Photostability of Loratadine Inclusion Complexes with Natural Cyclodextrins

Abstract

The purpose of this study was to evaluate the photostability of inclusion complexes of the histamine antagonist loratadine (LORA) with $\alpha$-, $\beta$-, and $\gamma$-cyclodextrins (CDs). Accordingly, binary drug-CD complexes were prepared using the coevaporation method at 1 : 1, 1 : 2, and 1 : 3 stoichiometric ratios, which were characterized by thermal analysis. Subsequently, solutions of the complexes at 500 μg mL ⁻¹in HCl 0.1 M were subjected to irradiation in a photostability chamber for 12 hours, and the content of the remaining active ingredient was quantified by means of high-performance liquid chromatography. It is possible to observe the presence of two products originating from photodegradation (P1 and P2), which were identified in solutions of loratadine with $\alpha$- and $\beta$-CD. By means of statistical analysis, we conclude that the drug: $\alpha$-CD and drug: $\gamma$-CD (1 : 1) complexes proved to be more efficient in the photostability assay, obtaining a nonsignificant level of degradation and full recovery of LORA.