7 research outputs found
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Topotecan uptake and elution by drug eluting embolic beads
The in vitro loading and subsequent elution of topotecan (used to treat a variety of cancers) from drug-eluting beads (DEBs) was assessed, while evaluating the effects of selected physical attributes (size and compressibility
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Thermal stability assessment of alanine stereo-isomers using thermally stimulated current spectroscopy (TSC)
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Design and formulation of a novel polymer-based buccal film
The aim of this work was to develop a novel film for delivering amorphous drugs into the systemic circulation via the buccal mucosa. The advantage of the buccal mucosa over the sublingual, such as better systemic effects, has led to its exploration as a functional administration route [1]. Buccal formulations can be developed as films, freeze- dried wafers [2] which are suitable alternatives to deliver drugs promptly and safely
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Modelling of dosator operation for improved manufacturing performance
Purpose: To develop an improved mathematical model for the prediction of dose accuracy of Dosators - based upon the geometry of the machine in conjunction with measured flow properties of the powder.
Methods: A mathematical model has been created, based on a analytical method of differential slices - incorporating measured flow properties. The key flow properties of interest in this investigation were: flow function, effective angle of wall friction, wall adhesion, bulk density, stress ratio K and permeability. To simulate the real process and (very importantly) validate the model, a Dosator test-rig has been used to measure the forces acting on the Dosator during the filling stage, the force required to eject the dose and the dose weight.
Results: Preliminary results were obtained from the Dosator test-rig. Figure 1 [Omitted] shows the dose weight for different depths to the bottom of the powder bed at the end of the stroke and different levels of pre-compaction of the powder bed. A strong influence over dose weight arising from the proximity between the Dosator and the bottom of the powder bed at the end of the stroke and the conditions of the powder bed has been established.
Conclusions: The model will provide a useful tool to predict dosing accuracy and, thus, optimise the future design of Dosator based equipment technology ā based on measured bulk properties of the powder to be handled. Another important factor (with a significant influence) on Dosator processes, is the condition of the powder bed and the clearance between the Dosator and the bottom of the powder bed
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The impact of powder flowing properties on dosator filling system operation
Purpose: To study the impact of powder flow properties on dosator filling systems, with particular focus on improvements in dose weight accuracy and repeatability.
Method: This study evaluates a range of critical powder flow properties such as: flow function, cohesion, wall friction, adhesion to wall surfaces, density/compressibility data, stress ratio āKā and gas permeability. The characterisations of the powders considered in this study were undertaken using an annular shear cell using a sample size of 0.5 litres. This tester also incorporated the facility to measure bed expansion during shear in addition to contraction under consolidation forces. A modified Jenike type linear wall friction tester was used to develop the failure loci for the powder sample in conjunction with multiple wall samples (representing a variety of material types and surface finishes). Measurements of the ratio of applied normal stress versus lateral stress were determined using a piece of test equipment specifically designed for the purpose.
Results: The correct characterisation of powders and the incorporation of this data into the design of process equipment are recognised as critical for reliable and accurate operation. An example of one aspect of this work is the stress ratio āKā. This characteristic is not well understood or correctly interpreted in many cases ā despite its importance. Fig 1 [Omitted] (illustrates a sample of test data. The slope of the line gives the stress ratio in a uniaxial compaction system ā indicating the behaviour of the material under compaction during dosing processes.
Conclusions: A correct assessment of the bulk powder properties for a given formulation can allow prediction of: cavity filling behaviour (and hence dosage), efficiency of release from dosator, and strength and stability of extruded dose en route to capsule filling Influences over the effectiveness of dosator systems have been shown to be impacted upon by: bed pre-compaction history, gas permeability in the bed (with respect to local density effects), and friction effects for materials of construction for dosator
Design and photocatalytic ability of ordered mesoporous TiO2 thin films
Homogeneous and crack-free TiO2 films with templated mesoporosity were prepared by the dip coating technique using an evaporation-induced, self-assembly method. The synthesized mesoporous TiO2 films were characterized using SEM/TEM, BET and XRD techniques. Degradation reactions of methylene blue and crystal violet dyes were used to test the photocatalytic capability of mesoporous TiO2 films. The degradation kinetics of methylene blue and crystal violet were investigated over a broad range of initial concentrations of the organic dyes. The kinetic data were correlated with the specific surface area and thickness of mesoporous TiO2 films, as well as number of reaction cycles