home > drugs a-z list > avonex (interferon beta-1a) drug center > avonex (interferon beta-1a) drug - side effects and drug interactions

Depression, suicidal ideation, and new or worsening other psychiatric disorders have been observed to be increased in patients using interferon compounds including AVONEX® (see WARNINGS: Depression and Suicide). Anaphylaxis and other allergic reactions have been reported in patients using AVONEX® (see WARNINGS: Anaphylaxis). Decreased peripheral blood counts have been reported in patients using AVONEX® (see WARNINGS: Decreased Peripheral Blood Counts). Hepatic injury, including hepatic failure, hepatitis, and elevated serum hepatic enzyme levels, has been reported in post-marketing experience (see WARNINGS: Hepatic Injury). Seizures, cardiovascular adverse events, and autoimmune disorders also have been reported in association with the use of AVONEX® (see PRECAUTIONS).

The adverse reactions most commonly reported in patients associated with the use of AVONEX® (interferon beta-1a) were flu-like and other symptoms occurring within hours to days following an injection. Symptoms can include myalgia, fever, fatigue, headaches, chills, nausea, and vomiting. Some patients have experienced paresthesias, hypertonia and myasthenia.

The most frequently reported adverse reactions resulting in clinical intervention (e.g., discontinuation of AVONEX® (interferon beta-1a) , or the need for concomitant medication to treat an adverse reaction symptom) were flu-like symptoms and depression.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of AVONEX® (interferon beta-1a) cannot be directly compared to rates in clinical trials of other drugs and may not reflect the rates observed in practice.

The data described below reflect exposure to AVONEX® (interferon beta-1a) in 351 patients, including 319 patients exposed for 6 months, and 288 patients exposed for greater than one year in placebo-controlled trials. The mean age of patients receiving AVONEX® (interferon beta-1a) was 35 years, 74% were women and 89% were Caucasian. Patients received either 30 mcg AVONEX® (interferon beta-1a) or placebo.

Table 3 enumerates adverse events and selected laboratory abnormalities that occurred at an incidence of at least 2% higher frequency in AVONEX® (interferon beta-1a) -treated subjects than was observed in the placebo group. Reported adverse events have been classified using standard COSTART terms.

Table 3 : Adverse Events and Selected Laboratory Abnormalities in the Placebo-Controlled Studies

No AVONEX® (interferon beta-1a) -treated patients attempted suicide in the two placebo-controlled studies. In Study 2, AVONEX® (interferon beta-1a) -treated patients were more likely to experience depression than placebo-treated patients (20% in AVONEX® (interferon beta-1a) group vs. 13% in placebo group). The incidences of depression in the placebo-treated and AVONEX® (interferon beta-1a) -treated patients in Study 1 were similar. In Study 1, suicidal tendency was seen more frequently in AVONEX® (interferon beta-1a) -treated patients (4% in AVONEX® (interferon beta-1a) group vs. 1% in placebo group) (see WARNINGS).

Seizures

Seizures have been reported in 4 of 351 AVONEX® (interferon beta-1a) -treated patients in the placebo-controlled studies, compared to none in the placebo-treated patients (see PRECAUTIONS: Seizures).

Post-Marketing Experience

The following adverse events have been identified and reported during post-approval use of AVONEX® (interferon beta-1a) : New or worsening other psychiatric disorders, and anaphylaxis (see WARNINGS). Autoimmune disorders including autoimmune hepatitis, idiopathic thrombocytopenia, hyper- and hypothyroidism, and seizures in patients without prior history (see PRECAUTIONS).

Infrequent reports of congestive heart failure, cardiomyopathy, and cardiomyopathy with congestive heart failure with rare cases being temporally related to the administration of AVONEX® (see PRECAUTIONS: Cardiomyopathy and Congestive Heart Failure).

Decreased peripheral blood counts in all cell lines, including rare pancytopenia and thrombocytopenia (see WARNINGS: Decreased Peripheral Blood Counts). Some cases of thrombocytopenia have had nadirs below 10,000/μL. Some of these cases reoccur upon rechallenge.

Hepatic injury, including hepatic failure and elevated serum hepatic enzyme levels, some of which have been severe, has been reported post-marketing (see WARNINGS: Hepatic Injury).

Meno- and metrorrhagia, rash (including vesicular rash), and rare cases of injection site abscess or cellulitis that may require surgical intervention have also been reported in post-marketing experience.

Because reports of these reactions are voluntary and the population is of an uncertain size, it is not always possible to reliably estimate the frequency of the event or establish a causal relationship to drug exposure.

Adverse Reactions Associated with Subcutaneous Use

AVONEX® (interferon beta-1a) has also been evaluated in 290 patients with diseases other than multiple sclerosis, primarily chronic viral hepatitis B and C, in which the doses studied ranged from 15 mcg to 75 mcg, given SC, 3 times a week, for up to 6 months. Inflammation at the site of the subcutaneous injection was observed in 52% of treated patients in these studies. Subcutaneous injections were also associated with the following local reactions: injection site necrosis, injection site atrophy, injection site edema and injection site hemorrhage. None of the above was observed in the multiple sclerosis patients participating in Study 1. Injection site edema and injection site hemorrhage were observed in multiple sclerosis patients participating in Study 2.

Immunogenicity

As with all therapeutic proteins, there is a potential for immunogenicity. In recent studies assessing immunogenicity in multiple sclerosis patients administered AVONEX® (interferon beta-1a) for at least 1 year, 5% (21 of 390 patients) showed the presence of neutralizing antibodies at one or more times. The clinical significance of neutralizing antibodies to AVONEX® (interferon beta-1a) is unknown.

These data reflect the percentage of patients whose test results were considered positive for antibodies to AVONEX® (interferon beta-1a) using a two-tiered assay (ELISA binding assay followed by an antiviral cytopathic effect assay), and are highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of neutralizing activity in an assay may be influenced by several factors including sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to AVONEX® (interferon beta-1a) with the incidence of antibodies to other products may be misleading.

Anaphylaxis has been reported as a rare complication of AVONEX® (interferon beta-1a) use. Other allergic reactions have included dyspnea, orolingual edema, skin rash and urticaria (see WARNINGS: Anaphylaxis).

Drug Abuse And Dependence

There is no evidence that abuse or dependence occurs with AVONEX® (interferon beta-1a) therapy. However, the risk of dependence has not been systematically evaluated.

No formal drug interaction studies have been conducted with AVONEX® (interferon beta-1a) . In the placebo-controlled studies in multiple sclerosis, corticosteroids or ACTH were administered for treatment of exacerbations in some patients concurrently receiving AVONEX® (interferon beta-1a) . In addition, some patients receiving AVONEX® (interferon beta-1a) were also treated with anti-depressant therapy and/or oral contraceptive therapy. No unexpected adverse events were associated with these concomitant therapies. However, the potential for hepatic injury should be considered when AVONEX® (interferon beta-1a) is used in combination with other products associated with hepatic injury, or when new agents are added to the regimen of patients already on AVONEX® (see WARNINGS: Hepatic Injury).

Last reviewed on RxList: 2/21/2008
This monograph has been modified to include the generic and brand name in many instances.