Interferon beta-1a
Also known as: Avonex, Betaferon-1a, Betaseron, Extavia, IFN beta-1a, IFN‑β1a, Interferon beta‑1a, Plegridy (pegylated form), Rebif
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Summary
Interferon beta-1a is a recombinant type I interferon approved as a disease‑modifying therapy for relapsing forms of multiple sclerosis (MS). It is administered by injection (intramuscular or subcutaneous) and works to modulate immune activity, thereby reducing the frequency of clinical relapses and magnetic‑resonance imaging (MRI) evidence of disease activity.
Mechanism of Action
Interferon beta-1a binds the interferon‑α/β receptor (IFNAR) on immune cells, activating the JAK‑STAT signaling cascade. This leads to increased expression of anti‑inflammatory genes and reduced production of pro‑inflammatory cytokines, inhibition of leukocyte trafficking across the blood‑brain barrier, and promotion of regulatory T‑cell activity, collectively dampening the autoimmune attack on central‑nervous‑system myelin.
What the Research Shows
In the pivotal OPERA I and II phase‑3 trials, interferon beta‑1a (44 µg subcutaneously three times weekly) served as the active comparator to intravenous ocrelizumab in patients with relapsing MS. Over 96 weeks, interferon beta‑1a was associated with a higher annualised relapse rate, greater confirmed disability progression at 12 and 24 weeks, and more gadolinium‑enhancing MRI lesions than ocrelizumab. A pooled analysis of these trials showed that most disability accumulation occurred independent of overt relapses, with interferon beta‑1a patients experiencing more progression‑independent events. A 2024 Cochrane network meta‑analysis included interferon beta‑1a among many agents for relapsing‑remitting MS, noting that its relative benefit compared with newer therapies remains uncertain.
Reported Benefits
Interferon beta‑1a has demonstrated efficacy in reducing clinical relapses and MRI disease activity compared with untreated disease, forming the basis for its regulatory approval in relapsing MS. It remains an option for patients who cannot receive newer high‑efficacy agents, and its long‑standing use provides a well‑characterised safety and tolerability profile.
Limitations of the Evidence
Head‑to‑head trials show interferon beta‑1a is less effective than high‑efficacy monoclonal antibodies such as ocrelizumab in lowering relapse rates, slowing disability progression, and reducing MRI lesion formation. Network meta‑analysis suggests its relative advantage over other disease‑modifying therapies is modest, and trial heterogeneity plus potential bias limit definitive conclusions about its comparative potency.
Safety Considerations
In the OPERA trials, serious infections occurred in 2.9 % of interferon beta‑1a recipients, slightly higher than the 1.3 % observed with ocrelizumab. While the abstracts do not detail other adverse events, interferon beta‑1a is known to cause injection‑site reactions and flu‑like symptoms, which may affect adherence. Monitoring for infection and managing injection‑related discomfort are standard considerations.
How It Is Administered
Interferon beta‑1a is supplied for intramuscular or subcutaneous injection. The subcutaneous formulation used in clinical trials is 44 µg administered three times weekly; intramuscular products are typically dosed less frequently. No oral or intravenous routes are indicated.
Routes of Administration
Goals & Uses
- Reduction of MS relapse rateDisease ModificationHigh
- Reduce annualized relapse rateDisease ModifyingHigh
- Delay of second demyelinating event (CIS)Disease PreventionHigh
- Antiviral activityInfectious DiseaseLow
- Delay disability progressionEfficacyModerate
- Reduction of MRI lesion burdenNeurological / AutoimmuneHigh
- Decrease new/enlarging MRI lesionsRadiologicHigh
- Slowing disability progressionDisease ModificationHigh
Contraindications
- Severe active depression or suicidal ideationPsychiatricHigh
- Severe hepatic impairmentOrganModerateLiver function concerns
- Decompensated hepatic diseaseHepaticHigh
- PregnancyPopulationModeratePotential fetal risk or insufficient safety data
- Hypersensitivity to interferon beta‑1a or any excipientAllergyHigh
- Thyroid disease (uncontrolled)EndocrineModerate
- Hypersensitivity to natural or recombinant interferon beta or any excipientAllergy / ImmunologyHigh
Adverse Effects
- Hepatotoxicity / elevated liver enzymesHepaticUncommon
- Hematologic abnormalities (leukopenia, thrombocytopenia, anemia)HematologicUncommon
- LeukopeniaHematologicRareLow white blood cell count
- Neutralizing antibody formationImmunologicCommon
- Injection site reactionsLocalCommon
- Flu‑like syndromeSystemicCommon
- Flu-like symptoms (fever, chills, myalgia, fatigue)Systemic / ConstitutionalCommon
- Depression and suicidal ideationPsychiatricUncommon
- DepressionPsychiatricUncommon
- Elevated liver enzymesHepaticUncommonIncrease in AST/ALT or other hepatic markers
Drug Interactions
- AntidepressantsLow
- Immunosuppressants (e.g., azathioprine)Moderate
- Live attenuated vaccinesHigh
- Hepatic enzyme inducers (e.g., rifampin)Moderate
- CYP450 substrates (e.g., warfarin, phenytoin)Low
- Myelosuppressive agents (e.g., azathioprine, methotrexate)Moderate
- Hepatotoxic drugs (e.g., statins, valproate, alcohol)Moderate
Population Constraints
- Pediatric patients (<18 years)AgeRelative
- Elderly (>65 years)AgeRelative
- Elderly patients (over 65)AgeRelative
- Patients with pre-existing severe psychiatric disordersPsychiatricRelative
- Pregnant womenReproductiveRelative
- Patients with severe renal impairmentOrgan ImpairmentRelative
- Pediatric patients (under 18)AgeRelative
Regulatory Status
- European UnionApprovedApproved: relapsing forms of multiple sclerosisBiosimilar versions approved; dosing similar to US.
