Surface Treatment of Indomethacin Agglomerates with Eudragit

Edge activators and a polycationic polymer enhance the formulation of porous voriconazole nanoagglomerate for the use as a dry powder inhaler

PURPOSE

Voriconazole has both low aqueous solubility and stability. We hypothesize that designing voriconazole in the form of a nano powder inhaler at a geometric diameter within 1-5 μm will enhance its stability and solubility. Therefore, we prepared nanoagglomerates of voriconazole which will collapse in the lungs to reform the nanoparticles.

METHOD

The nanoparticles were formulated using both stearic acid and sodium deoxycholate as edge activators. Osmogenic polycation polyethyleneimine (PEI) was used to form agglomerates of controllable size.

RESULTS

Voriconazole nanoparticles and agglomerates showed a significant higher cumulative drug release than the pure powder (p < 0.05) with R(2 )=( )0.95. Small-sized particles were formed (353 nm), while their zeta potential was -30.7 mV. The agglomerates were 2.7 μm in size and their zeta potential was -20.9 mV. The formation of porous agglomerates was confirmed using a transmission electron microscope. Cascade impactor was used to evaluate the aerodynamic properties of the nanoparticles and the agglomerates. The aerodynamic characterization of the nanoparticles and the agglomerates resulted in a significant smaller mass median aerodynamic diameter (MMAD) (p < 0.05) and higher fine particle dose (FPD) (p < 0.01), fine particle fraction (FPF) (p < 0.01), and total emitted dose (TED) (p < 0.01) than the pure powder.

CONCLUSION

The results suggest that using the combination of edge activators and diluted polycationic polymer solution provides porous voriconazole nanoagglomerates in a respirable range, which is proved successful in enhancing both the deposition and the dissolution of water insoluble-drugs in the lung.

Surface self-diffusion of an organic glass

Surface self-diffusion has been measured for an organic glass for the first time. The flattening of 1000 nm surface gratings of liquid indomethacin occurs by viscous flow at 12 K or more above the glass transition temperature and by surface diffusion at lower temperatures. Surface diffusion is at least 10(6) times faster than bulk diffusion, indicating a highly mobile surface. Our data suggest that surface diffusion is the leading mechanism of surface evolution for organic glasses at micrometer to nanometer length scales.

Study of the Effect of Stirring on Foam Formation from Various Aqueous Acrylic Dispersions

Acrylic polymers in aqueous dispersions are very often used to prepare coating suspensions which contain insoluble particles. The mixing of the pigment suspension and the polymer dispersion is a very important step in the preparation of the liquid. The stirring can cause precipitation of the polymer and foam formation. Foam formation from different Eudragit dispersions was evaluated in this study. A high-speed mixer was applied and the foam and liquid phases formed were separated. The changes in concentration of the polymer in the two phases were studied by FT-IR with a horizontal attenuated total reflection (HATR) accessory. The presence of shape-holding foam can be detected at very different rates of stirring. The most intensive foam formation was detected for Eudragit FS 30 D. The Eudragit RL 30 D dispersion was the least sensitive to high-speed mixing. The relative content of the polymer in the foam was higher than that in the liquid. This is indicated by the accumulation of surface-active agent on the surface of the bubbles formed in the foam. This phenomenon differed considerably for the various dispersions. An exact knowledge of the foam formation from aqueous acrylic dispersions is very important in order to determine the parameters of mixing and the quantity of antifoaming agent.