Buccal permeation of [D-Ala2, D-Leu5]enkephalin from liquid crystalline phases of glyceryl monooleate

The ex vivo buccal permeability of a [D-Ala(2), D-Leu(5)]enkephalin (DADLE) and glyceryl monooleate (GMO) was examined from the cubic and lamellar liquid crystalline phases of GMO and aqueous phosphate-buffered saline (pH 7.4, PBS) solution across excised porcine buccal mucosa mounted in a Franz cell. GMO was released in vitro from the liquid crystalline phases indicating the erosion of the liquid crystal matrices. GMO released from the liquid crystalline matrices permeated the porcine buccal mucosa with fluxes of 0.10 +/- 0.03 and 0.07 +/- 0.00%/cm(2) per h for the cubic and lamellar phases, respectively. The flux of DADLE (1.21 +/- 0.32 and 1.15 +/- 0.11%/cm(2) per h for the cubic and lamellar phases, respectively) from the liquid crystalline phases was significantly enhanced by the GMO compared with PBS solution (0.43 +/- 0.08%/cm(2) per h) during the initial permeation phase (I < 3 h). Our results suggest that the cubic and lamellar liquid crystalline phases can be considered as promising buccal drug carriers for peptide drugs as well as acting as permeation enhancers. (C) 2000 Elsevier Science B.V. All rights reserved.