- United StatesApprovedApproved: relapsing‑remitting multiple sclerosis, active secondary progressive multiple sclerosisAvonex (IM weekly), Rebif (SC three times weekly), Betaseron/Extavia (SC every other day).
- United KingdomApprovedApproved: relapsing‑remitting multiple sclerosisSame formulations as EU.
Multiple brand formulations (Avonex, Rebif, Betaseron, Extavia) differ in dosing schedule and route; biosimilar versions approved in EU.
Evidence & Sources
- Journal ArticleModerateLamb YN2022-01-01T00:00:00.000000Z
- Journal ArticleModerateKappos L, et al.2020-01-01T00:00:00.000000Z
- Journal ArticleModerateHauser SL, et al.2017-01-01T00:00:00.000000Z
- Journal ArticleHighGonzalez-Lorenzo M, et al.2024-01-01T00:00:00.000000Z
- Journal ArticleModerateOstojic SM2022-01-01T00:00:00.000000Z
Frequently Asked Questions
How does interferon beta‑1a differ from newer MS therapies?
Clinical trials comparing it directly with agents such as ocrelizumab show that interferon beta‑1a leads to higher relapse rates, more disability progression, and more MRI lesions, indicating lower efficacy than newer high‑efficacy monoclonal antibodies.
What are the common side effects of interferon beta‑1a?
The most frequently reported adverse events include injection‑site reactions, flu‑like symptoms, and a modest increase in serious infections (about 3 % of patients in trial comparisons).
Is interferon beta‑1a still used despite newer drugs?
Yes; it remains an approved option for relapsing MS, especially for patients who cannot access or tolerate newer agents, because its long‑term safety record and administration schedule are well established.
How is interferon beta‑1a administered?
It is given by injection, either intramuscularly or subcutaneously. The subcutaneous regimen studied in trials is 44 µg three times per week; intramuscular products are typically given less often.
What monitoring is needed while on interferon beta‑1a?
Patients should be observed for signs of infection, injection‑site irritation, and flu‑like symptoms. Periodic blood tests may be performed to assess liver function and blood counts, reflecting the drug’s known safety profile.
What is Interferon beta-1a?
Interferon beta-1a is a recombinant type I interferon approved as a disease‑modifying therapy for relapsing forms of multiple sclerosis (MS). It is administered by injection (intramuscular or subcutaneous) and works to modulate immune activity, thereby reducing the frequency of clinical relapses and magnetic‑resonance imaging (MRI) evidence of disease activity.
What is Interferon beta-1a used for?
Interferon beta-1a is educationally associated with: Reduction of MS relapse rate, Reduce annualized relapse rate, Delay of second demyelinating event (CIS), Antiviral activity, Delay disability progression, Reduction of MRI lesion burden, Decrease new/enlarging MRI lesions, Slowing disability progression. Educational only — not medical advice.
How is Interferon beta-1a administered?
Recorded routes of administration: Intramuscular, Subcutaneous.
What are the potential side effects of Interferon beta-1a?
Reported adverse effects include: Hepatotoxicity / elevated liver enzymes, Hematologic abnormalities (leukopenia, thrombocytopenia, anemia), Leukopenia, Neutralizing antibody formation, Injection site reactions, Flu‑like syndrome, Flu-like symptoms (fever, chills, myalgia, fatigue), Depression and suicidal ideation, Depression, Elevated liver enzymes. This list is not exhaustive — consult a qualified clinician.
Who should avoid Interferon beta-1a?
Recorded contraindications: Severe active depression or suicidal ideation, Severe hepatic impairment, Decompensated hepatic disease, Pregnancy, Hypersensitivity to interferon beta‑1a or any excipient, Thyroid disease (uncontrolled), Hypersensitivity to natural or recombinant interferon beta or any excipient. Consult a qualified clinician before use.