Effect of powder properties on the aerosolization performance of nanoporous mannitol particles as dry powder inhalation carriers

Posaconazole nanocrystals dry powder inhalers for the local treatment of invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis poses a significant threat to immunocompromised patients, characterized by high mortality rates. Posaconazole (PSZ), a second-generation triazole antifungal, exhibits broad-spectrum activity but suffers from limited pulmonary concentrations and notable systemic side effects when administered orally or intravenously. This study focuses on optimizing PSZ nanocrystals-agglomerated particles for dry powder inhalers (DPIs) to enhance solubility, dissolution rates, and pulmonary deposition, ultimately improving therapeutic efficacy while minimizing systemic adverse effects. We employed wet medium milling and spray-drying techniques to formulate PSZ nanocrystals-agglomerated DPIs. Various stabilizers including HPMC, HPC, Soluplus, and PVPK30, were systematically evaluated to optimize physicochemical properties. Aerosolization performance was assessed using the Next Generation Impactor, while antifungal efficacy was evaluated through in vitro and in vivo studies. The optimized PSZ DPIs demonstrated significant enhancements in solubility and dissolution rates, with a fine particle fraction (FPF) of 78.58 ± 3.21%, ensuring optimal lung delivery. In vitro experiments revealed potent effects with minimal cytotoxicity to lung cells. In vivo studies indicated that the optimized formulation achieved a Cmax/AUC0→∞ ratio in lung tissues that was 27.32 and 6.76-fold higher than that of the oral suspension, highlighting increased local drug concentrations. This approach presents a scalable, cost-effective strategy for the pulmonary delivery of PSZ, ensuring high drug loading and promising clinical outcomes in treating pulmonary fungal infections.

Effect of lubricants type and particle size on the rheological properties and aerosolization behavior of dry powder inhalers

A commonly used strategy to improve aerosolization behavior of carrier-based dry powder inhalers (DPIs) is the addition of magnesium stearate as a lubricant, yet it may also negatively affect properties of DPIs. Thus, the aim of this study was to find lubricants that could be used as alternatives of magnesium stearate and meanwhile verify the applicability of using powder rheological properties to predict the performance of different lubricants in DPIs. Here, using fluticasone propionate as a model drug, LH200 as the carrier, influence of lubricants type and particle size, including magnesium stearate, sodium stearate, Leucine, sodium stearate fumarate, Compritol® 888 ATO, and Compritol® HD5 ATO, on the physicochemical properties, powder rheology and aerosolization behavior of the DPI formulations was characterized. Further, the relationship between powder rheological parameters and in-vitro drug deposition parameter, fine particle fraction (FPF), were explored, and the contribution of powder flowability and adhesion was evaluated using principal component analysis (PCA). The results showed that magnesium stearate, sodium stearate and smaller sized leucine significantly reduced the basic flowability energy, aeration energy and Permeability of the DPI formulations, leading to improved aerosolization behavior. A robust linear correlation was established between rheological parameters and FPF. PCA showed that in lubricants containing formulations, the contribution of flowability (74.69%) was greater than that of adhesion (25.31%). In conclusion, sodium stearate and smaller particle size Leucine can be considered as substitutes of magnesium stearate in DPI formulations.

Breath and Beyond: Advances in Nanomedicine for Oral and Intranasal Aerosol Drug Delivery

Designing and standardizing drug formulations are crucial for ensuring the safety and efficacy of medications. Nanomedicine utilizes nano drug delivery systems and advanced nanodevices to address numerous critical medical challenges. Currently, oral and intranasal aerosol drug delivery (OIADD) is the primary method for treating respiratory diseases worldwide. With advancements in disease understanding and the development of aerosolized nano drug delivery systems, the application of OIADD has exceeded its traditional boundaries, demonstrating significant potential in the treatment of non-respiratory conditions as well. This study provides a comprehensive overview of the applications of oral and intranasal aerosol formulations in disease treatment. It examines the key challenges limiting the development of nanomedicines in drug delivery systems, formulation processes, and aerosol devices and explores the latest advancements in these areas. This review aims to offer valuable insights to researchers involved in the development of aerosol delivery platforms.

