Drug penetration model of vinblastine-treated Caco-2 cultures

Discovery and Characterization of RGH-122, a Potent, Selective, and Orally Bioavailable V1a Receptor Antagonist

The V1a receptor is a major contributor in mediating the social and emotional effects of arginine-vasopressin (AVP); therefore it represents a promising target in the treatment of several neuropsychiatric conditions. The aim of this research was to design and synthesize novel and selective V1a antagonists with improved in vitro and in vivo profiles. Through optimization and detailed SAR studies, we developed low nanomolar antagonists, and further characterizations led to the discovery of the clinical candidate compound 43 (RGH-122). The CNS activity of the compound was determined in a 3-chamber social preference test of autism in which RGH-122 successfully enhanced social preference with the lowest effective dose of 1.5 mg/kg.

Enhancing Oral Bioavailability of Domperidone Maleate: Formulation, In vitro Permeability Evaluation In-caco-2 Cell Monolayers and In situ Rat Intestinal Permeability Studies

BACKGROUND

The domperidone maleate, a lipophilic agent classified as a Biopharmaceutical Classification System Class II substance with weak water solubility. Self- Emulsifying Drug Delivery System is a novel approach to improve water solubility and, ultimately bioavailability of drugs.

OBJECTIVE

This study aimed to develop and characterize new domperidone-loaded self-emulsifying drug delivery systems as an alternative formulation and to evaluate the permeability of domperidone-loaded self-emulsifying drug delivery systems by using Caco-2 cells and via single-pass intestinal perfusion method.

METHODS

Three self-emulsifying drug delivery systems were prepared and characterized in terms of pH, viscosity, droplet size, zeta potential, polydispersity index, conductivity, etc. Each formulation underwent 10, 100, 200, and 500 times dilution in intestinal buffer pH 6.8 and stomach buffer pH 1.2, respectively. Female Sprague Dawley rats were employed for in situ single-pass intestinal perfusion investigations.

RESULTS

Results of the study revealed that the ideal self-emulsifying drug delivery systems formulation showed narrow droplet size, ideal zeta potential, and no conductivity. Additionally, as compared to the control groups, the optimum formulation had better apparent permeability (12.74 ± 0.02×10-4) from Caco-2 cell monolayer permeability experiments. The study also revealed greater Peff values (2.122 ± 0.892×10-4 cm/s) for the optimal formulation from in situ intestinal perfusion analyses in comparison to control groups (Domperidone; 0.802 ± 0.418×10-4 cm/s).

CONCLUSION

To conclude, prepared formulations can be a promising way of oral administration of Biopharmaceutical Classification System Class II drugs.

Optimization of Novel α7 Nicotinic Acetylcholine Receptor Positive Allosteric Modulators and the Discovery of a Preclinical Development Candidate Molecule (RGH-560)

During optimization of a previously identified lead compound, attempts were made to optimize the reactive indole structural element, the suboptimal metabolic stability, as well as the low kinetic solubility. It was concluded that the indole was important for in vitro activity. With the aim of further improvements, more thorough modifications were also carried out. As a result, a new chemotype (the azetidinespirochromone family) was identified, which proved to be 1 order of magnitude less lipophilic retaining the same high level of in vitro potency as the lead series itself, however, with improved metabolic stability and kinetic solubility. Compound 53 showed the most balanced physicochemical and pharmacological profile with significant in vivo efficacy in the scopolamine-induced amnesia test. Based on these promising results, cognitive enhancement through the positive modulation of α7 nAChRs appears to be a viable approach. Compound 53 was selected to be a preclinical development candidate (as RGH-560).

