Myobloc (botulinum toxin type B) was approved by the FDA in December 2000 “for the symptomatic treatment of patients with cervical dystonia (CD) to reduce the severity of abnormal head position and neck pain associated with CD.” Cervical dystonia is a neurological movement disorder in which a person’s neck and shoulder muscles are subject to contractions that force the head and neck into abnormal and sometimes painful positions, making it difficult for some people to function normally in their daily activities.
For those receiving Myobloc treatments for CD, the side effects may include dry mouth, dysphagia, dyspepsia, and injection site pain. These adverse effects are generally mild to moderate, transient, self-resolving, and more common only with higher doses. The side effects are also related to the location of the injection site and the muscles involved and not the drug itself. Myobloc was formerly known as BotB and is marketed outside the United States as Neurobloc.
Few trials have compared the efficacy of Botox with Myobloc. Overall, the evidence suggests that although both are safe and effective. Myobloc has a more rapid onset but a shorter duration of action, and may be associated with slightly more discomfort at the time of injection. Myobloc is mostly useful for people who receive minimal or no results with Botox, although this is a rare problem.
(Sources: Journal of Cosmetic and Laser Therapy, September 2007, pages 186-192; and Dermatologic Surgery, May 2003, pages 519-522.)