Open Application Test (open + application_test)

Distribution by Scientific Domains

Selected Abstracts

FS04.6 Dose/unit area and time , key factors influencing the elicitation capacity of MCI/MI

Claus Zachariae
The objective of the study was to investigate, using the Repeated Open Application Test (ROAT), two key parameters of exposure , allergen concentration (dose/unit area) and time in terms of the elicitation capacity of methylchloroisothiazolinone and methylisothiazolinone (MCI/MI) in MCI/MI-sensitised individuals and to explore the inter-relationship between these two key factors. The study was designed as a double-blind, placebo-controlled, dose-response ROAT preceded by a Diagnostic Patch Test (DPT). 79 patients with a known MCI/M allergy were contacted, 29 were diagnostically patch tested and 25 had their allergy confirmed. 25 MCI/M-allergic subjects and 10 healthy non-allergic control subjects were challenged with 2 ppm of MCI/MI/unit area of skin for 4 weeks. After a wash out period of at least 4 weeks the subjects were challenged with 7.5 ppm of MCI/MI/unit area of skin for 4 weeks. A ROAT with 2 drops of solution twice a day was conducted on the volar aspect of the left and right forearms on a 3 × 3 cm area resulting in dose/unit area of MCI/MI of 0.025 mg/cm2 and 0.095 mg/cm2 for 2 ppm and 7,5 ppm MCI/MI respectively. The elicitation capacity of MCI/MI in MCI/MI sensitive patients is dependent on the exposure dose/unit area and time The results of this study will be a useful addition to the risk assessment information available for MCI/MI. The risk assessment for the use of MCI/MI in rinse off consumer products is unaffected by the results of this study. [source]

Quantitative repeated open application testing with a rinse-off product in methyldibromo glutaronitrile-sensitive patients: results of the IVDK

Annice Heratizadeh
Background: While the use of methyldibromo glutaronitrile (MDBGN) in leave-on products is clearly associated with high sensitization or elicitation risk, such a clear-cut relation could be questioned with regard to rinse-off products. Objective: The objective of this study was to find a maximum non-eliciting concentration for rinse-off products in MDBGN patch test-positive patients. Patients and methods: We performed a use-related test [repeated open application test (ROAT)] in patients sensitized to MDBGN with a liquid soap containing three concentrations of MDBGN (50, 200, and 400 p.p.m. MDBGN, respectively). The soap at 50 p.p.m. was used twice daily for 4 weeks. If no reaction of the skin was observed, the product with the next higher concentration was used for another 4 weeks, etc. Results: In total, 32/37 evaluated cases [86.5%; lower exact one-sided 95% confidence limit (CL): 73.7%] did not react to any of the preparations. The remaining reacted as follows: 1/37 reacted to 50 p.p.m., 3/37 to 200 p.p.m., and 1/37 to 400 p.p.m. The cumulative non-response to 50 p.p.m. was 97.3% (lower CL: 87.8%). Conclusions: The majority of subjects sensitized to MDBGN-tolerated rinse-off products containing a maximum concentration of 400 p.p.m. A concentration in rinse-off products in the range of 50 p.p.m. could be regarded as safe for most individuals already sensitized. These concentrations will presumably prevent induction (sensitization) also. [source]

Dose per unit area , a study of elicitation of nickel allergy

Louise Arup Fischer
Background:, Experimental sensitization depends upon the amount of allergen per unit skin area and is largely independent of the area size. Objectives:, This study aimed at testing if this also applies for elicitation of nickel allergy. Patients/methods:, 20 nickel allergic individuals were tested with a patch test and a repeated open application test (ROAT). Nickel was applied on small and large areas. The varying parameters were area, total dose and dose per unit area. Results:, In the patch test, at a low concentration [15 ,g nickel (,gNi)/cm2], there were significantly higher scores on the large area with the same dose per area as the small area. At higher concentrations of nickel, no significant differences were found. In the ROAT at low concentration (6.64 ,gNi/cm2), it was found that the latency period until a reaction appeared was significantly shorter on the large area compared to the small area. It was also found that the ROAT threshold (per application) was lower than the patch test threshold. Conclusion:, For elicitation of nickel allergy, the size of the exposed area and therefore the total amount of applied nickel, influence the elicitation reaction at some concentrations, even though the same dose per unit area is applied. [source]

