Physicochemical study on microencapsulation of hydroxypropyl-β-cyclodextrin in dermal preparations

Objective: To investigate the effect of hydroxypropyl-β-cyclodextrin (HP-β-CD) concentration on the physicochemical properties of the sunscreen agents, namely oxybenzone (Oxy), octocrylene (Oct), and ethylhexyl-methoxy-cinnamate (Cin), in aqueous solution and cream formulations. Methods: The inclusion complexes of sunscreen agents with hydroxypropyl-β-cyclodextrin (HP-β-CD) in aqueous solution and solid phase were studied by UV-vis spectrophotmetery, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and 13C-NMR techniques. The photodegradation reaction of the sunscreen agents' molecules in lotion was explored using UV-vis spectrophotometry and high-performance liquid chromatography (HPLC). Results: The formation of the inclusion complexes was confirmed experimentally using DSC, SEM, and 13C-NMR. The results of spectrophotometric and HPLC studies have shown that the inclusion complexation with HP-β-CD has the potential to enhance the photostability of the selected sunscreen agents in lotion. HPLC results indicated that HP-β-CD has approximately increases the photostability of Oct by six- to eightfold. Moreover, the presence of HP-β-CD in lotion controlled the isomerization process of Cin to a certain degree, which was found to be a function of the amount of HP-β-CD added. Conclusions: It has been demonstrated that the photostability of the tested sunscreen agents has been enhanced upon forming inclusion complexes with HP-β-CD in lotion. The results of this study demonstrate that HP-β-CD can be utilized as photostabilizer additive for enhancing the photostability of the sunscreen agents' molecules.