Variation in allergen content over time of acrylates/methacrylates in patch test preparations.

BACKGROUND: Acrylates/methacrylates are volatile substances. There might be a gradual decrease in acrylate/methacrylate allergen content over time in patch test preparations but this has not yet been documented. OBJECTIVES: To determine the allergen content of acrylates/methacrylates in patch test preparations over time under different storage conditions. METHODS: Five acrylate/methacrylate allergens [2-hydroxyethyl methacrylate (2-HEMA), methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA), triethylene glycol diacrylate (TREGDA) and 2-hydroxypropyl acrylate (2-HPA)] in syringes and IQ™ chambers (Chemotechnique Diagnostics, Vellinge, Sweden) were analysed using gel permeation chromatography and high-performance liquid chromatography to measure the allergen content over time in samples stored in the freezer, refrigerator and under room temperature. RESULTS: The concentration of allergens in syringes decreased with time. Those stored at room temperature had the fastest rate of decrease, followed by those in the refrigerator and freezer. In most cases, in syringes or IQ™ chambers under all storage conditions, the MMA decreased most rapidly, followed by 2-HPA, 2-HEMA, EGDMA and TREGDA. The allergens in the IQ™ chambers rapidly disappeared, with almost all samples reaching nondetectable levels by day 8. MMA was the first to reach a nondetectable level--at day 2. CONCLUSIONS: Acrylate/methacrylate allergens are lost rapidly from IQ™ chambers especially if stored at room temperature. Allergens in syringes remain above 80% of their initial concentrations for longer periods compared with IQ™ chambers. In syringes and IQ™ chambers there is a slower rate of decrease in concentration when the storage temperature is lower. Allergens should be stored refrigerated, replaced regularly, and freshly applied on to test patches on the day of use.

Study on the efficacy of ELA-Max (4% liposomal lidocaine) compared with EMLA cream (eutectic mixture of local anesthetics) using thermosensory threshold analysis in adult volunteers.

BACKGROUND: ELA-Max and EMLA cream are topical anesthetics that have been shown to have similar anesthetic efficacy in previous studies. OBJECTIVE: To evaluate the analgesic efficacy of ELA-Max in comparison with EMLA cream using a novel method of thermosensory threshold analysis. METHODS: A thermosensory analyzer was used to assess warmth- and heat-induced pain thresholds. RESULTS: No statistically significant difference was found in pain thresholds using either formulation. However, EMLA cream increased the heat-induced pain threshold to a greater extent than ELA-Max. Thermosensory measurement and analysis was well tolerated and no adverse events were encountered. CONCLUSIONS: EMLA cream may be superior to ELA-Max for heat-induced pain. This study suggests that thermosensory measurement may be another suitable tool for future topical anesthetic efficacy studies.

Itch characteristics in Chinese patients with atopic dermatitis using a new questionnaire for the assessment of pruritus.

BACKGROUND: Although pruritus is the predominant and commonest feature of atopic dermatitis, its clinical characteristics have not been explored. OBJECTIVE: To characterize the clinical pattern and sensory and affective dimensions of the itch experience utilizing a comprehensive itch questionnaire. METHODS: A structured itch questionnaire based on the McGill pain questionnaire was given to 102 Chinese patients with known atopic dermatitis. RESULTS: There were 100 patients with atopic dermatitis who fully filled the questionnaire. In 87% of the patients pruritus appeared on a daily basis. It had a prolonged duration (mean duration 10.7 7.3 years). It involved all body areas mostly in the lower limbs (83%), flexures (76%), upper limbs (71%) and neck (65%). Itch intensity during its peak was nearly twice higher than the itch of a mosquito bite. Itching was most frequent at night (65%), and 84% of patients reported of difficulty falling asleep. Daily life activities which increased the severity of itch were sweat in 96%, dryness in 71%, stress in 71% and physical effort in 73%. The major factors which were found to reduce the intensity of pruritus included: bathing with cold water in 55% and cold ambient environment in 56%. Associated symptoms were heat sensation (51%), sweating (40%) and pain in the pruritic area (45%). The various anti-pruritic therapies had limited long-term effect. The pruritus was bothersome (52%) and a major distress to the patient. The affective score correlated to itch intensity during its peak (r = 0.4, P < 0.001). CONCLUSIONS: The study provided a detailed description of pruritus in atopic dermatitis with new data on affective and sensory dimensions and associated symptoms. The questionnaire was found to be a useful tool in characterization of itch.