ASSESSMENT OF THE ACTIVITY OF TACALCITOL ON PSORIATIC PLAQUES BY MEANS OF COLORIMETRY AND HIGH-FREQUENCY ULTRASOUND - A DOUBLE-BLIND INTRASUBJECT HALF-SIDE RIGHT-LEFT COMPARISON WITH BETAMETHASONE VALERATE ANDPLACEBO

The aim of our study was to further investigate and to objectively ass ess the effects of tacalcitol on psoriasis by means of double-blind co mparisons with placebo and betamethasone valerate, documented by instr umental evaluation. The study was conducted as intrasubject half-side right-left comparisons. Twelve subjects entered a double-blind placebo -controlled treatment (tacalcitol/placebo group), whereas 14 subjects received double-blind medication with tacalcitol/betamethasone valerat e. Medications were applied once daily without occlusion to affected s kin areas. Instrumental evaluations were carried out by means of a col orimeter and a 20-MHz B scanner. The colour co-ordinate a, representi ng the colour range from green (-) to red (+), was used for assessing erythema. B scan images were processed according to segmentation proce dures. A 0-10 interval, marking the hyporeflecting dermal areas, was u sed for assessing oedema and inflammatory infiltration at psoriatic pl aque sites. Twenty-two patients (11 of the tacalcitol/betamethasone gr oup and 11 of the tacalcitol/ placebo group) completed the treatment p eriod. Mean a values showed an increase in the tacalcitol/betamethaso ne group after the first week of therapy on both sides, followed by a slight decrease, the values of which did not reach statistical relevan ce for either treatment. The decrease observed at tacalcitol-treated s ites in patients of the tacalcitol/placebo group was not significant e ither with respect to baseline values during the first weeks of therap y. The extension of 0-10 dermal areas decreased both in betamethasone- and tacalcitol-treated areas in both patient groups. No significant d ifferences were noticeable between the two treatments at all assessmen t points, although both by clinical and echographic evaluation a more pronounced decrease in clinical scores and in echogenicity values was observable at betamethasone-valerate-treated sites, especially at week s 6 and 8. According to our data, assessment of erythema does not alwa ys represent a valid method for monitoring the response to therapy in psoriatic patients. In fact, modifications of a values did not allow a distinction between different treatments, whereas processing of echo graphic images by the 0-10 segmentation enabled tacalcitol to be class ified as a topical drug, the activity of which approaches that of a po tent steroid.