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Complications in investigations of the swelling of hydrogel matrices due to the presence of trapped gas

TitleComplications in investigations of the swelling of hydrogel matrices due to the presence of trapped gas
Publication TypeJournal Article
Year of Publication1998
AuthorsFyfe, CA, Blazek, AI
JournalJournal of Controlled Release
Volume52
Pagination221-225
Date PublishedMar
Type of ArticleArticle
ISBN Number0168-3659
KeywordsBEHAVIOR, CONTROLLED RELEASE, DRUG-RELEASE, GEL, HPMC TABLETS, hydrophilic matrix tablet, hydroxypropylmethylcellulose, IMAGING METHOD, LAYER, MECHANISMS, NMR imaging, RELEASE DOSAGE FORMS, swelling
Abstract

In recent studies, NMR imaging has been used to investigate the swelling of hydroxypropylmethylcellulose (HPMC) tablets and to determine polymer concentration distributions in the swollen matrix. The total amount of polymer in the system was computed from these distributions and was up to 35% greater than the known weight of HPMC in the tablet. This deviation was traced to the presence of air bubbles in the swollen matrix which occupied a significant volume previously assumed to be occupied by polymer and water. When the air in the tablet was removed by vacuum, the swollen gel contained no evidence of air bubbles and the calculated total polymer weights from the HPMC distributions were equal to the amount of HPMC in the tablet. (C) 1998 Elsevier Science B.V.

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