Solubilisation of salicylate in F127 micelles: Effect of pH and temperature on morphology and interactions with cyclodextrin

Abstract The present work examines the behavior of salicylic acid (SAL)-loaded F127 micelles as drug nanocarriers for controlled release by means of interaction with 2,6-dimethyl-β-cyclodextrin (DIMEB) in the intestine at basic pH = 7–8, both important excipients, of pharmaceutical formulations. The results show that acidic pH (pH = 1) strongly increases the partitioning of SAL in F127 micelles compared to neutral pH, due to the drug being in its molecular form. Fluorescence spectroscopy and small-angle neutron scattering show that free and SAL-loaded F127 micelles transition to cylindrical micelles at pH = 1 and high temperatures (37 °C). Micelles loaded with SAL are disrupted by DIMEB to a higher extent than at pH = 7 at physiological temperature. This study reveals that F127 could be a valuable nanocarrier for intestine controlled release of SAL. Taken together, our results highlight the importance of water in the structure of the micelles and their interaction with DIMEB, and bring precious insights into the mechanisms that regulate drug loading and release in complex formulations.