SwePub - search: WFRF:(Abrahmsen Alami Susanna)

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1.	Abrahmsén-Alami, Susanna, et al. (author) New release cell for NMR microimaging of tablets Swelling and erosion of poly(ethylene oxide) 2007 In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 342:1-2, s. 105-114 Journal article (peer-reviewed)abstract A small release cell, in the form of a rotating disc, has been constructed to fit into the MRI equipment. The present work show that both qualitative and quantitative information of the swelling and erosion behavior of hydrophilic extended release (ER) matrix tablets may be obtained using this release cell and non-invasive magnetic resonance imaging (MRI) studies at different time-points during matrix dissolution. The tablet size, core size and the gel layer thickness of ER matrix formulations based on poly(ethylene oxide) have been determined. The dimensional changes as a function of time were found to correspond well to observations made with texture analysis (TA) methodology. Most importantly, the results of the present study show that both the erosion (displacement of the gel-dissolution media interface) and the swelling (decrease of dry tablet core size) proceed with a faster rate in radial than in axial direction using the rotating disk set-up. This behavior was attributed to the higher shear forces experienced in the radial direction. The results also indicate that front synchronization (constant gel layer thickness) is associated with the formation of an almost constant polymer concentration profile through the gel layer at different time-points.
2.	Bernin, Diana, 1979, et al. (author) Real time MRI to elucidate the functionality of coating films intended for modified release 2019 In: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 311-312, s. 117-124 Journal article (peer-reviewed)abstract Polymer films based on mixtures of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) have been widely used to coat pellets and tablets to modify the release profile of drugs. For three different EC/HPC films we used 1H and 19F MRI in combination with a designed release cell to monitor the drug, polymer and water in 5 dimensional (5D) datasets; three spatial, one diffusion or relaxation and a temporal dimension, in real time. We observed that the water inflow through the films correlated with the initiation of the dissolution of the drug in the tablet beneath the film. Leaching of the pore forming HPC further accelerated water penetration and resulted in a drug release onset after a hydrostatic pressure was generated below the film indicated by positional changes of the film. For the more permeable film, both water ingress and drug egress showed a large variability of release over the film surface indicating the heterogeneity of the system. Furthermore, the 1H diffusion dataset revealed the formation of a gel layer of HPC at the film surface. We conclude that the setup presented provides a significant level of details, which are not achieved with traditional methods.
3.	Caccavo, D., et al. (author) Effects of HPMC substituent pattern on water up-take, polymer and drug release: An experimental and modelling study 2017 In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 528:1-2, s. 705-713 Journal article (peer-reviewed)abstract The purpose of this study was to investigate the hydration behavior of two matrix formulations containing the cellulose derivative hydroxypropyl methylcellulose (HPMC). The two HPMC batches investigated had different substitution pattern along the backbone; the first one is referred to as heterogeneous and the second as homogenous. The release of both the drug molecule theophylline and the polymer was determined. Additionally, the water concentrations at different positions in the swollen gel layers were determined by Magnetic Resonance Imaging. The experimental data was compared to predicted values obtained by the extension of a mechanistic Fickian based model. The hydration of tablets containing the more homogenous HPMC batch showed a gradual water concentration gradient in the gel layer and could be well predicted. The hydration process for the more heterogeneous batch showed a very abrupt step change in the water concentration in the gel layer and could not be well predicted. Based on the comparison between the experimental and predicted data this study suggests, for the first time, that formulations with HPMC of different heterogeneities form gels in different ways. The homogeneous HPMC batch exhibits a water sorption behavior ascribable to a Fick's law for the diffusion process whereas the more heterogeneous HPMC batches does not. This conclusion is important in the future development of simulation models and in the understanding of drug release mechanism from hydrophilic matrices.
4.	Deshmukh, Shivprasad, et al. (author) Injection moulded controlled release amorphous solid dispersions: Synchronized drug and polymer release for robust performance 2020 In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 575 Journal article (peer-reviewed)abstract A study has been carried out to investigate controlled release performance of caplet shaped injection moulded (IM) amorphous solid dispersion (ASD) tablets based on the model drug AZD0837 and polyethylene oxide (PEO). The physical/chemical storage stability and release robustness of the IM tablets were characterized and compared to that of conventional extended release (ER) hydrophilic matrix tablets of the same raw materials and compositions manufactured via direct compression (DC). To gain an improved understanding of the release mechanisms, the dissolution of both the polymer and the drug were studied. Under conditions where the amount of dissolution media was limited, the controlled release ASD IM tablets demonstrated complete and synchronized release of both PEO and AZD0837 whereas the release of AZD0837 was found to be slower and incomplete from conventional direct compressed ER hydrophilic matrix tablets. The results clearly indicated that AZD0837 remained amorphous throughout the dissolution process and was maintained in a supersaturated state and hence kept stable with the aid of the polymeric carrier when released in a synchronized manner. In addition, it was found that the IM tablets were robust to variation in hydrodynamics of the dissolution environment and PEO molecular weight.
