Drug permeability across a phospholipid vesicle based barrier: 3. Characterization of drug–membrane interactions and the effect of agitation on the barrier integrity and on the permeability

Abstract

Recently we reported on the development and structural characterization of a phospholipid vesicle based barrier useful for medium throughput screening of passive drug permeability.Here, we investigate the physical and functional integrity of the phospholipid vesicle based barriers to agitation by stirring or shaking, and whether agitation affects drug permeability of sulpiride, metoprolol and testosterone. In addition, three drugs (caffeine, naproxen and sulphasalazine) which were shown in a previous study to affect the electrical resistance of the barriers, were investigated for their influence on the permeability of a simultaneously applied hydrophilic marker (calcein), and on the thermotropic phase transition of the phospholipid bilayers using differential scanning calorimetry (DSC).Electrical resistance measurements indicated that the barriers should withstand shaking speeds up to 150 rpm without losing their integrity, but significant release of phospholipids from the membrane barriers to the donor and acceptor chambers was observed under agitation ≥150 rpm. When using agitation up to 100 rpm no increase in permeability was observed for sulpiride, metoprolol and testosterone. The phospholipid vesicle-based barrier thus differ from other permeability models in that agitation does not lead to an increase in permeability, not even for highly lipophilic drugs such as testosterone. This is explained by the different morphology of the vesicle-based barrier which is containing a 100 µm thick layer of mostly aqueous compartments immobilised within a matrix of phospholipids vesicles.Sulphasalazine and naproxen were shown to decrease the electrical resistance and increase the permeability of the hydrophilic marker calcein. The DSC experiments showed that these two drugs probably interact with the head groups of the phospholipids. In contrast, caffeine gave an increase in electrical resistance and a decrease in permeability of calcein. From the DSC experiments no signs of interaction of caffeine with the phospholipid bilayer could be observed.3

Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology

“…Other approaches aimed at gaining preliminary permeability data in vitro include the artificial membrane-based PAMPA (Parallel Artificial Membrane Permeability Assay), discussed in more detail in the following chapter in the context of nonanimal intestinal models (Avdeef et al, 2007(Avdeef et al, , 2008Flaten et al, 2006bFlaten et al, , 2007Kansy et al, 1998Kansy et al, , 2004, as well as Strat-M™, available from Merck. The first commercially available PAMPA for performing penetration studies is the skin-PAMPA, as supplied by Pion Inc. Skin-PAMPA consists of a complete test system, including UV reader, as well as required technical support and is already in use for determination of temperature and protein-binding effects, for evaluation of new compounds and for predictive approaches studying quantitative structurepermeability relationships (Akamatsu et al, 2009;Bujard et al, 2014;Dobricic et al, 2014;Markovic et al, 2012;Vizseralek et al, 2014;Vucicevic et al, 2015).…”

Permeability of Fluid-Phase Phospholipid Bilayers: Assessment and Useful Correlations for Permeability Screening and Other Applications

“…8 Indeed, penetration of the cellular membrane figures heavily in standard definitions of the term "bioavailability." 2 Experimental assays quantifying the passive diffusive permeabilities of phospholipid membranes, such as the parallel artificial membrane permeation assay (PAMPA) 5,[9][10][11][12] and others, 5,13,14 have become essential tools empowering drug discovery and development. The focus on phospholipids is logical because viable cell membranes are bilayers of such polar lipids (with intercalated cholesterol, membrane proteins, and other constituents).…”

“…Although there is no avoiding some element of empiricism, we seek more fundamental understanding of the most basic property, namely the permeability coefficient P lip/w of a phospholipid bilayer isolated from any assay system, and deconvoluted from all other physicochemical factors 22 such as mass transfer resistances associated with unstirred water layers. 14,22 Furthermore, we focus on neutral permeant molecules, or the unionized (neutral) form of ionizable permeants, because the approach to treating ionization is well established. [22][23][24] Thus, there is no reason to burden a permeability correlation with the task of representing the effects of acid/base equilibria, when fitted constants might better be devoted to representing the intrinsic permeability of the bilayer for neutral species.…”

Biomimetic PVPA in vitro model for estimation of the intestinal drug permeability using fasted and fed state simulated intestinal fluids

“…Table 1 provides the composition of the different media and Table 2 gives an overview of the physicochemical and biopharmaceutical properties of employed model drugs and the marker calcein. Calcein was, based on experience from previous studies, chosen as a sensitive marker to detect any changes in barrier integrity (Engesland et al, 2014;Engesland et al, 2013;Fischer et al, 2011;Flaten et al, 2009;Flaten et al, 2006a;Flaten et al, 2006b;Flaten et al, 2008;Flaten et al, 2007;Naderkhani et al, 2014). The model drugs acyclovir (3 mM), griseofulvin (0.05 mM), indomethacin (0.3 mM) and nadolol (6 mM) were dissolved in concentrations that were high enough to facilitate reliable analyses of the samples from the acceptor compartments, but still well below the saturation limits.…”