title: Melted glyceryl palmitostearate (GPS) pellets for protein delivery.
abstract: Lysozyme was incorporated into glyceryl palmitostearate (GPS) pellets by compression and melting at loadings of 2, 5 and 10% (w/w). Released lysozyme from both compressed and melted pellets showed good retention of enzymatic activity (>80% active). The percentage lysozyme recovered during in vitro release experiments, over 120 h, was significantly lower from the melted pellets (<15%) compared with compressed pellets (71-85%). Scanning electron microscopy suggested this difference in release was due to differences in porosity of the compressed and melted pellets. Inclusion of hydrophilic components, PEG 4000 and Gelucire 50/13, in the melted matrices increased the percentage of lysozyme released in vitro. Lysozyme released from GPS/PEG 4000 matrices showed good retention of enzymatic activity (>88% active) while that from GPS/Gelucire 50/13 showed reduced activity (68 and 51% active). PEG 4000 was not completely miscible with GPS at the concentrations studied and heterogenous systems resulted. At a loading of 20-35% (w/w) PEG 4000 in GPS greater than 80% of the incorporated lysozyme was released, indicating the likely achievement of interconnecting hydrophilic channels throughout the GPS matrix. In conclusion, melted GPS demonstrated potential as a matrix for the controlled release of proteins and release rates could be modified by inclusion of hydrophilic components.
authors.affiliation: School of Pharmacy, University of Otago, P.O. Box 913 Dunedin, New Zealand.
authors.forename: Thaned
authors.initials: T
authors.lastname: Pongjanyakul
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Medlicott
authors.forename: Ian G
authors.initials: IG
authors.lastname: Tucker
mesh_terms: D004075:Diglycerides / Q000737:chemistry*; D005223:Fats / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D009113:Muramidase / Q000008:administration & dosage / Q000737:chemistry; D009821:Oils / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011506:Proteins / Q000008:administration & dosage / Q000737:chemistry*; D012995:Solubility; D013678:Technology, Pharmaceutical
chemical_list: D004075:Diglycerides; D005223:Fats; D009821:Oils; D011506:Proteins; C071184:Gelucire 50-13; D011092:Polyethylene Glycols; D009113:Muramidase; C009032:precirol