Innovative filter allows water phase dispersion

The way in which the final product will be used needs to be evaluated – daily use, for sport use, protection on the beach, etc. And of course the skin type needs to be considered – sensitive skin, easy burning skin, easy tanning etc. To ensure that the customer needs are met and that they continue to purchase and use the product, the sensoric virtues of the product must be right, it must be easy to use, water resistant, non-sticky and offer the desired level of protection. Once these points have been decided upon by the formulator, the application format for the customer and the appeal for the end consumer need to be considered. Based on these decisions, recommendations of standard formulations can be made, from creams and lotions right through to the new shaker type formulations, which are based on water/silicone formulations. These recommendations, however, still need to meet all the regulatory requirements which in different regions are often not the same and can also differ in countries within the same regions. But one trend has remained, as each new region has published its own sunscreen product standards and requirements: the continuous demand for higher and higher UVA performance and, therefore, better protection for the skin.

Achieving the right filter combination

It is no mean achievement to fulfill all goals. While sensory and delivery format can be influenced by the choice of cosmetic oils, emulsifiers, the actual level of SPF and UVA protection can only be achieved by the right combination of UV filters. There are 48 UV filters currently available worldwide, which are defined for use as UV filters, however, these 48 UV filters are not all available to use in each and every region (Figure 1 highlights the differences in the regions). The region with the most flexibility is Europe with 28 filters to choose from. However, it is valid for all regions that the majority of filters are UVB filters and UVA protection is still underrepresented. The region with the smallest choice of UVA filters is the US and this will remain the case until the final sunscreen monograph is published and a decision is taken on how to finalise the process for approving new UV filters. The other interesting point is that only approximately 10% of all filters are available for the water phase. Figure 2 shows UV filter development over the last few decades, where their progress through the approval system is highlighted by their Colipa reference number. Additional modifications and optimisations are topics that are continuously worked on. By modifying the delivery form it has been possible to expand the use of a traditionally oil soluble UV filter in the water phase of a formulation. Tinosorb S, the original broad-spectrum filter, is traditionally used in the oil phase and delivers strong, photostable broad-spectrum coverage. Through technological advances, it is now possible to use Tinosorb S in an alternative way and add it to the water phase.