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Botulinum Toxin Type B

Botulinum Toxin Type B (BTX-B) for Cervical Dystonia
On December 11, 2000, a botulinum toxin type B product (Myobloc®) was approved by the FDA in the United States as a treatment of patients with cervical dystonia to reduce the severity of abnormal head position and neck pain associated with cervical dystonia. MYOBLOC is the U.S. trade name for botulinum toxin type B, available in the U.S. from Solstice Neurosciences, Inc. This product also received marketing authorization from the European Union's Committee for Proprietary Medicinal Products and is available there as Neurobloc®.

Myobloc is available as a refrigerated, liquid formulation, which may be further diluted (with normal saline). It is an acidic solution with a Ph of 5.6. It is provided as a sterile injectable solution at a concentration of 5,000 U per 1 mL and a pH of 5.5. Vials contain 0.5 mL (2,500 U), 1.0 mL (5,000 U), or 2.0 mL (10,000 U). Because vials are actually overfilled, each vial contains slightly more toxin than these indicated volumes.

The duration of effect is approximately 12 to 16 weeks. The potential adverse effects of MYOBLOC/Neurobloc are similar to those seen after injections of botulinum toxin type A and may include difficulty swallowing and dry mouth. These effects are usually short-lived and reversible.

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Please see the following topics related to Botulinum Toxin Type B:

• Approaches to Treatment with Botulinum Toxin Type B
• Dosing of Botulinum Toxin Type B
• Injection of Botulinum Toxin Type B
• Side effects of botulinum toxin type B