Rebif Adverse Reactions

The highest incidence of adverse reactions associated with Rebif therapy is related to flu-like syndrome. Flu-like symptoms tend to be most prominent at the initiation of therapy and decrease in frequency with continued treatment. Approximately 70% of patients treated with Rebif can expect to experience the typical interferon flu-like syndrome within the first six months after starting treatment. Approximately 30% of patients will also experience reactions at the injection site, predominantly mild inflammation or erythema.
Asymptomatic increases in laboratory parameters of hepatic function and decreases in white blood cells (WBC) are also common.
The majority of adverse reactions observed with IFN beta-1a are usually mild and reversible, and respond well to dose reductions. In case of severe or persistent undesirable effects, the dose of Rebif may be temporarily lowered or interrupted, at the discretion of the physician.
The adverse reactions presented have been identified from clinical studies as well as from post-marketing reports (an asterisk [*] indicates adverse reactions identified during post-marketing surveillance). The adverse reactions reported as follows are classified according to frequency of occurrence as follows: (See Table 3.)

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Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.
The data presented is obtained from pooled clinical studies in multiple sclerosis (placebo= 824 patients; Rebif 22 micrograms three times per week (TIW)= 398 patients; Rebif 44 micrograms TIW=727 patients) and shows the frequency of adverse reactions observed at six months (excess over placebo). Adverse reactions are listed as follows by frequency of occurrence and by MedDRA System Organ Class. (See Table 4.)

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Interferon beta has a potential for causing severe liver injury. The mechanism for the rare symptomatic hepatic dysfunction is not known. The majority of the cases of severe liver injury occurred within the first six months of treatment. No specific risk factors have been identified. Treatment with Rebif should be stopped if icterus or other clinical symptoms of liver dysfunction appear (see Precautions).
Cases of pulmonary arterial hypertension (PAH) have been reported with interferon beta products. Events were reported at various time points including up to several years after starting treatment with interferon beta.
Class effect: The administration of interferons has been associated with anorexia, dizziness, anxiety, arrhythmias, vasodilation and palpitation, menorrhagia and metrorrhagia.
An increased formation of auto-antibodies may occur during treatment with interferon beta.