Patients should be informed of the most common adverse reactions associated with interferon β administration, including symptoms of flu-like syndrome (see Adverse Reactions). These symptoms tend to be most prominent at the initiation of therapy and decrease in frequency and severity with continued treatment.
Rebif should be administered with caution to patients with previous or current depressive disorders in particular to those with antecedents of suicidal ideation (see Contraindications). Depression and suicidal ideation are known to occur in increased frequency in the multiple sclerosis population and in association with interferon use. Patients treated with Rebif should be advised to immediately report any symptoms of depression and/or suicidal ideation to their prescribing physician. Patients exhibiting depression should be monitored closely during therapy with Rebif and treated appropriately. Cessation of therapy with Rebif should be considered (see Contraindications and Adverse Reactions).
Rebif should be administered with caution to patients with a history of seizures, to those receiving treatment with antiepileptics, particularly if their epilepsy is not adequately controlled with antiepileptics (see Interactions and Adverse Reactions).
Patients with cardiac disease eg, angina, congestive heart failure or arrhythmia, should be closely monitored for worsening of their clinical condition during initiation of therapy with interferon β-1a. Symptoms of the flu-like syndrome associated with interferon β-1a therapy may prove stressful to patients with cardiac conditions.
Injection site necrosis (ISN) has been reported in patients using Rebif (see Adverse Reactions). To minimise the risk of injection site necrosis patients should be advised to use an aseptic injection technique and rotate the injection sites with each dose.
The procedure for self-administration by the patient should be reviewed periodically, especially if injection site reactions have occurred.
If the patient experiences any break in the skin, which may be associated with swelling or drainage of fluid from the injection site, the patient should be advised to consult with their physician before continuing injections with Rebif. If the patient has multiple lesions, Rebif should be discontinued until healing has occurred. Patients with single lesions may continue provided that necrosis is not too extensive.
In clinical trials with Rebif, asymptomatic elevations of hepatic transaminases (particularly alanine aminotransferase (ALT) were common and 1-3% of patients developed elevations of hepatic transaminases >5 times the upper limit of normal (ULN). In the absence of clinical symptoms, serum ALT levels should be monitored prior to the start of therapy, at months 1, 3 and 6 on-therapy, and periodically thereafter. Dose reduction of Rebif should be considered if ALT rises >5 x ULN, and gradually re-escalated when enzyme levels have normalized. Rebif should be initiated with caution in patients with a history of significant liver disease, clinical evidence of active liver disease, alcohol abuse or increased serum ALT (>2.5 x ULN). Treatment with Rebif should be stopped if icterus or other clinical symptoms of liver dysfunction appear (see Adverse Reactions).
Rebif, like other interferons β, has a potential for causing severe liver injury (see Adverse Reactions) including acute hepatic failure. The mechanism for the rare symptomatic hepatic dysfunction is not known. No specific risk factors have been identified.
Laboratory abnormalities are associated with the use of interferons. Therefore, in addition to those laboratory tests normally required for monitoring patients with multiple sclerosis, liver enzyme monitoring and complete and differential blood cell and platelet counts are recommended at regular intervals (1, 3 and 6 months) following introduction of Rebif therapy and then periodically thereafter in the absence of clinical symptoms. These should be more frequent when initiating Rebif 44 mcg.
Patients being treated with Rebif may occasionally develop new or worsening thyroid abnormalities. Thyroid function testing is recommended at baseline and if abnormal, every 6-12 months following initiation of therapy. If tests are normal at baseline, routine testing is not needed but should be performed, if clinical findings of thyroid dysfunction appear (see Adverse Reactions).
Caution should be used, and close monitoring considered when administering interferon β-1a to patients with severe renal and hepatic failure, and to patients with severe myelosuppression.
Serum neutralising antibodies against interferon β-1a may develop. The precise incidence of antibodies is as yet uncertain. Clinical data suggest that after 24-48 months of treatment with Rebif 22 mcg and 44 mcg, approximately 24% and 13-14%, respectively, of patients develop persistent serum antibodies to interferon β-1a. The presence of antibodies has been shown to attenuate the pharmacodynamic response to interferon β-1a (β-2 microglobulin and neopterin). Although the clinical significance of the induction of antibodies has not been fully elucidated, the development of neutralising antibodies is associated with reduced efficacy on clinical and MRI variables. If a patient responds poorly to therapy with Rebif, and has neutralising antibodies, the treating physician should re-assess the benefit/risk ratio of continued Rebif therapy.
The use of various assays to detect serum antibodies and differing definitions of antibody positivity limits the ability to compare antigenicity among different products.
Only sparse safety and efficacy data are available from non-ambulatory patients with multiple sclerosis.
Effects on the Ability to Drive or Operate Machinery: Less commonly reported central nervous system-related adverse events associated with the use of interferon β might influence the patient's ability to drive or use machines (see Adverse Reactions).
Use in pregnancy: There is limited information on the use of Rebif in pregnancy. Available data indicates that there may be an increased risk of spontaneous abortion. Initiation of treatment is contraindicated during pregnancy (see Contraindications).
Women of Childbearing Potential: Women of childbearing potential should take appropriate contraceptive measures. If the patient becomes pregnant or plans to become pregnant while taking Rebif, the patient should be informed of the potential hazards and discontinuation of therapy should be considered (see Toxicology under Actions). In patients with a high relapse rate before treatment started, the risk of a severe relapse following discontinuation of Rebif in the event of pregnancy should be weighed against a possible increased risk of spontaneous abortion.
Use in lactation: It is not known whether Rebif is excreted in human milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue breastfeeding or Rebif therapy.