Screening novel CNS drug candidates for P-glycoprotein interactions using the cell line iP-gp: In vitro efflux ratios from iP-gp and MDCK-MDR1 monolayers compared to brain distribution data from mice

Drug efflux by P-glycoprotein (P-gp, ABCB1) is considered as a major obstacle for brain drug delivery for small molecules. P-gp-expressing cell monolayers are used for screening of new drug candidates during early states of drug development. It is, however, uncertain how well the in vitro studies can predict the in vivo P-gp mediated efflux at the blood-brain barrier (BBB). We previously developed a novel cell line of porcine origin, the iP-gp cell line, with high transepithelial resistance and functional expression of human P-gp. The aim of the present study was to evaluate the applicability of the cell line for screening of P-gp interactions of novel drug candidates. For this purpose, bidirectional fluxes of 14 drug candidates were measured in iP-gp cells and in MDCK-MDR1 cells, and compared with pharmacokinetic data obtained in male C57BL/6 mice. The iP-gp cells formed extremely tight monolayers (>15 000 Ω∙cm²) as compared to the MDCK- MDR1 cells (>250 Ω∙cm²) and displayed lower P_app,a-b values. The efflux ratios obtained with iP-gp and MDCK-MDR1 monolayers correlated with K_p,uu,brain values from the in vivo studies, where compounds with the lowest K_p,uu,brain generally displayed the highest efflux ratios. 12 of the tested compounds displayed a poor BBB penetration in mice as judged by K_p,uu less than 1. Of these compounds, nine compounds were categorized as P-gp substrates in the iP-gp screening, whereas analysis of data estimated in MDCK-MDR1 cells indicated four compounds as potential substrates. The results suggest that the iP-gp cell model may be a sensitive and useful screening tool for drug screening purposes to identify possible substrates of human P-glycoprotein.

Drug Penetration into the Central Nervous System: Pharmacokinetic Concepts and In Vitro Model Systems

Delivery of most drugs into the central nervous system (CNS) is restricted by the blood-brain barrier (BBB), which remains a significant bottleneck for development of novel CNS-targeted therapeutics or molecular tracers for neuroimaging. Consistent failure to reliably predict drug efficiency based on single measures for the rate or extent of brain penetration has led to the emergence of a more holistic framework that integrates data from various in vivo, in situ and in vitro assays to obtain a comprehensive description of drug delivery to and distribution within the brain. Coupled with ongoing development of suitable in vitro BBB models, this integrated approach promises to reduce the incidence of costly late-stage failures in CNS drug development, and could help to overcome some of the technical, economic and ethical issues associated with in vivo studies in animal models. Here, we provide an overview of BBB structure and function in vivo, and a summary of the pharmacokinetic parameters that can be used to determine and predict the rate and extent of drug penetration into the brain. We also review different in vitro models with regard to their inherent shortcomings and potential usefulness for development of fast-acting drugs or neurotracers labeled with short-lived radionuclides. In this regard, a special focus has been set on those systems that are sufficiently well established to be used in laboratories without significant bioengineering expertise.

HTS-based discovery and optimization of novel positive allosteric modulators of the α7 nicotinic acetylcholine receptor

HTS campaign of the corporate compound collection resulted in a novel, oxalic acid diamide scaffold of α7 nACh receptor positive allosteric modulators. During the hit expansion, several derivatives, such as 4, 11, 17 demonstrated not only high in vitro potency, but also in vivo efficacy in the mouse place recognition test. The advanced hit molecule 11 was further optimized by the elimination of the putatively mutagenic aromatic-amine building block that resulted in a novel, aminomethylindole compound family. The most balanced physico-chemical and pharmacological profile was found in case of compound 55. Docking study revealed an intersubunit binding site to be the most probable for our compounds. 55 demonstrated favorable cognitive enhancing profile not only in scopolamine-induced amnesia (place recognition test in mice) but also in natural forgetting (novel object recognition test in rats). Compound 55 was, furthermore, active in a cognitive paradigm of high translational value, namely in the rat touch screen visual discrimination test. Therefore, 55 was selected as a lead compound for further optimization. Based on the obtained favorable results, the invented aminomethylindole cluster may provide a viable approach for cognitive enhancement through positive allosteric modulation of α7 nAChRs.

