Towards a perfect vehicle(s) for diagnostic patch testing: an overview
ABSTRACT The correct selection of vehicles for patch testing is crucial in evaluating suspected allergic contact dermatitis. We reviewed literature by searching Pubmed and Embase for the years 1971-2011 utilizing the subjects "vehicle," "allergic contact dermatitis" and "patch test" for advances in knowledge of vehicles." A universal optimal vehicle more efficient than petrolatum remains undiscovered. Literature provides research supporting alternate vehicles for specific allergens and insights on vehicle characteristics, such as influence on bioavailability of chemicals and subsequent percutaneous absorption or interaction with allergens. These findings should accelerate our ability to define, and thus determine, the optimum vehicle(s).
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ABSTRACT: Background Epicutaneous patch tests are used to reproduce allergy and diagnose allergic contact dermatitis. Reliable allergen test preparations are required.Objectives The purpose of the present study was to measure the actual concentrations of nickel(II) sulfate hexahydrate (NiSO4), methyl methacrylate, formaldehyde, and glutaraldehyde, and to compare them with the labelled concentrations, in commercial patch test allergen preparations found in dermatology clinics where patch testing is routinely performed.Materials and methodsThe commercial in-date and out-of-date patch test allergen preparations concentrations of NiSO4, methyl methacrylate, formaldehyde and glutaraldehyde from one to three participating clinics were analysed with chromatographic or wet chemical techniques.ResultsNiSO4 and formaldehyde concentrations were at or above the labelled concentrations; however, formaldehyde loss occurred with storage. NiSO4 particulate was uniformly distributed throughout the petrolatum. ‘In-use’ methyl methacrylate reagent syringes all contained ≤ 56% of the 2% label concentration, with no observable relationship with expiration date. Lower methyl methacrylate cocentrations were consistently measured at the syringe tip end, suggesting loss resulting from methyl methacrylate's volatility. The concentrations of glutaraldehyde patch test allergen preparations ranged from 27% to 45% of the labelled (1% in pet.) concentration, independently of expiration date.Conclusions Some false-negative methyl methacrylate, formaldehyde or glutaraldehyde patch test results may be attributable to instability of the test preparations.Contact Dermatitis 05/2014; 70(5). DOI:10.1111/cod.12169 · 3.62 Impact Factor
- Dermatitis 09/2014; 25(5):279. DOI:10.1097/DER.0000000000000062 · 1.36 Impact Factor