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Entry port selection for detecting particle size differences in metered dose inhaler formulations using cascade
Venkatesh Naini1, Saeed Chaudhry, Julianne Berry
1Respiratory Formulation Development, Schering-Plough Research Institute, Kenilworth, New Jersey 07033, USA. venkatesh.naini@spcorp.com
Drug Development and Industrial Pharmacy
|March 6, 2004
Summary
The 1 L glass entry port improves drug collection efficiency for metered dose inhalers (MDIs) during aerodynamic particle sizing. This port better detects subtle particle size distribution changes crucial for MDI formulation development and stability testing.
Area of Science:
- Pharmaceutical Technology
- Aerosol Science
- Drug Delivery Systems
Background:
- Accurate aerodynamic particle sizing is critical for metered dose inhaler (MDI) performance.
- Cascade impaction is a standard method for characterizing particle size distribution (PSD).
- Entry port design significantly influences drug collection efficiency and data interpretation.
Purpose of the Study:
- To evaluate the drug collection efficiency of different sized glass entry ports during MDI aerodynamic particle sizing.
- To compare the performance of 1 L, 2 L, and 20 L glass entry ports against USP and twin impinger ports.
- To assess the ability of entry ports to detect subtle changes in particle size distribution (PSD) in MDI formulations.
Main Methods:
- Cascade impaction was employed to assess aerodynamic particle sizing of MDI formulations.
- Drug collection efficiency was measured in the entry port, impactor plates, and filter.
- Comparison of 1 L, 2 L, and 20 L glass entry ports with USP and twin impinger entry ports.
- Evaluation of the 1 L and USP entry ports' ability to discriminate PSD changes in an investigational hydrofluoroalkane (HFA)-based MDI.
Main Results:
- Entry port losses were dependent on the selected entry port size.
- 1 L and 2 L glass entry ports demonstrated optimal drug recovery on impactor plates compared to the USP entry port.
- The 1 L entry port successfully detected subtle PSD differences in the HFA-MDI formulation, while the USP port did not.
- The Andersen cascade impactor with the 1 L entry port easily identified deliberately induced manufacturing variations.
Conclusions:
- The 1 L glass entry port offers superior drug collection efficiency and improved discrimination of PSD compared to the USP entry port.
- The 1 L entry port is a valuable tool for characterizing PSD during MDI formulation development.
- This entry port can enhance stability testing of MDIs by reliably detecting small particle size variations.