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Goril Eide Flaten - One of the best experts on this subject based on the ideXlab platform.
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mucus pvpa mucus Phospholipid Vesicle based permeation assay an artificial permeability tool for drug screening and formulation development
International Journal of Pharmaceutics, 2018Co-Authors: Margherita Falavigna, Natasa Skalkobasnet, Mette Klitgaard, Christina Brase, Selenia Ternullo, Goril Eide FlatenAbstract:The mucus layer covering all mucosal surfaces in our body is the first barrier encountered by drugs before their potential absorption through epithelial tissues, and could thus affect the drugs' permeability and their effectiveness. Therefore, it is of key importance to have in vitro permeability models that can mimic this specific environment. For this purpose, the novel mucus Phospholipid Vesicle-based permeation assay (mucus-PVPA) has been developed and used for permeability screening of drugs and formulations. The model proved to be stable under the chosen conditions and demonstrated the ability to discriminate between compounds with different chemical structures and properties. Overall, a decrease in drug permeability was found in the presence of mucus on top of the PVPA barriers, as expected. Moreover, mucoadhesive (chitosan-coated) and mucopenetrating (PEGylated) liposomes were investigated in the newly developed model. The mucus-PVPA was able to distinguish between the different liposomal formulations, confirming the penetration potential of the tested formulations and the related drug permeability. The mucus-PVPA model appears to be a promising in vitro tool able to mimic the environment of mucosal tissues, and could therefore be used for further drug permeability screening and formulation development.
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Phospholipid Vesicle based permeation assay and episkin in assessment of drug therapies destined for skin administration
Journal of Pharmaceutical Sciences, 2015Co-Authors: Andre Engesland, Natasa Skalkobasnet, Goril Eide FlatenAbstract:Cost-effective and efficient methods for permeability screening are crucial during early development of drugs, drug formulations, and cosmeceuticals. Alternatives to animal experiments are impelled for both economical and ethical reasons. The aim of this study was to determine the ability of the Phospholipid Vesicle-based permeation assay (PVPA) to assess the effect of different formulations on drug permeability and thus establish its utility in formulation development. Three model drugs were tested in solutions and as liposomal formulations. The permeability results for the PVPA models were compared with the results for the reconstructed human skin model, EpiSkin(®). The drugs were ranked based on their estimated penetration potentials, and the results were in accordance with what was expected considering the physicochemical properties of the drugs. PVPAs (E-80, ceramide, cholesterol, cholesteryl sulfate, and palmitic acid) was able to distinguish between drug solutions and liposomal formulations; however, EpiSkin(®) detected only small differences between the drugs in solution and formulations. In contrast with EpiSkin(®), which is limited by a 3-day testing window, PVPA barriers can be stored frozen for up to 2 weeks or even up to 16 months, depending on their compositions. The PVPA models are thus more cost effective and efficient than the EpiSkin(®) model for permeability screening during early drug development.
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Liposomes for (trans)dermal drug delivery: the skin-PVPA as a novel in vitro stratum corneum model in formulation development
Journal of liposome research, 2014Co-Authors: Zora Palac, Goril Eide Flaten, Andre Engesland, Nataša Škalko-basnet, Jelena Filipović-grčić, Željka VanićAbstract:AbstractPenetration potential of Vesicles destined for trans(dermal) administration remains to be of great interests both in respect to drug therapy and cosmetic treatment. This study investigated the applicability of the Phospholipid Vesicle-based permeation assay (PVPA) as a novel in vitro skin barrier model for screening purposes in preformulation studies. Various classes of liposomes containing hydrophilic model drug were examined, including conventional liposomes (CLs), deformable liposomes (DLs) and propylene glycol liposomes (PGLs). The size, surface charge, membrane deformability and entrapment efficiency were found to be affected by the Vesicle lipid concentration, the presence of the surfactant and propylene glycol. All liposomes exhibited prolonged drug release profiles with an initial burst effect followed by a slower release phase. The permeation of the drug from all of the tested liposomes, as assessed with the mimicked stratum corneum – PVPA model, was significantly enhanced as compared to ...
