Drug powders with tunable wettability by atomic and molecular layer deposition: From highly hydrophilic to superhydrophobic

The wettability of pharmaceuticals is a key physical property which influences their dissolution rate, dispersibility, flowability and solid-state stability. Here, we provide a platform of surface nanoengineering methods capable of tuning the wettability of drug powders from high hydrophilicity to superhydrophobicity with drug loadings up to 95-99%. Specifically, we functionalize gram-scale micronized budesonide, a commercial active pharmaceutical ingredient for respiratory diseases, in a vibrated fluidized bed reactor with inorganic Al2O3, TiO2 and SiO2 by atomic layer deposition (ALD), organic poly(ethylene terephthalate) (PET) by molecular layer deposition (MLD) and inorganic/organic titanicone by hybrid ALD/MLD. Transmission electron microscopy shows the formation of smooth and uniform films for each deposition process without significantly affecting the surface morphology of the budesonide particles. Crucially, the deposition processes do not alter the solid-state structure and cytocompatibility of budesonide. The ceramic ALD films are able to convert the originally hydrophobic budesonide into highly hydrophilic powders with water contact angles (WCAs) of similar to 10 degrees within a few seconds. The purely organic PET films grown via MLD deliver superhydrophobic powders with a WCA of 145-150 degrees. In contrast, the titanicone hybrid ALD/MLD films lead to mild hydrophilicity with WCAs ranging from similar to 80 degrees to similar to 60 degrees. Modifying the wetting properties of inhaled drug powders such as budesonide is relevant to improve bioavailability, enhance the dispersion of formulations in suspension-based inhalers or prevent moisture interactions in dry powder inhalers. Moreover, by tuning the surface chemical composition at the atomic or molecular level, particle ALD, MLD and hybrid ALD/MLD enable control over powder wettability for several pharmaceutical dosage forms with applications in oral, orally inhaled and parenteral delivery. (C) 2021 The Author(s). Published by Elsevier Ltd.

Automated summary

The text discusses a surface nanoengineering method to tune the wettability of drug powders, from high hydrophilicity to superhydrophobicity, for inhaled drugs like budesonide. This allows for improved bioavailability and enhanced dispersion of formulations, showing the potential for controlling powder wettability in various pharmaceutical dosage forms.