Botulinum toxins in pain management

History and pharmacology of botulinum toxins In the century since their discovery, botulinum toxins (BTs) have gone from deadly poison to remarkably versatile therapeutic agent. In 1897, van Ermangen identified BT as the offending agent that caused a fatal food poisoning botulism outbreak 2 years earlier due to tainted food (adult botulism). In 1949, it was shown that BT type A (BTA) blocked transmission at the neuromuscular junction (NMJ). In 1989, the US Food and Drug Administration (FDA) approved BTA for use in treating strabismus, blepharospasm, and hemifacial spasm in patients older than age 12 years. In 2000, BT type B (BTB) and, shortly thereafter, BTA were approved by the FDA for use in treating cervical dystonia. In April 2002, BTA was approved for the temporary improvement of moderate-to-severe glabellar lines in adults age 65 years or younger. Although the cosmetic application (re-duction of facial wrinkling) of BTs has become the most widely known use [1], there has been tremendous interest in their potential for producing efficacy in various chronic pain syndromes. Many review articles on this topic have been published [2–8]; however, in the past few years, several new developments have occurred in this rapidly evolving therapeutic area