RESUMEN
Alginate-metal-complexes of Ca, Ba, Zn, Fe and Al were prepared in the form of beads. The preparation was based on the ionotropic method to obtain blank beads (unloaded) and beads loaded with tiaprofenic acid. IR spectra of blank beads, drug loaded beads and physical mixtures of the drug with the blank beads were recorded. The comparison of these spectra, especially in the region of hydroxyl group, implied chiral interactions between the drug and the complexes. Additionally, the drug was released from the loaded beads in aqueous phosphate buffer solutions (PBS) at pH = 7.4. Chiral HPLC was used to determine the enantiomeric excess, % ee, of the released drug. The determined % ee values indicated chiral interactions between tiaprofenic acid and alginate-metal-complexes. However, various mathematical models were used to simulate the release kinetics for each enantiomer. The metal content of Na, Ca, Ba, Zn, Fe and Al in the studied materials was measured using atomic absorption spectroscopy.
RESUMEN
It is demonstrated that (2)H NMR in chiral liquid crystalline solvents can be used to measure enantiomeric excesses using exchangeable deuterons in alcohols. This is performed in a trivial way at low temperature (260-270 K) where a slow exchange regime was reached. Among the various alcohols used to explore the possibilities of this technique, an unusually large isotopic effect on molecular orientation between two isotopomers has been observed.