5.	Govender, Rydvikha, 1989, et al. (author) Enabling modular dosage form concepts for individualized multidrug therapy: Expanding the design window for poorly water-soluble drugs 2021 In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 602 Journal article (peer-reviewed)abstract Multidrug dosage forms (aka combination dosage forms, polypills, etc.) create value for patients through reduced pill burdens and simplified administration to improve adherence to therapy. Enhanced flexibility of multidrug dosage forms would provide further opportunities to better match emerging needs for individualized therapy. Through modular dosage form concepts, one approach to satisfy these needs is to adapt multidrug dosage forms to a wider variety of drugs, each with a variety of doses and release profiles. This study investigates and technically explores design requirements for extending the capability of modular multidrug dosage form concepts towards individualization. This builds on our recent demonstration of independent tailoring of dose and drug release, which is here extended towards poorly water-soluble drugs. The challenging design requirement of carrying higher drug loads in smaller volumes to accommodate multiple drugs at their clinical dose is here met regarding dose and release performance. With a modular concept, we demonstrate high precision (<5% RSD) in dose and release performance of individual modules containing felodipine or naproxen in Kollidon VA64 at both a wide drug loading range (5% w/w and 50% w/w drug) and a small module size (3.6 mg). In a forward-looking design-based discussion, further requirements are addressed, emphasizing that reproducible individual module performance is predictive of dosage form performance, provided the modules are designed to act independently. Therefore, efforts to incorporate progressively higher drug loads within progressively smaller module volumes will be crucial to extend the design window further towards full flexibility of future dosage forms for individualized multidrug therapy.
6.	Govender, Rydvikha, 1989, et al. (author) High Content Solid Dispersions for Dose Window Extension: A Basis for Design Flexibility in Fused Deposition Modelling 2020 In: Pharmaceutical Research. - : Springer Science and Business Media LLC. - 1573-904X .- 0724-8741. ; 37:1 Journal article (peer-reviewed)abstract Purpose: This study uses high drug content solid dispersions for dose window extension beyond current demonstrations using fused deposition modelling (FDM) to; i) accommodate pharmaceutically relevant doses of drugs of varying potencies at acceptable dosage form sizes and ii) enable enhanced dose flexibility via modular dosage form design concepts. Methods: FDM was used to generate ~0.5 mm thick discs of varying diameter (2–10 mm) from melt-extruded feedstocks based on 10% to 50% w/w felodipine in ethyl cellulose. Drug content was determined by UV spectroscopy and dispensing precision from printed disc mass. Results: Mean felodipine content was within ±5% of target values for all print volumes and compositions including contents as high as ~50% w/w. However, poor dispensing precision was evident at all print volumes. Conclusions: In pursuit of dose flexibility, this successful demonstration of dose window extension using high content solid dispersions preserves FDM design flexibility by maintaining applicability to drugs of varying potencies. The achieved uniformity of content supports the application of varying content solid dispersions to modular dosage form concepts to enhance dose flexibility. However, poor dispensing precision impedes its utilisation until appropriate compatibility between FDM hardware and materials at varying drug contents can be attained.
7.	Govender, Rydvikha, 1989, et al. (author) Independent tailoring of dose and drug release via a modularized product design concept for mass customization 2020 In: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 12:8, s. 1-24 Journal article (peer-reviewed)abstract Independent individualization of multiple product attributes, such as dose and drug release, is a crucial overarching requirement of pharmaceutical products for individualized therapy as is the unified integration of individualized product design with the processes and production that drive patient access to such therapy. Individualization intrinsically demands a marked increase in the number of product variants to suit smaller, more stratified patient populations. One established design strategy to provide enhanced product variety is product modularization. Despite existing customized and/or modular product design concepts, multifunctional individualization in an integrated manner is still strikingly absent in pharma. Consequently, this study aims to demonstrate multifunctional individualization through a modular product design capable of providing an increased variety of release profiles independent of dose and dosage form size. To further exhibit that increased product variety is attainable even with a low degree of product modularity, the modular design was based upon a fixed target dosage form size of approximately 200 mm3 comprising two modules, approximately 100 mm3 each. Each module contained a melt-extruded and molded formulation of 40% w/w metoprolol succinate in a PEG1500 and Kollidon® VA64 erodible hydrophilic matrix surrounded by polylactic acid and/or polyvinyl acetate as additional release rate-controlling polymers. Drug release testing confirmed the generation of predictable, combined drug release kinetics for dosage forms, independent of dose, based on a product’s constituent modules and enhanced product variety through a minimum of six dosage form release profiles from only three module variants. Based on these initial results, the potential of the reconfigurable modular product design concept is discussed for unified integration into a pharmaceutical mass customization/mass personalization context.
