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Notes: Background The skin microdiallysis technique makes it possible to measure histamine release in intact human skin in vivo directly. In this study we have used the microdialysis technique to characterize histamine release by codeine after intracutaneous injectioin and following skin challenge by a novel atraumatic delivery technique.Objective The purpose of the study was to compare histamine release in human skin by codeine. delivered by an intraprobe drug delivery system (IPD) and intracutaneous injections (ICT), with respect to dose-response relations, kinetics of histamine appearance and decay, corelations between histamine release and skin respones, and reproducibility.Methods Hollow dialysis fibres were inserted intradermally in 12 healthy subjects. Twelve fibres were inserted in each subjects, six fibres in each arm. Each fibre was perfused at a rate of 3 μL/min, and samples were collected in 2 min fractions. By the IPD technique, codeine was administrered to the skin by adding codeine to the perfusion medium. Sequential IPD challenges were performed in one arm. and ICTs were done on the other arm.Results Sixfold serial dilutions of codeine (0.01-3 mg/mL) caused a significant doserelated histamine release by ICT and IPD. Peak histamine release was found within the first 4 min after skin challenge by ICT and IPD, followed by a fast decline with a dialysate histamine half life of approximately 2-3 min. Peak hisamine release was linearly correlates with cumulative release of the 20 min sampling period, and histamine release correlated with weal soze. The coefficient of variation on peak histamine releae was 18.9% and 4.8% for codeine ICT and IPD, respectively.Conclusioin We have described in detail codeine-induced histamine release in intact human skin in vivo by the microdialysis technique. It was possible to administer codeine atraumaticallyl to the skin by intraprobe delivery. The skin microdialysis codeine atraumaticallly to the skin by intraprobe delivery. The skin microdialysis technique opens up possibilities for measurement of infllammatory mediators release in normal and diseases skin, and it will be possible to deliver immunopharmacologically active drugsto the skin by intraprobe delivery.

Notes: We report the results of an open, prospective study on the efficacy of systemic ranitidine in the treatment of psoriasis. Twenty patients suffering from moderate to severe psoriasis were included in the study. The median pretreatment PASI score was 15·7 (range 6·0-24·7). The patients were treated with oral ranitidine 300 mg twice a day for 6 months; no other medication was allowed during the study period. Eighteen patients completed the study. The median PASI score was reduced from 15·7 to 14·5. 9·1 and 5·7. after 1, 3 and 6 months of treatment, respectively (P〈0·00001). A significant reduction in PASI score was evident at 3 months of treatment. A mild to moderate deterioration occurred in 15 patients within the first month of treatment, but this was followed by improvement during prolonged treatment in most patients. No other clinical and/or biochemical side-effects were observed. Eight patients continued therapy with ranitidine after the study was completed, and none of these patients relapsed during a follow-up period of 12–18 months. The results of the present study suggest that ranitidine may be a beneficial and safe treatment for psoriasis. In addition, high-dose, long-term ranitidine treatment appears to be free from severe adverse effects.

Notes: In 10 patients with chronic plaque type psoriasis one or two plaques affected equally with psoriasis were chosen for study. Five punched out rings of a hydrocolloid dressing were applied to the psoriasis plaque(s). In each circular test area 20 mg of one of the following creams was applied: base, 1% hydrocortisone (DAK), 0·1% triamcinolone acetonide (Kenalogue®), 0·1%, betamethasone-17-valerate cream (Betnovate®), and 0·05% clobetasol proprionate cream (Dermovate®). The areas were occluded with a thin Him of transparent hydrocolloid dressing (Comfeel® P Transparent Dressing), for 1 week. Non-invasive measurements (ultrasound skin thickness, laser-Doppler flowmetry, colorimetry) were performed before and after treatment. Therapeutic response was evaluated blindly by clinical score. The measurements showed a decline in blood How, a decrease in skin thickness, and normalization of colour approaching that of normal skin, the more potent the corticosteroid used. The clinical scores showed the same: the more potent a corticosteroid used, the closer to the score of normal skin. Data on variability and applications of the methods are presented. The study concludes that potent corticosteroids occluded with a hydrocolloid dressing can clear psoriasis in 1 week. Short-course corticosteroid therapy appears harmless and relevant for clinical dermatology.

Notes: In eight healthy individuals, the skin fold between the thumb and the forefinger was treated with 0·05% clobetasol propionate ointment under a hydrocolloid occlusive dressing. Using the atraumatic epieutaneous 133Xe wash-out technique on the outer 2 mm of the skin fold, covering the rest of the hand with a lead shield, we were able to monitor cutaneous blood flow. Blood flow was measured after 0, 10, 24, 48 and 72 h of treatment. During the first 10 h of treatment no significant change in blood flow was observed. However, compared to untreated tissue, cutaneous blood flow decreased significantly after a 24-h period (P 〈 0·05). Furthermore a significant blood flow reduction from 0–48 (P 〈 0·02) and from 0–72 h (P 〈 0·01) was observed. Placebo did not decrease cutaneous blood flow, but a minor increase was demonstrated. The results of the present work demonstrate a long-lasting blood flow reducing effect of topical corticosteroid in normal human cutaneous tissue.

Notes: A number of investigations have indicated that cholinergic agonists release histamine from isolated mast cells and suggested that cholinergic stimulation releases histamine in vivo. The purpose of this study was to investigate whether the cutaneous wheal-and-flare reaction induced by methacholine challenge in human skin involves histamine release as measured by the skin microdialysis technique. Five hollow dialysis fibers were inserted intradermally in forearm skin in eight healthy subjects. Each fiber was perfused with Kreb's-Ringer bicarbonate at a rate of 3 μl/min. Dialysates were collected in 2-min fractions before skin challenge and for 20 min after intradermal injection of methacholine 10–-3 -10-1 M, the vehicle, and a positive control, codeine phosphate 0.3 mg/ml. Histamine was assayed spectrofluorometrically. Methacholine caused a statistically significant dose-related wheal-and-flare reaction, the flare reaction to methacholine 10-1 M being comparable with that seen with codeine 0.3 mg/ml. No significant histamine release was observed with methacholine, cumulative histamine release of 16 ± 8nM by methacholine 10-1 M being similar to vehicle responses of 15 ± 9 nM. Histamine release by codeine was 2524 ± 435 nM. In conclusion, methacholine-induced wheal-and-flare reactions in human skin appeared not to involve histamine release from skin mast cells.

Notes: The purpose of this study was to evaluate the application of a microdialysis technique for measurement of interstitial histamine levels in intact human skin. Three allergic subjects were investigated. Single dialysis fibers were glued to nylon tubings and inserted in forearm skin by means of a fine cannula. Dialysis fibers were inserted in triplicate and perfused with isotonic saline at a rate of 3 μl/min. After a period of 2 h a 60-μl base-line period was established. Then the patients were skin prick tested (SPT) with allergen in duplicate and a single saline control. Dialysate was collected in consecutive 30 μl fractions. Histamine concentration in the dialysate was analyzed with a glass fiber fluorescence assay. Median base-line histamine level was 4 (range 4–7) ng/ml. Following allergen SPT, dialysate histamine concentration increased to 81 ng/ml (74–128), with maximum values 10–20 min after SPT. Intraindividual coefficient of variation on peak histamine levels was 18.9%. No histamine increase was seen following saline SPT. We consider microdialysis to be a valuable method for assessment of allergic mechanisms in intact human skin.