Developing an efficient and reliable dry powder inhaler for pulmonary drug delivery – A review for multidisciplinary researchers

Lipid polymer hybrid nanoparticles against lung cancer and their application as inhalable formulation

Lung cancer is a leading cause of global cancer mortality, often treated with chemotherapeutic agents. However, conventional approaches such as oral or intravenous administration of drugs yield low bioavailability and adverse effects. Nanotechnology has unlocked new gateways for delivering medicine to their target sites. Lipid-polymer hybrid nanoparticles (LPHNPs) are one of the nano-scaled delivery platforms that have been studied to exploit advantages of liposomes and polymers, enhancing stability, drug loading, biocompatibility and controlled release. Pulmonary administration of drug-loaded LPHNPs enables direct lung deposition, rapid onset of action and heightened efficacy at low doses of drugs. In this manuscript, we will review the potential of LPHNPs in management of lung cancer through pulmonary administration.

Dry powder inhaler design and particle technology in enhancing Pulmonary drug deposition: challenges and future strategies

OBJECTIVES

The efficient delivery of drugs from dry powder inhaler (DPI) formulations is associated with the complex interaction between the device design, drug formulations, and patient's inspiratory forces. Several challenges such as limited emitted dose of drugs from the formulation, low and variable deposition of drugs into the deep lungs, are to be resolved for obtaining the efficiency in drug delivery from DPI formulations. The objective of this study is to review the current challenges of inhaled drug delivery technology and find a way to enhance the efficiency of drug delivery from DPIs.

METHODS/EVIDENCE ACQUISITION

Using appropriate keywords and phrases as search terms, evidence was collected from the published articles following SciFinder, Web of Science, PubMed and Google Scholar databases.

RESULTS

Successful lung drug delivery from DPIs is very challenging due to the complex anatomy of the lungs and requires an integrated strategy for particle technology, formulation design, device design, and patient inhalation force. New DPIs are still being developed with limited performance and future device design employs computer simulation and engineering technology to overcome the ongoing challenges. Many issues of drug formulation challenges and particle technology are concerning factors associated with drug dispersion from the DPIs into deep lungs.

CONCLUSION

This review article addressed the appropriate design of DPI devices and drug formulations aligned with the patient's inhalation maneuver for efficient delivery of drugs from DPI formulations.

Spray-Dried Nanolipid Powders for Pulmonary Drug Delivery: A Comprehensive Mini Review

Lung diseases have received great attention in the past years because they contribute approximately one-third of the total global mortality. Pulmonary drug delivery is regarded as one of the most appealing routes to treat lung diseases. It addresses numerous drawbacks linked to traditional dosage forms. It presents notable features, such as, for example, a non-invasive route, localized lung drug delivery, low enzymatic activity, low drug degradation, higher patient compliance, and avoiding first-pass metabolism. Therefore, the pulmonary route is commonly explored for delivering drugs both locally and systemically. Inhalable nanocarrier powders, especially, lipid nanoparticle formulations, including solid-lipid and nanostructured-lipid nanocarriers, are attracting considerable interest in addressing respiratory diseases thanks to their significant advantages, including deep lung deposition, biocompatibility, biodegradability, mucoadhesion, and controlled drug released. Spray drying is a scalable, fast, and commercially viable technique to produce nanolipid powders. This review highlights the ideal criteria for inhalable spray-dried SLN and NLC powders for the pulmonary administration route. Additionally, the most promising inhalation devices, known as dry powder inhalers (DPIs) for the pulmonary delivery of nanolipid powder-based medications, and pulmonary applications of SLN and NLC powders for treating chronic lung conditions, are considered.

Design, development, and technical considerations for dry powder inhaler devices

The dry powder inhaler (DPI) stands out as a highly patient-friendly and effective pulmonary formulation, surpassing traditional and other pulmonary dosage forms in certain disease conditions. The development of DPI products, however, presents more complexities than that of other dosage forms, particularly in device design and the integration of the drug formulation. This review focuses on the capabilities of DPI devices in pulmonary drug delivery, with a special emphasis on device design and formulation development. It also discusses into the principles of deep lung particle deposition and device engineering, and provides a current overview of the market for DPI devices. Furthermore, the review highlights the use of computational fluid dynamics (CFD) in DPI product design and discusses the regulatory environment surrounding these devices.

Formulation and evaluation of inhaled Sildenafil-loaded PLGA microparticles for treatment of pulmonary arterial hypertension (PAH): A novel high drug loaded formulation and scalable process via hot melt extrusion technology (Part Ⅰ)

In recent years, several techniques were employed to develop a local sustained pulmonary delivery of sildenafil citrate (SC) as an alternative for the intravenous and oral treatment of pulmonary arterial hypertension (PAH). Most of these methods, however, need to be improved due to limitations of scalability, low yield production, low drug loading, and stability issues. In this study, we report the use of hot-melt extrusion (HME) as a scalable process for making Poly (lactic-co-glycolic acid) (PLGA) microparticles with high SC load. The prepared particles were tested in vitro for local drug delivery to the lungs by inhalation. Sodium bicarbonate was included as a porogen in the formulation to make the particles more brittle and to impart favorable aerodynamic properties. Six formulations were prepared with different formulation compositions. Laser diffraction analysis was used to estimate the geometric particle size distribution of the microparticles. In-vitro aerodynamic performance was evaluated by the next-generation cascade impactor (NGI). It was reported in terms of an emitted dose (ED), an emitted fraction (EF%), a respirable fraction (RF%), a fine particle fraction (FPF%), a mass median aerodynamic diameter (MMAD), and geometric standard deviation (GSD). The formulations have also been characterized for surface morphology, entrapment efficiency, drug load, and in-vitro drug release. The results demonstrated that PLGA microparticles have a mean geometric particle size between 6 and 14 µm, entrapment efficiency of 77 to 89 %, and SC load between 17 and 33 % w/w. Fifteen percent of entrapped sildenafil was released over 24 h from the PLGA microparticles, and seventy percent over 7 days. The aerodynamic properties included fine particle fraction ranging between 19 and 33 % and an average mass median aerodynamic diameter of 6-13 µm.

Pulmonary inhalation for disease treatment: Basic research and clinical translations

Pulmonary drug delivery has the advantages of being rapid, efficient, and well-targeted, with few systemic side effects. In addition, it is non-invasive and has good patient compliance, making it a highly promising drug delivery mode. However, there have been limited studies on drug delivery via pulmonary inhalation compared with oral and intravenous modes. This paper summarizes the basic research and clinical translation of pulmonary inhalation drug delivery for the treatment of diseases and provides insights into the latest advances in pulmonary drug delivery. The paper discusses the processing methods for pulmonary drug delivery, drug carriers (with a focus on various types of nanoparticles), delivery devices, and applications in pulmonary diseases and treatment of systemic diseases (e.g., COVID-19, inhaled vaccines, diagnosis of the diseases, and diabetes mellitus) with an updated summary of recent research advances. Furthermore, this paper describes the applications and recent progress in pulmonary drug delivery for lung diseases and expands the use of pulmonary drugs for other systemic diseases.