A Review on Micro and Nanoengineering in Powder-Based Pulmonary Drug Delivery

Pulmonary delivery of drugs has emerged as a promising approach for the treatment of both lung and systemic diseases. Compared to other drug delivery routes, inhalation offers numerous advantages including high targeting, fewer side effects, and a huge surface area for drug absorption. However, the deposition of drugs in the lungs can be limited by lung defence mechanisms such as mucociliary and macrophages' clearance. Among the delivery devices, dry powder inhalers represent the optimal choice due to their stability, ease of use, and absence of propellants. In the last decades, several bottom-up techniques have emerged over traditional milling to produce inhalable powders. Among these techniques, the most employed ones are spray drying, supercritical fluid technology, spray freeze-drying, and thin film freezing. Inhalable dry powders can be constituted by micronized drugs attached to a coarse carrier (e.g., lactose) or drugs embedded into a micro- or nanoparticle. Particulate-based formulations are commonly composed of polymeric micro- and nanoparticles, liposomes, solid lipid nanoparticles, dendrimers, nanocrystals, extracellular vesicles, and inorganic nanoparticles. Moreover, engineered formulations including large porous particles, swellable microparticles, nano-in-microparticles, and effervescent nanoparticles have been developed. Particle engineering has also a crucial role in tuning the physical-chemical properties of both carrier-based and carrier-free inhalable powders. This approach can increase powder flowability, deposition, and targeting by customising particle surface features.

Supercritical antisolvent-fluidized bed for the preparation of dry powder inhaler for pulmonary delivery of nanomedicine

The supercritical antisolvent-fluidized bed coating process (SAS-FB) shows great potential as a technique to manufacture dry powder inhaler (DPI) that incorporate nanodrugs onto micronized matrix particles, capitalizing on the merits of both nanoparticle and pulmonary delivery. In this study, naringin (NAR), a pharmacologically active flavonoid with low solubility and in vivo degradation issues, was utilized as a model active pharmaceutical ingredient to construct nanomedicine-based DPI through SAS-FB. It is showed that processed NAR exhibited a near-spherical shape and an amorphous structure with an average size of around 130 nm. Notably, SAS-FB products prepared with different fluidized matrices resulted in varying deposition patterns, particularly when mixed with a coarse lactose to enhance the fine particle fraction (FPF) of the formulations. The FPF was positively associated with specific surface area of the SAS-FB products, while the specific surface area was directly related to surface roughness and particle size. In vitro dissolution studies using simulated lung fluid revealed that the NAR nanoparticles coated on the products were released immediately upon contact with solution, with a cumulative dissolution exceeding 90% within the first minute. Importantly, compared to oral raw NAR, the optimized DPI formulation demonstrated superior in vivo plasmatic and pulmonary AUC0→∞ by 51.33-fold and 104.07-fold respectively in a Sprague-Dawley rat model. Overall, SAS- FB technology provides a practical approach to produce nanomedicine DPI product that combine the benefits of nanoparticles with the aerodynamics properties of inhaled microparticles.

Complexities related to the amorphous content of lactose carriers

Although the amount of amorphous content in lactose is low, its impact on the performance of a dry powder inhalation formulation might be high. Many formulators and regulatory agencies believe that the levels of amorphous content should be controlled once there is a relationship with the final product performance. This is however not an easy task. The current paper elaborates on multiple challenges and complexities that are related to the control of the amorphous content in lactose. The definition and quantification methods of amorphous lactose are reviewed, as well as challenges related to thermodynamic instability. Additionally, current monographs and recent position papers considering this parameter are discussed to provide an overview of the regulatory landscape. Development of a control strategy is recommended, provided that the amorphous content at a specific moment in the process has shown to have an impact on the performance of the dry powder inhaler.

Exploring the influence of magnesium stearate content and mixing modality on the rheological properties and in vitro aerosolization of dry powder inhaler

