Multiparticulate carriers for sun‐screening agents

Abstract

SynopsisMany molecular sunscreens penetrate into the skin causing photo-allergic and photo-toxic reactions as well as skin irritations establishing an urgent need for the development of a safer sunscreen formulation. The search for active substances, efficient combinations, and the design of novel vehicles or carriers has led to the implementation of new cosmetic systems in contrast to the classic forms such as creams or gels. Amongst various approaches utilized to improve performance of sunscreening agents, the use of multiparticulate delivery systems is gaining increasing attention amongst researchers. Multiparticulate delivery systems can be incorporated into gels, creams, liquids, powders or other formulations, and can release active agents depending on their temperature, moisture, friction, volatility of the entrapped ingredients or time. These systems also have the ability of scattering or reflecting incoming UV radiations and therefore can act as physical sunscreens on their own. Ré suméBeaucoup de filtres solaires pénètrent à l'état moléculaire dans la peau provoquant des réactions photo-allergiques et photo-toxiques ainsi que des irritations ce qui nécessite un développement urgent de formulation solaire plus sû re. La recherche de substances actives, des mélanges efficaces et la conception de nouveaux véhicules ou de transporteurs a abouti à la mise en oeuvre de nouveaux systèmes cosmétiques face aux formules classiques que sont des crèmes ou des gels. Parmi ces diverses approches utilisées pour améliorer la performance des filtres solaires, l'utilisation de systèmes multi particulaires de délivrance suscite un intérêt croissant parmi les chercheurs. Ces systè-mes multi particulaires peuvent être incorporés à des gels, des crèmes, des liquides, des poudres ou d'autres formulations et peuvent libérer des agents actifs en fonction du temps, ou selon la tempéra-ture, l'humidité, la friction, ou la volatilité des ingrédients encapsulés. Ces systèmes ont aussi la capacité de disperser ou de refléter les radiations UV et peuvent donc agir à eux seuls comme des filtres solaires physiques.

Inorganic UV filters

“…Furthermore, UVA radiation penetrates deeper into the skin, reaching the dermis and leading to the onset of many age-related skin alterations. UVB radiation is the mainly responsible for immediate damage to the skin, which leads to erythema and sunburns (Jain, Jain, 2010), besides the possibility of attacking directly the cell DNA, with subsequent potential to induce changes that characterize skin cancer.…”

“…Even though UVC radiation has some desirable properties, such as germicidal activity, reports show that UVC radiation can be harmful to the skin, as it exhibits potential mutagenic and carcinogenic activity (Jain, Jain, 2010). Some studies on the ozone layer have stimulated rising concern among the scientific community, mainly grounded on its increasing destruction, but also because there are only a few studies that report the quantity of UVC radiation that currently crosses the ozone layer and while the sunscreens on the market are not active at the wavelength of UVC rays.…”

“…The action mode of the organic protector molecules is reversible, so that the same molecule can function repeatedly. Examples of organic sunscreens are salicylates, cinnamates, benzophenones, anthranilates, dibenzoylmethanes and p-aminobenzoates (Antoniou et al, 2008;Jain, Jain, 2010). Figure 1 illustrates the different modes of action of the organic and inorganic UV filters.…”

“…Furthermore, on absorbing the UV photons, organic UV filters can release free radicals and consequently cause damage to collagen, elastin or skin cell DNA. Thus, the frequent use of organic UV filters could be questioned on safety grounds, since their utilization right causes non negligible adverse reactions (Jain, Jain, 2010).…”

“…Titanium dioxide may be incorporated into several types of cosmetic sunscreen formulations, such as emulsions, lotions, sprays and gels (Jain, Jain, 2010). Among such marketed preparations, the emulsions are unquestionably the main vehicle for the incorporation of inorganic UV filters like TiO 2.…”