Clinical Applications for Botulinum Toxin Type A
While much attention has been paid to the cosmetic application of botulinum toxin type A recently, there are a number of other valuable uses for this agent. In both children and adults, botulinum toxin has been used to treat a wide range of muscular and autonomic disorders. This issue of Pediatric Pharmacotherapy will review the uses of botulinum toxin type A in pediatrics, focusing on its use in children with cerebral palsy.
Botulinum toxins are produced by the bacterium Clostridium botulinum. There are seven distinct botulinum toxin serotypes (A through G). Of these, only A and B are commercially available. Most of the research conducted to date with botulinum toxin in children has involved the A serotype. Botulinum toxin type A blocks neuromuscular conduction by binding to receptor sites on motor nerve terminals, entering the nerve terminals and inhibiting release of acetylcholine (ACh). The mechanism for this inhibition involves cleavage of SNAP-25, a protein necessary for the release of ACh from vesicles within nerve endings. The resulting effect of this partial chemical denervation is a localized paralysis, typically lasting 3 to 6 months.
Botulinum toxin type A (Botox; Allergan) is currently approved by the Food and Drug Administration for the treatment of cervical dystonia in patients ≥ 16 years of age and the treatment blepharospasm (focal dystonia of the orbicularis oculi muscles) or strabismus in patients ≥ 12 years of age. A separate product, Botox Cosmetic, is indicated for improvement in the appearance of glabellar lines.
While much attention has been paid to the cosmetic application of botulinum toxin type A recently, there are a number of other valuable uses for this agent. In both children and adults, botulinum toxin has been used to treat a wide range of muscular and autonomic disorders. This issue of Pediatric Pharmacotherapy will review the uses of botulinum toxin type A in pediatrics, focusing on its use in children with cerebral palsy.
Botulinum toxins are produced by the bacterium Clostridium botulinum. There are seven distinct botulinum toxin serotypes (A through G). Of these, only A and B are commercially available. Most of the research conducted to date with botulinum toxin in children has involved the A serotype. Botulinum toxin type A blocks neuromuscular conduction by binding to receptor sites on motor nerve terminals, entering the nerve terminals and inhibiting release of acetylcholine (ACh). The mechanism for this inhibition involves cleavage of SNAP-25, a protein necessary for the release of ACh from vesicles within nerve endings. The resulting effect of this partial chemical denervation is a localized paralysis, typically lasting 3 to 6 months.
Botulinum toxin type A (Botox; Allergan) is currently approved by the Food and Drug Administration for the treatment of cervical dystonia in patients ≥ 16 years of age and the treatment blepharospasm (focal dystonia of the orbicularis oculi muscles) or strabismus in patients ≥ 12 years of age. A separate product, Botox Cosmetic, is indicated for improvement in the appearance of glabellar lines.