| Summary: | 碩士 === 嘉南藥理科技大學 === 化妝品科技研究所 === 100 === In the past two decades, the increased amounts of UV radiation reach the surface of the earth due to the collapsed ozone layer. When we are overexposed to the circumstances of the UV sunlight, it may cause a number of skin troublesome such as spots, wrinkle, hyperpigmentation , and even skin cancer . Obviously, it is important for us to intensively protect the skin from the damage of the UV sunlight. Among the stage of protecting from the damage, wearing efficacy suncreams is popular and promising method. Although a variety of commercial suncreams are available, most of them always have a low stability in storage and SPF valve during the accelerated tests.
The o/w/o multiple emulsions are known as “emulsions of emulsions”. In theory they have significant potential in pharmacy and cosmetics providing prolonged release of active substances and protection of fragile substances. However, significant problems may arise due to their thermodynamical instability and strong tendency for coalescence, flocculation and creaming. This study is to develop a stable o/w/o multiple emulsions both containing UV filters and a whitening agent. There are three different types of emulsifiers were examined. GMS/EmulsifierII was selected as surfactants for optimizing the character of o/w/o emulsions. Regarding to the functional ingredients, octyl methoxy cinnamate (PMCX) and/or avobenzone (P1789) as UV filters, and ascorbyl palmitate (AP) as a whitening agent, were incorporated into the o/w/o emulsions to obtain o/w/o whitening suncreams. Their physicochemical properties and effectiveness on sun protection and depigmentation were characterized and their stability over the time was evaluated by rheological measurements, microscopic analysis, SPF measurements and whitening ability with or without the accelerated tests. All the obtained whitening suncreams exhibited a reasonable stability and shear- thinning rheological behavior before and after the ageing time. Concentration of the functional ingredients markedly affected the viscosity and the droplet size. The apparent viscosity of the multiple emulsions was increased by UV filters and/or AP whitening agent. In addition, AP was able to stabilize SPF during the accelerated tests but make the suncreams’ storage stability reduced. In photoageing tests, it showed that the use of o/w/o type allow octyl methoxy cinnamate having lower photodegradation. Regarding to the whitening ability, the results showed that many different matrix in multiple emulsion would influence the in vitro measurements and result in unaccepted and unexpected data. Therefore, it was considered that in vivo method should be selected for whitening emulsion samples.
Based on these findings, a desired whitening suncreams was obtained. With high SPF of (32), a stability at 45℃ testing for 14days, good photostability, and esthetic appearance, it is composed of GMS 1.6%、Amphisol K 0.64%、Mineral oil 27.0%、PMCX 5.0%、P1789 2.0%、 EmulsifierⅡ 5.0% 、 Germaben II 0.64%、 Carbopol 1342 0.104% 、 Ascorbyl Palmitate 0.6% 、TEA 0.10%、D.W 57.316%。
|
|---|
