Persistent allergic contact dermatitis at the site of primary sensitization with squaric acid dibutyl ester

Application of Topical Immunotherapy in the Treatment of Alopecia Areata: A Review and Update

Treatment of extensive or recalcitrant alopecia areata (AA) is a major clinical challenge. Even after thorough investigation of several medications, its treatment outcomes have remained unsatisfactory. While there is no US Food and Drug Administration-approved medication for AA yet, topical immunotherapy has been a well-documented treatment option. Dinitrochlorobenzene, squaric acid dibutylester, and diphenylcyclopropenone are three substances that have demonstrated efficacy in the treatment of extensive or recalcitrant AA. Despite being commonly used, the mechanism underlying topical immunotherapy is not well-elucidated and a wide range of clinical efficacies have been reported in the literature. The aim of this review was to summarize and update the pharmacology, mechanism of action, therapeutic efficacy, and tolerability of topical immunotherapy in the treatment of AA.

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who showed unresponsiveness were either switched to SADBE application for up to 48 weeks (if in the vehicle group) or withdrawn from the study (if under SADBE).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.

Treatment of cutaneous warts: an evidence-based review

Cutaneous warts are common skin lesions caused by human papillomavirus infection. Treatment is aimed at relieving the patient's physical and psychological discomfort and at preventing the spread of infection by autoinoculation. Among the available medical and destructive therapeutic options for cutaneous warts, none is uniformly effective or virucidal. Moreover, in most cases their safety and efficacy has not been assessed in double-blind, controlled clinical trials, so that the reproducibility of many of the listed treatments is difficult to evaluate and a possible placebo effect cannot be ruled out. The aim of this article is to describe the outcome of current therapies for each clinical wart type according to evidence-based medicine studies published in the literature. For each clinical form, the existing treatments are classified as first-, second-, and third-line therapy. First-line therapy includes medical treatments (salicylic acid, silver nitrate, glutaraldehyde) that are useful to treat a single wart or a few and/or small common warts of short duration (less than 1 year). If these treatments have failed or are contraindicated, cryotherapy may be considered as second-line therapy. For recurrent or difficult-to-treat lesions, third-line therapy includes a variety of alternative therapeutic options (topical, intralesional, systemic, and physical destruction) that are generally off-label (not US FDA approved), and whose use is limited by drawbacks or adverse effects. From pooled evidence-based medicine data, it is possible to conclude that significantly higher remission rates may be expected only with cryotherapy and salicylic acid used in combination.

The therapeutic use of topical contact sensitizers in benign dermatoses

Topical therapy using contact sensitizers has been practised since the 1960s to treat conditions associated with an altered immunological state. Dinitrochlorobenzene, squaric acid dibutyl ester and diphencyprone are most commonly employed in the therapy of alopecia areata and viral warts. Few dermatology departments in the U.K. provide such treatment. This systematic review discusses the various contact sensitizers used for topical immunotherapy, the methodology of treatment, factors influencing efficacy and likely adverse effects.

Efficacy of topical sensitizers in the treatment of alopecia areata

It has been more than 2 decades since the first report of the use of dinitrochlorobenzene to induce hair growth in 2 patients with alopecia areata. Other topical sensitizers, namely squaric acid dibutylester and diphenylcyclopropenone, have been used with variable success. This article reviews the efficacy and safety of the use of topical sensitizers in the treatment of alopecia areata.