318 JOURNAL OF COSMETIC SCIENCE RESULTS and DISCUSSION Investigations by means of polarized light microscope showed the spherical shape of lipospheres. Amount of OMC in lipid microsphere was found to be 67.52 %. In vitro release and penetration from skin of OMC from various vehicles are shown in Figures 1-2. Figure 1- Release profiles of free OMC and OMC incorporated in !ipid microsphere from oleagenous cream, o/w emulsion and Carbopol gel (n:6) Figure 2-Penetration profiles of free OMC and OMC incorporated in !ipid microsphere from oleagenous cream, o/w emulsion and Carbopol gel (n:6) Table 1- Released amount and release rate of free OMC and OMC incorporated in !ipid microsphere from oleagenous cream, o/w emulsion and Carbopol gel (n:6) Release and penetration rates of OMC and the amount released and penetrated were decreased when OMC is in microsphere forin. Differences in release and penetration rates were also observed due to vehicles. Release of free OMC was found to be highest fi'om oleagenous cream and lowest from o/w emulsion in lipid microsphere form (Table 1). Photodecomposition products of free OMC were observed whereas OMC was found stable in liposphere form kept in irradiation chamber. CONCLUSION Results of this study have shown that solid lipid microspheres can be suggested as carders for OMC in order to decrease the release and penetration rate and amount of this UV absorber and choosing the suitable vehicle plays an important role in formulating a sunscreen product. Incorporation of OMC into solid lipid microsphere also enhanced the photostability of OMC xvhen compared to plain absorber in various vehicles. Another important aspect was the effectiveness of OMC in liposphere fonu which showed nearly the stone protection as the free form alter exposing to UV light. Acknowledgement We would like to extend our thanks to Eng. Nanilk Yener and Dr. Onsal Hekiman, Managers of Bilim Pharmaceutics and Aventis in Istanbul.

2002 ANNUAL SCIENTIFIC SEMINAR 319 Figure 1- Release profiles of free OMC and OMC incorporated in lipid microsphere from oleagenous cream, o/w emulsion and carbopol gel (n:6) --•--• ß OMC i• o•e.crenm e '-•-LM • o•.crenm •cß OMC in gel LM in õel .. •tt•ee OIVIC' h• olw • LM in o/w ½re•rn ':•. :. • Figure 2- Penetration profiles of free OMC and OMC incorporated in lipid microsphere from oleagenous cream, o/w emulsion and carbopol gel (n:6) i ii Penetration Profiles of O!V!C -.- free CNIC in ole. .• • cream •..::... • , .• • ,.,. . LM in de.cream 0 2 4 6 8 free CtvlC in gd LM in gel Time (hour) + free OMC in o/w cream