g. antiepileptics, some antidepressants).
- Corticosteroids or ACTH can be given during relapses.
Pregnancy and breastfeeding
- Data from more than 1,000 pregnancy outcomes show no increased risk of major congenital anomalies; use may be considered during pregnancy if clinically needed.
- Levels excreted in breast milk are negligible; see the full text for breast-feeding details.
Summary of the official product information, written with AI on 2026-10-29. Every number was checked automatically against the original text. Not reviewed by a physician – the full official text is authoritative.
Common questions – ask Medelix
For patients
Package leaflet, verbatim
This product has no separate US patient information.
Authorisation and brand names by country
Medicines with exactly this active-substance composition, as listed in the national registers – alphabetical and without ranking. Whether a product is currently available is not shown here.
EU – centrally authorised (all member states)
Source: European Medicines Agency (EMA), product information
Turkey
- AvonexBİOGEN TURKEY İLAÇ TİC. LTD. ŞTİ. · 1 register entry
- RebifMERCK İLAÇ ECZA VE KİMYA TİC. A.Ş. · 7 register entries
Source: TİTCK – Ruhsatlı Beşeri Tıbbi Ürünler Listesi, as of 2026-10-16
Brand names in 3 more European countries
- Iceland
- Avonex, Rebif
- Liechtenstein
- Avonex, Rebif
- Norway
- Avonex, Rebif
EMA – Article 57 product data (EU/EEA), 2026-10-29
Medelix receives no money from pharmaceutical companies. Brand names are listed alphabetically and without ranking.
Other substances in the same group
Another question about this substance?
Medelix answers clinical questions from guidelines, studies and product information – every claim with its source.
Sources
- European Medicines Agency. Avonex – EPAR, Product Information. 2026-10-29. https://www.ema.europa.eu/en/documents/product-information/avonex-epar-product-information_en.pdf
- European Medicines Agency. Rebif – EPAR, Product Information. 2026-10-29. https://www.ema.europa.eu/en/documents/product-information/rebif-epar-product-information_en.pdf
- TİTCK – Ruhsatlı Beşeri Tıbbi Ürünler Listesi, 2026-10-16. https://www.titck.gov.tr/dinamikmodul/85
- Wikidata (CC0): ATC L03AB.
Editorial: Medelix editorial team · last updated 2026-10-29 · How these pages are made · Report an error
Source: European Medicines Agency (EMA), product information. Not advertising, not a treatment recommendation. For questions about your own treatment, ask your doctor or pharmacist.