Biologic
RCSB PDB 3BTA
OnabotulinumtoxinA
Botox
- Mechanism of action
- Acetylcholine release inhibitor (SNAP-25-cleaving neurotoxin)
- In plain language
- Works by cutting a protein that nerve endings need to release their chemical signal, temporarily stopping a nerve from telling a muscle to contract or a gland to activate.
- How it works
- OnabotulinumtoxinA is a two-chain polypeptide neurotoxin produced by Clostridium botulinum, consisting of a heavy chain and a light chain joined by a single disulfide bond. The heavy chain binds receptors on presynaptic cholinergic nerve terminals and mediates internalization of the toxin. Once inside the cell, the light chain — a zinc-dependent endopeptidase — cleaves SNAP-25, a protein required for docking and fusion of acetylcholine-containing synaptic vesicles with the presynaptic membrane. This blocks stimulus-evoked acetylcholine release at the neuromuscular junction and, depending on injection site, at autonomic cholinergic nerve terminals such as sweat glands. The result is temporary, localized chemical denervation; effect typically resolves over roughly three months as new nerve terminal sprouts restore transmission.
- Therapeutic applications
- Per FDA-approved labeling, BOTOX (onabotulinumtoxinA) is indicated for prophylaxis of headaches in adult patients with chronic migraine; treatment of spasticity in patients 2 years of age and older; treatment of cervical dystonia in adults; treatment of severe axillary hyperhidrosis; treatment of overactive bladder and neurogenic detrusor overactivity; treatment of blepharospasm associated with dystonia in patients 12 and older; and treatment of strabismus in patients 12 and older. Under a separate BOTOX Cosmetic label, onabotulinumtoxinA is also indicated in adults for temporary improvement in the appearance of glabellar lines, lateral canthal lines, forehead lines, and platysma bands.
- Class
- Bacterial neurotoxin
- Therapeutic area
- Neurology
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