Rebetron Side Effects

Please note - some side effects for Rebetron may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects by Body System

Hematologic

Hemolytic anemia occurred within 1 to 2 weeks of initiation of ribavirin therapy. The mean maximum decrease from baseline hemoglobin levels observed in US and international studies ranged from 2.6 g/dL to 3.1 g/dL. Hemoglobin values returned to pretreatment levels within 4 to 8 weeks of cessation of therapy in most patients. Neutrophil and platelet values returned to pretreatment levels within 4 weeks. Complete blood counts should be obtained pretreatment, at week 2, and week 4 of therapy (more frequently if clinically indicated) and then monitored as clinically appropriate.

Approximately 20% of patients on interferon alfa-2b-ribavirin therapy have to discontinue such treatment as a result of ribavirin induced anemia.

Hematologic side effects have included bone marrow toxicity associated with interferon alfa-2b-ribavirin therapy. Hemolytic anemia (hemoglobin less than 10 g/dL) was observed in approximately 10% of patients on combination therapy in clinical trials. Aplastic anemia has been rarely reported with interferon alfa-2b-ribavirin therapy. Decreases in neutrophil and platelet counts have been observed.

Respiratory

Patients should be closely monitored if there is evidence of pulmonary infiltrates or pulmonary function impairment. Treatment should be stopped if appropriate.

Respiratory side effects including dyspnea (18%), sinusitis (10%), pulmonary infiltrates, pneumonitis, and pneumonia (including fatality) have been reported and are associated with ribavirin induced anemia.

Cardiovascular

Cardiovascular side effects have included chest pain (5% to 9%). Deterioration of cardiac function and/or exacerbation of the symptoms of coronary disease may occur due to the anemia associated with ribavirin therapy.

Patients should be assessed before initiation of therapy and monitored during therapy. Patients with a history of significant or unstable cardiac disease should not use interferon alfa-2b-ribavirin.

Psychiatric

Psychiatric side effects include insomnia (26% to 39%), depression (23% to 34%), irritability (25%), impaired concentration (11%), emotional lability (7% to 12%), and nervousness (5%). Suicidal behavior such as ideation, attempts, and suicides occurred in 1% of patients enrolled in US studies.

Therapy should be used with extreme caution in patients with a history of preexisting psychiatric disorders. All patients should be monitored for evidence of depression and other psychiatric symptoms. Patients with persistently severe or worsening signs or symptoms of these conditions should be withdrawn from therapy. In many but not all cases these disorders resolve after stopping interferon alfa-2b.

General

General side effects observed in US studies have included fatigue (60% to 70%) and asthenia (10%). Influenza-like symptoms occur frequently.

Nervous system

Nervous system side effects include headache (65%) and dizziness (17% to 26 %).

Gastrointestinal

Gastrointestinal side effects have included nausea (38% to 47%), anorexia (21% to 27%), dyspepsia (15%), and vomiting (11%). Pancreatitis, including fatal and nonfatal, has been observed.

Therapy should be suspended if signs and symptoms of pancreatitis develop and discontinued in patients with confirmed cases.

Musculoskeletal

Musculoskeletal side effects have been reported and include myalgia (61%), rigors (42%), arthralgia (30%), and pain (20% to 28%).

Ocular

Patients who experience loss of visual acuity or visual field should have an eye examination. A visual exam is recommended prior to initiation of combination therapy in patients with diabetes mellitus or hypertension because they are already at risk for these ocular events.

Ocular side effects such as retinal hemorrhages, cotton wool spots, and retinal artery or vein obstruction have been reported in rare instances.

Hypersensitivity

If a hypersensitivity reaction develops, therapy should be discontinued immediately and appropriate medical therapy instituted.

Hypersensitivity reactions reported in patients treated with interferon alfa-2b have included urticaria, angioedema, bronchoconstriction, and anaphylaxis.

Dermatologic

Dermatologic side effects have included alopecia (32% to 37%), rash (20% to 28%), and pruritus (13% to 21%). Exacerbation of preexisting psoriasis has been reported.

Therapy should only be used in patients with a history of psoriasis if the potential benefit justifies the potential risk.

Endocrine

Endocrine side effects have included hyperglycemia, new onset diabetes mellitus, exacerbation of preexisting diabetes mellitus, pancreatitis, and thyroid abnormalities.

Careful monitoring of blood glucose levels and thyroid function tests should take place. Interferon alfa-2b-ribavirin should be discontinued for patients whose thyroid function cannot be controlled by medication. Similarly, for patients with persistently elevated triglycerides (> 1000 mg/dL) associated with symptoms of potential pancreatitis, such as abdominal pain, nausea, or vomiting.

A case report of hyperthyroidism, manifested in the form of thyroiditis, in a 28-year-old woman responding well to interferon alfa-2b-ribavirin therapy, suggests that temporary interferon alfa-2b dose reduction and symptomatic treatment may be all that is needed in destructive thyroiditis.

Diabetic ketoacidosis is reported in a 53-year-old white female after week 24 of treatment, who had in the in the first 12 weeks of treatment normal random blood glucose limits (<110 mg/dL), and requires insulin. Interferon alfa-2b-ribavirin were stopped.

Other

Taste perversion occurs in approximately 7% of patients.

Local

Local side effects due to the administration of interferon alfa-2b subcutaneously have included inflammation (6% to 13%) and reactions (5% to 8%).

Other

Increases in both bilirubin and uric acid, associated with hemolysis, have been reported in clinical trials.

Most cases were moderate biochemical changes, reversed within 4 weeks after treatment discontinuation, and were not associated with hepatic dysfunction.

Other

Hearing disorder and vertigo have been reported in postmarketing studies.

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