title: A new approach to characterise pharmaceutical aerosols: measurement of aerosol from a single dose aqueous inhaler with an optical particle counter.
abstract: An in-line sampling system with dilution units for aqueous droplet aerosols from single dose inhalers (Berodual Respimat, Boehringer Ingelheim Pharma GmbH & Co. KG, Germany) for an optical particle counter is described. The device has been designed to interface with a white light aerosol spectrometer (welas digital 2100, Palas GmbH, Germany) that allows the time-resolved measurement of highly concentrated aerosols. Performance of the sampling system with regard to the measured particle size distribution (PSD) is compared to Next Generation Impactor (NGI) and to laser diffraction measurements (Sympatec Inhaler and open bench). Optimal settings of the sampling system lead to PSDs that correspond well to those measured by the evaporation minimising NGI approach (15 L/min, cooled) and laser diffraction. The better accuracy of the new dilution unit in presence of an additional aerosol sampling filter in comparison to a previously described aerosol sampling system is shown for different settings of the sampling system. This allows a more precise quantification of the delivered drug amount which is also well correlated to the aerosol volume measured by the welas system. In addition, using time-resolved welas measurements provides insight into droplet size, evaporation and size changes of aerosol clouds delivered by liquid inhalers.
authors.affiliation: Christian Albrecht University of Kiel, Department of Pharmaceutics and Biopharmaceutics, Gutenbergstr. 76, 24118 Kiel, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Kuhli
authors.forename: Maximilian
authors.initials: M
authors.lastname: Weiss
authors.forename: Hartwig
authors.initials: H
authors.lastname: Steckel
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols / Q000008:administration & dosage / Q000737:chemistry*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000737:chemistry; D004338:Drug Combinations; D016503:Drug Delivery Systems / Q000379:methods*; D005280:Fenoterol / Q000008:administration & dosage / Q000737:chemistry*; D009241:Ipratropium / Q000008:administration & dosage / Q000737:chemistry*; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D010783:Photometry / Q000379:methods; D013678:Technology, Pharmaceutical / Q000295:instrumentation*; D013997:Time Factors
chemical_list: D000336:Aerosols; D001993:Bronchodilator Agents; D004338:Drug Combinations; C030809:fenoterol, ipratropium drug combination; D005280:Fenoterol; D009241:Ipratropium