Discovery of novel positive allosteric modulators of the α7 nicotinic acetylcholine receptor: Scaffold hopping approach

The paper focuses on the scaffold hopping-based discovery and characterization of novel nicotinic alpha 7 receptor positive modulator (α7 nAChR PAM) ligands around the reference molecule (A-867744). First, substantial efforts were carried out to assess the importance of the various pharmacophoric elements on the in vitro potency (SAR evaluation) by chemical modifications. Subsequently, several new derivatives with versatile, heteroaromatic central cores were synthesized and characterized. A promising, pyrazole-containing new chemotype with good physicochemical and in vitro parameters was identified. Retrospective analysis based on homology modeling was also carried out. Besides its favorable in vitro characteristics, the most advanced derivative 69 also showed in vivo efficacy in a rodent model of cognition (scopolamine-induced amnesia in the mouse place recognition test) and acceptable pharmacokinetic properties. Based on the in vivo data, the resulting molecule with advanced drug-like characteristics has the possibility to improve cognitive performance in a biologically relevant dose range, further strengthening the view of the supportive role of α7 nACh receptors in the cognitive processes.

Effect of co-administration of Acori Tatarinowii Rhizoma volatile oil on pharmacokinetic fate of xanthotoxol, oxypeucedanin hydrate, and byakangelicin from Angelicae Dahuricae Radix in rat

A combination of Angelicae Dahuricae Radix and Acori Tatarinowii Rhizoma has been widely used as the herb pair in traditional Chinese medicine to treat stroke, migraine, and epilepsy. However, the underlying synergistic mechanism of the herb pair remains unknown. This study was aimed at investigating the effects of Acori Tatarinowii Rhizoma volatile oil on the pharmacokinetic parameters of xanthotoxol, oxypeucedanin hydrate, and byakangelicin from Angelicae Dahuricae Radix in rat, and in vitro absorption behavior of the three compounds using rat everted gut sac, in situ single-pass intestinal perfusion, and Caco-2 cell monolayer models. The pharmacokinetic study exhibited clear changes in the key pharmacokinetic parameters of the three main coumarins through co-administering with Acori Tatarinowii Rhizoma volatile oil (50 mg/kg), the area under curve and the maximum plasma concentration of xanthotoxol increased 1.36 and 1.31 times; the area under curve, the maximum plasma concentration, mean residence time, half-life of elimination, and the time to reach peak concentration of oxypeucedanin hydrate increased by 1.35, 1.18, 1.24, 1.19 and 1.49 times, respectively; the area under curve, mean residence time, half-life of elimination, and time to reach peak concentration of byakangelicin climbed 1.29, 1.27, 1.37, and 1.28 times, respectively. The three coumarin components were absorbed well in the jejunum and ileum in the intestinal perfusion model, when co-administered with Acori Tatarinowii Rhizoma volatile oil (100 μg/mL). The in vivo and in vitro experiments showed good relevance and consistency. The results demonstrated that the three coumarin compounds from Angelicae Dahuricae Radix were absorbed through the active transportation, and Acori Tatarinowii Rhizoma volatile oil could promote the intestinal absorption and transport of these compounds by inhibiting P-glycoprotein (P-gp)-mediated efflux.

A Miniaturized Pump Out Method for Characterizing Molecule Interaction with ABC Transporters

Characterizing interaction of newly synthetized molecules with efflux pumps remains essential to improve their efficacy and safety. Caco-2 cell line cultivated on inserts is widely used for measuring apparent permeability of drugs across biological barriers, and for estimating their interaction with efflux pumps such as P-gp, BCRP and MRPs. However, this method remains time consuming and expensive. In addition, detection method is required for measuring molecule passage across cell monolayer and false results can be generated if drugs concentrations used are too high as demonstrated with quinidine. For this reason, we developed a new protocol based on the use of Caco-2 cell directly seeded on 96- or 384-well plates and the use of fluorescent substrates for efflux pumps. We clearly observed that the new method reduces costs for molecule screening and leads to higher throughput compared to traditional use of Caco-2 cell model. This accelerated model could provide quick feedback regarding the molecule design during the early stage of drug discovery and therefore reduce the number of compounds to be further evaluated using the traditional Caco-2 insert method.

