The
protein botulinum neurotoxin A (
BoNT/A) is one of seven distinct
neurotoxins produced by Clostridium botulinum.
BoNT/A blocks
cholinergic synapses with an extremely high specificity and potency. Appropriately purified and diluted,
BoNT/A serves as a reliable and well tolerated
drug that is applied by local injection.The efficacy of
BoNT/A is evident in the symptomatic
therapy of disorders in which muscular hyperactivity plays a prominent role, such as
focal dystonias and
hemifacial spasm; in these disorders,
BoNT/A is considered first-line
therapy.
BoNT/A is also beneficial in the treatment of both adults and children with spasticity of various causes. The
pain that frequently accompanies these conditions is effectively reduced by
BoNT/A. A genuine
analgesic effect for
BoNT/A unrelated to skeletal muscle spasmolysis has been suggested on the basis of in vitro and in vivo (animal) data. However, studies in humans designed to detect such an effect were negative, as were controlled studies of
BoNT/A in patients with
primary headache disorders.
BoNT/A also acts on
cholinergic synapses of the autonomic nervous system, and injection of
BoNT/A into salivary glands significantly decreases the production of saliva. This may be beneficial for patients with
Parkinson's disease, in whom the excessive production of saliva may be problematic.Overall,
BoNT/A has been confirmed as an efficacious, predictable and well tolerated
drug in an ever-increasing number of
neurological disorders.