Since carrier-based dry powder inhalers (DPIs) suffer from inadequate drug deposition in the lung, an increasing number of marketed products have added magnesium stearate (MgSt) to improve the aerosolization, dispersion, and stability against moisture of DPI. However, for carrier-based DPI, there is a lack of examination of the optimal MgSt content as well as the mixing modality, and there is also a need to verify the applicability of rheological properties to predict the in vitro aerosolization of DPI formulations containing MgSt. Therefore, in this work, DPI formulations were prepared using fluticasone propionate as a model drug and commercial crystalline lactose Respitose® SV003 as a carrier within 1% MgSt content, the effect of MgSt content on the rheological and aerodynamic properties were investigated. After the optimal MgSt content was determined, the effects of mixing modality, mixing order, and carrier size on formulation properties were further investigated. Meanwhile, correlations were established between rheological parameters and in vitro drug deposition parameters, and the contribution of rheological parameters were determined using principal component analysis (PCA). The results showed that the optimal content of MgSt in DPI formulations is 0.25%-0.5% under both high-shear and low-shear, using medium-sized carriers (D50 around 70 μm) and low-shear mixing are beneficial for improving in vitro aerosolization. Good linear relationships between powder rheological parameters such as basic flow energy (BFE), specific energy (SE), Permeability and fine particle fraction (FPF) were established, PCA showed that both flowability and adhesion are key properties affecting FPF. In conclusion, both MgSt content and mixing modality can influence rheological properties of the DPI, which can be used as a screeing tool for DPI formuluation and preparation process optimization.

Predicting in vitro lung deposition behavior of combined dry powder inhaler via rheological properties

Dry powder inhaler (DPI) for pulmonary delivery is currently the primary treatment for asthma and COPD (chronic obstructive pulmonary disease), an increasing number of combined DPIs (containing two or more drugs in one inhaler) have been developed to complement the effect of single DPIs. Based on our previous studies, the rheological properties can be a potential tool used to predict the in vitro lung deposition behavior of DPI formulations. However, it is unknown whether such a prediction model is suitable for combination systems. Therefore, this study aimed to verify the applicability of using powder rheological properties to predict in vitro drug deposition behavior in combined DPI formulations. Two drugs (fluticasone propionate and salmeterol xinafoate) and their combination of DPI formulations were prepared using fine lactose content (in the range of 1%-20%) as a variable. The physicochemical properties of the powder mixtures such as particle size and content uniformity were characterized. The rheological properties of the powder mixtures were measured by FT4 rheometer, the aerodynamic behavior of the DPI formulations was evaluated by a new generation impactor (NGI), and the effect of flowability and adhesion on the deposition of the fine particle fraction (FPF) was investigated by principal component analysis (PCA). The results showed that the combined DPI formulations with larger particle interaction forces have certain differences from the aerodynamic behavior of the single DPI formulations. The regularity of rheological properties affecting FPF revealed in single DPI is still applicable to combined DPI, the parameters basic flowability energy (BFE), representing flowability, and flow factor (ff), Cohesion representing adhesion, can be well linearly related to the FPF. The results of the principal component analysis showed that better flowability and suitable adhesion contributed to higher in vitro deposition of the drug in the formulation, and the contribution of adhesion (75.42%) was greater than that of flowability (24.58%). In conclusion, rheological properties is an effective tool for predicting the deposition behavior of DPI not only in single but also in combined DPIs.

Influence of milling methods on the flow properties of ivory teff flour

Increasing teff (Eragrostis tef) consumption has been recorded in recent years due to its gluten-free nature and exceptional nutritional composition. Studies on the particle level that relates to processing and handling of teff flour are limited. The effect of different milling methods (roller mill, pin mill, and hammer mill) on size distribution, shape characteristics, and flowability of teff flour was evaluated. Physical properties (angle of repose, tapped and bulk densities, size distribution, and shape characteristics) and proximate composition were investigated and correlated with flow properties. Flowability was measured in terms of bulk, shear, and dynamic flow properties using the FT4 powder rheometer. Particle size distribution significantly (p < .05) influenced the angle of repose, aeration energy, and wall friction angle while shape characteristics (circularity and aspect ratio) significantly (p < .05) affected the aerated and tapped bulk densities and basic flow energy. Hammer-milled flour had the highest aerated (548.00 kg/m³ ) and tapped bulk densities (804.33 kg/m³ ). Pin-milled flour had the highest compressibility index (38.46%), Hausner ratio (1.62), angle of repose (71.57°), and wall friction angle (25.92° at 3 kPa) indicating poorer flowability. Stability index and specific energy did not vary significantly (p > .05) among the milled flours. Highest basic flow (1,191.03 mJ) and aerated energies (272.32 mJ) were required to induce flow in hammer-milled flour due to greater proportion of large particles. Based on the flow function, all flours fall under the "easy flowing" category, but the pin-milled flour exhibited the poorest flowability.