Emollients in a propanol-based hand rub can significantly decrease irritant contact dermatitis

Günter Kampf
The objective of this study is to determine the effect of emollients in a propanol-based hand rub on skin dryness and erythema. In this prospective, randomized, controlled, double-blind trial, 35 subjects participated; of them approximately half were atopic (modified Erlanger atopy score ,8). 2 propanol-based formulations were tested in a repeated open application test, 1 contained a mixture of emollients (0.81%, w/w). 2 aliquots of 0.7 ml of each formulation were applied twice per day over 2 weeks to the cubital fossa of each subject after random assignment of the preparations. Treatment areas were assessed before each application and 3 days postfinal application by visual inspection for erythema and dryness according to a standard scale. The sum score over all assessment time-points served as primary parameter. The mean sum score for erythema and dryness was significantly lower for the hand rub with emollients (0.8 ± 2.4) in comparison with that for the hand rub without emollients (1.5 ± 3.5; P = 0.022; Wilcoxon signed rank test). A comparison of the atopic and non-atopic subjects revealed no significant difference for any of the products (P > 0.05; Mann,Whitney U -test). It is concluded that the addition of emollients to a propanol-based hand rub can significantly decrease irritant contact dermatitis under frequent-use conditions. [source]

Use tests: ROAT (repeated open application test)/PUT (provocative use test): an overview

Tokio Nakada
As one step in defining the clinical relevance of exposure to an allergen identified with patch testing, use tests (provocative use test (PUT), and repeated open application test (ROAT)) have been used. In 1/2 of the cases of seemingly reliable patch tests, use tests are negative, suggesting that the patient's biologic threshold of response had not been reached with open application dosing. Dramatic differences exist in regional skin reactivity and percutaneous penetration. Negative results of use tests on normal skin may become positive on diseased skin. To refine this assay further, more controlled observations and analysis of reaction differences between normal and damaged skin, and among regional anatomic sites might be performed. In addition, we require a standardized measurement for the results. Use testing has significant potential in refinement of the evidence-based diagnosis of clinical relevance. However, for general validation, we should fill the deficiencies described above. [source]

Methyldibromoglutaronitrile in rinse-off products causes allergic contact dermatitis: an experimental study

C.D. Jensen
Summary Background The frequency of sensitivity to the cosmetic preservative methyldibromoglutaronitrile (MDBGN) has increased significantly in Europe. Most cases of allergic contact dermatitis from MDBGN are caused by leave-on cosmetic products. The risk of developing allergic contact dermatitis from rinse-off products has been less studied. Objectives To investigate the allergic response elicited in presensitized individuals from exposure to a rinse-off product preserved with the maximum permitted level of MDBGN. Methods Nineteen contact allergic individuals and nine controls participated in a double-blind, randomized repeated open application test (ROAT) using two coded liquid soaps with and without MDBGN. Areas of 50 cm2 on the lower arms were washed with the soaps twice a day for up to 28 days; two of the subjects continued for 34 days. The subjects were also patch tested with a dilution series of MDBGN to determine their patch test threshold values. Results Seven presensitized individuals (37%) developed allergic contact dermatitis from the soap containing MDBGN. The mean dose of MDBGN per application was 2·2 µg cm,2 and the reactions appeared between days 6 and 34. All nine controls had negative ROATs. The difference in reactivity between test subjects and controls was significant (one-sided Fisher's exact test, P = 0·04). Patch test threshold values ranged from <,0·001% to 0·2% MDBGN in ethanol/water. Conclusions This study shows that the exposure to a rinse-off product containing the maximum permitted level of MDBGN can easily elicit an allergic response in presensitized individuals. Along with reported cases of induction and elicitation caused by MDBGN in rinse-off products the study indicates that the permitted level of MDBGN in rinse-off products is too high. We recommend that this level should be re-evaluated. [source]