Background: Intradermal injections of type A botulinum toxin have been reported to reduce excessive sweating in patients with primary palmar hyperhidrosis. Two preparations are commercially available in Europe: Botox (Allergan; 100 U per vial) and Dysport (Beaufour Ipsen Biotech; 500 U per vial), which are not bioequivalent. A few studies have tried to find an appropriate conversion factor between the two preparations in dystonic patients but results remain controversial.
Objectives: To compare the efficacy of Botox and Dysport in palmar hyperhidrosis using a conversion factor of 1 : 4.
Methods: In a double-blind, randomized study, eight patients with severe primary palmar hyperhidrosis received in the same session intradermal injections of Dysport in one palm and Botox in the other, after regional median and ulnar nerve blocks. Quantification of sweat production was performed by Minor's iodine starch test at baseline, 1, 3 and 6 months after the treatment. Subjective assessment of sweat production was performed using a visual analogue scale.
Results: The mean +/- SD number of injection sites (28 +/- 1), mean volume of reconstituted solution injected (2.8 mL) and mean sweating area at baseline (BSA) were similar in each palm group. The mean +/- SD dose injected was 69.3 +/- 3.1 U for the Botox-treated palms and 283.7 +/- 11.3 U for the Dysport-treated palms (1 : 4). At 1 month, Minor's test revealed significant decreases in mean sweating area for each preparation (Dysport palms: -78.6% vs. BSA, P = 0.0002; Botox palms: -56.6% vs. BSA, P = 0.003). The percentage of decrease was more pronounced in Dysport palms compared with Botox palms but the difference did not reach statistical significance. At 3 months, the decrease in sweating area remained significant for Dysport palms (-69.4% vs. BSA, P = 0.008) but not for Botox palms (-48.8% vs. BSA). Self-evaluation showed a similar amount of improvement in both palm groups at 1 and 3 months (77% and 75% for Dysport; 68% and 72% for Botox). Local side-effects were more frequent in Dysport palms (weakness of thumb-index pinch in four cases, lasting 8-30 days) than in Botox palms (weakness of thumb-index pinch in two cases, lasting 15-21 days). The mean duration of positive effect was similar: 17 weeks in Dysport (range 8-32) and 18 weeks in Botox palms (range 8-32).
Conclusions: Using a conversion factor of 1 : 4, the efficacy of Botox and Dysport injections was similar. However, there was a trend towards a larger improvement after Dysport treatment but with a higher incidence of adverse effects.