Scientific and regulatory activities initiated by the U.S. food and drug administration to foster approvals of generic dry powder inhalers: Quality perspective

Regulatory science for generic dry powder inhalation products worldwide has evolved over the last decade. The revised draft guidance Metered Dose Inhaler (MDI) and Dry Powder Inhaler (DPI) Products - Quality Considerations [1] (Revision 1, April 2018) that FDA issued summarizes product considerations and potential critical quality attributes (CQAs). This guidance emphasizes the need to apply the principles of quality by design (QbD) and elements of pharmaceutical development discussed in the International Conference for Harmonisation of (ICH) guidelines. Research studies related to quality were used to support guidance recommendations, which preceded the first approval of a generic DPI product in the U.S. This review outlines scientific and regulatory hurdles that need to be surmounted to successfully bring a generic DPI to the market. The goal of this review focuses on relevant issues and various challenges pertaining to CMC topics of the generic DPI quality attributes. Furthermore, this review provides recommendations to abbreviated new drug application (ANDA) applicants to expedite generic approvals.

Co-spray-dried poly-L-lysine with L-leucine as dry powder inhalations for the treatment of pulmonary infection: Moisture-resistance and desirable aerosolization performance

Poly-L-lysine (PLL) is a promising candidate for the treatment of pulmonary infection with lower occurrence of drug-resistance due to its unique antibacterial mechanisms. Dry powder inhalations (DPIs) are considered as the first choice for formulating PLL to treat pulmonary infection on account of direct delivery and satisfactory stability. However, hygroscopicity of PLL limited its therapeutic effect on pulmonary infection when PLL developed into DPIs. The hygroscopicity caused two obstacles including the low drug deposition in the lower respiratory tract and undesirable aerosolization performance deterioration. In this study, PLL was co-spray-dried with L-leucine (LL) to achieve moisture-resistance and desirable aerosolization performance. The ratio of PLL and LL was optimized to obtain particles with different morphology, hygroscopicity and aerodynamic properties. The obtained PLL DPIs were suitable for inhalation with a corrugated surface formed by hydrophobic LL. The anti-hygroscopicity, aerosolization performance and rheological properties of P2 DPIs were optimal when PLL:LL = 85:15. The DPIs particles were stable after being stored at high relative humidity (60 ± 5%), and their superiority in treating pulmonary infections was also proved by in vitro and in vivo experiments. The established PLL DPIs were proved to be a feasible and desirable approach to treat pulmonary infections.

Elucidation of lactose fine size and drug shape on rheological properties and aerodynamic behavior of dry powders for inhalation

Pulmonary drug delivery has gained great attention in local or systemic diseases therapy, however it is still difficult to scale-up DPI production due to the complexity of interactions taking place in DPI systems and limited understanding between flowability and inter-particle interactions in DPI formulations. Therefore, finding some quantitative parameters related to DPI delivery performance for predicting the in vitro drug deposition behavior is essential. Therefore, this study introduces a potential model for predicting aerodynamic performance of carrier-based DPIs, as well to find more relevant fine powder size and optimal shape to improve aerodynamic performance. Using salbutamol sulfate as a model drug, Lactohale®206 as coarse carrier, Lactohale®300, Lactohale®230, and Lactohale®210 as third fine components individually, the mixtures were prepared at 1% (w/w) drug content accompanied with carriers and the third component (ranging from 3 - 7%), influence of lactose fines size on DPI formulation's rheological and aerodynamic properties was investigated. The optimum drug particle shape was also confirmed by computer fluid dynamics model. This study proved that pulmonary deposition efficiency could be improved by decreasing lactose fines size. Only fines in the size range of 0-11 μm have a good linear relationship with FPF, attributed to the fluidization energy enhancement and aggregates mechanism. Once exceeding 11 μm, fine lactose would act as a second carrier, with increased drug adhesion. Computational fluid dynamics (CFD) models indicated fibrous drug particles were beneficial to transfer to the deep lung. Furthermore, good correlations between rheological parameters and FPF of ternary mixtures with different lactose fines were established, and it was disclosed that the FPF was more dependent on interaction parameters than that of flowability.

