title: Anionic clays for sunscreen agent safe use: photoprotection, photostability and prevention of their skin penetration.
abstract: The use of sunscreen preparations is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently and for many hours. Exposition to sunlight, in fact, can cause sunscreen photodegradation and determine their decrease in UV protection often with the occurrence of allergic and/or toxic degradation products. A high photostability is hence very important for their effectiveness and safety. The aim of this work is to obtain new sunscreen formulations stabilized by intercalating PABA, within the lamellar structures of two kinds of hydrotalcite. PABA was chosen as model sunscreen because of its high photoinstability and photosensitizing properties that nowadays bar its utilization. Both intercalated products showed an increased protection range and, in one case, an improved sunscreen photostability. Sunscreen release from creams containing intercalated or free PABA was evaluated as well. The very low or negligible sunscreen release, obtained from the intercalated product loaded formulations, resulted in a lack of a close contact between skin and filter with the consequence that cutaneous reactions and allergy problems are eliminated. The use of these materials resulted in a good strategic technological approach in order to increase efficacy and safety of solar products.
authors.affiliation: Dipartimento di Chimica e Tecnologia del Farmaco, Università degli Studi di Perugia, Perugia, Italy. luanaper@unipg.it
authors.forename: Luana
authors.initials: L
authors.lastname: Perioli
authors.forename: Valeria
authors.initials: V
authors.lastname: Ambrogi
authors.forename: Barbara
authors.initials: B
authors.lastname: Bertini
authors.forename: Maurizio
authors.initials: M
authors.lastname: Ricci
authors.forename: Morena
authors.initials: M
authors.lastname: Nocchetti
authors.forename: Loredana
authors.initials: L
authors.lastname: Latterini
authors.forename: Carlo
authors.initials: C
authors.lastname: Rossi
mesh_terms: D010129:4-Aminobenzoic Acid / Q000737:chemistry* / Q000528:radiation effects; D000536:Aluminum Hydroxide / Q000737:chemistry* / Q000378:metabolism; D000538:Aluminum Silicates / Q000737:chemistry* / Q000378:metabolism; D000838:Anions; D002152:Calorimetry, Differential Scanning; D000077215:Clay; D004355:Drug Stability; D006878:Hydroxides; D007364:Intercalating Agents / Q000138:chemical synthesis; D008276:Magnesium Hydroxide / Q000737:chemistry* / Q000378:metabolism; D009824:Ointments / Q000138:chemical synthesis; D010777:Photochemistry; D012869:Skin Absorption; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013473:Sunscreening Agents / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays; D017967:Zinc Compounds
chemical_list: D000538:Aluminum Silicates; D000838:Anions; D006878:Hydroxides; D007364:Intercalating Agents; D009824:Ointments; D013473:Sunscreening Agents; D017967:Zinc Compounds; C010467:hydrotalcite; D000536:Aluminum Hydroxide; D008276:Magnesium Hydroxide; C052745:zinc hydroxide; D000077215:Clay; D010129:4-Aminobenzoic Acid