Pulmonary administration of inhalable nanoparticles (NPs) is an emerging area of interest. Dry powder inhalers may offer particular advantages for pulmonary administration of NPs. This article reviews research performed on the formulation of inhalable NPs as dry powder to achieve deep-lung deposition and enhance NP redispersibility. Moreover, the article summarizes up-to-date in vivo applications of inhalable NPs as dry powder inhalers.

Background: Effervescent inhalable nanoparticles (NPs) have previously been shown to be a promising alternative to conventional lung cancer treatment in animals. This study investigates the biodistribution of effervescent inhalable NPs after a single dose administration via pulmonary route in lung cancer-bearing mice. Methods & results: Whole-body autoradiography and confocal laser-scanning microscopy (CLSM) were used to investigate the distribution of inhalable NPs loaded in an effervescent microcarrier. Inhalable doxorubicin-loaded NPs were tagged with 14C for whole-body autoradiography, or with fluorescein isothiocyanate for CLSM imaging. After pulmonary delivery, NPs were widely disseminated in the lungs with a long retention time (24 h). The heart was radioactivity free at all time points of the study. CLSM images showed that inhalable NPs were taken up by cells and that doxorubicin was released to the cell nuclei. Conclusion: This is the first study to investigate the distribution of inhalable NPs in a lung cancer-bearing animal model. Inhalable NPs achieved deep lung deposition, were actively released from microcarrier particles, spread to different parts of the lung and released doxorubicin in vivo. These NP characteristics contribute to the efficacy of effervescent inhalable NPs as a lung cancer treatment.

The purpose of the present study was to investigate the effect of thermal-treating on the release of ibuprofen from the granules prepared using aqueous dispersions of Eudragit. To accomplish this goal, different formulations were prepared using wet granulation method containing two different types of Eudragit aqueous dispersions, RS30D, RL30D and Avicel as filler. Tablets were prepared using direct compression method. The prepared tablets were thermally treated at 50 and 70°C for 24 h. The drug release from tablets was assessed before and after thermal-treating. The results of release study showed that, thermally-treating the tablets at the temperatures higher than glass transition temperature (Tg) of the polymer can decrease the drug release from matrices. For mechanistic evaluation of the effect of thermal-treating, powder X-ray diffraction (XPD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), Fourier transform infrared (FT-IR) and helium pycnometer have been employed. The SEM graphs showed that the tablets have smoother surface with less porosity after thermal-treating. FT-IR spectra showed no change in the spectrum of thermally-treated tablet compared to control. In DSC graphs, no crystalline change was seen in the heat-treated samples of ibuprofen tablets, but decreased and widened peak size were related to the probable formation of solid solution of ibuprofen in Eudragit matrix. The results of helium pycnometer showed a significant decrease in the total porosity of some heat-treated samples. This study revealed the importance of thermal treating on the drug release from sustained release tablets containing Eudragit polymer.