Botulinum Neurotoxin Type A Free of Complexing Proteins (XEOMIN®) in Focal Dystonia
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Botulinum neurotoxin type A (BTX-A) weakens voluntary muscle strength and is an effective therapy for focal dystonia, including cervical dystonia (CD) and benign essential blepharospasm (BEB). It is also known to relieve hemifacial spasm and focal spasticity in children and adults. In addition, BTX-A has been shown to be effective in a wide range of other indications, such as gastrointestinal disorders, hyperhidrosis and cosmetic wrinkle correction (e.g. glabellar frown lines). A new formulation of BTX-A, NT 201 (XEOMIN®) has been developed. NT 201 is a formulation of pure BTX-A free of complexing proteins and, therefore, may have a reduced immunogenic potential compared with other BTX-A preparations. The pre-clinical and clinical development of NT 201 is reviewed in this article.
A total of five clinical trials were completed in Europe and Israel. Two studies were conducted in 46 healthy volunteers. A further three studies in 816 patients were conducted to provide data on the safety and efficacy of NT 201 in the treatment of CD and BEB. NT 201 was found to provide non-inferior efficacy and safety profiles in the treatment of CD and BEB compared with a BTX-A preparation containing complexing proteins (BOT [BOTOX®]). The clinical development programme of NT 201 showed a 1 : 1 NT 201 to BOT dose ratio. The pre-clinical studies conducted with NT 201 showed an acceptable safety profile and support the use of NT 201 in an intramuscular administration regimen for patients with CD and BEB. NT 201 was effective, well tolerated and non-inferior to BOT in the treatment of both CD and BEB. In addition, there were no differences between the two therapies in terms of onset of action, duration and waning of effect. Further research is required to determine the long-term efficacy and safety profile of NT 201.