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improved permeability of acyclovir optimization of mucoadhesive liposomes using the Phospholipid Vesicle based permeation assay
Journal of Pharmaceutical Sciences, 2014Co-Authors: Elenaz Naderkhani, Natasa Skalkobasnet, Astrid Erber, Goril Eide FlatenAbstract:The antiviral drug acyclovir (ACV) suffers from poor solubility both in lipophilic and hydrophilic environment, leading to low and highly variable bioavailability. To overcome these limitations, this study aimed at designing mucoadhesive ACV-containing liposomes to improve its permeability. Liposomes were prepared from egg phosphatidylcholine (E-PC) and E-PC/egg phosphatidylglycerol (E-PC/E-PG) and their surfaces coated with Carbopol. All liposomal formulations were fully characterized and for the first time the Phospholipid Vesicle-based permeation assay (PVPA) was used for testing in vitro permeability of drug from mucoadhesive liposome formulations. The negatively charged E-PC/E-PG liposomes could encapsulate more ACV than neutral E-PC liposomes. Coating with Carbopol increased the entrapment in the neutral E-PC liposomes. The incorporation of ACV into liposomes exhibited significant increase in its in vitro permeability, compared with its aqueous solution. The neutral E-PC liposomal formulations exhibited higher ACV permeability values compared with charged E-PC/E-PG formulations. Coating with Carbopol significantly enhanced the permeability from the E-PC/E-PG liposomes, as well as sonicated E-PC liposomes, which showed the highest permeability of all tested formulations. The increased permeability was according to the formulations' mucoadhesive properties. This indicates that the PVPA is suitable to distinguish between permeability of ACV from different mucoadhesive liposome formulations developed for various routes of administration.
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Development of a biomimetic Phospholipid Vesicle-based permeation assay for the estimation of intestinal drug permeability
Journal of Pharmaceutical Sciences, 2014Co-Authors: Elenaz Naderkhani, Johan Isaksson, Alexey Ryzhakov, Goril Eide FlatenAbstract:Permeability is a crucial property of orally administered drugs. Therefore, in drug discovery, it is important to employ methods suitable for rapidly and reliably screening the permeability of large numbers of new drug candidates. The Phospholipid Vesicle-based permeation assay (PVPA), a model consisting of a tight layer of liposomes immobilized on a filter, offers potential advantages unmet by other methods and has been successfully used in permeability testing of novel active substances as well as formulations. In this study, the PVPA was developed into a more robust, biomimetic model by employing a lipid composition matching that of the intestinal permeation barrier and performing the experiments at the more biologically relevant pH 6.2. As expected, positively charged basic compounds demonstrated increased permeability through the negatively charged biomimetic barriers, and the degree of correct classification according to in vivo absorption was comparable between the original PVPA and the biomimetic PVPA. The biomimetic PVPA further proved to be tremendously more robust toward the presence of tensides compared with the original PVPA; this is a promising finding that renders the biomimetic PVPA an enhanced ability to estimate the permeability of poorly soluble compounds. Hence, the PVPA model developed in this study has evolved an important step forward.
Martin Brandl - One of the best experts on this subject based on the ideXlab platform.
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application of simulated intestinal fluid on the Phospholipid Vesicle based drug permeation assay
International Journal of Pharmaceutics, 2012Co-Authors: Sarah Maud Fischer, Gert Fricker, Stephen Timothy Buckley, Wiebke Kirchmeyer, Martin BrandlAbstract:The compatibility of fasted state simulated intestinal fluid (FaSSIF) in drug permeation studies employing the Phospholipid Vesicle-based permeation assay (PVPA) model was confirmed by a set of different integrity indicators. Neither calcein permeability nor electrical resistance were found significantly changed indicating unaffected barrier tightness. Furthermore, the release of Phospholipid from the barriers in contact with FaSSIF was negligible, although sodium taurocholate disappeared from the donor - possibly due to transfer into the barrier. Visual examination of the barrier structure by confocal laser scanning microscopy (CLSM) revealed no changes. The model drugs, cimetidine, nadolol, ketoprofen and griseofulvin showed either slightly enhanced or unchanged permeability values in the presence of FaSSIF. This may be attributed to micellar encapsulation and/or slight changes in barrier characteristics. Particularly for poorly soluble drugs, FaSSIF appeared favourable in terms of markedly improved recovery. Moreover, utilisation of BSA in the receiver compartment seems to augment this beneficial effect on recovery rate. It is likely that this experimental set-up affords better sink conditions in the receiver phase, which results in higher fluxes. Overall, a combination of FaSSIF in the donor phase and BSA in the receiver phase facilitates improved experimental output.
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in vitro permeability of poorly water soluble drugs in the Phospholipid Vesicle based permeation assay the influence of nonionic surfactants
Journal of Pharmacy and Pharmacology, 2011Co-Authors: Goril Eide Flaten, Gert Fricker, Sarah Maud Fischer, Ellen Hagesaether, Martin BrandlAbstract:Objectives The aim of this study was to determine the influence of nonionic surfactants on drug permeability using the Phospholipid Vesicle-based permeation assay (PVPA), which excludes other than trans-membrane diffusion pathways. Methods Barrier integrity was monitored both by electrical resistance and permeability measurement of the hydrophilic marker calcein. Permeability of the model drugs ketoprofen and nadolol across the PVPA-barrier was measured by HPLC-UV. Micelle association of the model drugs was determined using ultrafiltration, whereby micelle-bound drug and molecular drug were separated. Key findings The nonionic surfactant poloxamer 188 was demonstrated not to affect barrier integrity. Drug permeability was found depressed in the presence of poloxamer 188 in a concentration-dependent manner. Both drugs were found to associate with poloxamer 188 micelles. The extent of the decrease in permeability correlated mostly, but not in all cases, with the fraction of micelle-bound drug. Conclusions Micelle association was one important but not the only factor affecting drug permeability across the PVPA-barrier.
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in vitro permeability screening of melt extrudate formulations containing poorly water soluble drug compounds using the Phospholipid Vesicle based barrier
Journal of Pharmacy and Pharmacology, 2010Co-Authors: Johanna Kanzer, Ingunn Tho, Goril Eide Flaten, Markus Magerlein, Peter Holig, Gert Fricker, Martin BrandlAbstract:Objectives The Phospholipid Vesicle-based barrier has recently been introduced as an in-vitro permeation model mimicking gastro-epithelial barriers in terms of passive diffusion of drugs. The aim of this study was to investigate whether the Phospholipid Vesicle-based barrier was suitable for permeability screening of complex formulations such as solid dispersions. Methods Solid dispersions containing the poorly water-soluble drugs HIV-PI 1 (log P = 6.2, molar mass = 628.80 g/mol) and HIV-PI 2 (log P = 5.3, molar mass = 720.95 g/mol), a hydrophilic polymer and different surfactants were tested with respect to their influence on integrity of the barrier in terms of electrical resistance and permeability for calcein. Furthermore, utilisation of a more biologically relevant medium, Hank's balanced salt solution supplemented with Mg2+- and Ca2+-ions (HBSS (Mg2+, Ca2+)), has been tested. Key findings Except for the polyoxyl 40 hydrogenated castor oil-containing solid dispersion, no influence on the Phospholipid Vesicle-based barrier could be observed from the tested samples. Presence of active pharmaceutical ingredients (APIs) in the solid dispersions led to the same results as the corresponding placebo results. First experiments analysing the passive diffusion of both APIs in HBSS (Mg2+, Ca2+), evaluated as suitable transport medium, have shown promising results regarding the suitability of the Phospholipid Vesicle-based barrier for investigation of solid dispersions. Conclusions The study indicated that the Phospholipid Vesicle-based barrier was compatible with selected melt extrudate formulations. The model seemed capable to reveal different transport routes in comparison with Caco-2 cell permeability tests.
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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
European Journal of Pharmaceutical Sciences, 2007Co-Authors: Goril Eide Flaten, Merete Skar, Kristina Luthman, Martin BrandlAbstract: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 150rpm without losing their integrity, but significant release of Phospholipids from the membrane barriers to the donor and acceptor chambers was observed under agitation >or=150rpm. When using agitation up to 100rpm 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 100microm 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.
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drug permeability across a Phospholipid Vesicle based barrier a novel approach for studying passive diffusion
European Journal of Pharmaceutical Sciences, 2006Co-Authors: Goril Eide Flaten, Kristina Luthman, Anand Babu Dhanikula, Martin BrandlAbstract:Abstract The aim of this study was to develop a novel predictive medium-throughput screening method for drug permeability, with use of a tight barrier of liposomes on a filter support. To our knowledge no one has succeeded in depositing membrane barriers without the use of an inert solvent such as hexadecane. The first part of the study involved development of a protocol for preparation of these barriers, which were made of liposomes from egg phosphatidylcholin in phosphate buffer pH 7.4 with 10 % (v/v) ethanol. The liposomes were deposited into the pores and onto the surface of a filter support (mixed cellulose ester) by use of centrifugation. Solvent evaporation and freeze–thaw cycling were then used to promote fusion of liposomes. A tight barrier could thus be obtained as shown with calcein permeability and electrical resistance. In the second part of the study the model was validated using 21 drug compounds, which cover a wide range of physicochemical properties and absorption (Fa) in humans (13–100%). The drug permeation studies were carried out at room temperature with phosphate buffer (pH 7.4) in both acceptor and donor chambers. The apparent permeability coefficients obtained from the Phospholipid Vesicle based model correlated well with literature data on human absorption in vivo, which suggests that its performance is adequate and that the method is suitable for rapid screening of passive transport of new chemical entities. The results obtained from our model were compared with polar surface area (PSA) and experimental log D and with results obtained by established permeability screening methods such as immobilized liposome chromatography (ILC), the PAMPA models and the Caco-2 model. Our approach seems to model the in vivo absorption better than PSA, experimental log D, the ILC and PAMPA models, when similar conditions are used as in our assay, and equally well as the Caco-2 model and the Double Sink PAMPA (DS-PAMPA) model.
