Botulinum Toxin Type A

**Semantic type:** Amino Acid, Peptide, or Protein|Pharmacologic Substance

**Definition:** An injectable formulation of a neurotoxin derived through the fermentation of the Hall strain of Clostridium botulinum type A with neuromuscular transmission inhibitory and analgesic activities. Upon injection into the affected muscle, the heavy chain portion of botulinum toxin type A (BTX-A) binds to the cell membrane of the motor nerve and is internalized via endocytosis. Upon entry, the light chain portion of the toxin is activated and cleaves the protein SNAP-25, thereby preventing the fusion of acetylcholine (ACh)-containing synaptic vesicles with the cell membrane and, so, the release of ACh into the neuromuscular junction; subsequent binding of ACH to motor end-plate nicotinic acid receptors and ACh-mediated muscle contraction are thus blocked. In addition to ACh, BTX-A may inhibit the release of neuropeptides, such as substance P and glutamate, which may contribute to its analgesic activity.

**Synonyms:** - AbobotulinumtoxinA - BOTULINUM TOXIN TYPE A - BTX-A - Botox - Botox - Botox Cosmetic - Botulinum A Toxin - Botulinum Neurotoxin Type A - Botulinum Toxin A - DaxibotulinumtoxinA - Dysport - EvabotulinumtoxinA - IncobotulinumtoxinA - OnabotulinumtoxinA - Onaclostox - Xeomin - botulinum toxin A - onabotulinumtoxinA