Anhidrotic effect of intradermal injections of botulinum toxin: a comparison of different products and concentrations.

Botulinum toxin is used in various fields of medicine, including in the treatment of hyperhidrosis. Three products containing botulinum toxin are commercially available in Sweden; Botox, Dysport and Neurobloc. In the literature dose-response has varied with respect to these 3 products. We hypothesized that the dilution level of botulinum toxin is of importance for the effect and we therefore investigated anhidrosis after intradermal injections of each product in 3 different concentrations. Nine healthy subjects received 0.1 ml injections in the back. The anhidrotic areas were identified by an iodine-starch test after 3 weeks. When the 3 products were diluted to 100 U/ml level the achieved mean anhidrotic areas were approximately the same. This is in strong contrast with the large dose conversion factors suggested for intramuscular injections of the products. Furthermore, the lowest used concentrations for Botox(R) (25 U/ml) and Neurobloc (100 U/ml) led to the largest anhidrotic mean area per unit, respectively. The optimal concentration in this study was 25 U/ml for Botox, 100 U/ml for Dysport and 100 U/ml for Neurobloc, but for Botox and Neurobloc the optimal concentrations may be even lower.