The aerodynamic behaviour of the spray dried powders from the Aerolizer® device (Novartis, Surrey, UK) was assessed using the Next Generation Impactor (NGI; Copley Scientific, Nottingham, UK). NGI setup comprises of a stainless steel induction port attached with a mouthpiece adaptor, eight removable stainless steel collection cups located at seven plus a micro orifice collector (MOC) stages, a high capacity vacuum pump (Model HCP5), and a critical flow controller (TPK 2000). Before each run, the NGI collection cups were coated with silicone oil to minimize the particle entrainment after deposition. The air flow rate (Q) was tested and tuned at 100 L/min using the Copley’s flow meter (Model DFM 2000; Copley Scientific, UK). Aerolizer® device with a powder sample (~ 20 mg) filled hard gelatine PEG capsule (size 3; colourless; Qualicaps, Osaka, Japan) was activated for 2.4 s into the NGI assembly at an air flow rate of 100 L/min. The Aerolizer® device with empty capsule shell, mouth piece, induction port, seven plus MOC stages were …show more content…
All the powders were protected from light by wrapping the vials with an aluminium foil. After one month storage, the powder samples were evaluated for drug content, in vitro aerosolization, surface morphology and solid state characterization by X-ray diffraction studies following the above mentioned procedures.
Statistical analysis
All the data was processed and their mean ± standard deviation values were determined using the Microsoft® Excel spreadsheets. Statistical analysis of the data (mean ± SD) was performed by one way analysis of variance (ANOVA) and Student-Newman-Keuls post-hoc testing using GraphPad Prism 5 software (GraphPad Software, USA) with p ≤ 0.05 as the minimum level of