Chitosan-alginate (CS/ALG) nanoparticles were prepared by ionotropic pre-gelation of an alginate core followed by chitosan polyelectrolyte complexation, nifedipine was chosen as a model drug. Morphology and structure characterization of nanoparticles were investigated by transmission electron microscope (TEM) and Fourier transform infrared spectra (FTIR), respectively. The diameter of the nanoparticles was about 20-50 nm, suitable for uptake within the gastrointestinal tract due to their nanosize range and mucoadhesive properties. A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of nifedipine in nanoparticulate dosage forms. In addition, the delivery behavior of nifedipine from nanoparticles was studied. Nifedipine released from chitosan-alginate nanoparticles was 26.52% at pH1.5, 69.69% at pH6.8 and 56.50% at pH7.4 within 24hour. This suggests that the release of nifedipine from nanoparticles was pH-responsive. Quick release occurred in simulated intestinal fluid (SIF, pH6.8) and phosphate buffer solution (pH7.4), while the release was slow in simulated gastric fluid (SGF, pH1.5). The release profile was characterized by an initial burst effect in three media, followed by a continuous and controlled release phase, the drug release mechanism from polymer was due to Fickian diffusion.
Keywords: chitosan; drug delivery system; hydrogels; nanoparticles; nifedipine.