Natural and bioinspired excipients for dry powder inhalation formulations

Pulmonary drug delivery can have several advantages over other administration routes, in particular when using dry powder formulations. Such dry powder inhalation formulations generally include natural and bio-inspired excipients, which, among other purposes, are used to improve dosing reproducibility and aerosolization performance. Amino acids can enhance powder dispersibility and provide protection against moisture uptake. Sugars are used as drug-carrying diluents, stabilizers for biopharmaceuticals, and surface enrichers. Lipids and lipid-like excipients can reduce interparticle adhesive forces and are also used as constituents of liposomal drug delivery systems. Finally, biodegradable polymers are used to facilitate sustained release and targeted drug delivery. Despite their promise, pulmonary toxicity of many of the discussed excipients remains largely unknown and requires attention in future research.