Applicability of RPMI 2650 and Calu-3 Cell Models for Evaluation of Nasal Formulations.

The RPMI 2650 and Calu-3 cell lines have been previously evaluated as models of the nasal and airway epithelial barrier, and they have demonstrated the potential to be used in drug permeation studies. However, limited data exist on the utilization of these two cell models for the assessment of nasal formulations. In our study, we tested these cell lines for the evaluation of in vitro permeation of intranasally administered drugs having a local and systemic effect from different solution- and suspension-based formulations to observe how the effects of formulations reflect on the measured in vitro drug permeability. Both models were shown to be sufficiently discriminative and able to reveal the effect of formulation compositions on drug permeability, as they demonstrated differences in the in vitro drug permeation comparable to the in vivo bioavailability. Good correlation with the available bioavailability data was also established for a limited number of drugs formulated as intranasal solutions. The investigated cell lines can be applied to the evaluation of in vitro permeation of intranasally administered drugs with a local and systemic effect from solution- and suspension-based formulations.

In Vitro Ciliotoxicity and Cytotoxicity Testing of Repeated Chronic Exposure to Topical Nasal Formulations for Safety Studies.

Certain active drugs and excipients of nasal formulations may impair ciliary function and mucociliary clearance. The ciliary beat frequency (CBF) is a key parameter for determining mucociliary clearance rate, and in vitro assessments of CBF have proven to be accurate and reproducible. Since topical nasal formulations are applied with repeated doses, it is essential to elucidate their chronic, as opposed to acute, effect on mucociliary clearance and nasal mucosa. The aim of this study was to assess for the first time the ciliotoxicity and cytotoxicity of nasal sprays intended for chronic treatment (with repeated doses) using a previously designed set-up for CBF measurements. For 2 weeks, the 3D nasal MucilAir™ in vitro models were treated daily with undiluted or clinically relevant doses of mometasone nasal spray, placebo nasal spray, culture medium, or they were untreated. We demonstrated a dose-dependent and time-dependent (cumulative) effect of the nasal sprays on ciliary activity and cytotoxicity using CBF measurements and ultrastructural analysis, respectively. Our results indicate that repeated administration of clinically relevant doses of mometasone nasal spray is safe for in vivo use, which is in good agreement with a previous clinical study. Overall, our study suggests that such in vitro assays have great potential for topical nasal drug screening.

Prediction of pharmacokinetic studies outcome for locally acting nasal sprays by using different in vitro methods.

Demonstration of bioequivalence of locally acting nasal spray formulations is a challenging task and the regulatory agencies have different approach towards this goal. The pharmacokinetic bioequivalence studies are recognized as necessary for assessment of equivalent systemic exposure. We utilized three different in vitro methods for nasal spray evaluation and compared those results with the results of pharmacokinetic studies of different formulations of four intranasal corticosteroids, in order to evaluate their in vivo relevance. Two cell lines, RPMI 2650 and Calu-3, Transwell® polycarbonate membranes with different pore size and lipid-oil-lipid tri-layer membrane in the parallel artificial membrane permeability assay (PAMPA) system were used for this purpose. The in vitro results correlated with the results of pharmacokinetic studies and correctly predicted (non)equivalence of the nasal sprays, showing that in vitro methods are good indicator of the in vivo outcome. The Transwell® and PAMPA in vitro methods were additionally implemented for testing batch-to-batch variability of reference nasal spray formulations. The results from the Transwell® assay for the two poorly soluble corticosteroids are possibly over-discriminatory in showing differences between batches of reference nasal sprays. Overall, the three in vitro methods have potential to predict the results of bioequivalence testing of nasal spray products.

Standardization of esophageal adenocarcinoma in vitro model and its applicability for model drug testing.

FLO-1 cell line represents an important tool in esophageal adenocarcinoma (EAC) research as a verified and authentic cell line to study the disease pathophysiology and antitumor drug screenings. Since in vitro characteristics of cells depend on the microenvironment and culturing conditions, we performed a thorough characterization of the FLO-1 cell line under different culturing conditions with the aim of (1) examining the effect of serum-free growth medium and air-liquid interface (A-L) culturing, which better reflect physiological conditions in vivo and (2) investigating the differentiation potential of FLO-1 cells to mimic the properties of the in vivo esophageal epithelium. Our study shows that the composition of the media influenced the morphological, ultrastructural and molecular characteristics of FLO-1 cells, such as the expression of junctional proteins. Importantly, FLO-1 cells formed spheres at the A-L interface, recapitulating key elements of tumors in the esophageal tube, i.e., direct contact with the gas phase and three-dimensional architecture. On the other hand, FLO-1 models exhibited high permeability to model drugs and zero permeability markers, and low transepithelial resistance, and therefore poorly mimicked normal esophageal epithelium. In conclusion, the identified effect of culture conditions on the characteristics of FLO-1 cells should be considered for standardization, data reproducibility and validity of the in vitro EAC model. Moreover, the sphere-forming ability of FLO-1 cells at the A-L interface should be considered in EAC tumor biology and anticancer drug studies as a reliable and straightforward model with the potential to increase the predictive efficiency of the current in vitro approaches.