[Consideration for future in vitro BBB models - technical development to investigate the drug delivery to the CNS]

Blood vessels in the central nervous system (CNS) limit the material exchange between blood and parenchyma by blood brain barrier (BBB). At present, no appropriate in vitro BBB models are available for the investigation whether or not the candidate compounds for new drugs could be delivered to the CNS. This causes huge difficulties of the development of CNS drugs and prediction of CNS adverse effects. In this review, I first outline the structures and functions of BBB, together with the parameters used for the quantification of BBB functions. I also introduce the history of in vitro BBB models used in the drug development so far, i.e., the transition from non-cell models to the models using primary culture of rodent cells, porcine, bovine, cell lines, etc. More recently, the application of human cells differentiated from human induced pluripotent stem cells and microfluidic engineering have already started. BBB is essential for the maintenance of brain homeostasis and the mechanisms of the BBB development will be clarified by reproducing functional BBB on the dish. The new in vitro models and the data may provide accurate prediction of drug delivery to the CNS and the improvement of the evaluation system for toxicity and safety, thereby leading to successful launch of new drugs on the market.

Dual Action of the PN159/KLAL/MAP Peptide: Increase of Drug Penetration across Caco-2 Intestinal Barrier Model by Modulation of Tight Junctions and Plasma Membrane Permeability

The absorption of drugs is limited by the epithelial barriers of the gastrointestinal tract. One of the strategies to improve drug delivery is the modulation of barrier function by the targeted opening of epithelial tight junctions. In our previous study the 18-mer amphiphilic PN159 peptide was found to be an effective tight junction modulator on intestinal epithelial and blood–brain barrier models. PN159, also known as KLAL or MAP, was described to interact with biological membranes as a cell-penetrating peptide. In the present work we demonstrated that the PN159 peptide as a penetration enhancer has a dual action on intestinal epithelial cells. The peptide safely and reversibly enhanced the permeability of Caco-2 monolayers by opening the intercellular junctions. The penetration of dextran molecules with different size and four efflux pump substrate drugs was increased several folds. We identified claudin-4 and -7 junctional proteins by docking studies as potential binding partners and targets of PN159 in the opening of the paracellular pathway. In addition to the tight junction modulator action, the peptide showed cell membrane permeabilizing and antimicrobial effects. This dual action is not general for cell-penetrating peptides (CPPs), since the other three CPPs tested did not show barrier opening effects.

Potential P-glycoprotein-mediated herb-drug interaction of phyllanthin at the intestinal absorptive barrier

Objectives

This study investigated the absorptive potential of phyllanthin across the polarized Caco-2 monolayers and the potential role of phyllanthin in P-glycoprotein (P-gp)-mediated drug interaction.

Methods

The absorptive potential of phyllanthin was predicted from its apparent permeability (Papp) across the Caco-2 monolayers under the pH gradient condition (pH 6.5AP–7.4BL) at 37°C. Integrity of paracellular transport was assessed by monitoring transepithelial electrical resistance (TEER) and lucifer yellow (LY) leakage. P-gp-mediated interaction was evaluated by transport studies of phyllanthin and rhodamine-123.

Key findings

The absorptive Papp of phyllanthin (34.90 ± 1.18 × 10−6 cm/s) was in the same rank order as the high permeable theophylline and antipyrine. Phyllanthin transport in the absorptive and secretive directions was comparable (the efflux ratio (ER) of 1.19 ± 0.01). Phyllanthin caused no changes in TEER nor LY leakage in the monolayers. However, phyllanthin increased rhodamine-123 ER in a concentration-dependent manner, suggesting its inhibition on P-gp function. In addition, phyllanthin aqueous solubility was <5 μg/ml at 37°C.

Conclusions

Phyllanthin is a highly permeable compound that could passively diffuse through the absorptive barrier via transcellular pathway with little hindrance from P-gp. Phyllanthin could interfere with transport of P-gp drug substrates, when concomitantly administered. In addition, aqueous solubility could be a limiting factor in phyllanthin absorption.

Optimization of a combined wet milling process in order to produce poly(vinyl alcohol) stabilized nanosuspension

Purpose

The article reports a wet milling process, where the planetary ball mill was combined with pearl milling technology to reach nanosize range of meloxicam (Mel; 100–500 nm). The main purpose was to increase the dissolution rate and extent of a poorly water-soluble Mel as nonsteroidal anti-inflammatory drug as well as to study its permeability across cultured intestinal epithelial cell layers.

