Design of rolipram-loaded nanoparticles: comparison of two preparation methods

The aim of the present work was to investigate the preparation of nanoparticles as a potential drug carrier and targeting system for the treatment of inflammatory bowel disease. Rolipram was chosen as the model drug to be incorporated within nanoparticles. Pressure homogenization-emulsification (PHE) with a microfluidizer or a modified spontaneous emulsification solvent diffusion method (SESD) were used in order to select the most appropriate preparation method. Poly(epsilon-caprolactone) has been used for all preparations. The drug loading has been optimized by varying the concentration of the drug and polymer in the organic phase, the surfactants (polyvinyl alcohol, sodium cholate) as well as the volume of the external aqueous phase. The rolipram encapsulation efficiency was high (>85%) with the PHE method in all cases, whereas with the SESD method encapsulation efficiencies were lower (<40%) when lower surfactant concentrations and reduced volume of aqueous phase were used. Release profiles were characterized by a substantial initial burst release with the PHE method (25-35%) as well as with the SESD method (70-90%). A more controlled release was obtained after 2 days of dissolution with the PHE method (70-90%), no further significant drug release was observed with the SESD method.