Suitability and functional characterization of two Calu-3 cell models for prediction of drug permeability across the airway epithelial barrier.

The Calu-3 cell line has been largely investigated as a physiological and pharmacological model of the airway epithelial barrier. Its suitability for prediction of drug permeability across the airway epithelia, however, has not been yet evaluated by using large enough set of model drugs. We evaluated two Calu-3 cell models (air-liquid and liquid-liquid) for drug permeability prediction based on the recent regulatory guidelines on showing suitability of in vitro permeability methods for drug permeability classification. Bidirectional permeability assays using 22 model drugs and several zero permeability markers, as well as using ABC transporter substrates were conducted. Functional activity of P-gp, but not of BCRP was revealed. The potential of the Calu-3 cells to be used as a model of the nasal epithelial barrier, despite their different anatomical origin, has been demonstrated by the obtained excellent correlation with the fully differentiated 3D human nasal epithelial model (MucilAir™) for 11 model drugs, as well as by the good correlation obtained with the human nasal epithelial cell line RPMI 2650. In addition, the permeability values determined in the two Calu-3 models correlated well with the intestinal permeability model Caco-2.

Biopharmaceutical classification of desloratadine - not all drugs are classified the easy way.

The biopharmaceutical classification of drugs was designed as a basis for bio-waivers - a mechanism with the double ethical benefit of delivering new drug formulations to the market with less human testing and lower cost. However, many drugs defy simple classification because in vitro permeability and stability assessment can be challenging as shown in this study for desloratadine. Literature shows that desloratadine is highly soluble, while data on luminal stability and permeability are circumstantial. Combined with borderline bioavailability and not really known fraction of absorbed dose, desloratadine was found to be a good example for showing the innovative in vitro approaches necessary to unambiguously classify desloratadine according to Biopharmaceutical Classification System (BCS) guideline. Presented study undoubtedly confirmed that desloratadine solubility is high and dissolution is very rapid for immediate release reference tablets. We have demonstrated deslorata-dine stability under legally required conditions and also in more physiologically relevant media. High in vitro desloratadine permeability was confirmed using Caco-2 and Parallel Artificial Membrane Permeability Assay (PAMPA). Well-established in vitro model with rat intestinal tissue could not be used due to reasons elaborated in this paper.

Suitability of RPMI 2650 cell models for nasal drug permeability prediction.

The RPMI 2650 cell line has been a subject of evaluation as a physiological and pharmacological model of the nasal epithelial barrier. However, its suitability for drug permeability assays has not yet been established on a sufficiently large set of model drugs. We investigated two RPMI 2650 cell models (air-liquid and liquid-liquid) for nasal drug permeability determination by adopting the most recent regulatory guidelines on showing suitability of in vitro permeability methods for drug permeability classification. The permeability of 23 model drugs and several zero permeability markers across the cell models was assessed. The functional expression of two efflux transporters P-glycoprotein (P-gp) and Breast Cancer Resistant Protein (BCRP) was shown to be negligible by bidirectional transport studies using appropriate transporter substrates and inhibitors. The model drug permeability determined in the two RPMI 2650 cell models was correlated with the fully differentiated nasal epithelial model (MucilAir™). Additionally, correlations between the drug permeability in the investigated cell models and the ones determined in the Caco-2 cells and isolated rat jejunum were established. In conclusion, the air-liquid RPMI 2650 cell model is a promising pharmacological model of the nasal epithelial barrier and is much more suitable than the liquid-liquid model for nasal drug permeability prediction.

Implementation of quality by design principles in the development of microsponges as drug delivery carriers: Identification and optimization of critical factors using multivariate statistical analyses and design of experiments studies.

Microsponges drug delivery system (MDDC) was prepared by double emulsion-solvent-diffusion technique using rotor-stator homogenization. Quality by design (QbD) concept was implemented for the development of MDDC with potential to be incorporated into semisolid dosage form (gel). Quality target product profile (QTPP) and critical quality attributes (CQA) were defined and identified, accordingly. Critical material attributes (CMA) and Critical process parameters (CPP) were identified using quality risk management (QRM) tool, failure mode, effects and criticality analysis (FMECA). CMA and CPP were identified based on results obtained from principal component analysis (PCA-X&Y) and partial least squares (PLS) statistical analysis along with literature data, product and process knowledge and understanding. FMECA identified amount of ethylcellulose, chitosan, acetone, dichloromethane, span 80, tween 80 and water ratio in primary/multiple emulsions as CMA and rotation speed and stirrer type used for organic solvent removal as CPP. The relationship between identified CPP and particle size as CQA was described in the design space using design of experiments - one-factor response surface method. Obtained results from statistically designed experiments enabled establishment of mathematical models and equations that were used for detailed characterization of influence of identified CPP upon MDDC particle size and particle size distribution and their subsequent optimization.