Primary irritant dermatitis from topical clioquinol

Evaluation of activity and toxicity of combining clioquinol with ciclopirox and terbinafine in alternative models of dermatophytosis

Dermatophytosis is a superficial fungal infection that affects humans and is very common in small animals. The treatment using the most commonly used antifungals is failing, and new therapeutic alternatives are required to combat the resistance of these fungal infections. Previous studies by the group have shown that clioquinol is an important therapeutic alternative in the treatment of dermatophytosis. The object was to conduct studies of antidermatophytic activity and the irritant potential from the double and triple combinations of clioquinol, terbinafine and ciclopirox in ex vivo and in vivo alternative models. To evaluate the irritant potential of antifungal combinations, the alternative HET-CAM method (chicken egg test chorioallantoic membrane) was used. Ex vivo models were used to assess the effectiveness of antifungal combinations, using pig hooves and veterinary fur. Any possible tissue damage was to assess through in histopathology of swine ears. HET-CAM results showed that all combinations can be classified as non-irritating, corroborated by the results of the histopathological evaluation of the pig's ear skin. Only the double combinations managed to remove 100% of the colony-forming units (CFU) formed on the pig's hooves. The clioquinol + terbinafine combination and the triple combination were more effective than clioquinol + ciclopirox in eradicating the preformed biofilm in fur of veterinary origin. These results show the potential of formulations of clioquinol in combination with antifungals for use in humans and in the veterinary field to combat dermatophytosis, as an important alternative therapy, for use in the near future.

Anogenitaldermatosen - allergische und irritative Auslosefaktoren Analyse von Daten des IVDK1 und Literaturubersicht. Anogenital dermatoses - allergic and irritative causative factors Analysis of IVDK2 data and review of the literature

BACKGROUND

Anogenital dermatoses (AGD) are common and often very distressing. Clinically it is often unclear if allergic contact dermatitis or irritant dermatitis is involved. In order to optimize therapy and prophylaxis, it is essential to identify relevant allergens or irritants.

PATIENTS AND METHODS

Data of the Information Network of Departments of Dermatology (IVDK, data center in Göttingen) collected between 1999 and 2003 were analyzed. The anogenital area was involved in 1 168 patients with suspected allergic contact dermatitis. Clinical variables and patch test results were statistically compared with the remaining IVDK patch test population, the latter standardized for age and sex.

RESULTS

Allergic contact dermatitis had been suspected prior to patch testing in 39.5 %, while in 24.6 % this diagnosis was eventually confirmed. Irritant contact dermatitis was diagnosed in 11.8 %. Other diagnoses, included balanitis, lichen sclerosus et atrophicus and herpes genitalis. Positive reactions to cinchocaine (6.6 %), bufexamac (3.5 %) and benzocaine (2.4 %) were observed significantly more often among patients with anogenital dermatitis. Among those in whom co-factors were considered important (n = 422), wetness (38.4 %), occlusion (30.3 %), mechanical strain (4.7 %) and heat (3.6 %) were mentioned as irritation factors.

CONCLUSION

Because of the significantly higher frequency of sensitization to cinchocaine, benzocaine and bufexamac in patients with anogenital dermatitis, these ingredients should be used only with caution. According to the literature, ingredients of toiletries, cosmetics and contraceptives of any kind seem to cause allergic contact dermatitis rarely although there are several case reports. Comprehensive patch test including the standard series plus major sensitizers such as cinchocaine, benzocaine and bufexamac, and in particular patients' own skin care products, is recommended.

A cream containing the chelator DTPA (diethylenetriaminepenta-acetic acid) can prevent contact allergic reactions to metals

Chelating agents in protective barrier creams have often been used in the prevention of allergic contact dermatitis to nickel. In a pilot study, we demonstrated the preventive effect of 10% diethylenetriaminepentaacetic acid (DTPA) in an oil-in-water emulsion in nickel-sensitized patients. Now we reproduced these results in a randomized, double-blind study. Additionally, we investigated the efficacy of the barrier cream in other clinically relevant metal allergies. Individuals sensitized to various metals had a significant decrease in positive patch test reactions after pre-treatment with the DTPA-cream: 2.5% nickel sulfate (24/28 positive without pre-treatment versus 1/28 with pre-treatment; p<0.0001), 5% nickel sulfate (30/32 versus 15/32; p=0.0003), 1% cobalt chloride (19/20 versus 6/20; p=0.001) and 5% copper sulfate (13/14 versus 5/14; p=0.02). However, the cream had no protective effect with 1% palladium chloride (17/23 versus 16/23) and with 0.5% potassium dichromate (9/13 versus 7/13). We conclude that the DTPA-cream clearly abrogates positive patch test reactions in nickel-, cobalt- and copper-sensitized subjects and that it may therefore be helpful in the management of allergic contact dermatitis.

The prevention of nickel contact dermatitis. A review of the use of binding agents and barrier creams

Chelating agents and other substances can be used to bind nickel or reduce its penetration through the skin, and hence to reduce the symptoms in subjects with nickel sensitivity. Topical usage is mostly described but, in some studies, chelating agents have been given systemically. The most effective ligand for nickel so far described is 5-chloro-7-iodoquinolin-8-ol. Although normally regarded as safe, its usage in some situations may be limited by concerns about its toxicity. Other ligands with demonstrable effect include ethylenediaminetetraacetic acid in various forms, diphenylglyoxime and dimethylglyoxime. Cation exchange resins can effectively bind nickel and work both in vitro and in vivo. Propylene glycol, petrolatum and lanolin reduce the absorption of nickel through the skin. Corticosteroids and cyclosporin work in nickel dermatitis by suppressing the immunological reaction rather than through an effect on nickel. Studies of the oral administration of ligands such as tetraethylthiuram disulphide have given conflicting results but the use of these agents is limited by hepatoxicity in any case. Some compounds offer potential for use in the prophylaxis of nickel dermatitis. Further work is required to develop the existing agents and to look at the use of novel combinations, such as that of a cation exchanger with a ligand.