Preparation and solid state properties of cyclodextrin complexes of selected drug molecules (original) (raw)
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Journal of Pharmaceutical Sciences, 1991
The solid complex of chlorambucil (CHL) and heptakis-(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) has been isolated from ethanol and analyzed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffractometry. The carbonyl stretching band of the complex, observed in the FTIR spectrum, was shifted to higher frequency, suggesting that intermolecular hydrogen bonds between CHL molecules are broken when the complex is formed. Since no melting endotherm was observed for CHL when the DSC thermogram of the complex was obtained, the crystal lattice of the compound must be disrupted upon complexation. X-ray diffraction patterns of the inclusion complex were different from those of the physical mixture and contained no peaks corresponding to free CHL, thus indicating the formation of a new crystalline material. The 1:1 CHL:β-cyclodextrin (β-CD) complex was isolated from aqueous solution at 3 °C. Results of analyses using FTIR and DSC were similar to those obtained with the CHL:DIMEB complex. The X-ray diffraction patterns of the complex suggest that its degree of crystallinity is higher than that of the CHL:DIMEB complex.
2018
The inclusion complexes of many organic ligands, drugs or metal ions, in cyclodextrins (CDs) represent a class of the simplest supramolecular systems widely studied for the last several decades. The increasing interest for their investigation arises from both a theoretical and an applicative points of view. Considering the first one, their study contributes to the understanding of the molecular recognition and molecular interactions, emphasizing the role of different structural factors. From a more practical purpose, the encapsulation of different drugs in the CD cavity produces an increase in the solubility (Brewster & Loftsson, 2007) and allows for a more controlled oral, parental, ocular, nasal or rectal drug release (Challa et al., 2005). A special interest resides in the CDs potential as alternatives for conventional anti-obesity medications (Grunberger et al., 2007). The same goal is also realized using the supramolecular systems, such as hydrogels, obtained by the selfassembl...
1999
Abstract. The interaction in solution between 2,4-dichlorophenoxyacetic acid with α- and β-cyclodextrins was evaluated by phase solubility studies. Association constants were calculated by this technique. The stoichiometries were 1: 2 and 1: 1 for the α- and β-cyclodextrin complexes, respectively. In order to corroborate the complexation and the knowledge of structural aspects of the host: guest interaction, proton nuclear magnetic resonance (1H-NMR) spectroscopy was employed. The application of the continuous variation technique corroborated the calculated complex stoi-chiometries by solubility assays. Complementary NOE studies were applied in order to corroborate the proposed complex structures. Key words: solubility, 1H-NMR, stoichiometry, cyclodextrins 1.
Inclusion Complexes of Cyclodextrins with 4Amino1,8-Naphthalimides
Journal of Inclusion Phenomena and Macrocyclic Chemistry - J INCL PHENOM MACROCYCL CHEM, 2002
The formation of inclusion complexes between 4-amino-1,8-naphthalimides and cyclodextrins (CDs) was investigated. The naphthalimides used in the study were 4-amino-1,8-naphthalimide (I) and4-(2-phosphonoethylamino)-N-(2-phosphonoethyl)-1,8-naphthalimide,tetraethylester (II). The CDs employed were a-CD, ß-CD, ?-CD, HP-a-CD, HP-ß-CD andHP-?-CD (HP = hydroxypropyl). Evidence for complex formation was obtained from the changes in the fluorescence spectra of the dyes in the presence of increasing amounts of the CDs. The most striking changes were observed with HP-ß-CD and HP-?-CD. Treatment of the data using Benesi–Hildebrand plotswas consistent with a 1:1 inclusion model. The determined stabilityconstants were (Keq, M-1): 106 (I:HP-ß-CD, pH = 2.0), 193 (I:HP-ß-CD, pH = 7.0), 113 (I:HP-?-CD, pH = 7.0), 155(II:HP-ß-CD, pH = 2.0), 121 (II:HP-ß-CD,pH = 7.0), 301 (II:HP-?-CD, pH = 7.0). It can beconcluded that compound I forms a more stable complex with HP-ß-CD than with HP-?-CD. Compound II...