Concentration variability of potent allergens of p-tert-butylphenol-formaldehyde resin (PTBP-FR) in patch test preparations and commercially available PTBP-FR

Background Patients with rosacea demonstrate a higher density of Demodex mites in their skin than do controls. A bacterium isolated from a Demodex mite from a patient with papulopustular rosacea (PPR) was previously shown to provoke an immune response in patients with PPR or ocular rosacea, thus suggesting a possible role for bacterial proteins in the aetiology of this condition. Objectives To determine the concentrations of the two main allergens of PTBP-FR in diagnostic patch testing preparations and PTBP-FR available to glue and adhesive manufacturers. Methods Nuclear magnetic resonance spectrometry was used to confirm the identity and determine the purity of reference materials. High-pressure liquid chromatography was used available PTBP-FR. Results In the PTBP-FR tion of the allergenic to analyse patch test preparations and commercially n analysed patch test preparations the highest concentradimer 4-tert-butyl-2-(5-tea-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-6-hydroxymethylphenol found was 1.79% and the lowest 0.21%. The highest concentration of the allergenic dimer 4-tert-butyl-2(5-tert-butyl-2-hydroxy-benzyloxymethyl)-6-hydroxymethylphenol found in PTBP-FR of analysed patch test preparations was 0+50% and the lowest concentration found was 0'04%. In commercially available PTBP-FR the highest concentration of 4-tea-butyl-2-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-6-hydroxymethylphenol found was 3.7% and the highest concentration of 4-tert-butyl-2(5-tert-butyl-2-hydroxy-benzyloxymethy1)-6-hydroxymethylphenol found was 1+1%. In three PTBP-FR samples neither allergen could be detected. Conclusions Our data suggest that reporting resin concentration in petrolatum is not predictive of a consistent concentration of the two main allergens of PTBP-FR. The 10-fold difference in allergen concentratioti between different patch test preparations has significant ramifications for maintaining consistent dose of delivered allergen. The results of this study reinforce the need for patch test product standardization in the contact dermatitis community.