The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Approval Status:

Approved December 2000

Specific Treatments:

Cervical dystonia

Therapeutic Areas

General Information

Myobloc, a sterile liquid formulation of purified neurotoxin, has been approved as an injectable solution for the treatment of abnormal head position and neck pain associated with cervical dystonia. Myobloc is available in three vial configurations of 2500 Units, 5000 Units, and 10000 Units, offering convenience and flexibility for dosing.

Cervical dystonia, also known as spasmodic torticollis, is a neurological disorder that affects the cervical area of the spine. It causes the neck and shoulder muscles to contract involuntarily, resulting in painful muscle spasms that often make daily functioning difficult. Myobloc is the first FDA approved drug for treatment of cervical dsytonia.

Clinical Results

Myobloc has been evaluated in two phase III studies involving a total of 186 adult subjects. The primary efficacy outcome of the trials was the Toronto Western Spasmodic Torticollis Rating Scale, which examines the severity of abnormal head position, the severity and duration of pain, and the disabiling effects placed on the person's activities. Subjects were randomized to receive placebo, 5000 Units, or 10000 Units in single treatment sessions and were evaluated for 16 weeks following injection.

There were no statistically significant differences between the 5000 U and the 10000 U doses. Most subjects who reported improvements after four weeks had returned to their baseline status by the end of the 16 weeks. Subjects in the two treatment groups did experience decreases in pain, though many also reported increases in symptoms regardless of receiving treatment or placebo.

Side Effects

Adverse events associated with the use of Myobloc may include (but are not limited to) the following:

  • Dry mouth
  • Dysphagia
  • Injection site pain
  • Dyspepsia
  • Headache

Mechanism of Action

Botulinum Toxin Type B is a sterile liquid formulation of a purified neurotoxin that acts at the neuromuscular junction to produce flaccid paralysis. The solution is injected directly into the muscle.

Additional Information

For additional information on Myobloc, please visit Myobloc.