Dose thresholds and duration of the local anhidrotic effect of botulinum toxin injections: measured by sudometry.
BACKGROUND
Local injections of botulinum toxin type A (BTX-A) have been used successfully to treat focal hyperhidrosis, but because experimental data were lacking, doses have been chosen arbitrarily or empirically.


OBJECTIVE
To analyse dose dependency and duration of BTX-A-derived suppression of sweat gland activity.


METHODS
Employing a standardized scheme (four injections, square 2 x 2 cm), different doses of BTX-A [Dysport(R); 2.5-120 mouse units (MU)] were injected subcutaneously at the lateral aspects of both of the lower legs in 15 healthy volunteers. Sweat tests were performed before, and 3 weeks and 6 months after, BTX-A injections. Sweating was visualized by staining with iodine starch, and quantified by capacitance hygrometry after carbachol iontophoresis, the quantitative sudomotor axon reflex test (QSART).


RESULTS
Iodine starch staining indicated a threshold dose of 10 MU (2.5 MU cm-2) leading to visible anhidrotic skin spots after 3 weeks in all subjects. This was maintained for 6 months with doses of 50 MU (12.5 MU cm-2) or higher, but the size of the anhidrotic skin area decreased over time (P < 0.001) indicating partial recovery at the edges. After 3 weeks QSART was significantly reduced (P < 0.02) and completely suppressed by doses of 80 MU (20 MU cm-2) or more, although after 6 months QSART increased again to pre-BTX-A levels (P < 0.001). Both methods indicated that the suppression of sweating is dose dependent (QSART: r = -0.70, P < 0.001; iodine starch staining: r = 0.74, P < 0.001).


CONCLUSIONS
Our findings suggest that BTX-A effectiveness can be quantified by testing sudomotor function. For the first time threshold doses for the suppression of sweating have been defined.
Braune
C
C
Neurologische Klinik, Friedrich-Alexander-Universität Erlangen, Germany.
Erbguth
F
F
Birklein
F
F
D000293:Adolescent; D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006945:Hyperhidrosis / Q000188:drug therapy; D007279:Injections, Subcutaneous; D007478:Iontophoresis; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage* / Q000494:pharmacology; D013213:Starch / Q000031:analogs & derivatives*; D013546:Sweating / Q000187:drug effects*; D013997:Time Factors
D009465:Neuromuscular Agents; C055509:iodinated starch; D013213:Starch; D019274:Botulinum Toxins, Type A