ASIAN SKIN: ROLE OF UVA IN HYPERPIGMENTATION AND PREVENTION

Transcription

1 1 RESEARCH & INNOVATION ASIAN SKIN: ROLE OF UVA IN HYPERPIGMENTATION AND PREVENTION Dominique MOYAL SUN PROTECTION & ANTI-AGEING SKIN CARE ASIA CONFERENCE 2014

2 CONTENT OF THE PRESENTATION The effects of sunlight on the skin of Asians Prevention by well-balanced UVB-UVA sunscreens UVA efficacy criteria and labelling Measurement methods

3 ASIAN SKIN Skin colour determined by total pigment content (Eumelanin & Pheomelanin) Asians skin color ranges from light to dark brown Eumelanin in a greater quantity than in Caucasian skin Bigger melanosomes (containing melanin granules) / Higher activity of melanocytes

4 ASIAN SKIN => These differences explain why mainly phototypes III and IV are found in Asia Phototype I Phototype II Phototype III Phototype IV Phototype V Phototype VI Porcelain Beige Intermediate Medium Brown Brown Black burns always easily burns always easily burns moderatly burns slightly burns rarely never burns Never tans Slightly tans Progressively tans Easily tans Tans intensively Highly pigmented 2 main phototypes* of Asian skin *[Determined after a 1st sun exposure after winter)

5 UVB- UVA PIGMENTATION Pigmentation is induced by UVB and UVA rays with different types of photobiological reactions of the skin pigmentary system Immediate reaction IPD and PPD : transient and persistent due to UVA IPD / PPD result from photo-oxidation and / or polymerisation of preexisting melanin and precursors More easily induced on skin types III / IV Delayed formation of new melanins: neomelanization due to UVB and UVA Compared to UVB, UVA-induced tanning lasts longer (several months or even a year) This difference is probably due to the more basal localization of UVAinduced pigmentation and may be the nature of melanin UVB radiation induces melanin which is more easily transferred to keratinocytes and disappears with epidermal turn-over, within a month

6 ASIAN SKIN Particularly vulnerable to UVA INDUCED BROWN SPOTS HIGH LEVEL OF MELANIN HIGHER UVA EXPOSURE 1.93 Irregular pigmentation, hyper-pigmented lesions Dark/aged spots Relative amount of UVA on a typical January 15th compared to Paris

7 ASIAN SKIN Pigmentation Prevention by well-balanced UVB-UVA sunscreens Product SPF50 UVAPF13 ratio SPF/UVAPF 3.8 PA+++ Product SPF50 UVAPF21 ratio SPF/UVAPF 2.4 PA++++ Pictures showing the difference of pigmentation obtained after UV exposure at the same UV doses comparing two SPF 50 products with different UVAPF (13 vs 21, PA+++ vs PA++++) The product with the higher UVA protection, ratio SPF/UVAPF=2.4 provides a very good protection 7

8 UVA EFFICACY CRITERIA AND LABELLING PRIMARY SUNSCREENS ONLY UVA EUROPE 2006 MERCOSUR MEXICO CANADA 2013 UVA efficacy criteria UVAPF/SPF At least 1/3 + λ c 370 nm UVAPF/SPF At least 1/3 + λ c 370 nm UVAPF/SPF At least 1/3 + λ c 370 nm λ c 370 nm And option: UVAPF/SPF at least 1/3 UVA Labelling Not defined Broadspectrum

9 UVA EFFICACY CRITERIA AND LABELLING PRIMARY AND SECONDARY SUNSCREENS UVA South Africa 2013 Australia USA 2011 Japan 2013 Korea 2002 China 2007 ASEAN UVA efficacy criteria UVAPF/SPF At least 1/3 + λc 370 nm UVAPF/SPF At least 1/3 + λc 370 nm λ c 370 nm UVAPF 2 to <4 PA+ UVAPF 4 to <8 PA++ UVAPF 8 PA+++ UVAPF 16 PA ++++ Europe ratio/ UK (Boots stars) / PA Labelling UVA Broad- Spectrum Broadspectrum PA+ PA++ PA+++ PA++++ PA+ PA++ PA+++ PA+ PA++ PA+++ PA+ PA++ PA+++ PA++++ For Australia, UVA protection mandatory excepted for make-up products with SPF < 30

10 UVA EFFICACY CRITERIA AND LABELLING UVA efficacy criteria not harmonized: different approaches Proportionality between UVA and UVB protection not always ensured Different labelling even for the same criteria (UVA logo or broadspectrum for 1/3 ratio criteria) Same labelling (broadspectrum) even if different criteria/ level of protection not equivalent Conclusion: we are far from the worldwide harmonization

