Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
9.6 million IU (0.3 mg) in 3 mL glass vials
Indication: multiple sclerosis
The clinical course of multiple sclerosis is variable. Some patients have attacks of neurological dysfunction followed by remission. Interferon beta-1b has been approved for use in patients with this relapsing-remitting type of multiple sclerosis, who have at least two attacks in a two-year period.
This is a recombinant product that is almost identical to human interferon beta which has antiviral and immuno regulatory effects. A subcutaneous injection given on alternate days can reduce the number of attacks experienced by the patient. In a randomised, double blind, placebocontrolled trial of interferon beta-1b in 372 patients, treatment significantly reduced exacerbation rates and a dose of 8 million IU doubled the number of patients who experienced no exacerbations at all.1 Magnetic resonance imaging revealed that the area of the lesions in patients using 8 million IU decreased while the affected area increased in patients given placebo. However, after two years, the study did not show a significant change in disability.
Most patients will experience injection site reactions during treatment and flu-like symptoms are frequently reported. Laboratory studies reveal that lymphopenia occurs at some time in most patients; concentrations of liver enzymes may also increase. Tests for neutralising antibodies to interferon will detect some neutralising activity in 45-50% of patients at some time during treatment. The product information contains a warning that suicidal ideation may be an adverse effect of treatment.
Although the number of patients studied is relatively small, interferon beta-1b appears to be effective in relapsing-remitting multiple sclerosis. Its long term safety and effectiveness are not yet known. Although the number of admissions to hospital is reduced, this is unlikely to offset the high cost of the treatment. Interferon beta-1b is not approved for use in progressive multiple sclerosis.
- IFNB Multiple Sclerosis Study Group. Interferon beta-1b is effective in relapsing-remitting multiple sclerosis. Neurology 1993;43:655-61.