Novel semisolid SNEDDS based on PEG-30-di-(polyhydroxystearate): Progesterone incorporation and in vitro digestion

The aim of this work is to study the digestibility of PEG-30-di-(polyhydroxystearate) (Cithrol(®) DPHS) and its semisolid novel self-nanoemulsifying drug delivery systems (SNEDDS). Furthermore, the SNEDDS-mediated solubility enhancement of the poorly water-soluble drug Progesterone was evaluated in different media. Additionally, the impact of digestion on Progesterone solubilization was investigated in vitro by a pancreatin digestion assay. The Progesterone-loaded semisolid self-nanoemulsifying formulation (F2) was comprehensively characterized by photon correlation spectroscopy (PCS), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). SNEDDS were able to enhance the equilibrium solubility of Progesterone at various media. Only a minor part of Cithrol(®) DPHS was digested by pancreatin (less than 6%). Furthermore, protection of Progesterone against digestion-mediated precipitation was observed. Therefore, DPHS containing SNEDDS are attractive candidates for the development of bio robust drug delivery systems for the oral delivery of poorly soluble drugs.