Efficacy and safety of incobotulinumtoxinA (NT 201, Xeomin) in the treatment of blepharospasm-a randomized trial

Treatment of focal dystonia

OPINION STATEMENT

Dystonia is characterized by repetitive twisting movements or abnormal postures due to involuntary muscle activity. When limited to a single body region it is called focal dystonia. Examples of focal dystonia include cervical dystonia (neck), blepharospasm (eyes), oromandibular dystonia, focal limb dystonia, and spasmodic dysphonia, which are discussed here. Once the diagnosis is established, the therapeutic plan is discussed with the patients. They are informed that there is no cure for dystonia and treatment is symptomatic. The main therapeutic option for treating focal dystonias is botulinum toxin (BoNT). There have been several attempts to characterize the procedure, the type of toxin, dosage, techniques, and combination with physical measures in each of the focal dystonia forms. The general treatment principles are similar. The affected muscles are injected at muscle sites based on evidence and experience using standard dosages based on the type of toxin used. The injections are repeated after 3 to 6 months based on the individual response duration. In the uncommon event of nonresponse with BoNT, the dose and site are reassessed. Oral drug treatment could be considered as an additional option. Once the condition is thought to be medically refractory, the opinion from the deep brain stimulation (DBS) team for the suitability of the patient for DBS is taken. The successful use of DBS in cervical dystonia has led to increased acceptance for trial in other forms of focal dystonias. DBS surgery in focal dystonias other than cervical is, however, still experimental. The patients may be offered the surgery with adequate explanation of the risks and benefits. Patient education and directing the patients towards dystonia support groups and relevant websites that provide scientific information may be useful for long-term compliance and benefit.

A guide to dosing in the treatment of cervical dystonia and blepharospasm with Xeomin®: a new botulinum neurotoxin A

Xeomin(®) (incobotulinumtoxinA; Merz Pharmaceuticals, Frankfurt am Main, Germany) was first introduced in Germany for movement disorders in 2005. In 2010, it was approved for use in the United States by the FDA for the treatment of cervical dystonia (CD) and blepharospasm. It is a unique botulinum type A formulation free of any complexing proteins and contains only the pure 150 kD neurotoxin. Thus, the formation of neutralizing antibodies is not induced even after long-term treatment. The purpose of this report is to review the safety profile and dosing schedule for Xeomin for the treatment of CD and blepharospasm. The recommended dose for patients with CD is 120 U/treatment, with administration intervals normally between 3 and 6 months. However, clinical studies have found Xeomin to be safe and effective at doses up to 400 U in both previously treated and treatment-naïve patients. The recommended starting dose in patients with blepharospasm is 2.5-5.0 U/injection site. Patients can be switched using a 1:1 conversion ratio from Botox(®) (onabotulinumtoxinA, Allergen Inc., Irvine, CA, USA) to Xeomin without any loss of efficacy or safety concerns. Xeomin does not differ from Botox in terms of its potency, onset, diffusion profile, or duration and waning of effect. It is the only botulinum treatment that is stable for up to 3 years at room temperature. Xeomin offers a new and important treatment option for movement disorders.

A new treatment for focal dystonias: incobotulinumtoxinA (Xeomin®), a botulinum neurotoxin type A free from complexing proteins

Dystonia is a movement disorder of uncertain pathogenesis that is characterized by involuntary and inappropriate muscle contractions which cause sustained abnormal postures and movements of multiple or single (focal) body regions. The most common focal dystonias are cervical dystonia (CD) and blepharospasm (BSP). The first-line recommended treatment for CD and BSP is injection with botulinum toxin (BoNT), of which two serotypes are available: BoNT type A (BoNT/A) and BoNT type B (BoNT/B). Conventional BoNT formulations include inactive complexing proteins, which may increase the risk for antigenicity, possibly leading to treatment failure. IncobotulinumtoxinA (Xeomin(®); Merz Pharmaceuticals GmbH, Frankfurt, Germany) is a BoNT/A agent that has been recently Food and Drug Administration-approved for the treatment of adults with CD and adults with BSP previously treated with onabotulinumtoxinA (Botox(®); Allergen, Inc, Irvine, CA) - a conventional BoNT/A. IncobotulinumtoxinA is the only BoNT product that is free of complexing proteins. The necessity of complexing proteins for the effectiveness of botulinum toxin treatment has been challenged by preclinical and clinical studies with incobotulinumtoxinA. These studies have also suggested that incobotulinumtoxinA is associated with a lower risk for stimulating antibody formation than onabotulinumtoxinA. In phase 3 noninferiority trials, incobotulinumtoxinA demonstrated significant improvements in CD and BSP symptoms in both primary and secondary measures, compared with baseline, and met criteria for noninferiority versus onabotulinumtoxinA. In placebo-controlled trials, incobotulinumtoxinA also significantly improved the symptoms of CD and BSP, with robust outcomes in both primary and secondary measures. The use of incobotulinumtoxinA has been well tolerated in all trials, with an adverse event profile similar to that of onabotulinumtoxinA. Based on these data, incobotulinumtoxinA is a safe and effective BoNT/A for the treatment of CD and BSP, and may pose a lower risk for immunogenicity leading to treatment failure compared with other available BoNT agents. This paper reviews the treatment of focal dystonias with BoNTs, in particular, incobotulinumtoxinA. Controlled trials from the existing incobotulinumtoxinA literature are summarized.