Methods

Viscosity of milled dispersion and particle size distribution and zeta potential of Mel were investigated and differential scanning calorimeter and X-ray powder diffractometer were used to analyse the structure of the suspended Mel. Finally in vitro dissolution test and in vitro cell culture studies were made.

Results

It was found that the ratio of predispersion and pearls 1:1 (w/w) resulted in the most effective grinding system (200-fold particle size reduction in one step) with optimized process parameters, 437 rpm and 43 min. Nanosuspension (1% Mel and 0.5% poly[vinyl alcohol]) as an intermediate product showed a stable system with 2 weeks of holding time. This optimized nanosuspension enhanced the penetration of Mel across cultured intestinal epithelial cell layers without toxic effects.

Conclusion

The dissolution rate of Mel from the poly(vinyl alcohol) stabilized nanosuspension justified its applicability in the design of innovative per oral dosage form (capsule) in order to ensure/give a rapid analgesia.

Comparison of a Rat Primary Cell-Based Blood-Brain Barrier Model With Epithelial and Brain Endothelial Cell Lines: Gene Expression and Drug Transport

Cell culture-based blood-brain barrier (BBB) models are useful tools for screening of CNS drug candidates. Cell sources for BBB models include primary brain endothelial cells or immortalized brain endothelial cell lines. Despite their well-known differences, epithelial cell lines are also used as surrogate models for testing neuropharmaceuticals. The aim of the present study was to compare the expression of selected BBB related genes including tight junction proteins, solute carriers (SLC), ABC transporters, metabolic enzymes and to describe the paracellular properties of nine different culture models. To establish a primary BBB model rat brain capillary endothelial cells were co-cultured with rat pericytes and astrocytes (EPA). As other BBB and surrogate models four brain endothelial cells lines, rat GP8 and RBE4 cells, and human hCMEC/D3 cells with or without lithium treatment (D3 and D3L), and four epithelial cell lines, native human intestinal Caco-2 and high P-glycoprotein expressing vinblastine-selected VB-Caco-2 cells, native MDCK and MDR1 transfected MDCK canine kidney cells were used. To test transporter functionality, the permeability of 12 molecules, glucopyranose, valproate, baclofen, gabapentin, probenecid, salicylate, rosuvastatin, pravastatin, atorvastatin, tacrine, donepezil, was also measured in the EPA and epithelial models. Among the junctional protein genes, the expression level of occludin was high in all models except the GP8 and RBE4 cells, and each model expressed a unique claudin pattern. Major BBB efflux (P-glycoprotein or ABCB1) and influx transporters (GLUT-1, LAT-1) were present in all models at mRNA levels. The transcript of BCRP (ABCG2) was not expressed in MDCK, GP8 and RBE4 cells. The absence of gene expression of important BBB efflux and influx transporters BCRP, MRP6, -9, MCT6, -8, PHT2, OATPs in one or both types of epithelial models suggests that Caco-2 or MDCK models are not suitable to test drug candidates which are substrates of these transporters. Brain endothelial cell lines GP8, RBE4, D3 and D3L did not form a restrictive paracellular barrier necessary for screening small molecular weight pharmacons. Therefore, among the tested culture models, the primary cell-based EPA model is suitable for the functional analysis of the BBB.

Inhibitory Effects of Benzaldehyde, Vanillin, Muscone and Borneol on P-Glycoprotein in Caco-2 Cells and Everted Gut Sac

