Swelling and polymer erosion for poly(ethylene oxide) tablets of different molecular weights polydispersities

Körner, Anna; Larsson, Anette; Andersson, A.; Piculell, Lennart

doi:10.1002/jps.21892

Cited by 33 publications

(16 citation statements)

References 18 publications

(33 reference statements)

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“…Since no systematic studies relating the polymer release rate to the intrinsic viscosity have been performed for hydrophilic matrix tablets other than PEO [ 7 , 14 , 16 ] one can ask if the model presented is also valid for other polymers. It is not obvious that this should be the case, since PEO is special in the sense that it is a synthetic semi-crystalline linear polymer.…”

Section: Introductionmentioning

confidence: 99%

Influence of Different Polymer Types on the Overall Release Mechanism in Hydrophilic Matrix Tablets

Körner¹,

Piculell

Iselau

et al. 2009

Molecules

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The effect of three different types of polymer chain structures on the polymer release from hydrophilic matrix tablets was investigated by comparing a synthetic semi-crystalline linear polymer (PEO), a branched amorphous polysaccharide (dextran) and an amorphous substituted cellulose derivative (HPMC). The polymer release rates for tablets containing mixtures of high and low molecular weight grades in different ratios were determined by using a modified USP II method and a SEC-RI chromatography system. The results showed that independent of polymer type: (i) plots of the release versus time had similar shapes, (ii) the release of long and short polymer chains was equal and no fractionation occurred during the release and (iii) the release rate could be related to the average intrinsic viscosity of the polymer mixtures. This confirms the hypothesis that the release rate can be related to a constant viscosity on the surface of the hydrophilic matrix tablet and that it is valid for all the investigated polymers.

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Section: Introductionmentioning

confidence: 99%

Influence of Different Polymer Types on the Overall Release Mechanism in Hydrophilic Matrix Tablets

Körner¹,

Piculell

Iselau

et al. 2009

Molecules

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“…The process of erosion or polymer dissolution under defined fluid dynamics conditions from a swollen polymer gel layer has been envisioned as polymer disentanglement from the polymer gel followed by polymer diffusion through the diffusion layer to the bulk solution (16,17). The polymer dissolution process can be described by the following equation (16,17):…”

Section: Water Uptake and Erosionmentioning

confidence: 99%

“…where m p is the remaining polymer weight at time t, m 0 is the dry tablet weight at t=0, k is a constant dependent on the average diffusion coefficient (D ave ) of the polymer in the diffusion layer, A is the surface area of the swelling tablet exposed to the dissolution medium, and C d is the disentanglement or critical concentration at which polymer chains start to disentangle from the polymer gel under the influence of external shear. The C d values correspond to polymer solutions with a certain threshold viscosity/viscoelasticity high enough to resist the external shear (17)(18)(19). Under the same shear conditions, the C d values of the matrix tablets prepared from the various grades of sodium alginate are a function, in part, of the rheological properties of the polymer solutions and would be constant during the polymer erosion process (17).…”

Section: Water Uptake and Erosionmentioning

confidence: 99%

“…The C d values correspond to polymer solutions with a certain threshold viscosity/viscoelasticity high enough to resist the external shear (17)(18)(19). Under the same shear conditions, the C d values of the matrix tablets prepared from the various grades of sodium alginate are a function, in part, of the rheological properties of the polymer solutions and would be constant during the polymer erosion process (17). The erosion data of the four grades of sodium alginate as shown in Fig.…”

Section: Water Uptake and Erosionmentioning

confidence: 99%

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Inter-Grade and Inter-Batch Variability of Sodium Alginate Used in Alginate-Based Matrix Tablets

Shao¹,

Buckner

Block

2014

AAPS PharmSciTech

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The purpose of this study is to characterize the inter-grade and inter-batch variability of sodium alginate used in the formulation of matrix tablets. Four different grades and three batches of one grade of sodium alginate were used to prepare matrix tablets. Swelling, erosion, and drug release tests of sodium alginate matrix tablets were conducted in a USP dissolution apparatus. Substantial differences in swelling and erosion behavior of sodium alginate matrix tablets were evident among different viscosity grades. Even different batches of the same grade exhibit substantial differences in the swelling and erosion behavior of their matrix tablets. The erosion behavior of sodium alginate matrix tablets can be partly explained by their rheological properties (both apparent viscosity and viscoelasticity) in solution. Sodium alginate with higher apparent viscosity and viscoelasticity in solution show slower erosion rate and higher swelling rate. Compacts prepared from grades or batches with higher viscosity and higher viscoelasticity show slower drug release. For grades or batches with similar apparent viscosities, apparent viscosities of sodium alginate solution at low concentration alone are not sufficient to predict the functionality of sodium alginate in matrix tablets. Viscoelastic properties of sodium alginate solutions at one high concentration corresponding to the polymer gel state, may be suitable indicia of the extended release behavior of sodium alginate matrix tablets.

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“…This layer acts as a diffusional and erosional barrier to control further uptake of water into the tablet, and to limit the rate of drug dissolution and release. In simple terms, water soluble drugs are extended by diffusion through the hydrated polymer layer and poorly soluble drugs by matrix erosion [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

The Properties of HPMC:PEO Extended Release Hydrophilic Matrices and their Response to Ionic Environments

Hu¹,

Chen

Mantle

et al. 2016

Pharm Res

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Abbreviations: Hydroxypropyl methylcellulose (HPMC), polyethylene oxide (PEO), Magnetic resonance imaging (MRI). Abstract PurposeInvestigate the extended release behaviour of compacts containing mixtures of hydrophilic HPMC and PEO in hydrating media of differing ionic strengths. MethodsThe extended release behaviour of various HPMC:PEO compacts was investigated using dissolution testing, confocal microscopy and magnetic resonance imaging, with respect to polymer ratio and ionic strength of the hydrating media. ResultsIncreasing HPMC content gave longer extended release times, but a greater sensitivity to high ionic dissolution environments. Increasing PEO content reduced this sensitivity. The addition of PEO to a predominantly HPMC matrix reduced release rate sensitivity to high ionic environments. Confocal microscopy of early gel layer development showed the two polymers appeared to contribute independently to gel layer structure whilst together forming a coherent and effective diffusion barrier. There was some evidence that poorly swollen HPMC particles added a tortuosity barrier to the gel layer in high ionic strength environments, resulting in prolonged extended release. MRI provides unique, non-invasive spatially resolved information from within the HPMC:PEO compacts that furthers our understanding of USP 1 and USP 4 dissolution data. ConclusionsConfocal microscopy and MRI data show that combinations of HPMC and PEO have advantageous extended release properties, in comparison with matrices containing a single polymer.

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Swelling and polymer erosion for poly(ethylene oxide) tablets of different molecular weights polydispersities

Cited by 33 publications

References 18 publications

Influence of Different Polymer Types on the Overall Release Mechanism in Hydrophilic Matrix Tablets

Influence of Different Polymer Types on the Overall Release Mechanism in Hydrophilic Matrix Tablets

Inter-Grade and Inter-Batch Variability of Sodium Alginate Used in Alginate-Based Matrix Tablets

The Properties of HPMC:PEO Extended Release Hydrophilic Matrices and their Response to Ionic Environments

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