Which medications in the drug class Botulinum Toxins are used in the treatment of Spasticity?

Updated: Mar 01, 2018
  • Author: Krupa Pandey, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Answer

Botulinum Toxins

Treatment with botulinum toxins are used to reduce muscle tone and improve passive and/or active function in adults with spasticity. Botulinum toxins are a neurotoxin derived from Clostridium botulinum. Botulinum toxin prevents acetylcholine from the presynaptic membrane, causing temporary calming of muscle contractions by blocking the transmission of nerve impulses.

OnabotulinumtoxinA (Botox)

Binds to the motor nerve terminal. The binding domain of the type A molecule appears to be the heavy chain, which is selective for cholinergic nerve terminals. It is then internalized via receptor-mediated endocytosis, a process in which the plasma membrane of the nerve cell invaginates around the toxin-receptor complex, forming a toxin-containing vesicle inside the nerve terminal. After internalization, the light chain of the toxin molecule, which has been demonstrated to contain the transmission-blocking domain, is released into the cytoplasm of the nerve terminal. Subsequently blocks acetylcholine release by cleaving SNAP-25, a cytoplasmic protein that is located on the cell membrane and that is required for the release of this transmitter. The affected terminals are inhibited from stimulating muscle contraction. The toxin does not affect the synthesis or storage of acetylcholine or the conduction of electrical signals along the nerve fiber.

Indications include cervical dystonia, severe primary axillary hyperhidrosis, strabismus, blepharospasm, upper and lower limb spasticity, overactive bladder, urinary incontinence, and migraine headache.

AbobotulinumtoxinA (Dysport)

Binds to receptor sites on the motor nerve terminals and, after uptake, inhibits release of acetylcholine, blocking transmission of impulses in neuromuscular tissue. At 7-14 days after administration of the initial dose, assess the patient for a satisfactory response. Increase the dose 2-fold over the previously administered dose in patients who experience incomplete paralysis of the target muscle.

Approved indications in the U.S. include upper and lower limb spasticity, cervical dystonia, and moderate-to-severe glabellar lines in adults. It is also indicated for lower limb spasticity in children aged 2 years or older.

IncobotulinumtoxinA (Xeomin)

IncobotulinumtoxinA is botulinum toxin type A that is free of complexing proteins found in the natural toxin from Clostridium botulinum. This drug is an acetylcholine release inhibitor and neuromuscular blocking agent. IncobotulinumtoxinA is indicated in adults for cervical dystonia in botulinum toxin–naive patients, and it is also indicated for blepharospasm in adults previously treated with onabotulinumtoxinA (Botox).

RimabotulinumtoxinB (Myobloc)

Inhibits acetylcholine release at the neuromuscular junction via a three stage process: 1) Heavy Chain mediated neurospecific binding of the toxin, 2) internalization of the toxin by receptor-mediated endocytosis, and 3) ATP and pH dependent translocation of the Light Chain to the neuronal cytosol where it acts as a zinc-dependent endoprotease cleaving polypeptides essential for neurotransmitter release. MYOBLOC specifically has been demonstrated to cleave synaptic Vesicle Associated Membrane Protein (VAMP, also known as synaptobrevin) which is a component of the protein complex responsible for docking and fusion of the synaptic vesicle to the presynaptic membrane, a necessary step to neurotransmitter release.

Indicated for cervical dystonia.


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