Treatment of Multiple-Resistant and/or Recurrent Cutaneous Warts with Squaric Acid Dibutylester: A Randomized, Double-blind, Vehicle-controlled Clinical Trial

Background Contact immunotherapy with squaric acid dibutylester (SADBE) for cutaneous warts has been reported to be effective, although no controlled studies are available so far. Objective The aim of this study was to evaluate the efficacy of SADBE on cutaneous warts by a randomized, double-blind, vehicle-controlled, clinical trial. Methods Thirty-six patients were randomly assigned to SADBE (18 cases) or vehicle (18 cases) group. At 8 weeks, subjects were clinically evaluated for number/size reduction rate and for Investigator Global Assessment. Those who showed improvement extended therapy up to 40 weeks, whereas those who showed unresponsiveness were either switched to SADBE application for up to 48 weeks (if in the vehicle group) or withdrawn from the study (if under SADBE). Results At 8 weeks, a significant reduction in wart number (P = 0.020) and size (P = 0.010) in the SADBE group, with clearing rates of 41.2% versus 12.5% in the SADBE and vehicle groups, respectively, was observed. Nine remaining SADBE responders who underwent treatment extension up to 40 weeks achieved clearing versus 2 patients of the vehicle group who remained unresponsive. Clearing was obtained in 81.8% of patients who underwent previous ineffective vehicle treatment and had been switched to SADBE. Conclusions Squaric acid dibutylester is an effective therapeutic option and is significantly more effective than vehicle.