Scott Tavernini1, Mellissa Gomez1, Hui Wang1, Maximilian Aisenstat1, John Z. Chen2, Wynton D. McClary2, Warren H. Finlay1, Alana Gerhardt2, Christopher Fox2,3, Reinhard Vehring1, & Andrew R. Martin1,4
1Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
2Access to Advanced Health Institute, Seattle, Washington, USA
3Department of Biological Engineering, Utah State University, Logan, Utah, USA
4Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
Summary
This work investigates the physical stability of an inhalable tuberculosis vaccine stored in hypromellose capsules for use in a capsule-based dry powder inhaler. The primary measure of stability was consistent regional deposition as predicted by an in vitro methodology; secondary measures included particle morphology assessed by scanning electron microscopy and solid phase analysis by Raman spectroscopy. The biological stability of the antigen-adjuvant system in powder form was demonstrated previously.
Regional deposition in the in vitro analogues of the upper respiratory tract, tracheobronchial, and alveolar regions remained consistent over nine months of storage at room temperature. Differences in regional deposition between the vaccine powder vs. a similarly manufactured vehicle powder were noted, highlighting the importance of device/formulation interactions. No morphological changes were observed over time indicating that storage of the vaccine powder within the hypromellose capsule did not compromise its previously demonstrated physical stability. This sustained performance supports the use of capsules filled with dry powder vaccines for global vaccination campaigns.