238 JOURNAL OF COSMETIC SCIENCE (3) V. Koivukangas, M. Kallionen, H. Autio-Harmainen, and A. Oikarinen, UV irradiation induces the expression of gelatinases in human skin in vivo, Acta Derm. Venereol., 74, 279-282 (1994). (4) M. Petersen, T. Hamilton, and H.L. Li, Regulation and inhibition of collagenase expression by long-wavelength ultraviolet radiation in cultured human skin fibroblasts, Photochem. Photobiol., 62, 444•i48 (1995). (5) C. Kut, W. Hornbeck, N. Groult, G. Redziniack, G. Godeau, and B. Pellat, Influence of successive and combined ultraviolet a and b irradiation on matrix metalloelastases produced by human dermal fibroblasts in culture, Cell Biol. Int., 21, 347-352 (1997). (6) M. Wlaschek, K. Briviba, G. P. Stricklin, H. Sies, and K. Scharffetter-Kochanek, Singlet oxygen may mediate the induced synthesis of interstitial collagenase, J. Invest. Dermatol., 104, 194-198 (1995). (7) M. Kiss, M. Wlaschek, P. Brenneisen, G. Michel, C. Hommel, T. S. Lang, D. Peus, L. Kemeny, A. Dobozy, K. Scharffetter-Kochanek, et al., Alpha-melanocyte stimulating hormone induces collagenase/ matrix metalloproteinase-1 in human dermal fibroblast, BioL Chem. Hoppe-Seyler, 376, 425•i30 (1995). (8) R. P. Huang, J. X. Wu, Y. Fan, and E. D. Adamson, UV activates growth factor receptors via reactive oxygen intermediates,J. Cell. BioL, 133, 211-220 (1996). (9) K. Bender, C. Blattner, A. Knebel, M. Iordanov, P. Herrlich, and M. L. Rahmsdorf, UV-induced signal transduction, J. Photochem. Photobiol., 37, 1-17 (1997). (10) G.J. Fisher, H. S. Talwar, J. Lin, F. McPhillips, Z. Wang, X. Li, Y. Wan, S. Kang, andJ. J. Voorhees, Retinoic acid inhibits induction of c-Jun protein by ultraviolet R. radiation that occurs subsequent to activation of mitogen-activated protein kinase pathways in human skin in vivo, J. Clin. Invest., 101, 1432-1440 (1998). (! 1) Y. Hirai, K. Migita, S. Honda, Y. Ueki, S. Yamasaki, S. Urayama, M. Kamachi, A. Kawakami, H. Ida, M. Kita, T. Fukuda, K. Shibatomi, Y. Kawabe, T. Aoyagi, and K. Eguchi, Effects of nitric oxide on matrix metalloproteinase-2 production by rheumatoid synovial cells, Lid• Sci., 68, 913-920 (2001). (12) M. Yoshida, N. Sagawa, H. Itoh, S. Yura, D. Korita, K. Kakui, N. Hirota, T. Sato, A. Ito, and S. Fujii, Nitric oxide increases matrix metalloproteinase-1 production in human uterine cervical fibroblast cells, Mol. Hum. Reprod., 7, 979-985 (2001). (13) C. Rom•ro-Graillet, E. Aberdam, M. Clement, J.P. Ortonne, and R. Ballotti, Nitric oxide produced by ultraviolet-irradiated keratinocytes stimulates melanogenesis, Clin. Invest., 99, 635-642 (1997). (14) G.I. Gorodeski, Role of nitric oxide and cyclic guanosine 3,5-monophosphate in the estrogen regu- lation of cervical epithelial permeability, Endocrinology, 141, 1658-1666 (2000). (15) R. Ferrero, F. Rodriguez-Pascual, M. T. Miras-Portugal, and M. Torres, Comparative effects of several nitric oxide donors on intracellular cyclic GMP levels in bovine chromaffin cells: Correlation with nitric oxide production, Br. J. Pharmacol., 127, 779-787 (1999). (16) M. Demeule, M. Brossard, M. Page, D. Gingras, and R. Beliveau, Matrix metalloproteinase inhibition by green tea catechins, Biochim. Biophys. Acta, 1478, 51-60 (2000). (17) S. Lauwers, Y. Vander Heyden, and B. Rombaut, J. Pharmaceut. Biomed. Anal., 25, 131-142 (2001). (18) G.J. Fisher, S.C. Dart, H. S. Talwar, Z. O. Wang, J. Varani, S. Kang, and