Influence of three synthetic membranes on the release of caffeine from concentrated W/O emulsions

We measured the release rate characteristics of caffeine from concentrated emulsions using three different sources of synthetic membranes. The formula tions tested included, on the one hand, two stable cosmetic concentrated W/ O emulsions (90% w/w) - one with a non ionic surfactant and one with a sili cone surfactant - and on the other hand, a commercially available hydroalco holic gel. All formulations contained 5% caffeine. In vitro diffusion measu rements (24 h) were performed with static diffusion Franz cells. A silicone membrane could not allow us to differentiate the two concentrated emulsion s (CE), but the two other membranes, not rate limiting, showed difference i n the release profile of caffeine from the two CE. Results with the cellulo se and polysulfone membrane showed that in vitro release of caffeine is inf luenced by the nature of the emulsifier in the concentrated emulsion, the n on ionic surfactant being more efficient than the silicone surfactant. The polysulfone membrane was the only one that allows statistical differentiati on of the three products. For further studies the polysulfone membrane will be use to make screening on concentrated emulsions. (C) 2000 Elsevier Scie nce B.V. All rights reserved.