Botulinum toxin type A
- Aust Prescr 1994;17:6-8
- 1 January 1994
- DOI: 10.18773/austprescr.1994.010
Botox (Allergan Australia)
vials containing 100 units of toxin, 0.5 mg human albumin and 0.9 ing sodium chloride as lyophilised powder
Clostridium botulinum produces a neurotoxin which blocks the release of acetylcholine in cholinergic nerves.
By blocking transmission at the neuromuscular junction, the toxin causes paralysis.
Small amounts of the toxin injected into muscles cause weakness and atrophy. The muscles only recover when new nerve terminals grow, a process which takes several months.
Botulinum toxin injections have been used clinically in several conditions characterised by muscle spasm. The treatment is particularly effective (>90%) in the treatment of blepharospasm. It has been approved for use by patients over the age of 12 years with blepharospasm associated with dystonia, including benign blepharospasm and VII cranial nerve disorders (hemifacial spasm). The treatment may be repeated when the muscle recovers, but the long term effects of repeated injections are unknown.
The toxin must be injected by a practitioner with a detailed knowledge of the anatomy in the orbital region. Adverse effects can occur due to the spread of the toxin from the injection site. Ptosis is a common adverse effect.