A new study suggests that taking an antibiotic in combination with interferon beta 1-a, a current disease-modifying medication for MS, could slow progression of the disease. Published in the online issue of the Archives of Neurology, the study was conducted by Dr Alireza Minagar and colleagues from the Louisiana State University Health Sciences Center, Shreveport. Interferon beta 1-a (Avonex) is injected into the muscle and is usually taken once a week. Although it is not a cure for MS, it often reduces the number of relapses and slows the progression of the disease. The study was a single-center trial with 15 participants (average age 44.5 years) who had relapsing-remitting MS. Although taking Avonex for at least six months, all were having symptoms and showing new brain lesions on MRI. Every day for four months, participants took a 100 mg dose of the antibiotic doxycycline in addition to the interferon. Doxycycline is in a class of medications called tetracycline antibiotics that work by preventing the growth and spread of bacteria. Once a month, study participants underwent a neurological exam, MRI, and blood tests. Combination of doxycycline and Avonex resulted in reductions in contrast-enhancing lesion numbers and post-treatment Expanded Disability Status Scale (EDSS) scores (P < .001 for both). For research findings to be significant, the p value should be less than 0.05. The smaller the number the more likely it is that the finding is significant. One patient relapsed. Adverse events were described as "mild" and not a result of the combination therapy. There is growing interest in combination therapy in MS to stabilize the disease course, reduce the rate of relapses and slow the progression of the disease. Overall, this study indicates that a combination of oral doxycycline and interferon beta 1-a may be safe and effective in some patients with MS. However, further controlled studies are needed to ensure both safety and efficacy. "The number of enhancing lesions went down after the doxycycline was added, which could indicate a treatment effect and certainly merits further study," comments MSF Medical Advisor Ben Thrower, M.D. "However, we don't know for sure that the decrease in enhancement is due to the addition of doxycycline because the number of enhancing lesions in MS does tend to decrease naturally as an individual transitions from relapsing-remitting MS to a secondary-progressive phase."