Micro-fluidic Spray Freeze Dried Ciprofloxacin Hydrochloride-Embedded Dry Powder for Inhalation

Active pharmaceutical ingredient (API)-embedded dry powder for inhalation (AeDPI) is highly desirable for pulmonary delivery of high-dose drug. Herein, a series of spray freeze-dried (SFD) ciprofloxacin hydrochloride (CH)-embedded dry powders were fabricated via a self-designed micro-fluidic spray freeze tower (MFSFT) capable of tuning freezing temperature of cooling air as the refrigerant medium. The effects of total solid content (TSC), mass ratio of CH to _L-leucine (Leu) as the aerosol dispersion enhancer, and the freezing temperature on particle morphology, size, density, moisture content, crystal properties, flowability, and aerodynamic performance were investigated. It was found that the Leu content and freezing temperature had considerable influence on the fine particle fraction (FPF) of the SFD microparticles. The optimal formulation (CH/Leu = 7:3, TSC = 2%w/w) prepared at - 40°C exhibited remarkable effective drug deposition (~ 33.38%), good aerodynamic performance (~ 47.69% FPF), and excellent storage stability with ultralow hygroscopicity (~ 1.93%). This work demonstrated the promising feasibility of using the MFSFT instead of conventional liquid nitrogen assisted method in the research and development of high-dose AeDPI.

Inhalable Nano-Dimpled Microspheres Containing Budesonide-PLGA for Improved Aerodynamic Performance

Introduction

Dry powder inhalations are an attractive pharmaceutical dosage form. They are environmentally friendly, portable, and physicochemical stable compared to other inhalation forms like pressurized metered-dose inhalers and nebulizers. Sufficient drug deposition of DPIs into the deep lung is required to enhance the therapeutic activity. Nanoscale surface roughness in microparticles could improve aerosolization and aerodynamic performance. This study aimed to prepare microspheres with nanoscale dimples and confirm the effect of roughness on inhalation efficiency.

Methods

The dimpled-surface on microspheres (MSs) was achieved by oil in water (O/W) emulsion-solvent evaporation by controlling the stirring rate. The physicochemical properties of MSs were characterized. Also, in vitro aerodynamic performance of MSs was evaluated by particle image velocimetry and computational fluid dynamics.

Results

The particle image velocimetry results showed that dimpled-surface MSs had better aerosolization, about 20% decreased X-axial velocity, and a variable angle, which could improve the aerodynamic performance. Furthermore, it was confirmed that the dimpled surface of MSs could cause movement away from the bronchial surface, which helps the MSs travel into the deep lung using computational fluid dynamics.

Conclusion

The dimpled-surface MSs showed a higher fine particle fraction value compared to smooth-surface MSs in the Andersen Cascade Impactor, and surface roughness like dimples on microspheres could improve aerosolization and lung deposition.

Dry Powder Inhalers Based on Chitosan-Mannitol Binary Carriers: Effect of the Powder Properties on the Aerosolization Performance

Carriers play an important role in improving the aerosolization performance of dry powder inhalers (DPIs). Despite that intensive attention had been paid to the establishment of the advanced carriers with controllable physicochemical properties in recent years, the design and optimization of carrier-based DPIs remain an empiricism-based process. DPIs are a powder system of complex multiphase, and thus their physicochemical properties cannot fully explain the powder behavior. A comprehensive exposition of powder properties is demanded to build a bridge between the physicochemical properties of carriers and the aerosolization performance of DPIs. In this study, an FT-4 powder rheometer was employed to explore the powder properties, including dynamic flow energy, aeration, and permeability of the chitosan-mannitol binary carriers (CMBCs). CMBCs were self-designed as an advanced carrier with controllable surface roughness to obtain enhanced aerosolization performance. The specific mechanism of CMBCs to enhance the aerosolization performance of DPIs was elaborated based on the theory of pulmonary delivery processes by introducing powder properties. The results exhibited that CMBCs with appropriate surface roughness had lower special energy, lower aeration energy, and higher permeability. It could be predicted that CMBC-based DPIs had greater tendency to fluidize and disperse in airflow, and the lower adhesion force between particles enabled drugs to be detached from the carrier to achieve higher fine particle fractions. The specific mechanism on how physicochemical properties influenced the aerosolization performance during the pulmonary delivery processes could be figured out with the introduction of powder properties.

