Assessing the physical-chemical properties and stability of dapivirine-loaded polymeric nanoparticles

Nanocarriers may provide interesting delivery platforms for microbicide drugs and their characterization should be addressed early in development. Differently surface-engineered dapivirine-loaded, poly( epsilon-caprolactone) (PCL)-based nanoparticles (NPs) were obtained by nanoprecipitation using polyethylene oxide (PEO), sodium lauryl sulfate (SLS), or cetyltrimethylammonium bromide (CTAB) as surface modifiers. Physical-chemical properties of NP aqueous dispersions were evaluated upon storage at -20-40 degrees C for one year. NPs presented 170-200 nm in diameter, roundish-shape, low polydispersity index (<= 0.18), and high drug association efficiency (>= 97%) and loading (>= 12.7%). NPs differed in zeta potential, depending on surface modifier (PEO: -27.9 mV; SLS: -54.7 mV; CTAB: +42.4 mV). No interactions among formulation components were detected by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), except for SLS-PCL NPs. Colloidal properties of NPs were lost at -20 degrees C storage. Negatively charged NPs were stable up to one year at 5-40 degrees C; as for CTAB-PCL NPs, particle aggregation was observed from 30 to 90 days of storage depending on temperature. Colloidal instability affected the in vitro drug release of CTAB-PCL NPs after 360 days. In any case, no degradation of dapivirine was apparent. Overall, PEO-PCL and SLS-PCL NPs presented suitable properties as nanocarriers for dapivirine. Conversely, CTAB-PCL NPs require additional strategies in order to increase stability. (C) 2013 Elsevier B.V. All rights reserved.