Long-acting inhaled medicines: Present and future

Inhaled medicines continue to be an essential part of treatment for respiratory diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis. In addition, inhalation technology, which is an active area of research and innovation to deliver medications via the lung to the bloodstream, offers potential advantages such as rapid onset of action, enhanced bioavailability, and reduced side effects for local treatments. Certain inhaled macromolecules and particles can also end up in different organs via lymphatic transport from the respiratory epithelium. While the majority of research on inhaled medicines is focused on the delivery technology, particle engineering, combination therapies, innovations in inhaler devices, and digital health technologies, researchers are also exploring new pharmaceutical technologies and strategies to prolong the duration of action of inhaled drugs. This is because, in contrast to most inhaled medicines that exert a rapid onset and short duration of action, long-acting inhaled medicines (LAIM) improve not only the patient compliance by reducing the dosing frequency, but also the effectiveness and convenience of inhaled therapies to better manage patients' conditions. This paper reviews the advances in LAIM, the pharmaceutical technologies and strategies for developing LAIM, and emerging new inhaled modalities that possess a long-acting nature and potential in the treatment and prevention of various diseases. The challenges in the development of the future LAIM are also discussed where active research and innovations are taking place.

Stability of Naked Nucleic Acids under Physical Treatment and Powder Formation: Suitability for Development as Dry Powder Formulations for Inhalation

A number of functional nucleic acids, including plasmid DNA (pDNA) and small interfering RNA (siRNA), have been attracting increasing attention as new therapeutic modalities worldwide. Dry pDNA and siRNA powder formulations for inhalation are considered practical in clinical applications for respiratory diseases. However, physical stresses in the powder-forming process may destabilize nucleic acids, particularly when vectors with stabilizing effects are not used. We herein compare the stability of naked pDNA and siRNA through various physical treatments and two powder-forming processes. The structural and functional integrities of pDNA were markedly reduced via sonication, heating, and atomization, whereas those of siRNA were preserved throughout all of the physical treatments investigated. Spray-dried and spray-freeze-dried powders of siRNA maintained their structural and functional integrities, whereas those of pDNA did not. These results demonstrate that siRNA is more suitable for powder formation in the naked state than pDNA due to its higher stability under physical treatments. Furthermore, a spray-freeze-dried powder with a high content of naked siRNA (12% of the powder) was successfully produced that preserved its structural and functional integrities, achieving high aerosol performance with a fine particle fraction of approximately 40%.

Inhalation Dosage Forms: A Focus on Dry Powder Inhalers and Their Advancements

In this review, an extensive analysis of dry powder inhalers (DPIs) is offered, focusing on their characteristics, formulation, stability, and manufacturing. The advantages of pulmonary delivery were investigated, as well as the significance of the particle size in drug deposition. The preparation of DPI formulations was also comprehensively explored, including physico-chemical characterization of powders, powder processing techniques, and formulation considerations. In addition to manufacturing procedures, testing methods were also discussed, providing insights into the development and evaluation of DPI formulations. This review also explores the design basics and critical attributes specific to DPIs, highlighting the significance of their optimization to achieve an effective inhalation therapy. Additionally, the morphology and stability of 3 DPI capsules (Spiriva, Braltus, and Onbrez) were investigated, offering valuable insights into the properties of these formulations. Altogether, these findings contribute to a deeper understanding of DPIs and their development, performance, and optimization of inhalation dosage forms.

CFD-DEM investigation of the effects of aperture size for a capsule-based dry powder inhaler

Capsule based dry powder inhalers (DPIs) often require piercing of the capsule before inhalation, and the characteristics of the apertures (punctured holes) affect air flow and the release of powders from the capsule. This work develops a numerical model based on the two-way coupling of computational fluid dynamics and discrete element method (CFD-DEM) to investigate the effect of aperture size on powder dispersion in the Aerolizer® device loaded with only carrier particles (lactose). Powders (carrier particles) in the size range 60-140 μm (d50: 90 μm and span: 0.66) were initialized in a capsule which had a circular aperture at each end. Boundary conditions corresponding to an air flow rate of 45 L/min were specified at each inlet to the mixing chamber (i.e., a total flow rate 90 L/min), and a capsule spin speed of ∼ 4050 rpm. The velocity magnitudes inside the capsule were considerably lower than those in the mixing chamber in the vicinity of the rotating capsule, with the exception of the capsules featuring 2.5 mm and 4 mm apertures. Larger apertures reduced the capsule emptying time and increased the particle evacuation velocity; the fluid drag force on the particles issuing from the capsule peaked for an aperture of 1.3 mm. Inside the capsule, particle-particle (PP) collisions were more frequent than particle-wall (PW) collisions due to high concentration of powder, but PP collisions had smaller (median) impact energy than PW collisions. Larger apertures resulted in fewer collisions in the capsule with higher PW and virtually unchanged PP collision energies. Outside the capsule (i.e., in the inhaler mixing chamber), PW collisions occurred more frequently than PP collisions with median collision energies typically two orders of magnitude higher than inside the capsule. Larger apertures resulted in more collisions with slightly reduced collision energy, but this effect plateaued for aperture sizes larger than 1.3 mm. Powder dispersion, expressed as the fine particle fraction (FPF) of the powder, was predicted using an empirical equation based on carrier PW collisions. Therefore, consistent with the model prediction of the effect of aperture sizes on the chamber collision frequency, FPF increased with aperture size but plateaued beyond 1.3 mm.

Computational, In Vitro, and In Vivo Models for Nose-to-Brain Drug Delivery Studies

Direct nose-to-brain drug delivery offers the opportunity to treat central nervous system disorders more effectively due to the possibility of drug molecules reaching the brain without passing through the blood-brain barrier. Such a delivery route allows the desired anatomic site to be reached while ensuring drug effectiveness, minimizing side effects, and limiting drug losses and degradation. However, the absorption of intranasally administered entities is a complex process that considerably depends on the interplay between the characteristics of the drug delivery systems and the nasal mucosa. Various preclinical models (in silico, in vitro, ex vivo, and in vivo) are used to study the transport of drugs after intranasal administration. The present review article attempts to summarize the different computational and experimental models used so far to investigate the direct delivery of therapeutic agents or colloidal carriers from the nasal cavity to the brain tissue. Moreover, it provides a critical evaluation of the data available from different studies and identifies the advantages and disadvantages of each model.

