Enhanced solubility and oral bioavailability of itraconazole by combining membrane emulsification and spray drying technique

The objective of the present study was to enhance solubility and bioavailability of itraconazole by a combined use of membrane emulsification and spray drying solidification technique. A shirasu-porous-glass (SPG) membrane with a mean pore size of 2.5 μm was used to produce monodispersed microemulsions of itraconazole consisting of methylene chloride as the dispersed phase, a mixture of Transcutol HP and Span 20 as a stabilizer, and dextran as solid carrier dissolved in water as the continuous phase. The dispersed phase permeated through the SPG membrane into the continuous phase at an agitator speed of 150 rpm, a feed pressure of 15 kPa and a continuous phase temperature of 25 °C and the resultant emulsion was solidified using spray-drying technique. Solid state characterizations of the solid emulsion showed that the crystal state of itraconazole in solid emulsion was converted from crystalline to amorphous form. The solid emulsion of itraconazole displayed a significant increase in the dissolution rate than that of pure itraconazole. Furthermore, the solid emulsion after oral administration gave about eight-fold higher AUC and about ten-fold higher Cmax in rats than pure itraconazole powder (p < 0.05), indicating this formulation greatly improved the oral bioavailability of drug in rats. Thus, these results demonstrated that the SPG membrane emulsification system combined with spray-drying technique could be used as a promising technique to develop solid formulation of itraconazole with enhanced solubility and bioavailability.