8.	Govender, Rydvikha, 1989, et al. (author) Therapy for the individual: Towards patient integration into the manufacturing and provision of pharmaceuticals 2020 In: European Journal of Pharmaceutics and Biopharmaceutics. - : Elsevier BV. - 1873-3441 .- 0939-6411. ; 149, s. 58-76 Research review (peer-reviewed)abstract Individualized therapy with pharmaceutical products aims to elicit predictable and optimized treatment responses from specific patients. Doing so requires production platforms and technology capable of tailoring products to individual patient needs. However, despite recent manufacturing innovations and key technologies on the rise, e.g. continuous manufacturing and additive manufacturing (3D printing), the prevailing production paradigm employed in the pharmaceutical industry is mass production. Although mass production is efficient and cost-effective, it is typically based on a ‘one-size-fits-all’ product concept and lacks the flexibility and agility required to fully meet the needs of the individual patient. Indeed, we present data that confirm a suspected major imbalance between the recent medical evolution underpinning personalized/precision medicine and the recent advances in the associated manufacturing technologies. In this context we target the needs of the individual as a main driver for pharmaceutical products which support individualized therapy. We particularly address that a wider integration of critical patient dimensions into the manufacture and provision of pharmaceutical products is pivotal for enabling a patient-centric and efficient mass customization-based production paradigm. Here, we present a critical review of the area and its inherent challenges which aims to clarify key design requirements for establishing mass customization opportunities. Through primary sources of scientific information for individualized therapies, patient needs are captured, analysed, and conceptualized. This summarized set of key drivers provides the basis for a proposed patient-centric framework of requirements for use in design of product and production platforms for mass customization. The extent to which emerging pharmaceutical manufacturing technologies satisfy key individual patient needs is explored through a high-level assessment against the proposed patient-centric framework, with special attention paid to oral dosage forms. Altogether this holistic review and position paper, with its constituent steps, reveals major gaps in the evolution of Product-Process-Production approaches and solutions required for producing affordable individualized/personalized pharmaceuticals that respond to the needs and demands of the individual patient. Lastly, in a brief commentary and outlook, we suggest key research directions for closing gaps and addressing manufacturing technology challenges. We also articulate the importance of tackling them in a holistic, integrated way, together with challenges in product individualization and personalization.
9.	Kaunisto, Erik, et al. (author) A mechanistic modelling approach to polymer dissolution using magnetic resonance microimaging 2010 In: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 147:2, s. 232-241 Journal article (peer-reviewed)abstract In this paper a computationally efficient mathematical model describing the swelling and dissolution of a polyethylene oxide tablet is presented. The model was calibrated against polymer release, front position and water concentration profile data inside the gel layer, using two different diffusion models. The water concentration profiles were obtained from magnetic resonance microimaging data which, in addition to the previously used texture analysis method, can help to validate and discriminate between the mechanisms of swelling, diffusion and erosion in relation to the dissolution process. Critical parameters were identified through a comprehensive sensitivity analysis, and the effect of hydrodynamic shearing was investigated by using two different stirring rates. Good agreement was obtained between the experimental results and the model. (C) 2010 Elsevier B.V. All rights reserved.
10.	Kaunisto, Erik, et al. (author) Mechanistic modelling of drug release from a polymer matrix using magnetic resonance microimaging. 2013 In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 1879-0720 .- 0928-0987. ; 48:4-5, s. 698-708 Journal article (peer-reviewed)abstract In this paper a new model describing drug release from a polymer matrix tablet is presented. The utilization of the model is described as a two step process where, initially, polymer parameters are obtained from a previously published pure polymer dissolution model. The results are then combined with drug parameters obtained from literature data in the new model to predict solvent and drug concentration profiles and polymer and drug release profiles. The modelling approach was applied to the case of a HPMC matrix highly loaded with mannitol (model drug). The results showed that the drug release rate can be successfully predicted, using the suggested modelling approach. However, the model was not able to accurately predict the polymer release profile, possibly due to the sparse amount of usable pure polymer dissolution data. In addition to the case study, a sensitivity analysis of model parameters relevant to drug release was performed. The analysis revealed important information that can be useful in the drug formulation process.
11.	Mcgowan, Asmaa, et al. (author) Injectable Biodegradable Silica Depot for Controlled Subcutaneous Delivery of Antisense Oligonucleotides with beyond Monthly Administration 2023 In: Molecular Pharmaceutics. - : AMER CHEMICAL SOC. - 1543-8384 .- 1543-8392. ; 21:1, s. 143-151 Journal article (peer-reviewed)abstract Single-stranded antisense oligonucleotides (ASOs) are typically administered subcutaneously once per week or monthly. Less frequent dosing would have strong potential to improve patient convenience and increase adherence and thereby for some diseases result in more optimal therapeutic outcomes. Several technologies are available to provide sustained drug release via subcutaneous (SC) administration. ASOs have a high aqueous solubility and require relatively high doses, which limits the options available substantially. In the present work, we show that an innovative biodegradable, nonporous silica-based matrix provides zero-order release in vivo (rats) for at least 4 weeks for compositions with ASO loads of up to about 100 mg/mL (0.5 mL injection) without any sign of initial burst. This implies that administration beyond once monthly can be feasible. For higher drug loads, substantial burst release was observed during the first week. The concentrations of unconjugated ASO levels in the liver were found to be comparable to corresponding bolus doses. Additionally, infusion using a minipump shows a higher liver exposure than SC bolus administration at the same dose level and, in addition, clear mRNA knockdown and circulating protein reduction comparable to SC bolus dosing, hence suggesting productive liver uptake for a slow-release administration.
12.	Nyström, Lina, et al. (author) In Vitro and In Vivo Performance of Pickering Emulsion-Based Powders of Omega-3 Polyunsaturated Fatty Acids 2024 In: Molecular Pharmaceutics. - : American Chemical Society. - 1543-8384 .- 1543-8392. ; 21:2, s. 677- Journal article (peer-reviewed)abstract Omega-3 polyunsaturated fatty acids (n-3 PUFA) are essential nutrients for human health and have been linked to a variety of health benefits, including reducing the risk of cardiovascular diseases. In this paper, a spray-dried powder formulation based on Pickering emulsions stabilized with cellulose nanocrystals (CNC) and hydroxypropyl methylcellulose (HPMC) has been developed. The formulation was compared in vitro and in vivo to reference emulsions (conventional Self-Emulsifying Drug Delivery System, SEDDS) to formulate n-3 PUFA pharmaceutical products, specifically in free fatty acid form. The results of in vivo studies performed in fasted dogs showed that Pickering emulsions reconstituted from powders are freely available (fast absorption) with a similar level of bioavailability as reference emulsions. In the studies performed with dogs in the fed state, the higher bioavailability combined with slower absorption observed for the Pickering emulsion, compared to the reference, was proposed to be the result of the protection of the n-3 PUFAs (in free fatty acid form) against oxidation in the stomach by the solid particles stabilizing the emulsion. This observation was supported by promising results from short-term studies of chemical stability of powders with n-3 PUFA loads as high as 0.8 g oil/g powder that easily regain the original emulsion drop sizes upon reconstitution. The present work has shown that Pickering emulsions may offer a promising strategy for improving the bioavailability and stability as well as providing an opportunity to produce environmentally friendly (surfactant free) and patient-acceptable solid oral dosage forms of n-3 PUFA in the free fatty acid form.
13.	Olsson, Martina, 1996, et al. (author) Multiscale X-ray imaging and characterisation of pharmaceutical dosage forms 2023 In: International Journal of Pharmaceutics. - 0378-5173 .- 1873-3476. ; 642 Journal article (peer-reviewed)abstract A correlative, multiscale imaging methodology for visualising and quantifying the morphology of solid dosage forms by combining ptychographic X-ray computed nanotomography (PXCT) and scanning small- and wide-angle X-ray scattering (S/WAXS) is presented. The methodology presents a workflow for multiscale analysis, where structures are characterised from the nanometre to millimetre regime. Here, the method is demonstrated by characterising a hot-melt extruded, partly crystalline, solid dispersion of carbamazepine in ethyl cellulose. Characterisation of the morphology and solid-state phase of the drug in solid dosage forms is central as this affects the performance of the final formulation. The 3D morphology was visualised at a resolution of 80 nm over an extended volume through PXCT, revealing an oriented structure of crystalline drug domains aligned in the direction of extrusion. Scanning S/WAXS showed that the nanostructure is similar over the cross section of the extruded filament, with minor radial changes in domain sizes and degree of orientation. The polymorphic forms of carbamazepine were qualified with WAXS, showing a heterogeneous distribution of the metastable forms I and II. This demonstrates the methodology for multiscale structural characterization and imaging to enable a better understanding of the relationships between morphology, performance, and processing conditions of solid dosage forms.
14.	Tajarobi, Farhad, 1971, et al. (author) Dissolution Rate Enhancement of Parabens in PEG Solid Dispersions and Its Influence on the Release from Hydrophilic Matrix Tablets 2011 In: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 1520-6017 .- 0022-3549. ; 100:1, s. 275-283 Journal article (peer-reviewed)abstract The dissolution rate of a homologous series of parabens and their dispersions inPEG 4x103 was examined. In light of these measurements, the release behavior of thesubstances from extended release hydrophilic matrix tablets based on PEO 5x106 was studied.Tablet release was examined for matrices comprising either a physical mixture of PEG, paraben,and PEO, or a solid solution of each paraben in PEG, incorporated in the PEO matrix.Considerable increase of the dissolution rate for the eutectic and in particular solid solutionform of the parabens was observed. The hydration rate of all matrices, as well as polymer release,was the same. The release rate of methyl, ethyl, and butyl parabens in solid solution form wassimilar to that of their crystalline form. However, the release rate of the solid solution form ofpropyl paraben was higher than that of its crystalline form, especially in the initial part of therelease. The results indicate that all parabens crystallized in the gel layer of the solid solutionformulations upon the process of tablet dissolution. This was proposed to be an effect ofdifferences in the dissolution and crystallization kinetics of the parabens.
15.	Tajarobi, Farhad, 1971, et al. (author) Simultaneous probing of swelling, erosion and dissolution by NMR-microimaging – Effect of solubility of additives on HPMC matrix tablets 2009 In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 37:2, s. 89-97 Journal article (peer-reviewed)abstract Extensive studies of extended release tablets based on hydrophilic polymers have illuminated severalaspects linked to their functionality. However, in some respects key factors affecting the mechanismsof release are yet unexplored. In the present study, a novel NMR-microimaging method has been usedto study the influence of the solubility of additives in extended release hydroxypropyl methylcellulose(HPMC) matrix tablets. During the course of the tablet dissolution the movement of the swelling anderosion fronts were studied simultaneously to the release of both polymer and additives. Moreover,the focused beam reflectance measurement (FBRM) technology was for the first time assessed for bothrelease and dissolution rate studies of poorly soluble particles. The studied formulations comprised solelyHPMC, 40% HPMC and 60% mannitol (Cs = 240 mg/ml) and 40% HPMC and 60% dicalcium phosphate (DCP)(Cs = 0.05 mg/ml). The dissolution rate of the tablets was highest for the HPMC/mannitol formulation,followed by HPMC/DCP and plain HPMC tablet. A contrasting order was found regarding the degree andkinetics of swelling. The results were interpreted in light of how the mass transport in the gel layer isinfluenced by the solubility of additives. A mechanistic model, considering osmotic pressure gradient andthe effective diffusion of the dissolution medium in the gel is proposed.
16.	Tajarobi, Farhad, 1971, et al. (author) The Impact of Dose and Solubility of Additives on the Release from HPMC Matrix Tablets-Identifying Critical Conditions 2009 In: Pharmaceutical Research. - : Springer Science and Business Media LLC. - 1573-904X .- 0724-8741. ; 26:6, s. 1496-1503 Journal article (peer-reviewed)abstract Purpose. The dissolution of HPMC matrix tablets containing different amounts of highly soluble(mannitol) or poorly soluble (dicalcium phosphate, DCP) was studied to deduce the parameters criticalto release robustness.Methods. The release of HPMC and additives was studied using a modified USP II method at two paddlestirring rates, 50 and 125 rpm, at HPMC content varying from 15% to 100%.Results. At HPMC contents between 30% and 35% a critical point was identified and found crucial to therelease from the HPMC/mannitol tablets. Below this point the matrix rapidly disintegrated in a non robustmanner. At higher HPMC contents the mannitol release became increasingly diffusion controlled withmaintained matrix integrity. The release robustness was lower for HPMC/DCP than HPMC/mannitoltablets at high HPMC contents, however, lacking critical points. The critical point was interpreted as thepercolation threshold for HPMC and differences explained in terms of water transport into the matrix.Conclusion. The release robustness was lower for formulations with additives of low solubility having anerosion controlled release than for additives with higher solubility and a diffusion controlled release.However, for additives creating a steep osmotic pressure gradient, an HPMC content above thepercolation threshold becomes vital for maintaining the release robustness.
17.	Tajarobi, Farhad, 1971, et al. (author) The influence of crystallization inhibition of HPMC and HPMCAS on model substance dissolution and release in swellable matrix tablets 2011 In: European Journal of Parenteral and Pharmaceutical Sciences. - 1740-6277 .- 0964-4679. ; 78, s. 125-133 Journal article (peer-reviewed)abstract Poorly soluble compounds are mainly released in particulate form from swellable matrixtablets. If the bioavailability of the drug substance is limited to dissolution, it can be advantageous toformulate the dosage form in a way, which promotes release of molecular form of the drug. In thisstudy, the solid state and dissolution behaviour of amorphous solid dispersions of a model crystallinesubstance, butylparaben in HPMC and HPMCAS was investigated. In addition, the suitability of HPMCASboth as effective solid solution carrier and as extended release matrix forming polymer was examined.The release from all systems investigated showed extended release capacity with release similar tomatrix erosion. However, a detailed study of the factors affecting the release mechanism revealed thatupon hydration, the model substance crystallized in the gel layer of the HPMC based formulation,whereas it remained in amorphous form in the HPMCAS tablets. In the case of HPMCAS formulationthis effect was attributed to i) the ability of this polymer to keep the model substance in asupersaturated state and ii) the very slow matrix hydration, resulting in a steep concentration gradientof the drug substance and a short diffusion path through the matrix into the dissolution bulk.
18.	Trotzig, Charlotte, et al. (author) Structure and mobility in water plasticized poly(ethylene oxide) 2007 In: Polymer. - : Elsevier BV. - 0032-3861. ; 48:11, s. 3294-3305 Journal article (peer-reviewed)abstract The change in structure and mobility of poly(ethylene oxide) (PEO) containing 2 wt% of fumed silica and the water self-diffusion coefficient in concentrated PEO-water systems have been investigated at room temperature in the water weight fraction, w(w) range 0-0.50 w/w. Pulsed field gradient nuclear magnetic resonance was used to measure the self-diffusion coefficients. Structure and mobility properties of PEO were measured with differential scanning calorimetry as well as with positron annihilation lifetime spectroscopy. The largest reduction of the degree of crystallinity of PEO was observed when ww was increased from 0.13 w/w to 0.50 w/w. Moreover, water induced relaxation of the PEO segments in the amorphous phase, which seemed to have been strained by the crystals during compression molding. The water self-diffusion coefficient increased logarithmically with increased water content below water weight fractions in the amorphous phase of 0.30 w/w and the water molecules were obstructed by the crystalline phase.
19.	Trotzig, Charlotte, et al. (author) Transport properties of water in hydroxypropyl methylcellulose 2009 In: European Polymer Journal. - : Elsevier BV. - 0014-3057. ; 45:10, s. 2812-2820 Journal article (peer-reviewed)abstract The relation between the self-diffusion coefficient, D-self, of water and the free volume hole size, V-h, has been investigated in a hydroxypropyl methylcellulose (HPMC)-water system in the water content range 0.08-0.36 w/w, at room temperature. Furthermore, the thermal properties of the water in the HPMC-water system, as measured with differential scanning calorimetry (DSC) and the tensile storage, E', and tensile loss, E '', moduli, of the HPMC-water systems, as determined with dynamic mechanical analysis (DMA), have been probed. Pulsed-field gradient nuclear magnetic resonance (PFG NMR) was used to measure the D-self of water and positron annihilation lifetime spectroscopy (PALS) was used to measure the ortho-Positronium (o-Ps) lifetime in the HPMC-water system. The glass transition temperature of the HPMC was found to be reduced by the water to room temperature in the water content range 0.10-0.15 w/w. The relation between ln D-self of water and the inverse free volume hole size of the HPMC-water system was non-linear. Furthermore, the PALS measurements showed that molecular water co-existed with water clusters in the HPMC-water system. (C) 2009 Elsevier Ltd. All rights reserved.
20.	Vaitukaitis, Povilas, et al. (author) Water transport and absorption in pharmaceutical tablets – a numerical study 2020 In: Meccanica. - : Springer Science and Business Media LLC. - 1572-9648 .- 0025-6455. ; 55:2, s. 421-433 Journal article (peer-reviewed)abstract The quality of a coated pharmaceutical tablet can be strongly affected by the interactions of water droplets with the porous substrate during processes such as coating process. Three different mechanisms co-exist in the coating process: water spreading, absorption and evaporation. Disentangling the fundamental understanding of these phenomena can therefore be crucial for achieving a higher quality of the products (e.g. a longer shelf-life of the tablets) and for controlling the efficiency of the process. This paper aims to investigate the spreading and absorption mechanisms after droplet impingement on a tablet using a Lattice-Boltzmann methodology. Our numerical results (droplet height and spreading, penetration depth and absorbed volume) are in a good agreement with experimental data and numerical simulations available in the literature. In particular, the spreading phase is characterised by the capillary spreading time scale, as confirmed by previous studies. In contrast to previous studies, we find that the absorption process begins at times shorter than the capillary spreading time but with a different power-law in the absorbed volume. We explain this behaviour through a modified Washburn law that takes into account three-dimensional effects. Our data can be used as a benchmark to test novel mathematical models.
21.	Viridén, Anna, 1977, et al. (author) Influence of Substitution Pattern on Solution Behavior of Hydroxypropyl Methylcellulose 2009 In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:3, s. 522-529 Journal article (peer-reviewed)abstract Industrially produced hydroxypropyl Me cellulose (HPMC) is a chem. heterogeneous material, and it is thus difficult to predict parameters related to function on the basis of the polymer's av. chem. values. In this study, the soln. behavior of 7 HPMC batches was correlated to the mol. wt., degree of substitution, and substituent pattern. The initial onset of phase sepn., so-called clouding, generally followed an increased av. mol. wt. and degree of substitution. However, the slope of the clouding curve was affected by the substitution pattern, where the heterogeneously substituted batches had very shallow slopes. Further investigations showed that the appearance of a shallow slope of the clouding curve was a result of the formation of reversible polymer structures, formed as a result of the heterogeneous substituent pattern. These structures grew in size with temp. and concn. and resulted in an increase in the viscosity of the solns. at higher temps.
22.	Viridén, Anna, 1977, et al. (author) Release of theophylline and carbamazepine from matrix tablets - Consequences of HPMC chemical heterogeneity 2011 In: European Journal of Mineralogy. - : Elsevier BV. - 0935-1221. ; 78:3, s. 470-479 Journal article (peer-reviewed)abstract The release of theophylline and carbamazepine from matrix tablets composed of microcrystalline cellulose, lactose and hydroxypropyl methylcellulose (HPMC) was studied. The aim was to investigate the effect of different substituent heterogeneities of HPMC on the drug release from matrix tablets composed of either 35% or 45% HPMC. The release of the poorly soluble carbamazepine was considerably affected by the HPMC heterogeneity, and the time difference at 80% drug release was more than 12 h between the formulations of different HPMC batches. This was explained by slower polymer erosion of the heterogeneous HPMC and the fact that carbamazepine was mainly released by erosion. In addition, results from magnetic resonance imaging showed that the rate of water transport into the tablets was similar. This explained the comparable results of the release of the sparingly soluble theophylline from the two formulations even though the polymer erosion and the swelling of the tablets were considerably different. Thus, it can be concluded that the drug release was highly affected by the substituent heterogeneity, especially in the case of carbamazepine, which was released mainly by erosion. (C) 2011 Elsevier B.V. All rights reserved.