11 SPF AND UVA METHODS TO ASSESS EFFICACY In vivo SPF test method: ISO Published on November 15, 2010 This method is very similar to the International SPF test method 2006 published by Colipa, JCIA, CTFA-SA ISO and FDA 2011 In vivo SPF test methods are both based on the 2006 International SPF test method and then are very close Some few differences which cannot induce different results but results differences between laboratories still exist

12 ADOPTION OF SPF METHODS Europe USA 2011 Canada 2013 Mercosur Mexico Chile Andean Community ISO FDA 2011 FDA 2011 ISO Inter2006 ISO FDA 2011 FDA 2011 ISO Inter2006 ISO FDA 2011 Australia South Africa 2010 Japan ISO ISO ISO Korea China Asean Taiwan India Inter 2006 ISO FDA 2011 China 2007 Inter2006 FDA 1999 all

13 UVA METHODS TO ASSESS EFFICACY In vivo UVA test method: ISO Published in Dec 2011 This method is very similar to the UVA test method published by JCIA in 1995 JCIA 1995 ISO 24442: 2011 Reference sunscreen formulations Acceptance limits S1 : 3.75 ( ) S1: 4.4 ( ) S2: 12.7 ( ) S2 used for expected UVAPF 12

14 UVA METHODS TO ASSESS EFFICACY In 2006, following the request from the EU Commission to have in vitro methods, Colipa (Cosmetics europe) developed a UVA in vitro method Objective was the determination of an in vitro UVA protection factor (UVAPF) validated (equivalent results) against the in vivo Persistent Pigment Darkening (PPD) method (JCIA 1995) Inclusion of irradiation of the samples to take into account photounstability as with the in vivo method First in vitro method published in 2007, revised in 2009 for inclusion of the critical wavelength calculation The Colipa UVA in vitro method was taken as the basis of the ISO standard/ Improvement have been done, Colipa published a revision in 2011 In vitro UVA test method: ISO Published in June This method is very similar to the in vitro UVA test method published by Colipa (Cosmetics Europe) in 2011 UVAPF and critical wavelength calculations

15 ISO data VALIDATION OF THE UVA IN VITRO METHOD

16 IN VITRO CRITICAL WAVELENGTH METHODS Main differences between the ISO 24443: and the FDA 2011 and influence of the conditions on the results Parameters FDA2011 ISO Differences Plates PMMA 2 to 7 µm PMMA 5µm Between 2 and 5 µm: + 2 nm 5 µm to be used for harmonization Product amount Irradiation dose Number of plates 0.75 mg/cm² 1.3 mg/cm² No significant difference due to product amount 4 MEDs (8J/cm²) 1.2 J/cm² x UVAPF0 Difference due to the UV dose : 1 nm At least 3 At least 4 No difference if 3 or 4 plates

17 IN VITRO CRITICAL WAVELENGTH METHODS Critical wavelength (CW) is an evaluation of the shape of the absorbance curve The shape is mostly impacted by the roughness of the plate when comparing 2µm and 5µm ( plates with 7µm not available) 5µm plate should be chosen for harmonization The shape is not significantly impacted by amount of product (0.75 vs 1.3 mg/cm²) for the 5µm plate The difference of UV dose has a very low impact on the CW when using the 5µm plate, below the variability of the measurements between laboratories Conclusion: FDA conditions when using the 5µm plate give equivalent results to the ISO 24443

18 ADOPTION OF UVA METHODS In vivo In vitro Europe ISO USA 2011 Not relevant Canada 2013 ISO ISO FDA 2011 FDA 2011 Colipa / ISO Mercosur JCIA 1995 and updates ISO Colipa 2009 or all updates (Colipa 2011 ISO 24443) Mexico ISO Colipa 2011 ISO FDA 2011 In vivo In vitro Australia South Africa 2013 Japan No ISO ISO JCIA 1995 ISO Korea China Asean China 2007 JCIA 1995 ISO ISO ISO No No No All All

19 CONCLUSION BENEFITS OF ISO STANDARDS When adopted by regulatory agencies: They provide guidelines allowing for conformity to a regulatory requirement They provide reference methods which could be used for inmarket control Points of reference for other key stakeholders (industry, consumers etc.) Harmonization to avoid local retesting ( good for cost, more ethical when in vivo human testing)

20 CONCLUSION In the last 8 years, there was progress made : Improvment of the UVA efficacy of the products thanks to new UVA efficacy criteria Improvment of harmonization for SPF testing, UVA testing However, we are far from a complete harmonization specially in terms of UVA efficacy / labelling which can confuse the consumers Only well-balanced UVB-UVA protection (SPF/UVAPF 3) can efficiently prevent UVA damage as hyperpigmentation in Asian skin

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