© 2019, Istanbul Medipol University. All rights reserved.Development and in vitro evaluation of dexketoprofen trometamol (DT)-loaded nanosized and controlled release drug delivery system was aimed in this study. DT-loaded Eudragit® RL 100 polymeric nanoparticles were prepared using nano spray-dryer. Structures of DT-loaded polymeric nanoparticles were elucidated by particle size and zeta potential measurements, shape and surface imaging, thermal analysis, X-ray diffraction and FT-IR and 1H-NMR determinations. The particle size of the formulations was measured in the range of 475.5-798.7 nm. The droplet size distribution of the formulations was observed in the range of 0.349-0.395. These results showed that nanosized and monodispersed formulations were prepared. The drug content was found to be in the range of 35-38%. DT-loaded particles exhibited nanostructured and spherical shape. In vitro release studies showed extended release of DT. Release was found to fit Korsmeyer-Peppas kinetic model using DDSolver software program. Depending on the in vitro test results obtained, formulations developed in this study seem to extend the release of DT from the nanoparticles prepared which are promising for prolonging analgesic activity.