Amino acid-modified spray-dried powders with enhanced aerosolisation properties for pulmonary drug delivery

In this study, the amino acids arginine, aspartic acid, leucine, phenylalanine and threonine were investigated as ‘dispersibility enhancers’ in spray-dried powders for inhalation. Parameters such as spray-dried yield, tapped density, and Carr's Index were not predictive of aerosolisation performance. In addition, whilst the majority of amino acid-modified powders displayed suitable particle size distribution for pulmonary administration and potentially favourable low moisture content, in vitro particle deposition was only enhanced for the leucine-modified powder. In summary, leucine can be used to enhance the dispersibility and aerosolisation properties of spray-dried powders for pulmonary drug delivery.

Graphical abstractThe potential for amino acids to modify the aerosolisation characteristics of spray-dried powders was investigated. Five amino acids (arginine, aspartic acid, leucine, phenylalanine and threonine) were incorporated into the spray-drying formulation at four different concentrations (0–20% w/w). Leucine-modified powders demonstrated the highest in vitro fine particle fractions (up to 78% of capsule contents), suggesting that leucine is an effective aerosolisation enhancer.Figure optionsDownload full-size imageDownload as PowerPoint slide