Graphene Oxide Hosting a pH-Sensitive Prodrug: An In Silico Investigation of Graphene Oxide-Based Nanovehicle toward Cancer Therapy

Prodrug and drug delivery systems are two effective strategies for improving the selectivity of chemotherapeutics. Herein, via molecular dynamics (MD) simulation and free energy calculation, the effectiveness of the graphene oxide (GO) decorated with the pH-sensitive prodrug (PD) molecules in cancer therapy is investigated. PEI-CA-DOX (prodrug) was loaded onto the GO surface, in which the hydrogen bonding and pi-pi stacking interactions play the main role in the stability of the GO-PD complex. Due to the strong interaction of GO and PD (about -800 kJ/mol), the GO-PD complex remains stable during the membrane penetration process. The obtained results confirm that GO is a suitable surface for hosting the prodrug and passing it through the membrane. Furthermore, the investigation of the release process shows that the PD can be released under acidic conditions. This phenomenon is due to the reduction of the contribution of electrostatic energy in the GO and PD interaction and the entry of water into the drug delivery system. Moreover, it is found that an external electrical field does not have much effect on drug release. Our results provide a deep understanding of the prodrug delivery systems, which helps the combination of nanocarriers and modified chemotherapy drugs in the future.

Asymmetric lung increases particle filtration by deposition

Human lung is known to be an asymmetric dichotomously branched network of bronchioles. Existing literature on the relation between anatomy and air-flow physics in the tracheobronchial trees has discussed the results of asymmetry. We discuss a secondary (but an important) lung function to seek asymmetry: to protect the acinus from a high pathogen load. We build morphometric parameter-based mathematical models of realistic bronchial trees to explore the structure-function relationship. We observe that maximum surface area for gas exchange, minimum resistance and minimum volume are obtained near the symmetry condition. In contrast, we show that deposition of inhaled foreign particles in the non-terminal airways is enhanced by asymmetry. We show from our model, that the optimal value of asymmetry for maximum particle filtration is within 10% of the experimentally measured value in human lungs. This structural trait of the lung aids in self-defence of the host against pathogen laden aerosols. We explain how natural asymmetric design of typical human lungs makes a sacrifice away from gas exchange optimality to gain this protection. In a typical human lung, when compared to most optimal condition (which is associated with symmetric branching), the fluidic resistance is 14% greater, the gas exchange surface area is about 11% lower, the lung volume is about 13% greater to gain an increase of 4.4% protection against foreign particles. This afforded protection is also robust to minor variations in branching ratio or variation in ventilation, which are both crucial to survival.

Evaluating dry powder inhalers: From in vitro studies to mobile health technologies

Dry powder inhalers (DPIs) are essential in treating patients with pulmonary diseases. Since DPIs were introduced in the 1960s, a remarkable improvement has been made in their technology, dose delivery, efficiency, reproducibility, stability, and performance based on safety and efficacy. While there are many DPIs on the market and several more under development, it is vital to evaluate the performance of DPIs for effective aerosol drug delivery to patients with respiratory disorders. Their performance evaluation includes particle size, metering system, device design, dose preparation, inhalation technique, and patient-device integration. The purpose of this paper is to review current literature evaluating DPIs through in vitro studies, computational fluid models, and in vivo/clinical studies. We will also explain how mobile health applications are used to monitor and evaluate patients' adherence to prescribed medications.

Near Elimination of In Vitro Predicted Extrathoracic Aerosol Deposition in Children Using a Spray-Dried Antibiotic Formulation and Pediatric Air-Jet DPI

PURPOSE

This study evaluated the in vitro aerosol performance of a dry powder antibiotic product that combined a highly dispersible tobramycin powder with a previously optimized pediatric air-jet dry powder inhaler (DPI) across a subject age range of 2-10 years.

METHODS

An excipient enhanced growth (EEG) formulation of the antibiotic tobramycin (Tobi) was prepared using a small particle spray drying technique that included mannitol as the hygroscopic excipient and trileucine as the dispersion enhancer. The Tobi-EEG formulation was aerosolized using a positive-pressure pediatric air-jet DPI that included a 3D rod array. Realistic in vitro experiments were conducted in representative airway models consistent with children in the age ranges of 2-3, 5-6 and 9-10 years using oral or nose-to-lung administration, non-humidified or humidified airway conditions, and constant or age-specific air volumes.

RESULTS

Across all conditions tested, mouth-throat depositional loss was < 1% and nose-throat depositional loss was < 3% of loaded dose. Lung delivery efficiency was in the range of 77.3-85.1% of loaded dose with minor variations based on subject age (~ 8% absolute difference), oral or nasal administration (< 2%), and delivered air volume (< 2%). Humidified airway conditions had an insignificant impact on extrathoracic depositional loss and significantly increased aerosol size at the exit of a representative lung chamber.

CONCLUSIONS

In conclusion, the inhaled antibiotic product nearly eliminated extrathoracic depositional loss, demonstrated high efficiency nose-to-lung antibiotic aerosol delivery in pediatric airway models for the first time, and provided ~ 80% lung delivery efficiency with little variability across subject age and administered air volume.

[Reducing the environmental impact of inhalers dispensed in France. From diagnosis to sustainable action]

OBJECTIVES

While inhaled drugs are mainly used to treat chronic respiratory diseases, they are also responsible for greenhouse gas (GHG) emission. To highlight this issue, a dispensed analysis and a carbon footprint evaluation of inhalers in France have been conducted.

METHODS

A national qualitative and quantitative analysis of dispensed inhalers in community pharmacies (CP) and hospitals (H) was conducted in France for 2019. A data review from the literature led to the determination of the inhalers carbon footprint, expressed in carbon dioxide equivalent (CO₂e) during the inhaler life cycle.

RESULTS

Close to 40 million inhalers were dispensed by community pharmacies and one million by hospitals in 2019. It concerned three types of inhalers: metered-dose inhalers (MDI) [CP: 49%; H: 45%], dry powder inhalers (DPI) [CP: 47%; H: 51%], and soft mist inhalers (SMI) [CP: 4%; H: 4%]. According to the literature, MDI have the highest carbon footprint, ranging from 11 to 28 kgCO2e versus less than 1 kgCO2e for DPI/SMI. In 2019, the national carbon footprint of salbutamol (MDI), the most dispensed inhaler, was estimated to be over 310 million kgCO2e (CP+H) corresponding to more than 310,000 round-trip Paris-New York.

CONCLUSIONS

This study shows the involvement of MDI in GHG emissions. Taking actions as part of a global and coordinated approach to limit their environmental impact is possible and thus is a priority.

Quantifying Agglomerate-to-Wall Impaction in Dry Powder Inhalers

PURPOSE

The probability of agglomerate-to-wall collision was quantified using a unique image processing technique applied to high-speed microscopic images. The study aimed to investigate the effects of flow rate and particle size on the percentage of colliding agglomerates detected within an in-house powder dispersion device.

METHOD

The device consists of a swirl chamber and two tangential inlets in various configurations, designed to emulate the geometric features of commercial devices such as the Aerolizer® and Osmohaler®. The test cases were conducted with constant flow rates of 30 SLPM and 60 SLPM. Four powder samples were tested, including carrier Respitose® SV010 (median volume diameter 104 µm, span 1.7) and mannitol of three constituent primary particle sizes (3 µm, 5 µm and 7 µm; span 1.6 - 1.9).

RESULTS

At the lower flow rate of 30 SLPM, collision frequencies were significantly different between powders of different constituent particle sizes, but the effects of powder properties diminished on increasing the flow rate to 60 SLPM. At the higher flow rate, all powders experienced a significant increase in the proportion of colliding particles.

