The minute quantities of botulinum toxin type A injected directly into its site of action (in this case, extraocular muscles) prevented systemic absorption of clinically significant amounts.
Following this initial success, Schantz, now working at the University of Wisconsin, began developing botulinum toxin type A for testing in humans for Dr. Scott, focusing on purification, high potency, and preservation. Because no protein drugs of this type had ever been developed, the methods and requirements were novel. Schantz selected the Hall strain of Clostridium botulinum for type A toxin for production because it yielded a good quantity of high-quality toxin, which was necessary for further purification and regulatory requirements. Scott went on to successfully use the botulinum toxin type A that Schantz had produced for the treatment of strabismus and blepharospasm in humans ( 2 ). The batch of botulinum toxin type A developed by Schantz was eventually approved for human use by the U.S. Food and Drug Administration (FDA) in 1989 ( Fig. 1.1 ) under the name Oculinum. This preparation was later acquired by Allergan Inc. and, under the name BOTOX®, has been the primary treatment for focal dystonias since the late 1980s, and, over the past decade, has become an important adjunctive treatment worldwide for adult spasticity and juvenile cerebral palsy. The FDA approved the use of BOTOX® Cosmetic in 2002 for the temporary improvement in the appearance of moderate to severe glabellar lines associated with corrugator and/or procerus muscle acidity in patients 18 to 65 years of age.