Intensity and area increase of UVB-induced erythema: two variables used for studies of the influence of topically applied drugs.
The area of UV erythema produced by a small beam head was found to increase with increasing doses. The aim was to investigate whether measurement of the area could be a more useful indicator of UV-induced damage than classic visual grading. Topical pretreatment with all-trans retinoic acid (tretinoin) and betamethasone valerate was used to test the applicability of the method in pharmacological studies. We used a round outlet head (5 mm2) connected by optical fibre to a monochromatic irradiator, and doses ranging from 0.05 to 0.2 Joule of 300 mm UV light were applied to the skin of 6 healthy subjects. Erythemal area was calculated by the measurement of two diameters, and intensity was graded visually (0-6 scale). The area of the erythema correlated with the increase in intensity up to score 6. Area measurement was less subject to intra-investigators' variability than the intensity score. By multiplying intensity by area, a good indicator of UV-induced reactivity was obtained. Pretreatment with betamethasone valerate decreased the area of erythema, as did tretinoin 12 h after irradiation. Thus, area measurement of erythema is a useful adjunct to visual grading of UV-induced skin reactions.
Juhlin
L
L
Department of Dermatology, University of Uppsala, Sweden.
Shroot
B
B
D000279:Administration, Cutaneous; D000328:Adult; D000704:Analysis of Variance; D001624:Betamethasone Valerate / Q000494:pharmacology / Q000627:therapeutic use; D004890:Erythema / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control; D005260:Female; D006801:Humans; D008297:Male; D010865:Pilot Projects; D011829:Radiation Dosage; D011836:Radiation Tolerance; D011837:Radiation-Protective Agents / Q000494:pharmacology / Q000627:therapeutic use; D011855:Radiodermatitis / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control; D012867:Skin / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects*; D014212:Tretinoin / Q000494:pharmacology / Q000627:therapeutic use; D014466:Ultraviolet Rays / Q000009:adverse effects*
D011837:Radiation-Protective Agents; D014212:Tretinoin; D001624:Betamethasone Valerate