J. J. Voorhees, Molecular basis of sun-induced premature skin aging and retinoid antagonism, Nature, 379, 335-339 (1996). (19) G.J. Fisher, Z. O. Wang, S.C. Datta, J. Varani, S. Kang, and J.J. Voorhees, Pathophysiology of premature skin aging induced by ultraviolet light, N. Engl. J. Med., 337, 1419-1428 (1997). (20) G.J. Fisher, H.S. Talwar, J. Y. Lin, and J.J. Voorhees, Molecular mechanisms of photoaging in human skin in vivo and their prevention by all-retinoic acid, Photochem. Photobiol., 69, ! 54-157 (1999). (21) C. Nathan, Nitric oxide as a secretory production of mammalian cells, FASEB J., 6, 3051-3064 (1992). (22) Y. C. Chen, S.C. Shen, L. G. Chen, T.J.F. Lee, and L. L. Yang, Wogonin, baicalin and baicalein inhibition of inducible nitric oxide synthase and cyclooxygenase-2 gene expression induced by nitric oxide synthase inhibitors and lipopolysaccharide, Biochem. Pharmacol., 61, 1417-1427 (2001).

j. Cosmet. Sci., 54, 239-250 (May/June 2003) Diffusion of preservatives from topical dosage forms' A comparative study ELISABETTA ESPOSITO, FABRIZIO BORTOLOTTI, CLAUDIO NASTRUZZI, ENEA MENEGATTI, and RITA CORTESI, Department of Pharmaceutical Sciences, University of Ferrara, 1-44100 Ferrara (E.E., F.B., E.M., R.C.), and Institute of Drug Chemistry and Technology, University of Perugia, 1-06100 Perugia (C. N.), Italy. Accepted for publication August 19, 2002. Synopsis A study of the diffusion of parabens from topical formulations is presented here. In particular, four different topical formulations, namely, a water-in-oil emulsion, an oil-in-water emulsion, and two hydrophilic gels (Pemulen gel and Carbopol gel) were produced, containing a mixture of three common parabens, namely, methylparaben (MP), ethylparaben (EP), and propylparaben (PP). An analytical method based on liquid extraction, followed by reversed-phase HPLC for the quantitative determination of MP, EP, and PP, was developed. The method allowed good separation of paraben mixtures and high percentages of recovery ( than 97%). The diffusion kinetics of parabens from the produced formulations was determined by an in vitro system based on a Franz cell assembled with a synthetic membrane, followed by a reversed-phase HPLC analytical method. The comparative study demonstrated that, in the case of emulsions, diffusion coefficients are a function of the substituent of preservatives: the higher the solubility, the higher the diffusion of parabens. On the contrary, in the case of the hydrophilic gels, the higher the parabens solubility, the lower the diffusion coefficients. The method described here could represent a means of controlling the extent of diffusion of parabens from topical formulations in order to minimize percutaneous absorption and to control the availability of microbes. INTRODUCTION The main deterioration factors in pharmaceutics or cosmetics can be divided into chemi- cophysical changes and microbial contamination. Among these, the importance of mi- crobial contamination is relevant for sanitary problems in dermal usage. Two strategies should be adopted in order to prepare microbiologically acceptable pharmaceutical formulations or cosmetic products: the minimization of the risks of contamination from sources and the addition of preservatives to the formulation. The use of preservatives is Address all correspondence to Elisabetta Esposito. 239