title: Interference of 1:1 and 2:1 layered phyllosilicates as excipients with ranitidine.
abstract: As natural ingredients and excipients, kaolinite and talc were frequently studied for their interactions with drugs in pharmaceutical formulations. In this study, the uptake of ranitidine (RT) on these two minerals was studied under different physic-chemical conditions and the mechanism of RT uptake on these two minerals contrasted. Although the thermodynamic and kinetic RT uptake on these two minerals was similar and the RT uptake on both minerals were limited to the external surfaces only, drastic difference in RT uptake was found under different equilibrium solution pH and ionic strength conditions. As cation exchange process was strongly affected by solution pH and ionic strength, the RT uptake on kaolinite was dominated by cation exchange and electrostatic interactions, while the RT uptake on talc was more controlled by inter- and intra- molecular hydrogen bonding interactions. For kaolinite, the limiting factor for RT uptake was the specific surface area due to monolayer RT adsorption. In contract, multilayer RT uptake was found on talc surfaces. No matter which mechanism dominated RT uptake on these minerals, the interaction should not be neglected in pharmaceutical formulations should these minerals be used as additives and/or excipients.
authors.affiliation: Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing, 29 Xueyuan Road, Beijing 100083, China; Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144, USA; Department of Earth Science, National Cheng Kung University, Tainan 70101, Taiwan. Electronic address: li@uwp.edu.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Li
authors.affiliation: Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Fitzgerald
authors.affiliation: Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144, USA.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Albert
authors.affiliation: Department of Earth Science, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Wei-Teh
authors.initials: WT
authors.lastname: Jiang
mesh_terms: D000327:Adsorption; D000465:Algorithms; D005079:Excipients / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007616:Kaolin / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D009994:Osmolar Concentration; D011899:Ranitidine / Q000737:chemistry*; D055672:Static Electricity; D013627:Talc / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D005079:Excipients; D013627:Talc; D007616:Kaolin; D011899:Ranitidine
keywords: Cation exchange; Drug uptake; Excipient; Kaolinite; Sorption mechanism; Talc