Does the United States Pharmacopeia throat introduce de-agglomeration of carrier-free powder from inhalers?
OBJECTIVE
We hypothesize that the USP induction port may de-agglomerate carrier-free powder emitting from dry powder inhalers (DPIs).


METHODS
Aerosols emitting from a range of DPIs (Spinhaler®, Turbuhaler® and Osmohaler™) and induction ports (USP throat, straight tube, Alberta idealized mouth-throat geometry (AG)) were sized by laser diffraction. Total drug recovery was obtained by HPLC and fine particle fraction computed. Air flow patterns were simulated using Computational Fluid Dynamics (CFD).


RESULTS
The straight tube did not de-agglomerate emitted powder. However, the USP throat and AG further de-agglomerated powders from the Spinhaler, but not the Turbuhaler and Osmohaler. While budesonide powder deposited similarly in all induction ports, deposition was significantly higher in the AG for both DSCG and mannitol. CFD revealed agglomerates impacting on the USP throat with higher localized velocity compared with the straight tube. CFD further showed a more complex flow pattern with high-velocity air jets in the AG, which explains the higher FPF for DSCG and the lower FPF for mannitol using the AG.


CONCLUSIONS
The USP throat further de-agglomerated the emitted powder from the DPI when it did not sufficiently disperse the powder. Other tools such as laser diffraction may be used for cross-examining to avoid artifacts in the results.
Advanced Drug Delivery Group, Faculty of Pharmacy, The University of Sydney, Sydney, NSW 2006, Australia.
Patricia
P
Tang
Philip Chi Lip
PC
Kwok
Zhenbo
Z
Tong
Runyu
R
Yang
Judy Agnes
JA
Raper
Hak-Kim
HK
Chan
D000280:Administration, Inhalation; D000336:Aerosols; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D019819:Budesonide / Q000008:administration & dosage*; D058995:Dry Powder Inhalers / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D057446:Hydrodynamics; D008353:Mannitol / Q000008:administration & dosage*; D010316:Particle Size; D011208:Powders; D014481:United States
D000336:Aerosols; D001993:Bronchodilator Agents; D011208:Powders; D008353:Mannitol; D019819:Budesonide