CONCLUSION

Analysis of collision events showed that the probability of collision for each agglomerate increased with agglomerate diameter and velocity. Experimental data of agglomerate-to-wall collision were utilised to develop a logistic regression model that can accurately predict collisions with various powders and flow rates.

Numerical Modeling of Particle Dynamics Inside a Dry Powder Inhaler

The development of novel dry powders for dry powder inhalers (DPIs) requires the in vitro assessment of DPI aerodynamic performance. As a potential complementary method, in silico numerical simulations can provide additional information about the mechanisms that guide the particles and their behavior inside DPIs. The aim of this study was to apply computational fluid dynamics (CFDs) coupled with a discrete phase model (DPM) to describe the forces and particle trajectories inside the RS01^® as a model DPI device. The methodology included standard fluid flow equations but also additional equations for the particle sticking mechanism, as well as particle behavior after contacting the DPI wall surface, including the particle detachment process. The results show that the coefficient of restitution between the particle and the impact surface does not have a high impact on the results, meaning that all tested combinations gave similar output efficiencies and particle behaviors. No sliding or rolling mechanisms were observed for the particle detachment process, meaning that simple bouncing off or deposition particle behavior is present inside DPIs. The developed methodology can serve as a basis for the additional understanding of the particles' behavior inside DPIs, which is not possible using only in vitro experiments; this implies the possibility of increasing the efficiency of DPIs.

Recent developments in the computational simulation of dry powder inhalers

This article reviews recent developments in computational modeling of dry powder inhalers (DPIs). DPIs deliver drug formulations (sometimes blended with larger carrier particles) to a patient's lungs via inhalation. Inhaler design is complicated by the need for maximum aerosolization efficiency, which is favored by high levels of turbulence near the mouthpiece, with low extrathoracic depositional loss, which requires low turbulence levels near the mouth-throat region. In this article, we review the physical processes contributing to aerosolization and subsequent dispersion and deposition. We assess the performance characteristics of DPIs using existing simulation techniques and offer a perspective on how such simulations can be improved to capture the physical processes occurring over a wide range of length- and timescales more efficiently.

State of the Art in Capsule-Based Dry Powder Inhalers: Deagglomeration Techniques and the Consequences for Formulation Aerosolization

Commercially available dry powder inhalers (DPIs) are usually devices in a fixed combination with the intended formulation, and a change in medication by the physician often forces the patient to use a different device, requiring the patient to relearn how to use it, resulting in lower adherence and inadequate therapy. To investigate whether DPIs can achieve successful outcomes regardless of the formulation and flow rate used, a novel DPI and two commercially available devices were compared in vitro for their deagglomeration behavior for different binary blends and a spray-dried particle formulation. The results demonstrate that the novel device achieved the highest fine particle fraction (FPF) regardless of the formulations tested. In the binary mixtures tested, the highest emitted fraction was obtained by shaking out the powder due to the oscillating motion of the capsule in the novel device during actuation. For DPIs with high intrinsic resistance to airflow, similar FPFs were obtained with the respective DPI and formulation, regardless of the applied flow rate. Additionally, the development and use of binary blends of spray-dried APIs and carrier particles may result in high FPF and overcome disadvantages of spray-dried particles, such as high powder retention in the capsule.

Leucine improves the aerosol performance of dry powder inhaler formulations of siRNA-loaded nanoparticles

Thermostable dry powder inhaler (DPI) formulations with high aerosol performance are attractive inhalable solid dosage forms for local treatment of inflammatory lung diseases. We recently demonstrated that lipidoid-polymer hybrid nanoparticles (LPNs) loaded with small interfering RNA (siRNA) directed against tumor necrosis factor alpha (TNF-α) mediate efficient intracellular siRNA delivery and reduce inflammation in vivo. Here, we show that mixtures of the stabilizing excipients trehalose (Tre) and dextran (Dex), in combination with the shell-forming dispersion enhancer leucine (Leu), stabilize TNF-α siRNA-loaded LPNs during spray drying into nanocomposite microparticles (DPI formulations), and result in DPI formulations with high aerosol performance. At low Leu content (0 to 10%, w/w), the DPI formulations were amorphous, and exhibited poor aerosol performance. When the Leu content was increased from 20 to 60% (w/w), the surface content of Leu increased from 39.2 to 68.1 mol%, and the flowability was significantly improved. Microscopy analyses suggest that the improved powder dispersibility is the result of a wrinkled surface morphology, which reduces the surface area available for interparticle interactions. Increasing the Leu content further (above 10%, w/w) did not influence the aerosol performance, and the aerosol yield was maximal at 30-40% Leu (w/w). Formulations containing 40% Leu and a Tre:Dex ratio of 10:90 (w/w) displayed a high fine particle fraction and aerosol properties suitable for inhalation. The chemical integrity of TNF-α siRNA was preserved in the solid state, and biodistribution studies in mice showed that pulmonary administration of DPI formulations with high aerosol performance resulted in homogenous deep lung deposition. Our results demonstrate that at optimal ratios, ternary excipient mixtures of Leu, Tre and Dex protect TNF-α siRNA-loaded LPNs during spray drying. Hence, this study shows that microparticles with an amorphous Tre/Dex matrix and a crystalline Leu shell are required for stabilizing the nanocomposite LPNs in the solid state, and for ensuring aerosol properties suitable for inhalation.

Application of Micro-Engineered Kidney, Liver, and Respiratory System Models to Accelerate Preclinical Drug Testing and Development

Developing novel drug formulations and progressing them to the clinical environment relies on preclinical in vitro studies and animal tests to evaluate efficacy and toxicity. However, these current techniques have failed to accurately predict the clinical success of new therapies with a high degree of certainty. The main reason for this failure is that conventional in vitro tissue models lack numerous physiological characteristics of human organs, such as biomechanical forces and biofluid flow. Moreover, animal models often fail to recapitulate the physiology, anatomy, and mechanisms of disease development in human. These shortfalls often lead to failure in drug development, with substantial time and money spent. To tackle this issue, organ-on-chip technology offers realistic in vitro human organ models that mimic the physiology of tissues, including biomechanical forces, stress, strain, cellular heterogeneity, and the interaction between multiple tissues and their simultaneous responses to a therapy. For the latter, complex networks of multiple-organ models are constructed together, known as multiple-organs-on-chip. Numerous studies have demonstrated successful application of organ-on-chips for drug testing, with results comparable to clinical outcomes. This review will summarize and critically evaluate these studies, with a focus on kidney, liver, and respiratory system-on-chip models, and will discuss their progress in their application as a preclinical drug-testing platform to determine in vitro drug toxicology, metabolism, and transport. Further, the advances in the design of these models for improving preclinical drug testing as well as the opportunities for future work will be discussed.

