Dr. Margarita Valero, Associate Professor, Department of Physical Chemistry, Facultad de Farmacia, Universidad de Salamanca, Spain

Title: Pluronic F127 polymeric micelles as drug carriers for pH controlled release of Salicylate

Abstract: Polymeric micelles are very attractive candidates to help formulate poorly water soluble drugs, improving their solubility, stability, circulation time and ultimately bioavailability. Pluronics, triblock copolymers of poly(ethylene oxide)-poly(propylene oxide) poly(ethylene oxide) have been widely used for this purpose; they offer a number of advantages, amongst which, low toxicity, selectivity, commercial availability, low cost and variability of architecture. There is little rationale behind the formulations, due to a blatant shortage of structural data on the nanoscopic core-shell structures formed by the drug/polymer complexes. Determining the partitioning of the drug into the micelles and the locus of solubilisation is however paramount as it is directly related to drug loading capacity and release profile. The research aims at achieving a detailed characterisation of these key-parameters as a function of salicylate charge, modulated by the pH, using a combination of Small-angle neutron scattering and physico-chemical techniques, including spectroscopy, in order to finally provide the basis of a formulation rationale. In addition, we propose to impart responsiveness to the system by using ß-cyclodextrin to trigger and control the release of the drug, using a recognition mechanism between the central PPO block and ß-cyclodextrins. This process offers a very novel type of trigger, and also leads to a competitive complexation mechanism between the 3 species (drug, polymer, ß-cyclodextrin), which are fascinating to explore from a fundamental point of view.

Keywords: cyclodextrin, salicylate, partition, controlled release, SANS, NMR, fluorescence