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Layered Silicate-Alginate Composite Particles for the pH-Mediated Release of Theophylline

Layered Silicate-Alginate Composite Particles for the pH-Mediated Release of Theophylline

Nandi, Uttom ORCID: 0000-0003-1777-3862, Trivedi, Vivek ORCID: 0000-0001-9304-9214, Douroumis, Dennis ORCID: 0000-0002-3782-0091, Mendham, Andrew P. and Coleman, Nichola J. (2020) Layered Silicate-Alginate Composite Particles for the pH-Mediated Release of Theophylline. Pharmaceuticals, 13 (8):182. ISSN 1424-8247 (Online) (doi:

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Numerous natural and synthetic clay minerals have proven to be excellent drug carriers for high drug-loaded and sustained release formulations due to their considerable ion exchange, adsorption, and swelling capacities. Moreover, the synthetic smectite clays have added advantages in terms of compositional purity and controlled cation exchange capacity in comparison to natural clays. This study involves the intercalation of theophylline (TP) in a synthetic clay, Laponite® (LP), followed by the inclusion of the resulting intercalates into sodium alginate (SA) beads to achieve pH-controlled drug release. Maximum intercalated drug incorporation of 68 mg/g was obtained by ion exchange at pH 1.2 and confirmed by an increase in basal spacing of the clay from 12.9 to 15.5 Å. TP release from the binary LP-TP intercalates in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was found to be 40% and 70%, respectively. LP-TP particles were also incorporated in an SA matrix via polymer crosslinking using CaCl2(aq) to improve the pH selective release. The ternary polymer-clay-drug composite particles effectively prevented the release of TP at low pH in SGF and resulted in sustained release in SIF, with 40% dissolution within 120 min.

Item Type: Article
Additional Information: © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Uncontrolled Keywords: Laponite; alginate; composite particles; theophylline; pH-dependent release
Subjects: R Medicine > RM Therapeutics. Pharmacology
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > School of Science (SCI)
Last Modified: 11 Aug 2020 12:38

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