In Vitro Analysis of Nasal Interface Options for High-Efficiency Aerosol Administration to Preterm Infants

Background: An infant air-jet dry powder inhaler (DPI) platform has recently been developed that in combination with highly dispersible spray-dried powder formulations can achieve high-efficiency aerosolization with low actuation air volumes. The objective of this study was to investigate modifications to the nasal interface section of this platform to improve the aerosol delivery performance through preterm nose-throat (NT) models. Methods: Aerosol delivery performance of multiple nasal interface flow pathways and prong configurations was assessed with two in vitro preterm infant NT models. Two excipient-enhanced growth (EEG) dry powder formulations were explored containing either l-leucine or trileucine as the dispersion enhancer. Performance metrics included aerosol depositional loss in the nasal interface, deposition in the NT models, and tracheal filter deposition, which was used to estimate lung delivery efficiency. Results: The best performing nasal interface replaced the straight flexible prong of the original gradual expansion design with a rigid curved prong (∼20° curvature). The prong modification increased the lung delivery efficiency by 5%-10% (absolute difference) depending on the powder formulation. Adding a metal mesh to the flow pathway, to dissipate the turbulent jet, also improved lung delivery efficiency by ∼5%, while reducing the NT depositional loss by a factor of over twofold compared with the original nasal interface. The platform was also found to perform similarly in two different preterm NT models, with no statistically significant difference between any of the performance metrics. Conclusions: Modifications to the nasal interface of an infant air-jet DPI improved the aerosol delivery through multiple infant NT models, providing up to an additional 10% lung delivery efficiency (absolute difference) with the lead design delivering ∼57% of the loaded dose to the tracheal filter, while performance in two unique preterm airway geometries remained similar.

From laminar to turbulent flow in a dry powder inhaler: The effect of simple design modifications

In order to better understand powder dispersion in dry powder inhaler (DPI) devices, a new powder disperser was designed, which uses flow modifiers to alter powder fluidization behavior so as to physically replicate various flow conditions observed in a range of commercial DPIs. The influence of these modifiers on the performance of the DPI was analyzed for flowrates progressing from laminar (15 L/min) to transitional (30 L/min), and finally turbulent flow regimes (60 L/min) in the device. The aerosol performance of the disperser was measured using a Next Generation Impactor. For flowrate in the laminar regime, powder evacuation from the disperser was generally insufficient (<30%), which was increased to >85% when the device was operated in the turbulent flow regime. In contrast, the highest fine particle fraction (FPF) and lowest throat deposition were achieved when operating in the transitional flow regime. The FPF could be increased further by applying flow modifications such as narrowing the air passage before the powder pocket, inducing localized turbulence (by a grid) near the powder pocket, and by changing the loading position of the powder. Flow modifiers had the most noticeable effect under a laminar flow regime, however, the device operated most efficiently under a transitional flow regime.

The future of dry powder inhaled therapy: Promising or Discouraging for systemic disorders?

Dry powder inhalation therapy has been shown to be an effective method for treating respiratory diseases like asthma, Chronic Obstructive Pulmonary Diseases and Cystic Fibrosis. It has also been widely accepted and used in clinical practices. Such success has led to great interest in inhaled therapy on treating systemic diseases in the past two decades. The current coronavirus (COVID-19) pandemic also has increased such interest and is triggering more potential applications of dry powder inhalation therapy in vaccines and antivirus drugs. Would the inhaled dry powder therapy on systemic disorders be as encouraging as expected? This paper reviews the marketed and in-development dry powder inhaler (DPI) products on the treatment of systemic diseases, their status in clinical trials, as well as the potential for COVID-19 treatment. The advancements and unmet problems on DPI systems are also summarized. With countless attempts behind and more challenges ahead, it is believed that the dry powder inhaled therapy for the treatment of systemic disorders still holds great potential and promise.

Combining experimental and computational techniques to understand and improve dry powder inhalers

INTRODUCTION

: Dry Powder Inhalers (DPIs) continue to be developed to deliver an expanding range of drugs to treat an ever-increasing range of medical conditions; with each drug and device combination needing a specifically designed inhaler. Fast regulatory approval is essential to be first to market, ensuring commercial profitability.

AREAS COVERED

: In vitro deposition, particle image velocimetry, and computational modelling using the physiological geometry and representative anatomy can be combined to give complementary information to determine the suitability of a proposed inhaler design and to optimise its formulation performance. In combination they allow the entire range of questions to be addressed cost-effectively and rapidly.

EXPERT OPINION

: Experimental techniques and computational methods are improving rapidly, but each needs a skilled user to maximize results obtained from these techniques. Multidisciplinary teams are therefore key to making optimal use of these methods and such qualified teams can provide enormous benefits to pharmaceutical companies to improve device efficacy and thus time to market. There is already a move to integrate the benefits of Industry 4.0 into inhaler design and usage, a trend that will accelerate.

Effects of dose loading conditions and device geometry on the transport and aerosolization in dry powder inhalers: A simulation study

The transport and aerosolization of particles are studied in several different dry powder inhaler geometries via Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) simulations. These simulations combine Large Eddy Simulation of gas with Discrete Element Model simulation of all the carrier particles and a representative subset of the active pharmaceutical ingredient (API) particles. The purpose of the study is to probe the dominant mechanism leading to the release of the API particles and to demonstrate the value of the CFD-DEM simulations where one tracks the motion of all the carrier and API particles. Simulations are performed at different inhalation rates and initial dose loading conditions for the screen-haler geometry, a simple cylindrical tube inhaler, and five different geometry modifications that took the form of bumpy walls and baffles. These geometry modifications alter the residence time of the powder sample in the inhaler, pressure drop across the inhaler, the severity of gas-carrier interactions, and the number of collisions experienced by the carrier particles, all of which are quantified. The quality of aerosolization is found to correlate with the average air-carrier slip velocity, while collisions played only a secondary role. Some geometry modifications improved aerosolization quality with very little increase in the pressure drop across the device.

Understanding the Importance of Capsules in Dry Powder Inhalers

Pulmonary drug delivery is currently the focus of research and development because of its potential to produce maximum therapeutic benefit to patients by directing the drug straight to the lung disease site. Among all the available delivery options, one popular, proven and convenient inhaler device is the capsule-based dry powder inhaler (cDPI) for the treatment of an increasingly diverse range of diseases. cDPIs use a hard capsule that contains a powder formulation which consists of a mixture of a micronized drug and a carrier usually the lactose, known for its good lung tolerance. The capsule is either inserted into the device during manufacturer or by the patient prior to use. After perforating, opening or cut the capsule in the device, patients take a deep and rapid breath to inhale the powder, using air as the vector of drug displacement. The system is simple, relatively cheap and characterized by a lower carbon footprint than that of pressurized metered dose inhalers. This article reviews cDPI technology, focusing particularly on the importance of capsule characteristics and their function as a drug reservoir in cDPIs.

