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Estimation of the percolation thresholds in acyclovir hydrophilic matrix tablets.
Eur J Pharm Biopharm. 2006 Nov; 64(3):336-42.EJ

Abstract

The principles of percolation theory were applied to design controlled release matrix tablets containing acyclovir. This statistical theory studies disordered or chaotic systems where the components are randomly distributed in a lattice. The application of this theory to study the release and hydration rate of hydrophilic matrices allows to explain the changes in release and hydration kinetics of swellable matrix type controlled delivery systems. The objective of the present paper is to estimate the percolation threshold of HPMC K4M in matrices of acyclovir and to apply the obtained result to the design of hydrophilic matrices for the controlled delivery of this drug. Matrix tablets have been prepared using acyclovir as drug and HPMC K4M as matrix forming material, employing five different excipient/drug percentages. Dissolution studies were carried out using the paddle method. Water uptake measurements were performed using a modified Enslin apparatus. In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to the excipient volumetric fraction at time zero plus initial porosity was studied. According to percolation theory, the critical points observed in dissolution and water uptake studies can be attributed to the excipient percolation threshold. This threshold was situated between between 20.76% and 26.41% v/v of excipient plus initial porosity. The knowledge of the percolation threshold of the components of the matrix formulations contributes to improve their design. First, reducing the time to market and second, increasing their robustness when they are prepared at Industrial scale, avoiding the formulation in the nearby of the percolation threshold.

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Authors+Show Affiliations

Fuertes I
Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Seville, Spain. inmafuercri@terra.es
Miranda A
No affiliation info available
Millán M
No affiliation info available
Caraballo I
No affiliation info available

MeSH

AcyclovirAntiviral AgentsChemistry, PharmaceuticalDelayed-Action PreparationsExcipientsHypromellose DerivativesKineticsMethylcelluloseModels, ChemicalNonlinear DynamicsPorositySolubilityTabletsWater

Pub Type(s)

Journal Article

Language

eng

PubMed ID

16876392

Citation

Fuertes, Inmaculada, et al. "Estimation of the Percolation Thresholds in Acyclovir Hydrophilic Matrix Tablets." European Journal of Pharmaceutics and Biopharmaceutics : Official Journal of Arbeitsgemeinschaft Fur Pharmazeutische Verfahrenstechnik E.V, vol. 64, no. 3, 2006, pp. 336-42.
Fuertes I, Miranda A, Millán M, et al. Estimation of the percolation thresholds in acyclovir hydrophilic matrix tablets. Eur J Pharm Biopharm. 2006;64(3):336-42.
Fuertes, I., Miranda, A., Millán, M., & Caraballo, I. (2006). Estimation of the percolation thresholds in acyclovir hydrophilic matrix tablets. European Journal of Pharmaceutics and Biopharmaceutics : Official Journal of Arbeitsgemeinschaft Fur Pharmazeutische Verfahrenstechnik E.V, 64(3), 336-42.
Fuertes I, et al. Estimation of the Percolation Thresholds in Acyclovir Hydrophilic Matrix Tablets. Eur J Pharm Biopharm. 2006;64(3):336-42. PubMed PMID: 16876392.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Estimation of the percolation thresholds in acyclovir hydrophilic matrix tablets. AU - Fuertes,Inmaculada, AU - Miranda,Antonia, AU - Millán,Mónica, AU - Caraballo,Isidoro, Y1 - 2006/07/28/ PY - 2006/03/03/received PY - 2006/05/18/revised PY - 2006/05/18/accepted PY - 2006/8/1/pubmed PY - 2007/1/6/medline PY - 2006/8/1/entrez SP - 336 EP - 42 JF - European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V JO - Eur J Pharm Biopharm VL - 64 IS - 3 N2 - The principles of percolation theory were applied to design controlled release matrix tablets containing acyclovir. This statistical theory studies disordered or chaotic systems where the components are randomly distributed in a lattice. The application of this theory to study the release and hydration rate of hydrophilic matrices allows to explain the changes in release and hydration kinetics of swellable matrix type controlled delivery systems. The objective of the present paper is to estimate the percolation threshold of HPMC K4M in matrices of acyclovir and to apply the obtained result to the design of hydrophilic matrices for the controlled delivery of this drug. Matrix tablets have been prepared using acyclovir as drug and HPMC K4M as matrix forming material, employing five different excipient/drug percentages. Dissolution studies were carried out using the paddle method. Water uptake measurements were performed using a modified Enslin apparatus. In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to the excipient volumetric fraction at time zero plus initial porosity was studied. According to percolation theory, the critical points observed in dissolution and water uptake studies can be attributed to the excipient percolation threshold. This threshold was situated between between 20.76% and 26.41% v/v of excipient plus initial porosity. The knowledge of the percolation threshold of the components of the matrix formulations contributes to improve their design. First, reducing the time to market and second, increasing their robustness when they are prepared at Industrial scale, avoiding the formulation in the nearby of the percolation threshold. SN - 0939-6411 UR - https://www.unboundmedicine.com/medline/citation/16876392/Estimation_of_the_percolation_thresholds_in_acyclovir_hydrophilic_matrix_tablets_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0939-6411(06)00139-1 DB - PRIME DP - Unbound Medicine ER -