The effect of carrier surface roughness on wall collision‐induced detachment of micronized pharmaceutical particles

Modelling Deaggregation Due to Normal Carrier–Wall Collision in Dry Powder Inhalers

Powder deaggregation in Dry Powder Inhalers (DPI) with carrier-based formulations is a key process for the effectiveness of drug administration. Carrier-wall collisions are one of the recognised mechanisms responsible for active pharmaceutical ingredient (API) aerosolisation, and DPI geometries are designed to maximise their efficacy. The detachment of fine and cohesive API particles is investigated at a fundamental level by simulating with DEM the normal collision of a carrier sphere with an API particle attached. The impact velocity at which detachment occurs (escape velocity) is determined as a function of key parameters, such as cohesiveness, coefficient of restitution, static and rolling friction. An analytical model for the escape velocity is then derived, examining the role of the initial position of the particle, cohesion model and particle size. Finally, the results are framed in the context of DPI inhalers, comparing the results obtained with impact velocities typically recorded in commercial devices.

Solidification of volatile D-Limonene by cyclodextrin metal-organic framework for pulmonary delivery via dry powder inhalers: In vitro and in vivo evaluation

D-Limonene (D-Lim), a volatile oil extracted from citrus fruits, has therapeutic effects on lung inflammation and cancer, whilst the deep delivery of D-Lim was challenging due to its physical instability for a long period of time. To prevent the volatilization of D-Lim and achieve efficient pulmonary delivery, herein, D-Lim was loaded into biodegradable γ-cyclodextrin metal-organic framework (γ-CD-MOF) with optimal loading efficiency achieving 13.79 ± 0.01% (molar ratio of D-Lim and γ-CD-MOF was 1.6:1), which possessed cubic shape with controllable particle size (1-5 μm). The experimental results indicated that γ-CD-MOF could improve the stability of D-Lim. A series of characterizations and molecular docking were used to reveal the interaction between D-Lim and γ-CD-MOF. The solidification of D-Lim by γ-CD-MOF played a crucial role in the exploitation of its inhalable dosage form, dry powder inhaler (DPI). Specifically, the aerosolization of D-Lim@γ-CD-MOF for inhalation was satisfactory with a fine particle fraction (FPF) of 33.12 ± 1.50% at 65 L/min of flow rate. Furthermore, in vivo study had shown a 2.23-fold increase in bioavailability of D-Lim solidified by γ-CD-MOF for inhalation compared to D-Lim for oral administration. Therefore, it is considered that γ-CD-MOF could be an excellent carrier for pulmonary drug delivery to realize solidification and lung therapeutic effects of volatile oils.

Flow and Particle Modelling of Dry Powder Inhalers: Methodologies, Recent Development and Emerging Applications

Dry powder inhaler (DPI) is a device used to deliver a drug in dry powder form to the lungs. A wide range of DPI products is currently available, with the choice of DPI device largely depending on the dose, dosing frequency and powder properties of formulations. Computational fluid dynamics (CFD), together with various particle motion modelling tools, such as discrete particle methods (DPM) and discrete element methods (DEM), have been increasingly used to optimise DPI design by revealing the details of flow patterns, particle trajectories, de-agglomerations and depositions within the device and the delivery paths. This review article focuses on the development of the modelling methodologies of flow and particle behaviours in DPI devices and their applications to device design in several emerging fields. Various modelling methods, including the most recent multi-scale approaches, are covered and the latest simulation studies of different devices are summarised and critically assessed. The potential and effectiveness of the modelling tools in optimising designs of emerging DPI devices are specifically discussed, such as those with the features of high-dose, pediatric patient compatibility and independency of patients' inhalation manoeuvres. Lastly, we summarise the challenges that remain to be addressed in DPI-related fluid and particle modelling and provide our thoughts on future research direction in this field.

A Systematic Safety Evaluation of Nanoporous Mannitol Material as a Dry-Powder Inhalation Carrier System

For carrier-based dry-powder inhaler (DPI) formulations, the adhesion between carrier particles and active pharmaceutical ingredients (API) particles have a significant influence on the aerosolization performance of the API-carrier complexes and the desired detachment of the API for efficient pulmonary delivery. In our previous study, nanoporous mannitol material was successfully fabricated as carriers by a one-step nonorganic solvent spray drying method with the thermal degradation of ammonium carbonate. These carriers were shown to achieve excellent aerosolization performance. In addition, no residue of ammonium carbonate was detected on the powder surface. However, the safety of nanoporous mannitol carriers (Nano-PMCs) during pulmonary administration/delivery was still unknown because the lung is vulnerable to the inhaled particles. To address this question, the present study was conducted to construct a systematic safety evaluation for DPIs carriers to investigate the safety of Nano-PMCs in the whole inhalation, which would make up for the lack of detailed and standardized method in this field. In vitro safety evaluation was carried out using respiratory and pulmonary cytotoxicity tests, hemolysis assay, and ciliotoxicity test. In vivo safety evaluation was studied by measuring inflammatory indicators in the bronchoalveolar lavage fluid, assessing the pulmonary function and observing pulmonary pathological changes. Nano-PMCs showed satisfactory biocompatibility on respiratory tracts and lungs in vitro and in vivo. It was suggested that Nano-PMCs were safe for intrapulmonary delivery and potential as DPI carriers.