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| |  AAN: No Need for Concern About Antibody Formation With Repeat Botulinum Toxin Type Injections By Jill Stein MIAMI, FL -- April 12, 2005 -- New results indicate that repeated treatments using the current Botox formulation of botulinum toxin type A results in low rates of neutralising antibody formation in patients treated for cervical dystonia, chronic headache, and poststroke spasticity. The data were reported here on April 12th at the American Academy of Neurology 57th Annual Meeting. Stuart A. Yablon, MD, director, Brain Injury Program, Methodist Rehabilitation Center, Jackson, Mississippi, United States, and associates examined the incidence of neutralising antibody formation in previously botulinum toxin-naïve patients being treated for cervical dystonia, headache, and spasticity. "While most patients continue to respond to botulinum toxin type A for several years, some studies have suggested that up to 17% of cervical dystonia patients develop neutralising antibodies when administered repeated injections of botulinum toxin type A using the prior Botox formulation," Dr. Yablon explained. Factors believed to be important for minimising neutralising antibody formation and maintaining long-term patient response include treatment with the minimal effective botulinum toxin type A dose, maximising treatment interval, minimising protein exposure, and proper injection technique. The currently approved botulinum formulation has a lower neurotoxin complex protein load per 100 U (5 ng) than the original preparation (25 ng), which may reduce immunogenic potential, he added. In the present analysis, antibody samples were obtained from 6 clinical studies in which patients for cervical dystonia, headache, or poststroke spasticity were treated with botulinum toxin type A. Serum samples were obtained at baseline, before each repeat injection, and at the end of the study. Of the 929 patients treated, 880 had samples that could be analysed. Of these, 0.6% tested positive on the mouse protection assay (MPA), which detects the presence of specific antibodies that neutralise the biologic activity of botulinum toxin type A. Of the 5 patients with a positive MPA result, 4 were cervical dystonia patients, with a maximum exposure to botulinum toxin type A ranging from 300 to 2300 U. The other patient with a positive MPA result was a spasticity patient who received 4 treatments with botulinum in type A with a cumulative dose of 960 U max. Only the spasticity patient did not demonstrate clinical responsiveness at the time of reporting the positive MPA. Dr. Yablon emphasised that the results of this analysis are based on the Botox formulation of botulinum toxin type A and cannot be generalised to the other formulations of botulinum toxin type A or to other botulinum toxin serotypes. The study was sponsored by Allergan Inc.
[Presentation title. Toxin Neutralizing Antibody Formation With Botulinum Toxin Type A (BoNTA) Treatment in Neuromuscular Disorders. Abstract P01.153.]
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