2003 ANNUAL SCIENTIFIC MEETING 231 Experimental Results The proposed method has been evaluated in PF A studies of fifteen sunscreens that contained various combinations of FDA approved organic and inorganic actives. Estimated in vitro PFA values for tested sunscreens were calculated by simultaneously utilizing 2 integration areas (UV A 1 only and UVAl&UVA2) and compared with in vivo results. It was found (Graph) that the integration area of UV Al provides superior in vitro/in vivo con-elation versus the integration area of UVAl&UVA2. The comparison of the in vitro PF A values with the perfect fit (predicted in vitro = measured in vivo) indicated that the prediction based on the integration area of UV Al only, gives a better fit (sum of squared residuals is 24.97) than the one based on both UV Al and UVA2 (sum of squared residuals is 162.50). These findings were also confirmed by the retrospective analysis of the results from the CTFA round-robin study of seven sunscreen compositions. Graph. In vitro/In vivo Correlation 22 A ·� 17 A 12 c.. g ..':: �/ 2 2 4 12 14 16 In Vivo PFA (PPD, JCIA) • In Vitro Based on UVA! A In Vitro Based on UVA] & UVA2 ·~ 0-· In Vivo Perfect Fit Conclusion The proposed method for in vitro prediction of a sunscreen's PFA can be successfully employed as a preliminary step before human tests. It provides excellent in vitro/in vivo correlation, saves time and resources and serves as an optimization tool for sunscreen development and evaluation. This method is equally applicable to sunscreens with low, medium and high PF A values and a wide range of actives. Our findings are in agreement with the existing knowledge regarding the effects of UV A 1 and UV A2 wavelength bands on skin. A similar approach may be applied for in vitro determination of the sunscreen's protection potential against other types of UV damage by utilizing various action spectra, emission spectrum of the specific light source and integration areas that are relevant to the test conditions and skin biological response. References I. JC/A Technical Bulletin. JC/A Measurement Standard for UVA Protection Efficacy, Issued Nov. 21 (1995) 2. Chardon A, Moya! D, and Hourseau C. In: Lowe NJ, Shaath NA, Pathak MA eds. Sunscreens: de1·elopment, evaluation and regulatory aspects. New York: Marcel Dekker, 559-582 (/997) 3. Moyal D, Chardon A and Kollias N. Photodermatol Photoi111111unol Photomed, 16, 250-255 (2000) 4. Wendel V, Klette E, and Gers-Barlag H. SOWF, 127 (IO), 12-30 (2001) 5. Kligman LH and Kligman AM. In: Lowe NJ, Shaath NA, Pathak MA eds. Sunscreens: development, evaluation and regulato,y aspects. New York: Marcel Dekker, 117-137 (/997) 6. http://www. bccancer. bc.ca/H PI/Education/CM ESki nCancer/PreExami nation Reading/_Carcinogenesis.htm 7. http://www.labsphere.com/tech info/docs/SPF of Sunscreens.pdf 8. Sottery J. IMS S�minar Series (2002) - - 9. DGK -Task Force "Sun Protection" IFSCC Magazine, vol. 5, No 3, 161-166 (2002) Acknowledgements We are very grateful for the support of our colleagues at Playtex Products, Inc., especially Mike Gallagher, Dr. Paul Siracusa and Evan Hutchison. We would like to thank Dr. John Sottery ofIMS and Dr. Robert M. Sayre of RPTL for valuable discussions.