Skin healing preparations: compared in vitro diffusion of the active ingredients

We have developed skin healing preparations based on propolis extract:ointments, emulsions, and transparent oil-water (TOW) gels. The formulations were optimized in terms of macroscopic characteristics including spreadability and penetrability, and limpidity and isotropy for the TOW gels. We describe here the results of a study of in vitro diffusion of the active ingredients, flavonoids, and phenolic acids, from some of the preparations we developed. These results show the influence of the dosage form and the choice of excipients on the release of the active product. The least satisfactory results were obtained for hydrophobic ointments and o/w emulsions. The strongest diffusion was obtained with a TOW gel associating isopropyl palmitate, Eumulgin B3, and Cetiol HE.