Botulinum toxin is a neurotoxic protein produced by the bacterium Clostridium botulinum and related species. It is one of the most poisonous naturally occurring substances in the world.
Though it is highly toxic, it is used in minute doses both to treat painful muscle spasms, and as a cosmetic treatment in some parts of the world. The neurotoxin works by weakening the muscles and stopping them from contracting very well, which can lead to paralysis.
The commercial medical drug is a highly purified form of this toxin that can actually be very useful for lots of different medical conditions, not just the cosmetic ones for which it is better known. Some of these are neurological conditions due to muscles being too tight or over contracted, while it can also be helpful in some other medical indications such as excessive sweating and drooling.
It is sold commercially under the brand names Botox and Dysport for this purpose.
The terms Botox and Dysport are trade names and are not used generically to describe the neurotoxins produced by Clostridia species.
How does botulinum toxin work ?
there are two commercially available forms of the most common preparation, botulinum toxin type A, in Australia. They are BotoxTM (Allergan pharmaceuticals) and DysportTM (Ipsen pharmaceuticals).
The term ‘botox’ is often used interchangeably with botulinum toxin, but this can be problematic given the very different equivalent doses available of these two common preparations.
The preparations are purified forms of the toxin, and contain rather minute quantities of the toxin produced by the bacterium. Usually, the infection that produces this toxin, botulism, is quite serious and can cause weakness and even paralysis. The toxin does this by stopping the nerve fibres that control muscles from working the way they normally do. Usually, nerves release a chemical called acetylcholine from its endings which signals the muscle to contract. Botulinum toxin stops this substance from being released, and so the muscle does not contract. While this action is dangerous if released by infection, when purified and injected, it can be incredibly useful in diseases where the muscles are too tight/overcontracted, or where doctors want to stop the release of acetylcholine.
By making sure the injections are in just the right spot, botulinum toxin can provide very effective treatment for lots of conditions with very few side effects. Although the weakening of the muscle is felt to be important, some recent research suggests that some conditions like dystonia, which is an involuntary tightening of muscle, may be the result of abnormal incoming signals from nerves and muscle. This has led to recent thinking that the toxin may exert its beneficial effect by interrupting these incoming signals to the brain as well.
Botulinum toxin is indicated for:
- Hemifacial spasm*;
- Cervical dystonia/torticollis*;
- Spasticity: Cerebral palsy and stroke upper* and lower limb, other cerebral and spinal disorders (e.g. multiple sclerosis);
- Other focal dystonia (e.g. writer’s cramp, oromandibular dystonia);
- Spasmodic dysphonia;
- Hypersecretory disorders: Primary (axillary) hyperhidrosis*, hypersalivation (e.g. in Parkinson’s disease);
- Bladder: Detrusor-sphincter dyssynergy and detrusor instability;
- Headache: Tension and migraine;