148 JOURNAL OF COSMETIC SCIENCE water on the skin, dries quickly, and leaves a continuous film on the skin surface to deliver adenosine, an active anti-wrinkle cosmetic ingredient. MATERIALS AND METHODS FILM FORMULATION AND MANUFACTURING Materials. The films were composed of hydroxypropylmethylcellulose (HPMC Metolose 60 SH 50, USP, Syntapharm) and hydroxypropylcellulose (HPC, Klucel EF, pharma grade, Hercules). Glycerol (85%, pharma grade, Brenntag) was added as the plasticizer. Panthenol (D-Panthenol, USP, Roche), adenosine (Pharma Waldhof), and magnesium sulfate (Mallinckrodt Chemicals) were used as cosmetic active ingredients. The re­ lease liner consisting of polyethylene terephthalate (PET, Siphan) was obtained from Siliconature, Italy. Preparation of the film. HPMC was dissolved in distilled water to produce a 12.5% w/w stock solution. HPC was dissolved in distilled water to produce a 25% w/w stock solution. For each batch (of 150 g), 83.6 g of the HPMC stock solution and 20.6 g of the HPC stock solution were mixed and stirred at 30 rpm using a propeller stirrer to avoid air bubble inclusion. Then, 10.9 g of glycerol, 0.3 g of adenosine, 5.8 g of panthenol, and 0.2 g of magnesium sulfate were added. Finally, 28.6 g of distilled water was poured into the mixture, which was then stirred for 30 min under the same conditions. The resulting mixture was spread on a siliconized PET release liner using a film casting knife with a gap of 250 µm, and then oven dried at 70°C for 45 min. The final film had an area weight of 50 g/m2 . Individual squares of 1.5 x 1.5 cm were punched out of the film and packed in aluminum/polyethylene pouches. FILM CHARACTERIZATION The dissolution of the film in water was assessed by the following method. The film (1.5 cm x 1.5 cm) was clamped with tweezers and immersed in 10 ml of water under slow stirring (20 rpm) at room temperature. The time after which no more film residue could be visually detected was recorded. The total amount of residual water contained in the film was measured by Karl Fischer titration. The water activity, which measures the vapor pressure generated by the mois­ ture present in the film, was determined using a Hygromer® apparatus (Rotronic, USA). The moisture sorption/desorption kinetics at 25°C was obtained using a dynamic vapor sorption apparatus comprising an ultra-sensitive microbalance (Surface Measurement Systems, UK). The films, placed on a polyethylene terephthalate release liner and packaged in alu­ minum/polyethylene pouches, were also stored at 45°C for one month. The weight, water content, and adenosine concentration of the films were measured and compared to values at initial time. VISUALIZATION OF THE DISSOLVABLE FILM ON THE SKIN The area around the corner of the eye (crow's feet) of volunteers was moistened with water, and the film was subsequently applied on the skin wrinkles. The skin surface

DISSOL V ABLE ANTI-WRINKLE FILM 149 covered by the film (2.25 cm2 ) was approximately 20 to 25 cm2 , representing about 0.5 mg of material, i.e., 5 µg of adenosine per cm2 of skin. The visualization of the film was performed by scanning electron microscopy (SEM) as follows: Skin Siflo replicas were taken after one and six hours of drying time and compared with those taken before application on the same person. These negative replicas (See Figure 1, right panel) were transformed to positive ones using an epoxy resin, Araldit© 2011 (Vantico, Fr). These new imprints were then glued to a copper cylindrical sample holder using a silver-based varnish and eventually coated with a thin film of conducting platinum using an HTS 010 sputter coater (Balzers, Fr). Finally, all the observations were done in a field-emission high-resolution JEOL 6300F microscope. EVALUATION OF ANTI-WRINKLE EFFICACY IN FEMALE VOLUNTEERS A randomized, placebo-controlled, investigator-blind study was conducted to assess the efficacy of the dissolvable film. One hundred and twenty-six female volunteers, 45-65 years old, were enrolled with distinct wrinkles at least 2 cm long on the right and left crow's feet. The subject applied either the 1 % adenosine-containing dissolvable film, a 0.1 % adenosine-containing cream, or a placebo cream according to randomization, twice a day on the crow's feet areas, for eight weeks. To apply the film, the volunteer first moistened the treated area with water and then dissolved the film by gentle circular massage. Fast optical in vivo topomerry (FOITS) measurements (4,5) were made three times for the evaluation of wrinkles: before the first application (baseline), and after three and eight weeks of the application 12 hours after the last application. FOITS classical analysis was used to record the two roughness parameters, Ra (average roughness) and Rz (average of the heights measured between the peaks and troughs of each relief feature), as previously described (4). Ra and Rz were determined on 50 parallel lines perpen­ dicular to the axis of the main wrinkle and starting from the corner of the eye (for periorbital lines), two lines being separated by 250 µm. S.E.M. JEOL 6300F Silflo replica (negative) Positive image on a resin Figure 1. Methodology used for the scanning electron microscopy sample preparation.