Preparation and characterization of physically modified glass beads used as model carriers in dry powder inhalers

Surface modified glass beads as model carriers in dry powder inhalers—Influence of drug load on the fine particle fraction

“…So, the slopes of a graph, where the FPF is plotted versus the surface coverage before aerodynamic assessment, may vary depending on the energy distribution of adhesion sites on the glass beads surface and thus on the modification of the glass beads. From AFM images that have been reported in a previous paper (Zellnitz et al 2013) it can be taken that the surface roughness introduced by physical surface modification was in a size range smaller than the API particles, so compared to untreated glass beads it was expected that the FPF of physically modified glass beads increases with increasing surface roughness (Q4h, TC 4 h, TC 8 h and plasma 1 min). Due to the surface roughness the contact area between API and glass bead surface should have been reduced and thus interparticle interactions, what consequently would lead to increased drug detachment and FPFs.…”

“…By using two different grinding materials (tungsten carbide (TC) and quartz (Q)) with different hardness and two different processing times (4 h and 8 h) glass beads with different shades of roughness could be generated [13]. Additionally physical surface modification was performed by plasma etching with a TEGAL901.…”

“…By processing the glass beads in a ball mill and using different grinding materials and processing times glass beads with increasing shades of roughness could be generated. The discussion and more detailed characterization have already been published [13] and are not part of the present work. Additionally to further increase the surface roughness, glass beads were etched with Plasma for 1 min.…”

“…Although it is known that the density of glass beads is rather high, this disadvantage was accepted, because of the advantages from the surface modification point of view. Other advantages of glass beads as potential model carrier have been mentioned in a previous work [13]. Nevertheless, it has to be mentioned that glass beads are neither typical nor conventional carrier particles.…”

Characterisation of dry powder inhaler formulations using atomic force microscopy

“…Both properties affect the adhesive interactions and therefore the performance of the formulation. Numerous groups (Bosquillon et al, 2001;Donovan and Smyth, 2010;Flament et al, 2004;Heng et al, 2000;Jones and Price, 2006;Kinnunen et al, 2014;Ooi et al, 2011;Young et al, 2009;Zellnitz et al, 2013Zellnitz et al, , 2014 investigated the correlation between excipient particle size, surface roughness and formulation performance with the aim of optimising these properties. Formulation performance was related to particle size and roughness of a budesonide-lactose formulation by Donovan and Smyth (2010); particle roughness and adhesion of a terbutaline sulphate-lactose formulation by Flament et al (2004); and to the percentage of carrier surface coverage in a model salbutamol sulphate formulation by Zellnitz et al (2014).…”