Formulation and characterization of novel lipid-based drug delivery systems containing polymethacrylate polymers as solid carriers for sustained release of simvastatin

Abstract

Formulation of lipid-based drug delivery systems is recognized as a promising strategy to increase bioavailability of simvastatin (SV). The purpose of this study was to formulate advantageous lipid-based drug delivery systems for pH-controlled release of SV using polymethacrylate polymers (Eudragit®) as carriers. Liquid SV-loaded self-microemulsifying drug delivery systems (SMEDDS), composed of oils (PEG 300 oleic glycerides, propylene glycol monocaprylate, or propylene glycol monolaurate), surfactant (PEG 400 caprylic/capric glycerides) and cosurfactant (PEG-15 hydroxystearate), were characterized in terms of emulsification time, robustness to dilution, and droplet size. To enable targeted SV release at desired pH, the liquid SMEDDS were mixed with solid carriers, Eudragit® L100 and/or Eudragit® S100. The resulting gel-like lipid-based drug delivery systems were transparent and ductile, and exhibited viscoelastic rheological properties. In vitro dissolution data indicated sustained SV release in pH medium corresponding to distal ileum. The simulation results revealed that sustained SV release from the designed systems is expected to increase SV bioavailability. Overall, our results demonstrate that sustained-release drug delivery systems, composed of liquid SMEDDS and polymethacrylate carriers (Eudragit® polymers), have the potential to enhance oral bioavailability of drugs with preferred absorption site in the pH medium corresponding to distal ileum.