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Nottingham, United Kingdom

Moyal D.,LOreal | Alard V.,LVMH Recherche | Bertin C.,Johnson and Johnson Sante Beaute France | Boyer F.,Pierre Fabre | And 4 more authors.
International Journal of Cosmetic Science

Synopsis A multicentred study derived from the COLIPA in vitro UVA method was performed to assess the influence of test conditions on UVA protection factor (UVAPF) values in terms of amplitude, reproducibility between laboratories and correlation with in vivo UVA results. Eight products with a range of in vivo UVAPF from three to 29 were used. Two different types of plates, namely high-roughness (5 μm) and low-roughness (2 μm) plates, were used with a different application rate for each (1.3 mg cm-2 and 0.75 mg cm-2 respectively). The UVR dose applied to both plate types followed the same principle as the original test (1.2 J. cm-2 × UVAPF0). Strong, significant correlations between in vitro and in vivo UVAPF values were observed for both plate types (Pearson correlation > 0.9, P ≤ 0.01). The correlation and slope obtained with the low-roughness plates confirmed the previous results obtained by COLIPA. Across all laboratories, higher UVAPF values were obtained on the high-roughness plates (P < 0.01). Reproducibility of UVAPF values between laboratories was comparable between the two plate roughness values (low roughness, COV = 8%; high roughness, COV = 12%). Considering the in vitro/in vivo comparisons, a regression slope of 0.83 was observed for the low-roughness plates, in comparison with a value of 1.05 for the high-roughness plates. The accuracy of the method was improved, therefore, with the use of the high-roughness plates. With a constraint to recommend the use of only one plate type in the COLIPA UVA in vitro Test, the high-roughness plate was selected on an on-going basis to limit variability of results and to provide better accuracy with in vivo data. © 2012 Society of Cosmetic Scientists. Source

Diffey B.L.,Newcastle University | Brown M.W.,Alliance Boots Ltd
Photochemistry and Photobiology

Sunscreens were originally designed to prevent sunburn and incorporated active ingredients that absorbed principally in the UVB region. However, over the past 20 years or so new ingredients have been developed that extend absorption across a much wider range of the solar ultraviolet spectrum in the belief that sunscreens should provide balanced spectral absorption. This article develops the rationale for spectral uniformity by showing that this requirement is aligned to more natural forms of photoprotection. It is shown that a modern sunscreen can provide a spectrally balanced absorption profile in line with shade and many types of clothing fabric. Finally, a new metric is introduced that measures how well the spectral absorption profile of topical sunscreens performs against this ideal. For two decades manufacturers have sought to develop sunscreens with spectral profiles that approach uniform absorption across the solar ultraviolet spectrum. There has been considerable success in this regard and today we have available products that virtually meet this criterion of spectral uniformity. Yet to ensure optimal compliance by consumers, sunscreens need to be colorless when applied to the skin and hence their absorbance needs to fall to zero as the nonvisible UV wavelengths merge into the visible region. This figure compares our proposed ideal spectral profile of a topical sunscreen with the spectral sensitivity of the eye. © 2012 The American Society of Photobiology. Source

Bradley E.J.,Alliance Boots Ltd | Griffiths C.E.M.,University of Manchester | Sherratt M.J.,University of Manchester | Bell M.,Alliance Boots Ltd | Watson R.E.B.,University of Manchester

Ultraviolet radiation (UVR)-induced photoageing of the skin is associated with characteristic clinical features including a sallow complexion, deep, coarse wrinkles and a loss of elasticity. Remodelling of the dermal extracellular matrix (ECM) with changes to fibrillar collagens, elastic fibres and glycosaminoglycans is likely to be a major contributing factor to these particular clinical signs. Over-the-counter (OTC) topical formulations are one popular management strategy for preventing and/or repairing photoaged skin, most commonly targeting wrinkles as these are often the most concerning clinical feature. Due to the cosmetic nature of such formulations, evidence of their clinical efficacy and mechanism of action is often limited. However, these formulations usually contain putative active ingredients which individually have been subject to in vitro and in vivo investigation for efficacy as photoageing interventions. This review highlights commonly found ingredients within OTC formulations and assesses the evidence for: (i) their efficacy in clinically and histologically improving photoaged skin; (ii) the potential mechanisms of action; and (iii) their ability to act synergistically with complementary ingredients to enhance the clinical outcome. © 2015 Elsevier Ireland Ltd All rights reserved. Source

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