Development of drug alone and carrier-based GLP-1 dry powder inhaler formulations

The study aimed to develop two types of dry powder inhaler (DPI) formulations containing glucagon-like peptide-1(7-36) amide (GLP-1): carrier-free (drug alone, no excipients) and carrier-based DPI formulations for pulmonary delivery of GLP-1. This is the first study focusing on the development of excipient free GLP-1 DPI formulations for inhaled therapy in Type 2 diabetes. The aerosolisation performance of both DPI formulations was studied using a next generation impactor and a DPI device (Handihaler®) at flow rate of 30 L min^-1. Carriers employed were either a 10% w/w glycine-mannitol prepared by spray freeze drying or commercial mannitol. Spray freeze dried (SFD) carrier was spherical and porous whereas commercial mannitol carrier exhibited elongated particles (non-porous). GLP-1 powder without excipients for inhalation was prepared using spray drying and characterised for morphology including size, thermal behaviour, and moisture content. Spray dried (SD) GLP-1 powders showed indented/dimpled particles in the particle size range of 1 to 5 µm (also mass median aerodynamic diameter, MMAD: <5 µm) suitable for pulmonary delivery. Across formulations investigated, carrier-free DPI formulation showed the highest fine particle fraction (FPF: 90.73% ± 1.76%, mean ± standard deviation) and the smallest MMAD (1.96 µm ± 0.07 µm), however, low GLP-1 delivered dose (32.88% ± 7.00%, total GLP-1 deposition on throat and all impactor stages). GLP-1 delivered dose was improved by the addition of SFD 10% glycine-mannitol carrier to the DPI formulation (32.88% ± 7.00% -> 45.92% ± 5.84%). The results suggest that engineered carrier-based DPI formulations could be a feasible approach to enhance the delivery efficiency of GLP-1. The feasibility of systemic pulmonary delivery of SD GLP-1 for Type 2 diabetes therapy can be further investigated in animal models.

A real-time and modular approach for quick detection and mechanism exploration of DPIs with different carrier particle sizes

Dry powder inhalers (DPIs) had been widely used in lung diseases on account of direct pulmonary delivery, good drug stability and satisfactory patient compliance. However, an indistinct understanding of pulmonary delivery processes (PDPs) hindered the development of DPIs. Most current evaluation methods explored the PDPs with over-simplified models, leading to uncompleted investigations of the whole or partial PDPs. In the present research, an innovative modular process analysis platform (MPAP) was applied to investigate the detailed mechanisms of each PDP of DPIs with different carrier particle sizes (CPS). The MPAP was composed of a laser particle size analyzer, an inhaler device, an artificial throat and a pre-separator, to investigate the fluidization and dispersion, transportation, detachment and deposition process of DPIs. The release profiles of drug, drug aggregation and carrier were monitored in real-time. The influence of CPS on PDPs and corresponding mechanisms were explored. The powder properties of the carriers were investigated by the optical profiler and Freeman Technology four powder rheometer. The next generation impactor was employed to explore the aerosolization performance of DPIs. The novel MPAP was successfully applied in exploring the comprehensive mechanism of PDPs, which had enormous potential to be used to investigate and develop DPIs.

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.

Feasibility of an inhaled antibiotic/adjuvant dry powder combination using an experimental design approach

The global increase of multidrug resistant bacteria and the lack of new classes of antibiotic especially those targeting Gram-negative pathogens are leaving the clinicians disarmed to treat numerous bacterial infections. Recently, the design of adjuvants able to enhance antibiotics activities appears to be one of the most promising investigated solutions to circumvent this problem. In this context, we have recently identified a new polyamino-isoprenyl derivative NV716 able to potentiate, at a very low concentration the activity of doxycycline against resistant P. aeruginosa bacterial strains by increasing its intracellular concentration. In this study we will report an experimental protocol to optimize a dry powder for inhalation ensuring the simultaneous delivery of an antibiotic (doxycycline) and an adjuvant (the polyaminoisoprenyl derivative NV716 since aerosol therapy could allow a rapid drug administration and target the respiratory system by avoiding the first pass effect and minimizing undesirable systemic effects. Thus, an experimental design was carried out permitting to identify the influence of several factors on the aerosolization efficiency of our combination and allowing us to find the right composition and manufacture leading to the best optimization of the simultaneous delivery of the two compounds in the form of an inhalable powder. More precisely, the powders of the two active ingredients were prepared by freeze drying and their aerosolization was improved by the addition of carrier particles of lactose inhalation grade. Under these conditions, the best formulation was defined by combining the optimal factors leading to the best aerodynamic properties' values (the lowest MMAD (Mass Median Aerodynamic Diameter) and the highest FPF (Fraction of Fine Particles)) without even using sophisticated engineering techniques. Finally, our results suggest that these molecules could be successfully delivered at the requested concentration in the lungs and then able to decrease drug consumption as well as increase treatment efficacy.