23.	Wanselius, Marcus (author) Development and characterization of an in vitro method for interaction studies between polymers and pharmaceuticals : Aiding in the development of new drug delivery systems 2023 Doctoral thesis (other academic/artistic)abstract Polymers are a group of macromolecules used in formulations of pharmaceuticals, one example being the delivery system DC Bead™. Further, some of the most abundant and for drug delivery important constituents of the subcutaneous tissue are charged polymers (polyelectrolytes), e.g. collagen, hyaluronic acid, and chondroitin sulfate. The interactions between these subcutaneous polyelectrolytes and drug molecules are believed to heavily affect the transport and absorption of subcutaneously injected drugs. To increase the understanding of how the interactions between subcutaneous polymers and drug molecules affect the pharmaceutical behavior in subcutaneous tissue, we developed a new microfluidic-based platform. The platform is used to study interactions between polyelectrolytes and drug molecules, and can beyond the investigation of subcutaneous interactions be used to develop polyelectrolyte-based microgel formulations. In this thesis, the microfluidic method denoted “Microfluidic chip for interactions studies” (MIS) is presented, and the design, validation, and several examples of usage are described. The method which is based on microfluidic instrumentation, utilizes spherical microgels created using different types of polymers/polyelectrolytes. These hydrogels collapse when experiencing attractive interactions with drug molecules making it possible to investigate drug binding by studying the volume change of the microgels. We prove that the interactions are strongly affected by charges both on the gel networks and the drug molecules. Further, the aggregation behavior of drugs in a polyelectrolyte-rich environment is studied in detail. Results show that both a strong aggregation behavior and a high charge on the drugs may affect the transport through a network of polyelectrolytes. The behavior of drugs in subcutaneous polyelectrolyte-rich environments such as hyaluronic acid networks, can partly explain bioavailability and absorption rates of the drugs in vivo. Several potential drug delivery systems in the form of microgels were investigated together with both small amphiphilic molecules and larger peptides exhibiting a wide range of physicochemical properties. The results indicate a possibility of delivering large amounts of drug in low volumes of microgel suspensions but with varying release times, ranging from seconds to days. The MIS was able to provide information about the interactions in a large number of polyelectrolyte-drug systems. The studies were performed in a highly efficient and cost-effective way, with experiments being mostly automated. This makes it a suitable method for rapid screening experiments in the development of new microgel formulations, and as part of larger studies utilizing several different methods to better understand and predict the behavior and absorption profiles of potential subcutaneously administrated drugs.
24.	Wanselius, Marcus, et al. (author) Evaluation of microfluidic in vitro method developed for behavior prediction of pharmaceuticals in subcutaneous tissue Other publication (other academic/artistic)
25.	Wanselius, Marcus, et al. (author) Microfluidics platform for studies of peptide - polyelectrolyte interaction 2022 In: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 621 Journal article (peer-reviewed)abstract Subcutaneous injection is one of the most common approaches for administering biopharmaceuticals unsuitable for oral delivery. However, there is a lack of methods to predict the behavior of biopharmaceuticals within the extracellular matrix of the subcutaneous tissue. In this work, we present a novel miniaturized microfluidic-based in vitro method able to investigate interactions between drug molecules and the polymers of the subcutaneous extracellular matrix. To validate the method, microgels consisting of, respectively, covalently cross-linked hy-aluronic acid, polyacrylic acid, and commercially available DC BeadTM, were exposed to three model substances: cytochrome C, protamine sulfate and amitriptyline hydrochloride. These components were chosen to include systems with widely different physiochemical properties (charge, size, self-assembly, etc.) The experimental results were compared with theoretical predictions from a gel model developed earlier. The results show that the method is suitable as a rapid screening method for automated, large-scale, probing of interactions between biopolymers and drug molecules, with small consumption of material.
26.	Wanselius, Marcus, et al. (author) Responsive Hyaluronic Acid-Ethylacrylamide Microgels Fabricated Using Microfluidics Technique 2022 In: Gels. - : MDPI. - 2310-2861. ; 8:9 Journal article (peer-reviewed)abstract Volume changes of responsive microgels can probe interactions between polyelectrolytes and species of opposite charges such as peptides and proteins. We have investigated a microfluidics method to synthesize highly responsive, covalently crosslinked, hyaluronic acid microgels for such purposes. Sodium hyaluronate (HA), pre-modified with ethylacrylamide functionalities, was crosslinked in aqueous droplets created with a microfluidic technique. We varied the microgel properties by changing the degree of modification and concentration of HA in the reaction mixture. The degree of modification was determined by H-1 NMR. Light microscopy was used to investigate the responsiveness of the microgels to osmotic stress in aqueous saline solutions by simultaneously monitoring individual microgel species in hydrodynamic traps. The permeability of the microgels to FITC-dextrans of molecular weights between 4 and 250 kDa was investigated using confocal laser scanning microscopy. The results show that the microgels were spherical with diameters between 100 and 500 mu m and the responsivity tunable by changing the degree of modification and the HA concentration. Microgels were fully permeable to all investigated FITC-dextran probes. The partitioning to the microgel from an aqueous solution decreased with the increasing molecular weight of the probe, which is in qualitative agreement with theories of homogeneous gel networks.

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