Characterisation of dry powder inhaler formulations using atomic force microscopy

Weiss, Cordula; McLoughlin, Peter; Cathcart, Helen

doi:10.1016/j.ijpharm.2015.08.051

Cited by 29 publications

(10 citation statements)

References 156 publications

(263 reference statements)

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“…The feedback controller evaluates the signal coming out of the photodiode. Moreover, piezoelectric elements are included in the scan head to ensure precise nanoscale motion [100]. Comprehensive information on this technique can be found in [101,102].…”

Section: Atomic Force Microscopy (Afm)mentioning

confidence: 99%

Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

et al. 2017

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Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD), osmotic distillation (OD) and osmotic membrane distillation (OMD) use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED), membrane capacitive deionization (MCD), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), microfiltration (MF), etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling), fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

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Section: Atomic Force Microscopy (Afm)mentioning

confidence: 99%

Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

et al. 2017

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“…The treatment of asthma is most effective when drugs are delivered to the upper airways, and various pharmaceutical companies have developed formulations and devices for this purpose, including nebulizers, metered dose inhalers, soft inhalers and dry powder inhalers (DPIs) . In particular, DPI formulations have received significant attention due to their convenient methods of drug delivery, in addition to easy handling and relatively high patient compliance . However, the effectiveness of inhaler therapy is dependent on the ability of the patient to master proper inhaler techniques .…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5] In particular, DPI formulations have received significant attention due to their convenient methods of drug delivery, in addition to easy handling and relatively high patient compliance. [6,7] However, the effectiveness of inhaler therapy is dependent on the ability of the patient to master proper inhaler techniques. [8,9] Therefore, one of the most important factors for determining the therapeutic effect of DPI formulations is breath actuation for inhaling drugs from a DPI device.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations of particle behaviour in a realistic human airway model with varying inhalation patterns

et al. 2019

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Objectives For dry powder inhalers, the airflow properties in the airways could affect the deposition of inhaled particles; the flow patterns vary inherently between patients. This paper provides an evaluation of the effects of six airflow patterns on the behaviour of inhaled particles, as determined by using numerical simulations. Methods Constant‐velocity and unsteady inhalation flows were employed. The unsteady inhalation flow was set as an inhalation curve with a peak inspiratory flow rate. Under a constant flow of 28.3 l/min, the total flow rates were calculated to confirm the validity of the numerical simulation. The effects of different inhalation patterns on the particle behaviour in a realistic human airway model were revealed via numerical simulation. Key findings Different flow rates affected the behaviour and deposition of the inhaled particles. Under an inhalation flow pattern, different airflow tendencies were observed between the right and left bronchi. Particle deposition in the airways was promoted by a vortex following terminal‐velocity‐like breath‐holding. The inhalation flow pattern affected the behaviour and deposition of inhaled particles in the airway. Conclusions Our results indicated that particle deposition in a realistic human airway model was promoted by a vortex formation following the terminal‐velocity‐like breath‐holding. Moreover, the inhalation flow pattern significantly influenced the behaviour and deposition of inhaled particles in the airways. Additionally, the effect of flow patterns on the particle deposition in each airway position was quantitatively evaluated by numerical simulations for a realistic human airway model.

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“…In particular, there is presently no theory that can be used to reliably predict the fine particle fraction of a formulation from a DPI. Numerous articles in the literature have discussed and compared the performance of different devices and even more work has been directed to comparing different formulations or drug substance, but no approach that can provide a quantitative link between the properties of the particles to the performance of the device has yet been proposed. This field is also still very much in development, with novel opportunities, such as porous particles and engineered composite particles applied …”

Section: Introductionmentioning

confidence: 99%

Simulation of dry powder inhalers: Combining micro‐scale, meso‐scale and macro‐scale modeling

et al. 2016

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The flow of carrier particles, coated with active drug particles, is studied in a prototype dry powder inhaler. A novel, multiscale approach consisting of a discrete element model (DEM) to describe the particles coupled with a dynamic large eddy simulation (LES) model to describe the dynamic nature of the flow is applied. The model consists of three different scales: the micro‐scale, the meso‐scale, and the macro‐scale. At the micro‐scale, the interactions of the small active drug particles with larger carrier particles, with the wall, with the air flow, and with each other is thoroughly studied using discrete element modeling and detailed computational fluid dynamics (CFD), i.e., resolving the flow structures around the particles. This has led to the development of coarse‐grained models, describing the interaction of the small active drug particles at the larger scales. At the meso‐scale the larger carrier particles, and all of their interactions are modeled individually using DEM and CFD‐LES. Collisions are modeled using a visco‐elastic model to describe the local deformation at each point of particle‐particle contact in conjunction with a model to account for cohesion. At the macro‐scale, simulations of a complete prototype inhaler are carried out. By combining the relevant information of each of the scales, simulations of the inhalation of one dose from a prototype inhaler using a patient relevant air flow profile show that fines leave the inhaler faster than the carrier particles. The results also show that collisions are not important for particle‐particle momentum exchange initially but become more important as the particles accelerate. It is shown that for the studied prototype inhaler the total release efficiency of the fine particles is between 10 and 30%, depending on the Hamaker constant, using typical settings for the properties of both particles. The results are also used to study regions of recirculation, where carrier particles can become trapped, and regions where fines adhere to the wall of the device. © 2016 American Institute of Chemical Engineers AIChE J, 63: 501–516, 2017

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Characterisation of dry powder inhaler formulations using atomic force microscopy

Cited by 29 publications

References 156 publications

Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

Numerical simulations of particle behaviour in a realistic human airway model with varying inhalation patterns

Simulation of dry powder inhalers: Combining micro‐scale, meso‐scale and macro‐scale modeling

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