Anna Fassio - One of the best experts on this subject based on the ideXlab platform.
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The highly conserved synapsin domain E mediates synapsin dimerization and Phospholipid Vesicle clustering.
The Biochemical journal, 2010Co-Authors: Ilaria Monaldi, Silvia Giovedi, Flavia Valtorta, Massimo Vassalli, Angela Bachi, Enrico Millo, Roberto Raiteri, Anna FassioAbstract:Synapsins are abundant SV (synaptic Vesicle)-associated phosphoproteins that regulate synapse formation and function. The highly conserved C-terminal domain E was shown to contribute to several synapsin functions, ranging from formation of the SV reserve pool to regulation of the kinetics of exocytosis and SV cycling, although the molecular mechanisms underlying these effects are unknown. In the present study, we used a synthetic 25-mer peptide encompassing the most conserved region of domain E (Pep-E) to analyse the role of domain E in regulating the interactions between synapsin I and liposomes mimicking the Phospholipid composition of SVs (SV-liposomes) and other pre-synaptic protein partners. In affinity-chromatography and cross-linking assays, Pep-E bound to endogenous and purified exogenous synapsin I and strongly inhibited synapsin dimerization, indicating a role in synapsin oligomerization. Consistently, Pep-E (but not its scrambled version) counteracted the ability of holo-synapsin I to bind and coat Phospholipid membranes, as analysed by AFM (atomic force microscopy) topographical scanning, and significantly decreased the clustering of SV-liposomes induced by holo-synapsin I in FRET (Forster resonance energy transfer) assays, suggesting a causal relationship between synapsin oligomerization and Vesicle clustering. Either Pep-E or a peptide derived from domain C was necessary and sufficient to inhibit both dimerization and Vesicle clustering, indicating the participation of both domains in these activities of synapsin I. The results provide a molecular explanation for the effects of domain E in nerve terminal physiology and suggest that its effects on the size and integrity of SV pools are contributed by the regulation of synapsin dimerization and SV clustering.
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The highly conserved synapsin domain E mediates synapsin dimerization and Phospholipid Vesicle clustering
Biochemical Journal, 2010Co-Authors: Ilaria Monaldi, Silvia Giovedi, Flavia Valtorta, Massimo Vassalli, Angela Bachi, Enrico Millo, Roberto Raiteri, Anna FassioAbstract:Synapsins are abundant synaptic Vesicle (SV)-associated phosphoproteins that regulate synapse formation and function. The highly conserved COOH-terminal domain E was shown to contribute to several synapsin functions, ranging from formation of the SV reserve pool to regulation of the kinetics of exocytosis and SV cycling, although the molecular mechanisms underlying these effects are unknown. We used a synthetic 25-mer peptide encompassing the most conserved region of domain E (Pep-E) to analyze the role of domain E in regulating the interactions between synapsin I and liposomes mimicking the Phospholipid composition of SVs (SV-liposomes) and other presynaptic protein partners. In affinity chromatography and cross-linking assays, Pep-E bound to endogenous and purified exogenous synapsin I and strongly inhibited synapsin dimerization, indicating a role in synapsin oligomerization. Consistently, Pep-E (but not its scrambled version) counteracted the ability of holosynapsin I to bind and coat Phospholipid membranes, as analyzed by AFM topographical scanning, and significantly decreased the clustering of SV-liposomes induced by holosynapsin I in Förster Resonance Energy Transfer assays, suggesting a causal relationship between synapsin oligomerization and Vesicle clustering. Either Pep-E or a peptide derived from domain C was necessary and sufficient to inhibit both dimerization and Vesicle clustering, indicating the participation of both domains in these activities of synapsin I. The data provide a molecular explanation for the effects of domain E in nerve terminal physiology and suggest that its effects on the size and integrity of SV pools are contributed by the regulation of synapsin dimerization and SV clustering.
