Botulinum toxin

Also known as BOTOX.

• This is a toxin produced by Clostridium botulinum under specific environmental conditions.
• There are 8 types, named A to H. 
• Type H botox is the most lethal substance known. The human median lethal dose (LD50) is 1.3–2.1 ng/kg administered by IV or IM.

 

Pathophysiology

Acetylcholine is stored in vesicles inside the pre-synaptic terminal. These vesicles must fuse with the neuronal membrane to release acetylcholine into the synpase. Botox disrupts this fusion process, preventing acetylcholine release. This prevents neuromuscular signalling.

The effects of botox on the target proteins are permanent, so the effects on the nerves are very long-lasting. The effects only fade once the nerves have replaced the dysfunctional proteins. This can take weeks to months.

Botox is the mediator of botulism. This disease most commonly occurs when food contaminated with C. botulinum is prepared in specific conditions. The bacteria produce the toxin, which accumulates in the food.

Some forms of botulism are caused by active infection of the body with C. botulinum, which produces new toxin while living inside the body. These patients could benefit from anti-bacterial therapy. However, this is very rare. It usually occurs in infants, patients with immunocompromise or patients with abnormal bowel anatomy.

Medical uses

• Cosmetic therapy : Botox is famously used to paralyse muscles of facial expression, so that skin wrinkles appear less prominent. The effects are not permanent.
• Medical therapy : Botox injections can reverse muscle spasm or hypertonia in disorders such as achalasia. The effects are not permanent.