Storage stability of inhalable phage powders containing lactose at ambient conditions

Rachel Yoon Kyung Chang, Martin Wallin, Elizabeth Kutter, Sandra Morales, Warwick Britton, Jian Li, Hak Kim Chan

Research output: Contribution to journalArticleResearchpeer-review

14 Citations (Scopus)


The aim of this study was to evaluate the storage stability of inhalable phage powders containing lactose and leucine as excipient. As an FDA-approved excipient for inhalation, lactose is preferred over other sugars. PEV phages active against antibiotic-resistant Pseudomonas aeruginosa was spray dried with lactose (55–90%) and leucine (45–10%). Produced powders were heat-sealed in an aluminium pouch at 15% relative humidity (RH) with subsequent storage at 20 °C/60% RH for 12 months. Lactose concentration in the powder positively influenced the phage stability over time. Formulation containing 90% lactose maintained the viability of PEV61 across the study, while ∼1.2 log 10 titer reduction was observed in formulations with less lactose. PEV20 was more prone to inactivation (1.7 log 10 titer loss at 12-month) when lactose concentration in the particle was below 80%. The fine particle fraction (% wt. particles <5 μm in aerosol) of phage powders was 52–61% and remained the same after 12-month storage. The results demonstrate that spray dried PEV phage powders containing lactose and leucine are biologically and physically stable over long-term storage at ambient temperature. Furthermore, these spray dried phage powders were shown to be non-toxic to lung alveolar macrophage and epithelial cells in vitro.

Original languageEnglish
Pages (from-to)11-18
Number of pages8
JournalInternational Journal of Pharmaceutics
Publication statusPublished - 5 Apr 2019


  • Bacteriophage (Phage)
  • Inhalation aerosol
  • Lactose
  • Spray dried powders
  • Storage stability

Cite this