Botulinum Toxin Formulation, Concentration and Treatment

Abstract: Botulinum toxin (BTX) is used in various fields of medicine, including the treatment of hyperhidrosis and cervical dystonia. Botox®, Dysport®, Xeomin® and NeuroBloc® are commercially available BTX products, which are formulated differently and their dosing units are unique. Dosage and concentration of the prepared solution for injection varies considerably among studies comparing the products. Improved guidelines on concentration and dosing when changing from one product to another are warranted. This would ensure the use of the lowest effective doses for good effect, minimal risk of antibody formation and side-effects as well as reduced costs.The aim of the present work was to find the most appropriate BTX concentration for each of the four products to achieve the highest sweat reducing effect and to investigate dose conversion ratios between Botox and Dysport in the treatment of cervical dystonia when the products are diluted to the same concentration, 100 U/ml.Paper I and II clearly confirm that it is crucial to consider the BTX concentration in a treatment regimen, especially when changing between different products. The optimal concentration to reduce sweating varies among the products and was found to be 25 U/ml for Botox and Xeomin, approximately 100 U/ml for Dysport and 50 U/ml for NeuroBloc. However, for NeuroBloc the optimal concentration might be even lower.In Paper III, which is a retrospective study using casebook notes from 75 patients with cervical dystonia, it was found that the most appropriate dose conversion ratio to use when switching from Botox to Dysport was 1:1.7.In Paper IV, Botox and Dysport were prospectively compared in a double-blind, randomized clinical trial in two different dose conversion ratios (1:3 and 1:1.7) when diluted to the same concentration (100 U/ml). No statistically significant difference was seen between Botox (1:3) and Dysport nor between Botox (1:1.7) and Dysport four weeks after treatment. Some of the secondary outcome observations, however, did indicate that the ratio 1:3 resulted in suboptimal efficacy of Botox but this must be further validated in a larger patient material.