Susanna Abrahmsén-Alami

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Extensive studies of extended release tablets based on hydrophilic polymers have illuminated several aspects linked to their functionality. However, in some respects key factors affecting the mechanisms of release are yet unexplored. In the present study, a novel NMR-microimaging method has been used to study the influence of the solubility of additives in(More)
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 critical to release robustness. The release of HPMC and additives was studied using a modified USP II method at two paddle stirring rates, 50 and 125 rpm, at HPMC content varying(More)
One of the drawbacks with solid solution systems is their thermodynamic instability in solution. Considering the release of these systems from extended-release formulations, in particular swellable matrix tablets, a successful tablet formulation can be regarded as a composition able to maintain the molecular state of the poorly soluble crystalline drug(More)
The aim of the current work was to explore continuous dry powder mixing and direct compression for manufacturing of extended release (ER) matrix tablets. The study was span out with a challenging formulation design comprising ibuprofen compositions with varying particle size and a relatively low amount of the matrix former hydroxypropyl methylcellulose(More)
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(More)
Industrially produced hydroxypropyl methylcellulose (HPMC) is a chemically heterogeneous material, and it is thus difficult to predict parameters related to function on the basis of the polymer's average chemical values. In this study, the solution behavior of seven HPMC batches was correlated to the molecular weight, degree of substitution, and substituent(More)
Four different hydrophilic matrix formulations based on hydroxypropyl methylcellulose (HPMC) were investigated for erosion properties in vivo. Three formulations contained a fixed amount of HPMC (40%) with varying proportions of two HPMC grades with different molecular weights (Methocel K100LV and K4M), and a fourth formulation contained a lower amount of(More)
The aim of this study was to investigate the ability of ultrasound (US) techniques to monitor the swelling behaviour of hydrophilic polymer matrix tablets. Tablets were prepared from hydroxypropyl methylcellulose (HPMC) and polyethylene oxide (PEO) polymers. The movement of the eroding front was investigated with ultrasound scanning techniques on each(More)
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(More)
The dissolution rate of a homologous series of parabens and their dispersions in PEG 4 × 10(3) was examined. In light of these measurements, the release behavior of the substances from extended release hydrophilic matrix tablets based on PEO 5 × 10(6) was studied. Tablet release was examined for matrices comprising either a physical mixture of PEG, paraben,(More)