In Vitro Characterization of the OptiChamber Diamond Valved Holding Chamber

Background: Use of a valved holding chamber (VHC) in conjunction with a pressurized metered dose inhaler (pMDI) can reduce issues relating to poor actuation-inhalation coordination and potentially improve the lung deposition of aerosol, compared with use of a pMDI alone. However, the performance of a VHC is influenced by different device-related factors, including the size and shape of the VHC and the material it is manufactured from (conventional versus antistatic). This study aimed to provide an in vitro characterization of an antistatic VHC, the OptiChamber Diamond VHC, comparing the aerodynamic particle size distribution of aerosol delivered via this VHC with results from a second antistatic VHC and a conventional VHC. Methods: The pMDI drug formulations (albuterol, suspension; beclomethasone dipropionate, solution) were connected to a Next Generation Impactor, either directly (pMDI alone tests) or via a VHC (VHC tests). The pMDIs were actuated (10 per product pair) and tested at extraction flow rates of 15 L/min and 30 L/min, without any time delay between actuation and inhalation. Dose delivery using the two pMDI drug formulations was compared, and is presented with reference to key aerodynamic particle size parameters. Results: Compared with tests on pMDIs alone, use of a VHC increased the dose of aerosol within the respirable range, particularly at a 15 L/min flow rate. Between-VHC comparisons indicated that the two antistatic VHCs were equivalent. Delivery of albuterol appeared to be influenced by the VHC used, but beclomethasone dipropionate seemed unaffected. Conclusions: The two antistatic VHCs were equivalent for both pMDI brands. Aerosol delivered from the antistatic VHCs at 15 L/min had a higher proportion of fine particles compared with the conventional VHC.