Comparison of efficacy and immunogenicity of original versus current botulinum toxin in cervical dystonia

Abstract

Since its approval by the Food and Drug administration for the treatment of blepharospasm and other facial spasm in 1989, Botulinum toxin (BTX) type A has been used for a variety of diseases. The possibility of increasing immunoresistance due to the development of blocking antibodies has been raised in multiple studies. Some authors have suggested that up to 17% of patients treated repeatedly for cervical dystonia with BTX type A have such immunoresistance. However, these data were based on experience with the original preparation of BTX type A used before 1998. The authors compared 130 patients treated for cervical dystonia with the original botulinum toxin (BTX) type A (Botox; Allergan, Inc., Irvine, California, USA), 42 of whom were exposed only to the original BTX type A used before 1998 (25 ng protein/100 units), and 119 treated only with the current BTX type A (5 ng of protein/100 units). Blocking antibodies were detected in 4 of 42 (9.5%) patients treated only with original BTX type A but in none of the 119 patients treated exclusively with current BTX type A (P < .004). The current preparation decreased the risk of antibody formation by a factor of six. The authors conclude that the low risk of antibody formation after current BTX type A treatment is related to lower protein load.—Valérie Biousse