Aims: In clinical practice, herbal medicines have played an important role in the modulation of drug transporters through the combination of conventional prescription drugs, which necessitates the elucidation of herb-drug interactions. The present study was designed to investigate the inhibitory effects and mechanisms of benzaldehyde, vanillin, muscone, and borneol on P-glycoprotein (P-gp). Methods: The effects of the 4 compounds on the intracellular accumulation of rhodamine-123 (Rho-123) in vinblastine-treated Caco-2 (VB-Caco-2) cells were studied by monitoring fluorescence intensity through a flow cytometry assay, and the effects of these compounds on Rho-123 transport through VB-Caco-2 monolayers and Rho-123 intestinal absorption in the rat everted gut sac were investigated by high-performance liquid chromatography. Moreover, P-gp expression in VB-Caco-2 cells was assessed using flow cytometry and Western blot analysis, and the relative ABCB1 mRNA level was determined by Real-time RT-PCR. Key Findings: The results showed that benzaldehyde, vanillin, muscone, and borneol significantly increased Rho-123 uptake in VB-Caco-2 cells, increased the absorption rate and apparent permeability coefficient of Rho-123 in rat jejunum and ileum, and decreased the efflux ratio of Rho-123 from 6.52 to less than 2 during transport across VB-Caco-2 cell monolayers. In addition, these compounds reduced the protein and ABCB1 mRNA levels of P-gp in VB-Caco-2 cells. Conclusions: These data indicate that benzaldehyde, vanillin, muscone and borneol could effectively reverse multidrug resistance via inhibiting the P-gp function and expression pathway. The data provide fodder for further investigation into the interaction between the 4 compounds and other drugs transported by P-gp.

New P2X3 receptor antagonists. Part 1: Discovery and optimization of tricyclic compounds

Purinergic P2X3 receptors are trimeric ligand-gated ion channels whose antagonism is an appealing yet challenging and not fully validated drug development idea. With the aim of identification of an orally active, potent human P2X3 receptor antagonist compound that can penetrate the central nervous system, the compound collection of Gedeon Richter was screened. A hit series of tricyclic compounds was subjected to a rapid, two-step optimization process focusing on increasing potency, improving metabolic stability and CNS penetrability. Attempts resulted in compound 65, a potential tool compound for testing P2X3 inhibitory effects in vivo.

In vitro screening of nanomedicines through the blood brain barrier: A critical review

The blood-brain barrier accounts for the high attrition rate of the treatments of most brain disorders, which therefore remain one of the greatest health-care challenges of the twenty first century. Against this background of hindrance to brain delivery, nanomedicine takes advantage of the assembly at the nanoscale of available biomaterials to provide a delivery platform with potential to raising brain levels of either imaging or therapeutic agents. Nevertheless, to prevent later failure due to ineffective drug levels at the target site, researchers have been endeavoring to develop a battery of in vitro screening procedures that can predict earlier in the drug discovery process the ability of these cutting-edge drug delivery platforms to cross the blood-brain barrier for biomedical purposes. This review provides an in-depth analysis of the currently available in vitro blood-brain barrier models (both cell-based and non-cell-based) with the focus on their suitability for understanding the biological brain distribution of forthcoming nanomedicines. The relationship between experimental factors and underlying physiological assumptions that would ultimately lead to a more predictive capacity of their in vivo performance, and those methods already assayed for the evaluation of the brain distribution of nanomedicines are comprehensively discussed.

Molecular docking of selected phytocompounds with H1N1 Proteins

The H1N1 influenza virus is a serious threat to human population. Oseltamivir and Zanamivir are known antiviral drugs for swine flu with observed side effects. These drugs are viral neuraminidase and hemagglutinin inhibitor prevents early virus multiplication by blocking sialic acid cleavage on host cells. Therefore, it is of interest to identify naturally occurring novel compounds to control viral growth. Thus, H1N1 proteins (neuraminidase and hemagglutinin) were screened with phytocompounds isolated from Tulsi plant (Ocimum sanctum L.) using molecular docking tools. This identified Apigenin as an alternative to Oseltamivir and Zanamivir with improved predicted binding properties. Hence, it is of interest to consider this compound for further in vitro and in vivo evaluation.

Blood-brain barrier models and their relevance for a successful development of CNS drug delivery systems: a review

During the research and development of new drugs directed at the central nervous system, there is a considerable attrition rate caused by their hampered access to the brain by the blood-brain barrier. Throughout the years, several in vitro models have been developed in an attempt to mimic critical functionalities of the blood-brain barrier and reliably predict the permeability of drug candidates. However, the current challenge lies in developing a model that retains fundamental blood-brain barrier characteristics and simultaneously remains compatible with the high throughput demands of pharmaceutical industries. This review firstly describes the roles of all elements of the neurovascular unit and their influence on drug brain penetration. In vitro models, including non-cell based and cell-based models, and in vivo models are herein presented, with a particular emphasis on their methodological aspects. Lastly, their contribution to the improvement of brain drug delivery strategies and drug transport across the blood-brain barrier is also discussed.

