Proper concentration of diphenylcyclopropenone solution according to the anatomical location and application time interval for the treatment of warts

Background: Topical diphenylcyclopropenone (DPCP) application on a daily or weekly basis has been used for the treatment of warts that affect different sites of the body. The concentration of DPCP for the treatment of warts needs to be determined according to the body site. In addition, the therapeutic response to DPCP application intervals needs to be evaluated for the treatment of warts. Objective: The purpose of this study was to determine the minimal DPCP concentration required to induce an elicitation reaction in different body sites of patients with warts and to assess the therapeutic response of wart treatment with daily and weekly applications of DPCP. Methods: Thirty patients with warts were divided into two groups. Each patient in the two groups was sensitized with 0.1% or 0.2% DPCP. After sensitization, in the first group of patients, DPCP was applied to warts daily. In the second group of patients, DPCP was applied to warts weekly. The initial concentration of DPCP was 0.01% for warts located on the palmoplanar area, periungual area and the dorsum of the hand, knee and upper arm. The initial concentration of DPCP was 0.004% for warts on the face. If no reaction was observed, the DPCP concentration (0.01%, 0.025%, 0.05%, 0.1%, 0.25%, 0.5%, 1% and 2%) was increased stepwise. The minimal concentration of DPCP to induce an elicitation reaction and treatment results were evaluated. Results: The minimal concentrations of DPCP to induce an elicitation reaction were as follows: 0.004 - 0.01% for the face, 0.01 - 0.025% for the dorsum of the hand, 0.25 - 1 % for the periungual area and 0.5 - 2% for the palmoplantar area. The results of weekly application of DPCP were similar as compared to the daily application of DPCP for the treatment of warts. Conclusion: Although further studies are needed, our study suggests that the DPCP concentration needs to be adjusted according to the body site and that the weekly use of DPCP may be a convenient alternative to daily use to treat warts.