In this paper Interferon-alpha (IFN) was conjugated via its N-terminal amino group by reductive amination to α-aldehyde functional comb-shaped PolyPEG polymers (50 and70 kDa) and to linear PEG (30 kDa). Both PolyPEG−IFN conjugates retained a similar potency as that of the marketed comparator (PEGASYS®), whereas the linear PEG−IFN conjugate potency was greater. All conjugates showed extended half-lives compared to that of naked IFN, with the PolyPEG conjugates exhibiting the longest half-lives and the linear PEG conjugate, the shortest. Viscosity analysis showed that the linear PEG−IFN conjugate was over twice as viscous as both PolyPEG conjugates. Taken together, this work demonstrates the potential of PolyPEG conjugation to therapeutic proteins as a novel tool for optimizing pharmacokinetic profiles in a way that potentially allows administration of high-dose formulations because of lower conjugate viscosity.
In this study we have investigated the effects of different cell culture conditions on the Calu-3 epithelial cell model. Calu-3 cells were cultured in media A-MEM at the air–liquid (A–L) or liquid–liquid (L–L) interface for one or three weeks. Different cryopreservation methods were tested and the cell line was characterized using histochemistry, immunofluorescence, transmission and scanning electron microscopy, trans-epithelial electrical resistance (TEER) measurements, permeability studies, and gene profiling of 84 drug transporters. The A–L interface resulted in a more biomimetic native bronchial epithelium displaying pseudostratified columnar epithelium with more microvilli and secretory vesicles than at the L–L interface, where the epithelium was cuboidal, but exhibited higher TEER values and lower dextran permeability. Since cell culture interface and time in culture affect Calu-3 cell differentiation, barrier integrity, permeability properties, and drug transporter expression, culture conditions need to be considered and standardized when using the Calu-3 cell line as an in vitro model for aerosol drug delivery and screening of bronchial drug candidates.
In this study we have characterized the cell line RPMI 2650 and evaluated different culture conditions for an in vitro model for nasal mucosa. Cells were cultured in media MEM at the air–liquid (A–L) or liquid–liquid (L–L) interface for one or three weeks. Different cryopreservation methods and cell culture techniques were evaluated with immunolabelling of junctional proteins, ultrastructural analysis using electron microscopy, transepithelial electrical resistance (TEER) measurements, permeation studies with dextran and jacalin, and gene expression profiling of 84 drug transporters. Cells grown at the A-L interface formed more layers and exhibited a higher TEER and lower dextran and jacalin permeability than at the L-L interface, where cells morphologically exhibited a more differentiated phenotype. The RPMI 2650 cells form a polarized epithelium resembling nasal mucosa. However, different culture conditions have a significant effect on cell ultrastructure, barrier integrity, and gene expression, and should be considered when using this cell line as an in vitro model for drug permeability studies and screening of nasal drug candidates.
In the article we describe an automated high-throughput approach as an alternative to the classical dissolution testing methodology. We show that the method is applicable to various formulations of controlled release pellets. The method was demonstrated to be useful as a screening tool for characterization. Using statistical design of experiments we were able to further optimize the method performance for a particular formulation.
In this paper the effects of seven different chromatographic parameters and five sample preparation parameters in a high performance liquid chromatography (HPLC) method for assay determination of benzalkonium chloride (BKC) in a nasal formulation were evaluated using two fractional factorial experimental designs. The design space of the analytical method was modeled using Umetrics Modde software and the optimal method conditions were predicted. The optimal method was validated for linearity, accuracy and precision. The use of experimental designs enables obtaining the maximum amount of information with the least possible number of experiments. Such designs are an economical manner in evaluating a variety of different factors and their interactions.