Outdoor testing of the photoprotection provided by a new water-based broad-spectrum SPF50+ sunscreen product: two double-blind, split-face, randomized controlled studies in healthy adults
Received 6 April 2019
Accepted for publication 27 May 2019
Published 27 June 2019 Volume 2019:12 Pages 461—467
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Melinda Thomas
Peer reviewer comments 3
Editor who approved publication: Dr Jeffrey Weinberg
Corinne Granger,1 Yolanda Sola,2 Yolanda Gilaberte,3–6 Carles Trullàs1
1Innovation and Development, ISDIN, Barcelona, Spain; 2Meteorology Group, Department of Applied Physics, University of Barcelona, 08028 Barcelona, Spain; 3Dermatology Department, Hospital Universitario Miguel Servet, Zaragoza, Spain; 4Academia Española de Dermatología y Venereología, Zaragoza, Spain; 5Revista Actas Dermo-Sifiliográficas, Zaragoza, Spain; 6Health Sciences, University of Zaragoza, Zaragoza, Spain
Purpose: Users often under-apply sunscreens, and one of the main reasons cited for this is the cosmetic formulation of the product. To address this, we developed a water-based sunscreen. The product underwent standard laboratory testing (ISO 24444: 2010) and was determined as sun protection factor (SPF) 50+. However, such laboratory testing does not take into account environmental factors of in-use conditions that could potentially affect sunscreen efficacy, particularly of new cosmetic formulations. We aimed to test this product in conditions more representative of real-life solar exposure, to confirm its reported laboratory efficacy.
Methods: Two double-blind, randomized, controlled, split-face intra-individual studies were conducted during summer months in Barcelona. One study compared the product against an SPF15 control (reference standard P3 of ISO 24444: 2010), while the other compared against an SPF50+ control (another commercially available sunscreen). A technician applied the products before sun exposure: investigational product (IP) to one half of the face and the respective control product to the other. Subjects spent 4–6 hrs outdoors performing quiet activities, and sunscreens were reapplied at 2 hourly intervals. A dermatologist clinically scored facial erythema at baseline and at 24 hrs.
Results: Sixty-five subjects were included in total. In both studies, skin treated with the IP showed no significant increase in clinical erythema scoring at 24 hrs. There were statistically significant differences between the IP and the SPF15, but not between the IP and the SPF50+ control. SPF15 did not protect all subjects against solar-induced erythema.
Conclusion: These outdoor studies confirm the efficacy of this new SPF50+ water-based sunscreen in conditions that closer represent real-life sun exposure.
Keywords: erythema, sunburn, sunscreen, photoprotection, real-life testing
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