Forms of Botulinum Toxin
Two forms of botulinum toxin are available for patients.
These are botulinum toxin type A (trade names Botox® and Dysport®) and
botulinum toxin type B (trade names Myobloc® and Neurobloc®).Other “serotypes” of botulinum toxin are under investigation as potential therapeutic agents. These include (in addition to types A and B) types C, D, E, F, and G. Each one has different properties and actions. No two are exactly alike. At present, type F is the only additional form that is showing some promise as a viable treatment for humans.
Although the overall effect is similar, the specific mechanism by which each serotype achieves this effect is different. For example, both type A and type B block the neurotransmitter acetylcholine, but they do so by breaking up different proteins within the nerve cell.
Botulinum toxin type A is commercially available in the United States as Botox® from Allergan, Inc. and abroad as Dysport® from Ipsen, Ltd. Botulinum type B is available from Solstice Neurosciences as Myobloc® in the United States, and as Neurobloc® abroad.
Botulinum toxin type A is approved by the US Food and Drug Administration (FDA) or the treatment of blepharospasm and cervical dystonia. Botulinum toxin type-B is approved in the US for the treatment of cervical dystonia. Both type A and type B are used extensively to treat the various forms of dystonia. The regulations of the FDA allow physicians to use approved medications for conditions other than the specified indications. This is called "off-label" use.
No studies have been done to examine the effects of botulinum toxin during pregnancy. It is generally recommended that women not receive botulinum toxin injections while pregnant.
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