A pilot study of the effect of weekly intramuscular 30 mcg interferon beta-1a (Avonex (TM)) on monthly gadolinium-enhanced brain MRI activity in patients with relapsing multiple sclerosis.

We compared the number of new gadolinium-enhancing (Gd+) and T2-weighted (T 2W) lesions on 6-monthly MRI scans before and after initiating weekly intra muscular injections of interferon beta-1a (Avonex(TM)) 30 mcg. The mean num ber of new focal Gd+ lesions detected during the 6 monthly on-treatment sca nning sessions was 58 per cent less per MRI scan and 62.5 per cent less per patient than during the 6 monthly pre-treatment scanning sessions (p = 0,0 16 Wilcoxon signed rank test). The results are similar for new focal Gd+ an d T2W lesions. The reduction in disease activity detected by monthly Gd+ en hanced MRI scans after initiating weekly intramuscular interferon beta-1a 3 0 meg is consistent with benefits observed with thrice weekly subcutaneous interferon beta-1a 10 and 30 mcg and alternate day subcutaneous interferon beta-1b 8.0 MIU.