Thermodynamics of clay-drug complex dispersions: Isothermal titration calorimetry and high-performance liquid chromatography
- Author:
Totea ANA-MARIA
1
;
Sabin JUAN
;
Dorin IRINA
;
Hemming KARL
;
Laity R. PETER
;
Conway R. BARBARA
;
Waters LAURA
;
Asare-Addo KOFI
Author Information
1. School of Applied Sciences
- Keywords:
Clay-drug complex dispersions;
Magnesium aluminium silicate;
Diltiazem hydrochloride;
Isothermal titration calorimetry;
High performance liquid chromatography
- From:
Journal of Pharmaceutical Analysis
2020;10(1):78-85
- CountryChina
- Language:Chinese
-
Abstract:
An understanding of the thermodynamics of the complexation process utilized in sustaining drug release in clay matrices is of great importance. Several characterisation techniques as well as isothermal calo-rimetry were utilized in investigating the adsorption process of a model cationic drug (diltiazem hy-drochloride, DIL) onto a pharmaceutical clay system (magnesium aluminium silicate, MAS). X-ray powder diffraction (XRPD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and optical microscopy confirmed the successful formation of the DIL-MAS complexes. Drug quantification from the complexes demonstrated variable behaviour in the differing media used with DIL degrading to desacetyl diltiazem hydrochloride (DC-DIL) in the 2 M HCl media. Here also, the authors report for the first time two binding processes that occurred for DIL and MAS. A competitor binding model was thus proposed and the thermodynamics obtained suggested their binding processes to be enthalpy driven and entropically unfavourable. This information is of great importance for a formulator as care and consideration should be given with appropriate media selection as well as the nature of binding in complexes.
