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Intercalated theophylline-smectite hybrid for pH-mediated delivery

Intercalated theophylline-smectite hybrid for pH-mediated delivery

Trivedi, Vivek ORCID: 0000-0001-9304-9214, Nandi, Uttom ORCID: 0000-0003-1777-3862, Maniruzzaman, Mohammed and Coleman, Nichola J. (2018) Intercalated theophylline-smectite hybrid for pH-mediated delivery. Drug Delivery and Translational Research, 8 (6). pp. 1781-1789. ISSN 2190-393X (Print), 2190-3948 (Online) (doi:

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On the basis of their large specific surface areas, high adsorption and cation exchange capacities, swelling potential and low toxicity, natural smectite clays are attractive substrates for the gastric protection of neutral and cationic drugs. Theophylline is an amphoteric xanthine derivative that is widely used as a bronchodilator in the treatment of asthma and chronic obstructive pulmonary disease. This study considers the in vitro uptake and release characteristics of the binary theophylline-smectite system. The cationic form of theophylline was readily ion exchanged into smectite clay at pH 1.2 with a maximum uptake of 67±2 mg g−1. Characterisation of the drug-clay hybrid system by powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy confirmed that the theophylline had been exclusively intercalated into the clay system in an amorphous form. The drug remained bound within the clay under simulated gastric conditions at pH 1.2; and the prolonged release of approximately 40% of the drug was observed in simulated intestinal fluid at pH 6.8 and 7.4 within a 2-h timeframe. The incomplete reversibility of the intercalation process was attributed to chemisorption of the drug within the clay lattice. These findings indicate that smectite clay is a potentially suitable vehicle for the safe passage of theophylline into the duodenum. Protection from absorption in the stomach and subsequent prolonged release in the small intestine are advantageous in reducing fluctuations in serum concentration which may impact therapeutic effect and toxicity

Item Type: Article
Additional Information: © The Author(s) 2018. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Uncontrolled Keywords: Smectite, Montmorillonite, Theophylline, Intercalation, Drug release
Subjects: Q Science > QC Physics
Q Science > QD Chemistry
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > School of Science (SCI)
Last Modified: 19 Jun 2020 17:11

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