Exploring the potential influence of drug charge on downstream deposition behaviour of DPI powders

Dry powder inhaler (DPI) development is limited by the time- and labor-consuming in vitro lung deposition test. It's highly desirable to find an easy tool for DPI formulation screening. Dynamic powder rheological properties seem to present many advantages, however, the adoptability needs to be verified. Drug charge is an important parameter especially for DPI formulation design but how it affects the process of pulmonary drug delivery is unavailable. Therefore, the objective of this study is to explore the influence of drug charge on DPI powders, further testing the potentials of powder properties for downstream deposition behavior prediction. Taking five differently charged drugs as model, influence of drug charge on uniformity, rheological and aerodynamic properties of the mixtures were investigated systemically. It was found that mometasone furoate with near neutral charge presented better content homogeneity, while significantly decreased recovery was noted for charged drugs, such as positively charged drug (salbutamol sulphate and indacaterol maleate) mixtures and negatively charged drug (budesonide and fluticasone propionate) mixtures. Moreover, drug charge also influenced flowability and cohesion of their admixture with lactose. As for the downstream deposition, neutral drugs presented higher fine particle fraction (FPF), followed by positively charged drugs and negatively charged drugs. Good correlations between basic flowability energy, aeration energy, Permeability and FPF were established irrespective of different drugs. Principal component analysis results suggested flowability had a greater influence on FPF when mixtures were less cohesive. In conclusion, this study demonstrated drug charge can influence physicochemical, rheological and aerodynamic properties of the admixture, and DPIs' dynamic properties could be used as potential tools to predict downstream deposition with good accuracy.

Inhalable Nanocomposite Microparticles with Enhanced Dissolution and Superior Aerosol Performance

Previous studies have shown that combining colistin (Col), a cationic polypeptide antibiotic, with ivacaftor (Iva), a cystic fibrosis (CF) drug, could achieve synergistic antibacterial effects against Pseudomonas aeruginosa. The purpose of this study was to develop dry powder inhaler formulations for co-delivery of Col and Iva, aiming to treat CF and lung infection simultaneously. In order to improve solubility and dissolution for the water-insoluble Iva, Iva was encapsulated into bovine serum albumin (BSA) nanoparticles (Iva-BSA-NPs). Inhalable composite microparticles of Iva-BSA-NPs were produced by spray-freeze-drying using water-soluble Col as the matrix material and l-leucine as an aerosol enhancer. The optimal formulation showed an irregularly shaped morphology with fine particle fraction (FPF) values of 73.8 ± 5.2% for Col and 80.9 ± 4.1% for Iva. Correlations between "D×ρtapped" and FPF were established for both Iva and Col. The amorphous solubility of Iva is 66 times higher than the crystalline solubility in the buffer. Iva-BSA-NPs were amorphous and remained in the amorphous state after spray-freeze-drying, as examined by powder X-ray diffraction. In vitro dissolution profiles of the selected DPI formulation indicated that Col and Iva were almost completely released within 3 h, which was substantially faster regarding Iva release than the jet-milled physical mixture of the two drugs. In summary, this study developed a novel inhalable nanocomposite microparticle using a synergistic water-soluble drug as the matrix material, which achieved reduced use of excipients for high-dose medications, improved dissolution rate for the water-insoluble drug, and superior aerosol performance.

Novel approach for real-time monitoring of carrier-based DPIs delivery process via pulmonary route based on modular modified Sympatec HELOS

An explicit illustration of pulmonary delivery processes (PDPs) was a prerequisite for the formulation design and optimization of carrier-based DPIs. However, the current evaluation approaches for DPIs could not provide precise investigation of each PDP separately, or the approaches merely used a simplified and idealized model. In the present study, a novel modular modified Sympatec HELOS (MMSH) was developed to fully investigate the mechanism of each PDP separately in real-time. An inhaler device, artificial throat and pre-separator were separately integrated with a Sympatec HELOS. The dispersion and fluidization, transportation, detachment and deposition processes of pulmonary delivery for model DPIs were explored under different flow rates. