Botulinum toxin drugs: future developments.

Botulinum toxin (BoNT) drugs have been used with remarkable success for more than 20 years generating an industry with annual sales in excess of 1 billion US dollars. However, BoNT drugs are not at the end of their development cycle. Product development will focus on an improved antigenicity by increasing the specific biological activity, by separation of complexing proteins, by introduction of high affinity BoNT or by shielding of antigenic BoNT epitopes. Other development will include transdermal application, drug labeling for imaging guided applications, ready made solutions, and drug stability. New BoNT drugs are already offering some of these improved features. BoNT drugs are safe and effective, but need continuous development.