Contaminants of dinitrochlorobenzene

Use of Contact Immunotherapy in the Treatment of Skin Diseases Other than Alopecia Areata

For decades, contact immunotherapy with dinitrochlorobenzene, diphencyprone, and squaric acid dibutylester has played an important role in both clinical practice and scientific research. It is listed as the first-line treatment for extensive alopecia areata and was more recently approved for melanoma treatment as an orphan drug in the USA. Moreover, owing to the relative low cost and safety, topical immunotherapy has also been used in many infectious, neoplastic, and inflammatory dermatological diseases. It is especially valuable in vulnerable groups, for cosmetic/pain sensitive areas, or for multiple lesions. In this review, we summarize the current evidence supporting the use of contact immunotherapy for treatment of skin diseases, from articles collected from PubMed database. Owing to space limitation and already numerous studies focusing on alopecia areata, we include only skin diseases other than alopecia areata. In addition to diseases that have been reported to be treated by contact immunotherapy, the hypothesized mechanism, prognosis prediction, efficacy, and safety of these topical agents are discussed.

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.

Contact immunotherapy of resistant warts

Contact immunotherapy has been proved effective in the treatment of resistant warts. This report chronicles our experience with a new contact immunotherapy agent, diphenylcyclopropenone. We have achieved a cure rate of 62% in 45 patients with resistant warts of all types who came to our general dermatology clinic. Cure rates may be lower in patients who have experienced multiple treatment failures. The majority of cures were obtained within 3 to 4 months. Although it appears somewhat less effective than published reports of dinitrochlorobenzene contact immunotherapy, diphenylcyclopropenone contact immunotherapy is an effective treatment for resistant warts and avoids any potential problems from mutagenicity.

Squaric acid and esters: analysis for contaminants and stability in solvents

Two squaric acid diesters, squaric acid diethyl ester (SADEE) and squaric acid dibutyl ester (SADBE), have been suggested as replacements for 2,4-dinitrochlorobenzene in the treatment of alopecia areata and alopecia totalis. We synthesized these squaric acid diesters and examined them for the presence of carcinogenic contaminants, hexachlorobutadiene and tetrachloro-2-cyclobutene-1-one, by gas chromatography-mass spectrometry (GC-MS). The stability of SADBE to hydrolysis by water in acetone, butanol, isopropanol, and absorbent ointment with and without molecular sieves was examined. The stability of SADEE in ethanol and acetone, with and without molecular sieves, was also studied. Hydrolysis products were detected by their formation of a colored complex with ferric chloride. This complex absorbs in the visual range at 480 nm, thus affording a convenient method for determination of the concentration of free squaric acid in a solution. No contaminants were found by positive or negative ion detection in our GC-MS system. At the end of 3 weeks the extent of hydrolysis was greater in alcohols than in acetone when 10 and 100 molar excess of water were added to the solutions. In the presence of molecular sieves, hydrolysis was reduced even at 100 molar excess of added water in alcohol ar acetone. However, under storage conditions without sieves, acetone solutions and alcohol solutions were equally stable over a period of 2 months. Molecular sieves reduce hydrolysis of squarate esters in the presence of a large molar excess of water, regardless of solvent.

Alopecia areata: pathogenesis and treatment

Although its etiology remains unknown, evidence has accumulated to support an autoimmune pathogenesis for alopecia areata. Our review summarizes the immunologic data and also examines the role of genetics, atopy, and psychologic stress in this disorder. Until etiology is better understood, treatments for alopecia areata are likely to remain palliative. Nevertheless, newer therapies such as photochemotherapy, topical immunotherapy, and perhaps systemic immunotherapy (e.g., inosiplex) offer new hope for patients with extensive disease.