title: Simultaneous quantification of drug release and erosion from hypromellose hydrophilic matrices.
abstract: Hypromellose, HPMC, is frequently used to control drug release from matrix tablet formulations. Drug is released by a combination of diffusion through and erosion of, the matrix and is usually measured invitro by separate dissolution and swelling/erosion studies. The present study was designed to measure matrix erosion, polymer dissolution and drug release kinetics and their inter-relationship in a single experiment using a phenol-sulphuric acid assay to quantify dissolved HPMC alongside spectrophotometrical analysis of drug release. HPMC-based matrix tablets were manufactured containing two drugs at various drug:HPMC ratios. Drug release was determined and the degree of erosion was calculated by gravimetry. Results showed the matrix erosion rate and drug release were dependent on HPMC content and drug solubility, as expected. It was also apparent that the erosion rate was directly related to the drug release kinetics and comparative analysis of both matrix erosion techniques showed a high level of correlation. The findings show that a simple and inexpensive assay can be utilised not only to quantify HPMC but can also be used to calculate the degree of erosion of tablet matrices, negating the need for a separate study and providing a simplified practical approach that may be of use during product optimization.
authors.affiliation: Pharmacy and Pharmaceutical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom.
authors.forename: Muhammad U
authors.initials: MU
authors.lastname: Ghori
authors.affiliation: Pharmacy and Pharmaceutical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom.
authors.forename: Gidion
authors.initials: G
authors.lastname: Ginting
authors.affiliation: Pharmacy and Pharmaceutical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Smith
authors.affiliation: Pharmacy and Pharmaceutical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom. Electronic address: b.r.conway@hud.ac.uk.
authors.forename: Barbara R
authors.initials: BR
authors.lastname: Conway
mesh_terms: D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004058:Diffusion; D004337:Drug Carriers; D005480:Flurbiprofen / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D065347:Hypromellose Derivatives / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D019800:Phenol / Q000737:chemistry; D012995:Solubility; D013464:Sulfuric Acids / Q000737:chemistry; D013607:Tablets; D013678:Technology, Pharmaceutical / Q000379:methods; D013806:Theophylline / Q000737:chemistry*
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D013464:Sulfuric Acids; D013607:Tablets; D019800:Phenol; D065347:Hypromellose Derivatives; D005480:Flurbiprofen; D013806:Theophylline; C033158:sulfuric acid
keywords: Drug release; Hydrophilic matrix; Hydroxypropyl methylcellulose; Matrix erosion; Phenol-sulphuric acid assay