Botulinum toxin , or botulinum neurotoxin commonly called botox , is a neurotoxic protein produced by the bacterium Clostridium botulinum and related species. Botulinum toxins are among the most potent toxins known to science. The estimated human median lethal dose of type A toxin is 1. Botulinum toxin is used to treat a number of therapeutic indications, many of which are not part of the approved drug label.
Botulinum toxin is used to treat a number of disorders characterized by overactive muscle movement, including cerebral palsy , [ 32 ] [ 33 ] post-stroke spasticity , [ 39 ] post-spinal cord injury spasticity, [ 40 ] spasms of the head and neck, [ 41 ] eyelid , [ 26 ] vagina , [ 42 ] limbs, jaw, and vocal cords. Strabismus , otherwise known as improper eye alignment, is caused by imbalances in the actions of muscles that rotate the eyes. This condition can sometimes be relieved by weakening a muscle that pulls too strongly, or pulls against one that has been weakened by disease or trauma.
Muscles weakened by toxin injection recover from paralysis after several months, so injection might seem to need to be repeated, but muscles adapt to the lengths at which they are chronically held, [ 49 ] so that if a paralyzed muscle is stretched by its antagonist, it grows longer, while the antagonist shortens, yielding a permanent effect.
In January , botulinum toxin was approved by UK's Medicines and Healthcare products Regulatory Agency for treatment of restricted ankle motion due to lower-limb spasticity associated with stroke in adults.
However, prescribers may freely prescribe them for any condition they wish, also known as off-label use. AbobotulinumtoxinA has been approved for the treatment of axillary hyperhidrosis , which cannot be managed by topical agents. In , the FDA approved intramuscular botulinum toxin injections for prophylactic treatment of chronic migraine headache. In cosmetic applications, botulinum toxin is considered relatively safe and effective [ 61 ] for reduction of facial wrinkles , especially in the uppermost third of the face.