Effect of inflow conditioning for dry powder inhalers

The transport of pharmaceutical dry powder inside an optically accessible inhaler-like device is studied using both macro- and microscopic high-speed imaging. The investigation aims to systematically study the effect of inflow modifications on the dispersion characteristics of agglomerates inside a dry powder inhaler (DPI) geometry. An inhaler device was designed with geometrical features akin to commercial inhalers used in the current market and research oriented inhalers such as the Twincer®: two offset inlet channels (one with a powder pocket), a clockwise swirling chamber and a single outlet channel. At the device outlet, a vacuum pump was fitted with an actuator and calibrated to achieve a steady state inhalation with a peak flowrate of 85 and 125 L/min. Airflow conditions at the intake of the device were strategically perturbed in order to induce powder fluidisation and dispersion using turbulence grids and through physically obstructing channel streams in order to achieve changes in flow behaviour (e.g., flow separation). Complete fluidisation of the powder bed was observed with image processing enabling statistics on de-agglomerated fragment size and velocity. A range of behaviour was noted including local turbulence through introduction of a grid, bimodal fragment size behaviour for cohesive mannitol powder, as well as introduction of low velocity zones in the device through flow splitting. The geometry enables simple systematic study of inflow conditions into a DPI-like device with the data being useful for study of a given powder formulation (mannitol) and validation of computational models.

Spray-freeze-dried inhalable composite microparticles containing nanoparticles of combinational drugs for potential treatment of lung infections caused by Pseudomonas aeruginosa

The multi-drug resistance of Pseudomonas aeruginosa is an overwhelming cause of terminal and persistent lung infections in cystic fibrosis (CF) patients. Antimicrobial synergy has been shown for colistin and ivacaftor, and our study designed a relatively high drug-loading dry powder inhaler formulation containing nanoparticles of ivacaftor and colistin. The ivacaftor-colistin nanosuspensions (Iva-Col-NPs) were prepared by the anti-solvent method with different stabilizers. Based on the aggregation data, the formulation 7 (F7) with DSPG-PEG-OMe as the stabilizer was selected for further studies. The F7 consisted of ivacaftor, colistin and DSPG-PEG-OMe with a mass ratio of 1:1:1. The F7 powder formulation was developed using the ultrasonic spray-freeze-drying method and exhibited a rough surface with relatively high fine particle fraction values of 61.4 ± 3.4% for ivacaftor and 63.3 ± 3.3% for colistin, as well as superior emitted dose of 97.8 ± 0.3% for ivacaftor and 97.6 ± 0.5% for colistin. The F7 showed very significant dissolution improvement for poorly water soluble ivacaftor than the physical mixture. Incorporating two drugs in a single microparticle with synchronized dissolution and superior aerosol performance will maximize the synergy and bioactivity of those two drugs. Minimal cytotoxicity in Calu-3 human lung epithelial cells and enhanced antimicrobial activity against colistin-resistant P. aeruginosa suggested that our formulation has potential to improve the treatment of CF patients with lung infections.

Dry Powder Inhalers in the Digitalization Era: Current Status and Future Perspectives

During the last decades, the term "drug delivery systems" (DDSs) has almost fully replaced previously used terms, such as "dosage forms", in an attempt to emphasize the importance of the drug carrier in ensuring the claimed safety and effectiveness of the product. However, particularly in the case of delivery devices, the term "system", which by definition implies a profound knowledge of each single part and their interactions, is not always fully justified when using the DDS term. Within this context, dry powder inhalers (DPIs), as systems to deliver drugs via inhalation to the lungs, require a deep understanding of the complex formulation-device-patient interplay. As of now and despite the progress made in particle engineering and devices design, DPIs' clinical performance is limited by variable patients' breathing patterns. To circumvent this pitfall, next-generation DPIs should ideally adapt to the different respiratory capacity of individuals across age, health conditions, and other related factors. In this context, the recent wave of digitalization in the health care and industrial sectors may drive DPI technology towards addressing a personalized device-formulation-patient liaison. In this review, evolving technologies are explored and analyzed to outline the progress made as well as the gaps to fill to align novel DPIs technologies with the systems theory approach.

Advancement of the Infant Air-Jet Dry Powder Inhaler (DPI): Evaluation of Different Positive-Pressure Air Sources and Flow Rates

PURPOSE

In order to improve the delivery of dry powder aerosol formulations to the lungs of infants, this study implemented an infant air-jet platform and explored the effects of different air sources, flow rates, and pulmonary mechanics on aerosolization performance and aerosol delivery through a preterm nose-throat (NT) in vitro model.

METHODS

The infant air-jet platform was actuated with a positive-pressure air source that delivered the aerosol and provided a full inhalation breath. Three different air sources were developed to provide highly controllable positive-pressure air actuations (using actuation volumes of ~10 mL for the preterm model). While providing different flow waveform shapes, the three air sources were calibrated to produce the same flow rate magnitude (Q90: 90th percentile of flow rate). Multiple air-jet DPI designs were coupled with the air sources and evaluated with a model spray-dried excipient enhanced growth formulation.

RESULTS

Compared to other designs, the D1-Single air-jet DPI provided improved performance with low variability across all three air sources. With the tested D1-Single air-jet and Timer air source, reducing the flow rate from 4 to 1.7 L/min marginally decreased the aerosol size and significantly increased the lung delivery efficiency above 50% of the loaded dose. These results were not impacted by the presence of downstream pulmonary mechanics (resistance and compliance model).

CONCLUSIONS

The selected design was capable of providing an estimated >50% lung delivery efficiency of a model spray-dried formulation and was not influenced by the air source, thereby enabling greater flexibility for platform deployment in different environments.

Trileucine as a dispersibility enhancer of spray-dried inhalable microparticles

The formation of trileucine-containing spray-dried microparticles intended for pulmonary delivery was studied in depth. A single-particle method was employed to study the shell formation characteristics of trileucine in the presence of trehalose as a glass former, and an empirical correlation was proposed to predict the instance of shell formation. A droplet chain instrument was used to produce and collect monodisperse particles to examine morphology and calculate particle density for different levels of trileucine. It was observed that the addition of only 0.5 mg/mL (10% w/w) trileucine to a trehalose system could lower dried particle densities by approximately 1 g/cm³. In addition, a laboratory-scale spray dryer was used to produce batches of trileucine/trehalose powders in the respirable range. Raman spectroscopy demonstrated that both components were completely amorphous. Scanning electron microscopy and time-of-flight secondary ion mass spectrometry were used to study the particle morphologies and surface compositions. For all cases with trileucine, highly rugose particles with trileucine coverages of more than 60% by mass were observed with trileucine feed fractions of as little as 2% w/w. Moreover, it was seen that at lower trileucine content, smaller and larger particles of a polydisperse powder had slightly different surface compositions. The surface activity of trileucine was also modeled via a modified form of the diffusion equation inside an evaporating droplet that took into account initial surface adsorption and eventual surface desorption due to droplet shrinkage. Finally, using the Flory-Huggins theory, it was estimated that at room temperature, liquid-liquid phase separation would start when the trileucine reached an aqueous concentration of about 18 mg/mL. Besides the surface activity of trileucine, this low concentration was assumed to explain the substantial effect of trileucine on the morphology of spray-dried particles due to early phase separation. The methodology proposed in this study can be used in the rational design of trileucine-containing microparticles.

