STABILITY OF PEDIATRIC SUNSCREEN EMULSION 373 characteristics, dry matter, pH, microbiological contamination, density, and rheological properties. In parallel, a stability study was carried out on both formats at temperatures ranging from 4° to 40°C under light-protected conditions, in order to assess what effect the use of the towelette as a support vehicle may have on the stability of the emulsion. Stability was determined through centrifugation. Over a 30-day assay period, samples were taken on day 0, and at 1-, 15- and 30-day in- tervals. Determinations for samples from both vehicles were performed in triplicate. MATERIAL AND METHODS MATERIALS As emulsion components, Neo Heliopan AV® (ethylhexyl methoxycinnamate), Neo Heliopan MBC® (4-methylbenzylidene camphor), Neo Heliopan Hydro® (phenylbenz- imidazole sulfonic acid), and Neo Heliopan 357® (butyl methoxydibenzoyl methane) were obtained from Symrise Ibérica (Barcelona, Spain). Tioveil AQ-N® (aqua, tita- nium dioxide, alumina, silica, sodium polyacrylate, and methylparaben sodium) and triethanolamine (triethanolamine 99%), were obtained from Comercial Química Massó (Barcelona). Arlamol HD® (isohexadecane), was received from Uniquema (Barcelona), and Tefose 2000 (Peg-6 stearate, ceteth-20, steareth-20) was from Gateffose (Madrid, Spain). Other components were Alliant OPT® (acrylates/C12-22 alkylmethacrylate co- polymer) from Inquiaroma (Barcelona), and vitamin E acetate (tocopheryl acetate), methylparaben, ethylparaben, propylparaben, butylparaben, and chorphenesin from Impex Química (Madrid). Mineral oil fl uid (paraffi num liquidum) was obtained from Quimidroga (Madrid), and alcohol benzoate C12–C15 (benzoatyl alcohol), cetostearyl alcohol 25.OE (ceteareth-25), and Dub Diol® (methylpropanediol) were obtained from Campi & Jove (Madrid). Dow Corning 200® (dimethicone), from Safi c Alcan (Barce- lona), propolis hydroglycolic extract (propolis cera), from Biogründl (Madrid), Perfume Green Coco® (perfume), from GmbH & Co (Paris, France), and deionized distilled wa- ter (aqua), from Interapothek (Murcia, Spain), were additional emulsion components. We believe that an optimal sunscreen formulation depends not only on the total active fi lter content intended to prevent or mitigate harm from solar radiation, but also on other complimentary components. For this reason, hydroglycolic extract of propolis was in- cluded, due to its anti-infl ammatory and immunoregulatory activity (15). This active ingredient is also believed to have a protective effect on skin (16). A non-woven material was chosen as the physical support for the formulation (17), com- posed of directly ordered or randomly arranged sheets or membranes, forming fi bers con- nected through friction, and/or cohesion and/or accession, thus excluding paper or textiles, welded or joined through thread tying. The fi bers may be either natural or synthetic (18). A viscose non-woven product with a thickness of 50 g/m2 (LIDROTM, supplied by Jacob Holm Industries, Soultz, France) was chosen for its composition and weight (mesh size), and in particular for its smoothness and biodegradability. Unlike synthetic fi bers, such as polyester and polypropylene, this material decomposes rapidly (19). A sheet of micronized black polyethylene complex, composed of PET (polyethylene terephthalate), 12μ/coext, and PE (polyethylene), BCO/black 50 g, from Amcor (Madrid) was chosen as packaging material.

JOURNAL OF COSMETIC SCIENCE 374 METHODS Preparation of the sunscreen emulsion. The formulation was developed as a waterproof O/W emulsion, appropriate for children’s skin and produced with the aim of achieving high- level protection against UVA-UVB radiation. The composition of each phase is detailed in Table I. At each stage of preparation, the quantity of every component was determined by weight. Oil and water were added separately after previous heating to 80°C, taking care to ensure all components had fused after each addition. Phase N was prepared, ob- taining a transparent solution with a pH of between 7.00 and 7.50, and subsequently added to phase A. Shaking was used to ensure homogeneity, with the fi nal emulsion ob- tained after adding the water phase to the oil phase. At 40°C, T phase was added, fol- lowed by C and P phases at temperatures of between 30° and 35°C respectively. The system was then stabilized through further moderate shaking until cooling to room tem- perature. The formulation was then shaken for a further 20 minutes, after which 5.25 ml of emulsion was introduced into each envelope containing a towel (T) and 100 ml sealed in sterile containers (E). Table I Description of the Emulsion Phases Components % Oil phase (O) 4-Methylbenzylidene camphor (Neo Heliopan MBC®) 4% Ethylhexyl methoxycinnamate (Neo Heliopan AV®) 9% Butyl methoxydibenzoyl methane (Neo Heliopan 357®) 2% Peg-6 stearate, ceteth-20, steareth-20 (Tefose 2000®) 8% Isohexadecane (Arlamol HD®) 14% Cetostearyl alcohol 25O.E 2% Alcohol benzoate C12-C-15 3% Mineral oil fl uid 1% Vitamin E acetate 0.1% Aqueous phase (A) Deionized distilled water q s 100 Dimethicone (Dow Corning 200®) 1.5% Methylparaben 0.7% Ethylparaben 0.7% Propylparaben 0.7% Butylparaben 0.05% Phase N Deionized distilled water 2% Phenylbenzimidazole sulfonic acid (Neo Heliopan Hydro®) 4% Triethanolamine 2.4% Phase T Aqua, titanium dioxide, alumina, silica, sodium polyacrylate (Tioveil aq-N®) 6% Acrylates/C12-22 alkylmethacrylate copolymer (Alliant OPT®) 2% Phase C Chorphenesin 0.15% Methyl propanediol (Dub Diol®) 1% Phase P Propolis extract hydroglycolic 5% Perfume green coco 0.26%