Commonly used UV filter toxicity on biological functions: review of last decade studies.

Sunscreens provide broad-spectrum UV skin protection and contain more often UV filter combinations. Their efficacy reducing skin photo carcinogenesis and photo ageing is widely documented. However, there are many concerns about UV filter safety. Organic UV filters were the first targeted by scientist concerns, as they were showed to trigger skin allergic reactions. Inorganic UV filters were then at the heart of scientist debate especially because of their nanometric size. Over the last years, many studies have been published tending to highlight that organic as well as inorganic UV filters could lead to variable side effects after sunscreen application. However, these studies are still very controversial due to different experimental conditions and models. This review reveals that complementary studies using standardized methods are mandatory before ascertaining that UV filters threaten human health.

Simultaneous characterization of oxygen transport into and through porcine skin exposed to oxygen-saturated water.

Oxygen delivery to the skin is a promising approach for treatment of dermatological diseases (e.g. ischemic wound healing). However, characterization of oxygen transport into and through the skin exposed to oxygen carrier formulations has not been reported. In the present study, we developed an original lab-made static diffusion cell mounted with porcine skin enabling the assessment of oxygen uptake into the skin (i.e., oxygen penetration) and passage through the skin (i.e., oxygen permeation). Oxygen penetration and permeation were recorded by using an optical probe implanted into the skin tissue and a Clark-type electrode plunged into the receptor solution of the diffusion cells. Permeability parameters (i.e., maximal and steady-state flux; permeability coefficient) of oxygen were determined after a 2-hour application of oxygen-saturated water to either the skin surface (exogenous delivery) or the dermis (endogenous delivery). Similar experiments were performed by using intact or stripped skin in order to appreciate the role of the stratum corneum as oxygen barrier. Exogenous delivery of oxygen to skin tissue was found more effective than endogenous delivery through intact and stripped skin. However, exogenous oxygen permeation was found smaller than that determined from endogenous delivery. The upper layers of the skin would constitute a potential oxygen reservoir created by the high solubility of oxygen in epidermal lipids. Therefore, oxygen carrier formulations might significantly improve the oxygen status in the skin for further biological effects.

Effects of chitosan addition to self-setting bone cement.

The Cementek is a self-setting bone cement composed of a solid phase and a liquid phase. After mixing these two phases, it sets in situ to form an hydroxyapatite (HAp) as the only end product. It is difficult to introduce a new component into this cement without modifying the final product and its mechanical properties. In order to improve the mechanical properties of the Cementek, a natural polymer (chitosan) was added in the initial formulation. Two types of chitosan were added into the Cementek, at various concentration, in either the liquid or the solid phase. The effects of chitosan addition on the properties of the self-setting bone cement are examined. The different composites were characterized by the determination of the setting time, the chemical transformation by X-ray diffraction and mechanical tests. The chemical transformations were not affected by the addition of chitosan neither in the liquid nor in the solid phase. The maturation towards HAp appeared to be complete for all the composites. The setting time was decreased by the addition of chitosan in the solid phase. However the setting time value of each composite remained compatible with a practical use in situ. This study shows that the maturation mode of the samples directly affects the mechanical properties of the obtained composites. The sterilization of the cement with chitosan has been studied.

Assessment of sodium hyaluronate gel as vehicle for intracameral delivery of cefuroxime in endophthalmitis prophylaxis.

Sodium cefuroxime is a second-generation cephalosporin widely used at 10mg/mL for endophthalmitis prophylaxis after cataract surgery. Sodium cefuroxime solution is usually conditioned in pre-filled syringes then frozen for storage. In the present study, 0.2% sodium hyaluronate gel, natural extracellular polymer used in wound healing, was compared to conventional saline solution (0.9% sodium chloride) as drug delivery systems for cefuroxime loading in pre-filled syringes. Therefore, the temperature (4 and 25 degrees C) and time of storage (up to 21 days) varied in order to appreciate both cefuroxime and vehicle stability. Furthermore, the kinetics of drug release from both hyaluronate gel and saline solution were compared since in vitro sets of dialysis experiments. Results indicated that cefuroxime loaded in either saline solution or hyaluronate hydrogel was found stable in pre-filled syringes stored at 4 degrees C for 21 days, whereas cefuroxime degradations products appeared from the 2nd day of storage at 25 degrees C. Both drug delivery systems were found bioequivalent, although statistically slower cefuroxime dialysis was evidenced by using sodium hyaluronate vehicle. Noteworthy, cefuroxime concentration in drug delivery systems during dialysis experiment remained greater than the minimum inhibitory concentrations reported for resistant strains. In conclusion, the present stability and release study confirmed that sodium hyaluronate hydrogel is a promising vehicle for cefuroxime intracameral delivery in endophthalmitis prophylaxis.