ABSTRACTS 251 Original Article In vitro skin permeation of sunscreen agents from 0/W emulsions L. Montenegro, C. Carbone, D. Paolino, R. Drago, A. H. Stancampiano and G. Puglisi Department of Phannaceutical Sciences, University of Catania, V.le A. Doria, 95125 Catania, Italy Lucia Montenegro, Department of Pharmaceutical Sciences, University of Catania, V.le A. Doria 6, 1-95125 Catania, Italy. Tel.: +39 095 7384010 fax: +39 095 7384211 e-mail: lmontene@unict.it The effects of different emulsifiers on the in vitro permeation through human skin of two sunscreen agents [octylmethoxycinnamate (OMC) and butylmethoxydirenzoylmethane (BMBM)] were investigated from 0/W emulsions. The test formulations were prepared using the same oil and aqueous phase ingredients and the following emulsifier and coemulsifier systems: Emulgade SE_ (ceteareth-12 and ceteareth-20 and cetearyl alcohol and cetyl palmitate) and glycerylmonostearate (emulsion 1 ) Brij 72_ (steareth-2), Brij 721_ (steareth-21) and cetearyl alcohol (emulsion 2) Phytocream_ (potassium palmitoyl-hydrolysed wheat protein and glyceryl stearate and cetearyl alcohol) and glycerylmonostearate (emulsion 3) Montanov 68_ (cetearyl glucoside and cetearyl alcohol) (emulsion 4) Xalifin-15_ (ClS-20 acid PEG-8 ester) and cetearyl alcohol (emulsion 5). The cumulative amount of OMC that permeated in vitro through human skin after 22 h from the formulations being tested decreased in the order 3 1 @ 4 5 2 and was about nine-fold higher from emulsion 3 compared with that from emulsion 2. As regards BMBM, no significant difference was observed as regards its skin permeation from emulsions 1, 3, 4 and 5, whereas formulation 2 allowed significantly lower amounts of BMBM to permeate the skin. In vitro release experiments of OMC and BMBM from emulsions 1-6 through cellulose acetate membranes showed that only emulsions 4 and 5 provided p seudo-first-order release rates only for OMC. The results of this study suggest that the type of emulsifying systems used to prepare an 0/W emulsion may strongly affect sunscreen skin permeation from these fonnulations. Therefore, the vehicle effects should be carefully considered in the formulation of sunscreen products.