Involvement of AP-1 and NF-κB in the up-regulation of P-gp in vinblastine resistant Caco-2 cells

Caco-2 is a widely used cell model in drug absorption and P-glycoprotein (P-gp, MDR1) substrate identification. Long-term vinblastine treatment of Caco-2 cells could increase the expression of P-gp; thus, the vinblastine resistant Caco-2 (Caco-2 vbl) cells can be used as a rapid and sensitive alternative model in identifying P-gp substrates. The mechanism of P-gp induction in this model is not clear; this study was therefore intended to clarify the possible factors involved in P-gp up-regulation in Caco-2 vbl cells. Since vinblastine is the inducer of both activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB), we investigated the role of AP-1 and NF-κB in the regulation of MDR1 gene expression. Our results indicated that the AP-1 and NF-κB luciferase activity was higher in Caco-2 vbl cells than that in Caco-2 cells according to reporter gene assay. The mRNA expression of AP-1 subunit c-Jun and NF-κB was increased in Caco-2 vbl cells. The c-Jun inhibitor SP600125 and NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) suppressed the expression of MDR1 mRNA in Caco-2 vbl cells. In conclusion, this study provides the evidence that AP-1 and NF-κB are involved in the P-gp induction in Caco-2 vbl cells.

Retinoic acid and hydrocortisone strengthen the barrier function of human RPMI 2650 cells, a model for nasal epithelial permeability

The nasal pathway represents an alternative route for non-invasive systemic administration of drugs. The main advantages of nasal drug delivery are the rapid onset of action, the avoidance of the first-pass metabolism in the liver and the easy applicability. In vitro cell culture systems offer an opportunity to model biological barriers. Our aim was to develop and characterize an in vitro model based on confluent layers of the human RPMI 2650 cell line. Retinoic acid, hydrocortisone and cyclic adenosine monophosphate, which influence cell attachment, growth and differentiation have been investigated on the barrier formation and function of the nasal epithelial cell layers. Real-time cell microelectronic sensing, a novel label-free technique was used for dynamic monitoring of cell growth and barrier properties of RPMI 2650 cells. Treatments enhanced the formation of adherens and tight intercellular junctions visualized by electron microscopy, the presence and localization of junctional proteins ZO-1 and β-catenin demonstrated by fluorescent immunohistochemistry, and the barrier function of nasal epithelial cell layers. The transepithelial resistance of the RPMI 2650 cell model reached 50 to 200 Ω × cm(2), the permeability coefficient for 4.4 kDa FITC-dextran was 9.3 to 17 × 10(-6) cm/s, in agreement with values measured on nasal mucosa from in vivo and ex vivo experiments. Based on these results human RPMI 2650 cells seem to be a suitable nasal epithelial model to test different pharmaceutical excipients and various novel formulations, such as nanoparticles for toxicity and permeability.

De novo prediction of p-glycoprotein-mediated efflux liability for druglike compounds

P-glycoprotein (Pgp) is capable of recognizing and transporting a wide range of chemically diverse compounds in vivo. Overcoming Pgp-mediated efflux can represent a significant challenge when penetration into the central nervous system is required or within the context of developing anticancer therapies. While numerous in silico models have been developed to predict Pgp-mediated efflux, these models rely on training sets and are best suited to make interpolations. Therefore, it is desirable to develop ab initio models that can be used to predict efflux liabilities. Herein, we present a de novo method that can be used to predict Pgp-mediated efflux potential for druglike compounds. A model, which correlates the computed solvation free energy differences obtained in water and chloroform with Pgp-mediated efflux (in logarithmic scale), was successful in predicting Pgp efflux ratios for a wide range of chemically diverse compounds with a R(2) and root-mean-square error of 0.65 and 0.29, respectively.