Exploring the role of different drug transport routes in permeability screening.
ABSTRACT The influence of different drug transport routes in intestinal drug permeability screening assays was studied. Three experimental models were compared: the small-intestine-like 2/4/A1 cell model, which has a leaky paracellular pathway, the Caco-2 cell model, which has a tighter paracellular pathway, and artificial hexadecane membranes (HDMs), which exclusively model the passive transcellular pathway. The models were investigated regarding their ability to divide passively and actively transported compounds into two permeability classes and to rank compounds according to human intestinal absorption. In silico permeability models based on two-dimensional (2D) and three-dimensional (3D) molecular descriptors were also developed and validated using external test sets. The cell-based models classified 80% of the acceptably absorbed compounds (FA >/= 30%) correctly, compared to 60% correct classifications using the HDM model. The best compound ranking was obtained with 2/4/A1 (r(s) = 0.74; r(s) = 0.95 after removing actively transported outliers). The in silico model based on 2/4/A1 permeability gave results of similar quality to those obtained when using experimental permeability, and it was also better than the experimental HDM model at compound ranking (r(s) = 0.85 and 0.47, respectively). We conclude that the paracellular transport pathway present in the cell models plays a significant role in models used for intestinal permeability screening and that 2/4/A1 in vitro and in silico models are promising alternatives for drug discovery permeability screening.
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ABSTRACT: The entire panel of peptides produced from caseins (CN) and whey proteins (WP) that survive in vitro sequential gastro-pancreatic digestion and translocate across monolayers of Caco-2 cells, used as a model of the intestinal epithelium, has been characterised by HPLC and mass spectrometry. Among the milk-derived bioactive peptides, only minor amounts of mono-phosphorylated peptides arising from αs1- and β-CN were detected. The absorption behaviour of two resistant β-lactoglobulin (β-Lg) domains, β-Lg 125-135 and β-Lg 40-60, was studied in detail using synthetic peptides. The IgE-binding properties of the digests recovered from the apical and basolateral monolayer compartments were evaluated by dot-blot, using the sera of milk allergic children (N=5). Outcomes indicated β-Lg 127-135 as a possible "immune sensitising factor"in vivo. The almost complete loss of the IgE-affinity of CN and WP after digestion points out the need to design in vivo experiments to track the metabolic fate of dietary proteins.Food Chemistry 08/2013; 139(1-4):203-12. · 3.33 Impact Factor
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ABSTRACT: Preformulation measurements are used to estimate the fraction absorbed in vivo for orally administered compounds and thereby allow an early evaluation of the need for enabling formulations. As part of the Oral Biopharmaceutical Tools (OrBiTo) project, this review provides a summary of the pharmaceutical profiling methods available, with focus on in silico and in vitro models typically used to forecast active pharmaceutical ingredient's (APIs) in vivo performance after oral administration. An overview of the composition of human, animal and simulated gastrointestinal (GI) fluids is provided and state-of-the art methodologies to study API properties impacting on oral absorption are reviewed. Assays performed during early development, i.e. physicochemical characterization, dissolution profiles under physiological conditions, permeability assays and the impact of excipients on these properties are discussed in detail and future demands on pharmaceutical profiling are identified. It is expected that innovative computational and experimental methods that better describe molecular processes involved in vivo during dissolution and absorption of APIs will be developed in the OrBiTo. These methods will when successful provide early insights into successful pathways (medicinal chemistry or formulation strategy) and are anticipated to increase the number of new APIs with good oral absorption being discovered.European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 11/2013; · 2.61 Impact Factor
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ABSTRACT: Accurate prediction of the in vivo biopharmaceutical performance of oral drug formulations is critical to efficient drug development. Traditionally, in vitro evaluation of oral drug formulations has focused on disintegration and dissolution testing for quality control (QC) purposes. The connection with in vivo biopharmaceutical performance has often been ignored. More recently, the switch to assessing drug products in a more biorelevant and mechanistic manner has advanced the understanding of drug formulation behavior. Notwithstanding this evolution, predicting the in vivo biopharmaceutical performance of formulations that rely on complex intraluminal processes (e.g. solubilization, supersaturation, precipitation…) remains extremely challenging. Concomitantly, the increasing demand for complex formulations to overcome low drug solubility or to control drug release rates urges the development of new in vitro tools. Development and optimizing innovative, predictive Oral Biopharmaceutical Tools is the main target of the OrBiTo project within the Innovative Medicines Initiative (IMI) framework. A combination of physico-chemical measurements, in vitro tests, in vivo methods, and physiology-based pharmacokinetic modeling is expected to create a unique knowledge platform, enabling the bottlenecks in drug development to be removed and the whole process of drug development to become more efficient. As part of the basis for the OrBiTo project, this review summarizes the current status of predictive in vitro assessment tools for formulation behaviour. Both pharmacopoeia-listed apparatus and more advanced tools are discussed. Special attention is paid to major issues limiting the predictive power of traditional tools, including the simulation of dynamic changes in gastrointestinal conditions, the adequate reproduction of gastrointestinal motility, the simulation of supersaturation and precipitation, and the implementation of the solubility-permeability interplay. It is anticipated that the innovative in vitro biopharmaceutical tools arising from the OrBiTo project will lead to improved predictions for in vivo behavior of drug formulations in the GI tract.European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 08/2013; · 2.61 Impact Factor