Inhaled antibiotic-loaded polymeric nanoparticles for the management of lower respiratory tract infections

Lower respiratory tract infections (LRTIs) are one of the leading causes of deaths in the world. Currently available treatment for this disease is with high doses of antibiotics which need to be administered frequently. Instead, pulmonary delivery of drugs has been considered as one of the most efficient routes of drug delivery to the targeted areas as it provides rapid onset of action, direct deposition of drugs into the lungs, and better therapeutic effects at low doses and is self-administrable by the patients. Thus, there is a need for scientists to design more convenient pulmonary drug delivery systems towards the innovation of a novel treatment system for LRTIs. Drug-encapsulating polymer nanoparticles have been investigated for lung delivery which could significantly reduce the limitations of the currently available treatment system for LRTIs. However, the selection of an appropriate polymer carrier for the drugs is a critical issue for the successful formulations of inhalable nanoparticles. In this review, the current understanding of LRTIs, management systems for this disease and their limitations, pulmonary drug delivery systems and the challenges of drug delivery through the pulmonary route are discussed. Drug-encapsulating polymer nanoparticles for lung delivery, antibiotics used in pulmonary delivery and drug encapsulation techniques have also been reviewed. A strong emphasis is placed on the impact of drug delivery into the infected lungs.

Development and Characterization of Excipient Enhanced Growth (EEG) Surfactant Powder Formulations for Treating Neonatal Respiratory Distress Syndrome

This study aimed to develop and characterize a spray-dried powder aerosol formulation of a commercially available surfactant formulation, Survanta® intratracheal suspension, using the excipient enhanced growth (EEG) approach. Survanta EEG powders were prepared by spray drying of the feed dispersions containing Survanta® (beractant) intratracheal suspension, hygroscopic excipients (mannitol and sodium chloride), and a dispersion enhancer (l-leucine or trileucine) in 5 or 20% v/v ethanol in water using the Buchi Nano Spray Dryer B-90 HP. Powders were characterized for primary particle size, morphology, phospholipid content, moisture content, thermal properties, moisture sorption, and surface activity. The aerosol performance of the powders was assessed using a novel low-volume dry powder inhaler (LV-DPI) device operated with 3-mL volume of dispersion air. At both ethanol concentrations, in comparison to trileucine, l-leucine significantly reduced the primary particle size and span and increased the fraction of submicrometer particles of the Survanta EEG powders. The l-leucine-containing Survanta EEG powders exhibited good aerosolization performance with ≥ 88% of the mass emitted (% nominal) after 3 actuations from the modified LV-DPI device. In addition, l-leucine-containing powders had a low moisture content (< 3% w/w) with transition temperatures close to the commercial surfactant formulation and retained their surface tension reducing activity after formulation processing. A Survanta EEG powder containing l-leucine was developed which showed efficient aerosol delivery from the modified LV-DPI device using a low dispersion air volume.

Elucidating the Effect of Fine Lactose Ratio on the Rheological Properties and Aerodynamic Behavior of Dry Powder for Inhalation

Dry powder inhaler (DPI) is recognized as the first choice for lung diseases' treatment. However, it lacks a universal way for DPI formulation development. Fine lactose is commonly added in DPIs to improve delivery performance; however, the fine ratio-dependent mechanism is unclear. Therefore, the objective of this study is to explore the influence of fine lactose ratio on DPI powder properties and aerodynamic behavior, and the fine lactose ratio-dependent mechanism involved during powder fluidization and lung deposition. Here salbutamol sulfate was used as a model drug, Lactohale® 206 as coarse carrier, and Lactohale® 300 as fine component; the mixtures were prepared at 1% drug content, with fine content up to 20%. It was shown that with the fine addition, flowability of the mixtures was improved, interaction among particles was increased, and the presence of fines could help to improve DPI's aerosolization performance. When the fines added were less than 3%, the "active site" hypothesis played a leading role. When the added fines were over 3% but less than 10%, fluidization enhancement mechanism was more important. After the added fines reaching 10%, aggregate mechanism started to dominate. However, FPF cannot be further increased once the fines reached 20%. Moreover, the correlations between FPF and dynamic powder parameters were verified in ternary mixtures, and cohesion had a greater impact on FPF than that of flowability. In conclusion, adding lactose fines is an effective way to improve lung deposition of DPI, with the concrete mechanism lactose fine ratio dependent.

A quantitative approach to predicting lung deposition profiles of pharmaceutical powder aerosols

Dry powder inhalers (DPI) are widely used systems for pulmonary delivery of therapeutics. The inhalation performance of DPIs is influenced by formulation features, inhaler device and inhalation pattern. The current review presents the affecting factors with great focus on powder characteristics which include particle size, shape, surface, density, hygroscopicity and crystallinity. The properties of a formulation are greatly influenced by a number of physicochemical factors of drug and added excipients. Since available particle engineering techniques result in particles with a set of modifications, it is difficult to distinguish the effect of an individual feature on powder deposition behavior. This necessitates developing a predictive model capable of describing all influential factors on dry powder inhaler delivery. Therefore, in the current study, a model was constructed to correlate the inhaler device properties, inhalation flow rate, particle characteristics and drug/excipient physicochemical properties with the resultant fine particle fraction. The r² value of established correlation was 0.74 indicating 86% variability in FPF values is explained by the model with the mean absolute errors of 0.22 for the predicted values. The authors believe that this model is capable of predicting the lung deposition pattern of a formulation with an acceptable precision when the type of inhaler device, inhalation flow rate, physicochemical behavior of active and inactive ingredients and the particle characteristics of DPI formulations are considered.

High-Efficiency Dry Powder Aerosol Delivery to Children: Review and Application of New Technologies

While dry powder aerosol formulations offer a number of advantages, their use in children is often limited due to poor lung delivery efficiency and difficulties with consistent dry powder inhaler (DPI) usage. Both of these challenges can be attributed to the typical use of adult devices in pediatric subjects and a lack of pediatric-specific DPI development. In contrast, a number of technologies have recently been developed or progressed that can substantially improve the efficiency and reproducibility of DPI use in children including: (i) nose-to-lung administration with small particles, (ii) active positive-pressure devices, (iii) structures to reduce turbulence and jet momentum, and (iv) highly dispersible excipient enhanced growth particle formulations. In this study, these technologies and their recent development are first reviewed in depth. A case study is then considered in which these technologies are simultaneously applied in order to enable the nose-to-lung administration of dry powder aerosol to children with cystic fibrosis (CF). Using a combination of computational fluid dynamics (CFD) analysis and realistic in vitro experiments, device performance, aerosol size increases and lung delivery efficiency are considered for pediatric-CF subjects in the age ranges of 2-3, 5-6 and 9-10 years old. Results indicate that a new 3D rod array structure significantly improves performance of a nasal cannula reducing interface loss by a factor of 1.5-fold and produces a device emitted mass median aerodynamic diameter (MMAD) of 1.67 μm. For all ages considered, approximately 70% of the loaded dose reaches the lower lung beyond the lobar bronchi. Moreover, significant and rapid size increase of the aerosol is observed beyond the larynx and illustrates the potential for targeting lower airway deposition. In conclusion, concurrent CFD and realistic in vitro analysis indicates that a combination of multiple new technologies can be implemented to overcome obstacles that currently limit the use of DPIs in children as young as two years of age.

