[In vitro comparison of the efficacy and photostability of three sunscreen creams]

Introduction: While sun products are considered as cosmetics within the European Union, in the United States and Japan they are considered as medicines. Following the European market launch of the first sun product considered as a class-1 medical device, Daylong actinica, we compared products having different types of status.

Materials and methods: Three sun products underwent in vitro testing in order to determine their efficacy in terms of UVB and UVA protection, as well as their photostability. We used a classic cosmetic product (Nivea Sun 50+), a product displaying particular claims in terms of duration of efficacy (Dix20), and a medical device (Daylong actinica). The in vitro method used involves measuring the transmittance of a sample of the product applied to a polymethylmethacrylate plate using an integrating sphere spectrophotometer.

Results: In terms of efficacy, the three products tested were compliant with the European recommendations concerning sun products. In view of the results, the labelling for Nivea Sun 50+ and Daylong actinica) can both display the wording "50+". However, their photostability was poor under our experimental conditions. For Dix20), the labelling that may be displayed is 50. This value gradually decreases to 20 after 10hours of irradiation, accounting for the displayed claim.

Discussion: It is somewhat difficult to understand the coexistence on the market of products having different types of status without any prior establishment of clear limits in terms of indices, for example.