Botulinum toxin
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| Trade names | Botox, Myobloc, Jeuveau, Dysport, Letybo, and others |
| Other names | BoNT, botox |
| Biosimilars | abobotulinumtoxinA, daxibotulinumtoxinA, daxibotulinumtoxinA-lanm, evabotulinumtoxinA, incobotulinumtoxinA, letibotulinumtoxinA, letibotulinumtoxinA-wlbg, onabotulinumtoxinA, prabotulinumtoxinA, relabotulinumtoxinA, rimabotulinumtoxinB |
| AHFS/Drugs.com | |
| MedlinePlus | a619021 |
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| Routes of administration | Intramuscular, subcutaneous, intradermal |
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| Chemical and physical data | |
| Formula | C6760H10447N1743O2010S32 |
| Molar mass | 149323.05 g·mol−1 |
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| Bontoxilysin | |||||||||
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| EC no. | 3.4.24.69 | ||||||||
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| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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Botulinum toxin, botulinum neurotoxin, or botox is a neurotoxic protein produced by the bacterium Clostridium botulinum and related species, and it is considered the deadliest known natural substance ever recorded in the chemical literature. It prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction, thus causing flaccid paralysis. The toxin causes the disease botulism. The toxin is also used commercially for medical and cosmetic purposes. Botulinum toxin is an acetylcholine release inhibitor and a neuromuscular blocking agent. Botulinum toxin was developed as a biological agent by the Soviet, United States, and Iraqi biological weapons programs.
The seven main types of botulinum toxin are named types A to G (A, B, C1, C2, D, E, F and G). New types are occasionally found. Types A and B are capable of causing disease in humans, and are also used commercially and medically. Types C–G are less common; types E and F can cause disease in humans, while the other types cause disease in other animals.
In 2025 the structure of the complete 14 subunit botulinum neurotoxin complex (L-PTC) was solved.
Intoxication can occur naturally as a result of either wound or intestinal infection or by ingesting formed toxin in food. The estimated human median lethal dose of type A toxin is 1.3–2.1 ng/kg intravenously or intramuscularly, 10–13 ng/kg when inhaled, or 1 μg/kg when taken by mouth.
Botulinum toxin is also notable for the paradoxical relationship between its extreme toxicity and its controlled therapeutic use. When administered in highly diluted, precisely measured doses, it can selectively inhibit muscle contraction, making it valuable in the treatment of conditions such as muscle spasticity, chronic migraines, and certain neurological disorders. This dual nature underscores the importance of dosage and delivery route in toxicology, as a substance that is lethal at nanogram quantities can be safely and effectively employed in medicine under strict regulation and clinical oversight.