Novel Eudragit® -based polymeric nanoparticles for sustained release of simvastatin

This paper reports on the development of nanoparticles aiming at the in vitro controlled release of simvastatin (SVT). The nanoparticles were prepared by the nanoprecipitation method with polymers Eudragit® FS30D (EDGFS) or Eudragit® NE30D (EDGNE). EDGFS+SVT nanoparticles showed mean size of 148.8 nm and entrapment efficiency of 76.4%, whereas EDGNE+SVT nanoparticles showed mean size of 105.0 nm and entrapment efficiency of 103.2%. Infrared absorption spectra demonstrated that SVT incorporated into the polymer matrix, especially EDGNE. Similarly, the differential scanning calorimeter (DSC) curve presented no endothermic peak of fusion, indicating that the system is amorphous and the drug is not in the crystalline state. The maintenance of SVT in the amorphous state may favors its solubilization in the target release sites. In the in vitro dissolution assay, the SVT incorporated into the EDGFS+SVT nanoparticles showed a rapid initial release, which may be related to the pH of the dissolution medium used. Regarding the EDGNE+SVT nanoparticles, the in vitro release occurred in a bimodal behavior, i.e., an initial "burst" followed by a sustained delivery, with the kinetics of drug release following Baker-Lonsdale's mathematical model. All these features suggest the nanoparticulate system's potential to modulate SVT delivery and enhance its bioavailability.

Pharmaceutical composition of valsartan: beta-cyclodextrin: physico-chemical characterization and anti-hypertensive evaluation.

Valsartan, a water-insoluble drug, is mainly used in the treatment of hypertension albeit with reduced oral bioavailability. The aim of work was to develop a valsartan:beta-cyclodextrin (VAL:beta-CD) pharmaceutical composition in order to improve its water solubility and bioavailability. The VAL:beta-CD complexes were prepared by the kneading, solid dispersion and freeze-drying methods, of which the freeze-drying method (FDY) was found to be the best to prepare an inclusion complex. A physical mixture PM was also prepared. Complexes were characterized by thermal analysis, Fourier transformed-infrared (FTIR) spectroscopy, Powder X-ray diffractometry, intrinsic dissolution and NMR (2D-ROESY). Phase-solubility analysis showed A(L)-type diagrams with beta-cyclodextrin (beta-CD). Microcalorimetric titrations suggested the formation of 1:1 inclusion complex between VAL and beta-CD. The apparent stability constants K(1:1) calculated from phase-solubility plots were 165.4 M(-1) (298 K), 145.0 M(-1) (303 K) and 111.3 M(-1) (310 K). In vivo experiments in rats showed that reduction in arterial pressure for the FDY complex is better than with valsartan used alone. The better activity of FDY can be attributed to the higher solubility of valsartan after inclusion in the cyclodextrin cavity, as suggest by the intrinsic dissolution studies.