Incorporation of liposoluble vitamins within PVP microparticles using supercritical antisolvent precipitation

Graphical abstract: In this work, the incorporation of two liposoluble vitamins, α-tocopherol (TOC) and menadione (MEN), within polyvinylpyrrolidone (PVP) microparticles using Supercritical Antisolvent (SAS) coprecipitation is proposed. In order to control microspheres’ size and morphology, the effect of SAS main process parameters, such as polymer/vitamin ratio, operating pressure, temperature and overall concentration, was investigated. In the case of the system PVP/TOC, composite microparticles with mean diameters in the range 1.69-4.08μm were successfully produced; for the system PVP/MEN, composite microparticles with mean diameters in the range 2.64-5.09μm were obtained, depending on the operating conditions. Powders were characterized using UV-vis spectroscopy to calculate the vitamin entrapment efficiency and vitamin dissolution rate, FT-IR to identify possible interactions between the polymer and the vitamin, HPLC to verify the vitamin integrity, and GC to calculate the residual solvent. The analyses revealed that the drug entrapment efficiency was about 53% for TOC and 50% for MEN, and that the vitamin dissolution rate of the coprecipitates was between 3 and 3.5 times faster than the dissolution rate of unprocessed vitamins, respectively.