On the Use of Computational Fluid Dynamics (CFD) Modelling to Design Improved Dry Powder Inhalers

PURPOSE

Computational Fluid Dynamics (CFD) simulations are performed to investigate the impact of adding a grid to a two-inlet dry powder inhaler (DPI). The purpose of the paper is to show the importance of the correct choice of closure model and modeling approach, as well as to perform validation against particle dispersion data obtained from in-vitro studies and flow velocity data obtained from particle image velocimetry (PIV) experiments.

METHODS

CFD simulations are performed using the Ansys Fluent 2020R1 software package. Two RANS turbulence models (realisable k - ε and k - ω SST) and the Stress Blended Eddy Simulation (SBES) models are considered. Lagrangian particle tracking for both carrier and fine particles is also performed.

RESULTS

Excellent comparison with the PIV data is found for the SBES approach and the particle tracking data are consistent with the dispersion results, given the simplicity of the assumptions made.

CONCLUSIONS

This work shows the importance of selecting the correct turbulence modelling approach and boundary conditions to obtain good agreement with PIV data for the flow-field exiting the device. With this validated, the model can be used with much higher confidence to explore the fluid and particle dynamics within the device.

Present Situation and Future Progress of Inhaled Lung Cancer Therapy: Necessity of Inhaled Formulations with Drug Delivery Functions

Inhaled lung cancer therapy is promising because of direct and noninvasive drug delivery to the lungs with low potential for severe systemic toxicity. Thus chemotherapeutic drugs have been administered clinically by nebulization of solution or suspension formulations, which demonstrated their limited pulmonary absorption and relatively mild systemic toxicity. In all these clinical trials, however, there was no obviously superior anticancer efficacy in lung cancer patients even at the maximum doses of drugs limited by pulmonary toxicity. Therefore methods that deliver both higher anticancer efficacy and lower pulmonary toxicity are strongly desired. In addition to the worldwide availability of pressured metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) to treat local respiratory diseases, recent innovations in medicines and technologies are encouraging next steps toward effective inhaled lung cancer therapy with new therapeutic or drug delivery concepts. These include the discovery of target cells/molecules and drug candidates for novel cancer therapy, the development of high-performance inhalation devices for effective pulmonary drug delivery, and the establishment of manufacturing technologies for functional nanoparticles/microparticles. This review highlights the present situation and future progress of inhaled drugs for lung cancer therapy, including an overview of available inhalation devices, pharmacokinetics, and outcomes in clinical trials so far and some novel formulation strategies based on drug delivery systems to achieve enhanced anticancer efficacy and attenuated pulmonary toxicity.

Estimating inter-patient variability of dispersion in dry powder inhalers using CFD-DEM simulations

Drug delivery from a capsule-based dry powder inhaler depends on the inhaler's design, the drug's formulation, and the inhalation maneuver. The latter affects both the air flow and the capsule motion in the inhaler. It is well known that patient-to-patient variability is a major challenge in the design of new inhaler types. Modeling and simulation are important tools for understanding such systems, yet quite complex. Simulation studies of capsule-based dry powder inhalers have disregarded the transient nature of the inhalation process, adopting a constant flow rate through the inhaler instead. In addition, either no capsules, a capsule in a fixed position, or a capsule rotating at a constant rate have been considered. In this work, literature data for three inhalation flow profiles were incorporated into coupled simulations of the air flow and carrier particle motion through an Aerolizer® dry powder inhaler with a rotating capsule and compared to simulations at constant air flow rates. The results for the profile simulations indicated that the carrier powder experienced larger velocity fluctuations. Acceleration events were tracked as a measure of collision- and flow-induced dispersion. The majority of fast particle accelerations occurred when the particles collided with the swirl chamber walls. Of the two common particle dispersion metrics, only the peak particle force distribution appeared to be sensitive to the inhalation profiles, while the effect of the profiles on the cumulative impulse was small.

Development of High Dose Oseltamivir Phosphate Dry Powder for Inhalation Therapy in Viral Pneumonia

Oseltamivir phosphate (OP) is an antiviral drug available only as oral therapy for the treatment of influenza and as a potential treatment option when in combination with other medication in the fight against the corona virus disease (COVID-19) pneumonia. In this study, OP was formulated as a dry powder for inhalation, which allows drug targeting to the site of action and potentially reduces the dose, aiming a more efficient therapy. Binary formulations were based on micronized excipient particles acting like diluents, which were blended with the drug OP. Different excipient types, excipient ratios, and excipient size distributions were prepared and examined. To investigate the feasibility of delivering high doses of OP in a single dose, 1:1, 1:3, and 3:1 drug/diluent blending ratios have been prepared. Subsequently, the aerosolization performance was evaluated for all prepared formulations by cascade impaction using a novel medium-resistance capsule-based inhaler (UNI-Haler). Formulations with micronized trehalose showed relatively excellent aerosolization performance with highest fine-particle doses in comparison to examined lactose, mannitol, and glucose under similar conditions. Focusing on the trehalose-based dry-powder inhalers' (DPIs) formulations, a physicochemical characterization of extra micronized grade trehalose in relation to the achieved performance in dispersing OP was performed. Additionally, an early indication of inhaled OP safety on lung cells was noted by the viability MTT assay utilizing Calu-3 cells.

Pulmonary route of administration is instrumental in developing therapeutic interventions against respiratory diseases

Pulmonary route of drug delivery has drawn significant attention due to the limitations associated with conventional routes and available treatment options. Drugs administered through pulmonary route has been an important research area that focuses on to developing effective therapeutic interventions for asthma, chronic obstructive pulmonary disease, tuberculosis, lung cancer etc. The intravenous route has been a natural route of delivery of proteins and peptides but associated with several issues including high cost, needle-phobia, pain, sterility issues etc. These issues might be addressed by the pulmonary administration of macromolecules to achieving an effective delivery and efficacious therapeutic impact. Efforts have been made to develop novel drug delivery systems (NDDS) such as nanoparticles, microparticles, liposomes and their engineered versions, polymerosomes, micelles etc to achieving targeted and sustained delivery of drug(s) through pulmonary route. Further, novel approaches such as polymer-drug conjugates, mucoadhesive particles and mucus penetrating particles have attracted significant attention due to their unique features for an effective delivery of drugs. Also, use of semi flourinated alkanes is in use for improvising the pulmonary delivery of lipophilic drugs. Present review focuses on to unravel the mechanism of pulmonary absorption of drugs for major pulmonary diseases. It summarizes the development of interventional approaches using various particulate and vesicular drug delivery systems. In essence, the orchestrated attempt presents an inflammatory narrative on the advancements in the field of pulmonary drug delivery.