Current practices in the use of botulinum toxin A in the management of facial lines and wrinkles.

Botulinum toxin A (BTX-A) is a potent neurotoxin produced by the bacterium Clostridium botulinum. There are eight antigenically distinct serotypes, and they share a similar structure--a light chain with an associated molecule of zinc and a heavy chain linked by a disulfide bond. Each serotype has a separate site of action within the nerve ending. Only serotype A (Botox, Allergan, Irvine, CA) is available for clinical use in the United States.