PURPOSE: To evaluate micronized powder retention and detachment from inhaler surfaces following reproducible deposition by impaction, coupled with centrifugal particle detachment (CPD). METHODS: Micronized albuterol sulfate (AS) and beclomethasone dipropionate (BDP) were aerosolized as dry powders and deposited by cascade impaction onto different contact surfaces. Drug detachment from the surfaces was characterized using CPD, coupled with HPLC assay and scanning electron microscopy. RESULTS: Drugs which accumulated as aggregates on model surfaces detached with distinctive profiles for % remaining vs. applied centrifugal force; each profile showed reproducible values for the minimum force required to initiate drug detachment, Fyield. While differences occurred in the observed detachment profiles for different drugs and contact surfaces (polyacetal vs. aluminum), the deposited drug particle size had the most significant effect on these profiles, e.g., Fyield for AS (2.1-3.3 microm) was 383 +/- 12.7 microN compared with 18 +/- 13.8 microN for AS (4.7-5.8 microm). CONCLUSIONS: A technique was developed which enabled the experimental review, and subsequent data analysis, of the adhesive properties between different DPI construction materials and drug substances deposited from aerosol clouds. The technique appears to be of greater relevance to inhaler design decisions than earlier studies in the literature claiming to show differences in the adhesion of single drug particles to surfaces.
PURPOSE: To evaluate micronized powder retention and detachment from inhaler surfaces following reproducible deposition by impaction, coupled with centrifugal particle detachment (CPD). METHODS: Micronized albuterol sulfate (AS) and beclomethasone dipropionate (BDP) were aerosolized as dry powders and deposited by cascade impaction onto different contact surfaces. Drug detachment from the surfaces was characterized using CPD, coupled with HPLC assay and scanning electron microscopy. RESULTS: Drugs which accumulated as aggregates on model surfaces detached with distinctive profiles for % remaining vs. applied centrifugal force; each profile showed reproducible values for the minimum force required to initiate drug detachment, Fyield. While differences occurred in the observed detachment profiles for different drugs and contact surfaces (polyacetal vs. aluminum), the deposited drug particle size had the most significant effect on these profiles, e.g., Fyield for AS (2.1-3.3 microm) was 383 +/- 12.7 microN compared with 18 +/- 13.8 microN for AS (4.7-5.8 microm). CONCLUSIONS: A technique was developed which enabled the experimental review, and subsequent data analysis, of the adhesive properties between different DPI construction materials and drug substances deposited from aerosol clouds. The technique appears to be of greater relevance to inhaler design decisions than earlier studies in the literature claiming to show differences in the adhesion of single drug particles to surfaces.
Authors: Y Shimada; M Sunada; M Mizuno; Y Yonezawa; H Sunada; M Yokosuka; H Kimura; H Takebayashi Journal: Drug Dev Ind Pharm Date: 2000-02 Impact factor: 3.225
Authors: Anne H de Boer; Paul Hagedoorn; Doetie Gjaltema; Dorette Lambregts; Meike Irngartinger; Henderik W Frijlink Journal: Pharm Res Date: 2004-12 Impact factor: 4.200