Pharmacology of botulinum toxins: From poison to remedy

Abstract

Botulinum toxin (BTX) is produced by autolysis of several strains of Clostridium botulinum, a gram-positive, spore-forming, rod-shaped, strictly anaerobic bacterium. However there are also non-clostridial microorganisms that are enable to produce the toxin. As some other beneficial poison, BTX also fits well the quotations by old scientists and philosophers like “Almost every substance can become a poison but only thing is the dose discriminating the difference” (Paracelsus, XVI century) or “Poisons can be employed as a means for the destruction of life or as agents for the treatment of the sick” (Claude Bernard, XIX century) or “Poison is a medicine, medicine is a poison” (Ahi Evran, XIII century). In the 1980's, Alan Scott first published articles on the use of BTX for the treatment of strabismus. The Food and Drug Administration of the USA (FDA) first approved botulinum toxin for the treatment of strabismus (crossed eye) blepharospasm (uncontrollable eye blinking) in 1989 and for glabellar rhytides in 2002, the first cosmetic indication. Since then BTX has been used for a verity of indications not only dermatological but also non-dermatological indications including on-labelled as well as off-labelled uses. In this review you will find the pharmacological profile of botulinum toxins, i.e., mode of action, pharmacokinetics, adverse effects, indications and contrindications, drug interactions, duration and site of action, etc. Furthermore, current commercial products and novel dosage forms as well as new perspective of BTX use will also be discussed.