Hiroshi Umakoshi - One of the best experts on this subject based on the ideXlab platform.
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membrane interaction between span 80 Vesicle and Phospholipid Vesicle liposome span 80 Vesicle can perturb and hemifuse with liposomal membrane
Colloids and Surfaces B: Biointerfaces, 2013Co-Authors: Keita Hayashi, Toshinori Shimanouchi, Tsuyoshi Tatsui, Hiroshi UmakoshiAbstract:We have focused on the interaction between the Span 80 Vesicle and Phospholipid Vesicle (liposome). The Span 80 Vesicle was mixed with a Phospholipid Vesicle (liposome), used as a simplified model of plasma membrane. From calcein leakage experiments, it was revealed that the interaction between the Span 80 Vesicles and the liposomes could perturb the liposome membrane. In the experiments based on fluorescence resonance energy transfer, the lipid mixing between Span 80 Vesicle and liposome was observed. The above phenomena were also supported by the fluorescence spectroscopic analysis using laurdan, resulting in the variation in the membrane properties of liposome after its mixing with Span 80 Vesicle. These results suggest that the Span 80 Vesicles can easily interact and hemifuse with the liposome membrane, which depend on the membrane properties of the Span 80 Vesicle, "flexible" and "molecular structure" of the components.
Sarah Maud Fischer - One of the best experts on this subject based on the ideXlab platform.
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application of simulated intestinal fluid on the Phospholipid Vesicle based drug permeation assay
International Journal of Pharmaceutics, 2012Co-Authors: Sarah Maud Fischer, Gert Fricker, Stephen Timothy Buckley, Wiebke Kirchmeyer, Martin BrandlAbstract:The compatibility of fasted state simulated intestinal fluid (FaSSIF) in drug permeation studies employing the Phospholipid Vesicle-based permeation assay (PVPA) model was confirmed by a set of different integrity indicators. Neither calcein permeability nor electrical resistance were found significantly changed indicating unaffected barrier tightness. Furthermore, the release of Phospholipid from the barriers in contact with FaSSIF was negligible, although sodium taurocholate disappeared from the donor - possibly due to transfer into the barrier. Visual examination of the barrier structure by confocal laser scanning microscopy (CLSM) revealed no changes. The model drugs, cimetidine, nadolol, ketoprofen and griseofulvin showed either slightly enhanced or unchanged permeability values in the presence of FaSSIF. This may be attributed to micellar encapsulation and/or slight changes in barrier characteristics. Particularly for poorly soluble drugs, FaSSIF appeared favourable in terms of markedly improved recovery. Moreover, utilisation of BSA in the receiver compartment seems to augment this beneficial effect on recovery rate. It is likely that this experimental set-up affords better sink conditions in the receiver phase, which results in higher fluxes. Overall, a combination of FaSSIF in the donor phase and BSA in the receiver phase facilitates improved experimental output.
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in vitro permeability of poorly water soluble drugs in the Phospholipid Vesicle based permeation assay the influence of nonionic surfactants
Journal of Pharmacy and Pharmacology, 2011Co-Authors: Goril Eide Flaten, Gert Fricker, Sarah Maud Fischer, Ellen Hagesaether, Martin BrandlAbstract:Objectives The aim of this study was to determine the influence of nonionic surfactants on drug permeability using the Phospholipid Vesicle-based permeation assay (PVPA), which excludes other than trans-membrane diffusion pathways. Methods Barrier integrity was monitored both by electrical resistance and permeability measurement of the hydrophilic marker calcein. Permeability of the model drugs ketoprofen and nadolol across the PVPA-barrier was measured by HPLC-UV. Micelle association of the model drugs was determined using ultrafiltration, whereby micelle-bound drug and molecular drug were separated. Key findings The nonionic surfactant poloxamer 188 was demonstrated not to affect barrier integrity. Drug permeability was found depressed in the presence of poloxamer 188 in a concentration-dependent manner. Both drugs were found to associate with poloxamer 188 micelles. The extent of the decrease in permeability correlated mostly, but not in all cases, with the fraction of micelle-bound drug. Conclusions Micelle association was one important but not the only factor affecting drug permeability across the PVPA-barrier.