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Pharmacology of botulinum toxin: differences between type A preparations
Author(s) -
Rosales R. L.,
Bigalke H.,
Dressler D.
Publication year - 2006
Publication title -
european journal of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 124
eISSN - 1468-1331
pISSN - 1351-5101
DOI - 10.1111/j.1468-1331.2006.01438.x
Subject(s) - medicine , botulinum toxin , cholinergic , stimulation , pharmacology , atropine , adverse effect , anesthesia , endocrinology
Different types of botulinum neurotoxin (BoNT) block different proteins of the s oluble N ‐ethylmaleimide sensitive factor a ttachment protein re ceptor (SNARE) protein complex within cholinergic nerve terminals, producing blockade of cholinergic neuromuscular and autonomic synapses. Animal studies indicate the longest duration of action for BoNT type A (BoNTA) followed by types B, F, and E. Diffusion to adjacent and remote muscles may be related to protein composition, dilutions, volume, target muscle selection, and injection technique. A review of head‐to‐head, randomized, controlled trials of BoNTA preparations (Botox® and Dysport®) suggests that Dysport® tends to have higher efficacy, longer duration, and higher frequency of adverse effects. Conversion factors between the preparations varied, however, and remain controversial. In clinical settings, a Botox®:Dysport® conversion ratio of 1:3 may be appropriate. Animal studies suggest a conversion ratio of 1:2.5–3. When therapeutic effects between these preparations are attempting to be equalized, Dysport® seems to produce more adverse effects. In mice, Botox® appears to have a better safety margin than Dysport® and BoNTB. In rats, diffusion margins are similar for Botox® and Dysport®. Jitter derived from stimulation single‐fiber EMG of injected and remote muscles show no differences between Botox® and Dysport®. Atrophy of extrafusal muscle fibers of injected and remote muscles do not differ between the BoNTA preparations.