科研之友
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摘要
Background Solar urticaria is a rare photosensitivity disorder demonstrating a range of action spectra, which can inflict a very large impact on life quality despite available treatments. Melanin broadly reduces skin penetration by ultraviolet-visible wavelengths, thus increased melanization may protect in solar urticaria.
Objectives To examine quantitatively for impact of the potent alpha-melanocyte stimulating hormone analogue afamelanotide ([Nle(4)-D-Phe(7)]-alpha-MSH, Scenesse (R); Clinuvel Pharmaceuticals Ltd, Melbourne, Vic., Australia) on the solar urticaria response and skin melanization.
Methods Five patients with solar urticaria received a single dose of 16 mg subcutaneous afamelanotide implant in winter time. Melanin density was assessed spectrophotometrically from day 0 to day 60. Detailed monochromated light testing to geometric dose series (increment root 2) of wavelengths 300-600 nm was performed at 0, 30 and 60 days, with assessment of weal and flare area and minimum urticarial dose (MUD). Data were analysed by repeated-measures anova.
Results Mean melanin density increased by day 7, peaked at day 15 and remained elevated at day 60 (P = 0.03, 0.01, 0.02 vs. baseline, respectively). Baseline phototesting revealed action spectra of 320-400 (n = 1), 320-500 (n = 2), 300-600 (n = 1) and 370-500 nm (n = 1), and on afamelanotide mean rises in MUD of 1-12 and 1-3 dose increments were seen at the individual wavelengths tested, at 30 and 60 days, respectively. A significant fall in weal area occurred across responding wavelengths from 300 to 600 nm at 60 days postimplant (P = 0.049 vs. baseline), accompanied by greater than twofold overall increase in MUD (P = 0.058 vs. baseline).
Conclusions Melanization following afamelanotide is accompanied by reduction in solar urticaria response across a broad spectrum of wavelengths. Further study is warranted to assess clinical benefit under ambient conditions in summer.
- 出版日期2011-2
