Botulinum Toxin
Synonyms :
BTX or BoNT, Clostridium Botulinum Type A, Oculinum
Mechanism :
Botulinum toxin type A blocks neuromuscular conduction by binding to receptor sites on motor nerve terminals, entering the nerve terminals, and inhibiting the release of acetylcholine. When injected intramuscularly at therapeutic doses, botulinum toxin type A produces a partial chemical denervation of the muscle resulting in localized muscle paralysis.
Indication :
- Spasmodic torticollis
- Spasticity associated with cerebral palsy
- Blepharospasm
- VII nerve disorders in patients 12 years of age or older
- Strabismus in patients 12 years of age or older.
Contraindications :
In the presence of infection at the proposed injection site. In individuals with known hypersensitivity to any ingredient in the formulation.
Dosing :
Spasmodic Torticollis:
Dosing must be tailored to the individual patient based on the patient’s head and neck position, localization of pain and muscle hypertrophy, patient’s body weight, and patient response. In general, a total dose of 6 U/kg every 2 months should not be exceeded for treatment of cervical dystonia.
Spasticity associated with cerebral palsy:
Children >18 months: Small muscle: 1-2 units/kg; large muscle: 3-6 units/kg. (Maximum dose per injection site: 50 units; maximum dose at any one visit: 12 units/kg upto 400 units, no more than 400 units should be administered during a 3 month period).
Blepharospasm:
The initial recommended dose is 1.25 to 2.5 units IM, <200 units in a month.
Strabismus:
>12 years: 1.25-2.5 units IM, <25 units per injection.
Adverse Effect :
Anaphylaxis, arrhythmia, skin rash, pruritus, allergic reaction, urinary retention, somnolence, dizziness.
Interaction :
Aminoglycosides and Other Agents Interfering with Neuromuscular Transmission: Co-administration of BOTOX and aminoglycosides or other agents interfering with neuromuscular transmission (e.g., curare-like compounds) should only be performed with caution as the effect of the toxin may be potentiated.
Anticholinergic Drugs: Use of anticholinergic drugs after administration of BOTOX may potentiate systemic anticholinergic effects.
The effect of administering different botulinum neurotoxin products at the same time or within several months of each other is unknown. Excessive neuromuscular weakness may be exacerbated by administration of another botulinum toxin prior to the resolution of the effects of a previously administered botulinum toxin.
Muscle Relaxant: Excessive weakness may also be exaggerated by administration of a muscle relaxant before or after administration of BOTOX.
Hepatic Dose :
No dosage adjustments are recommended.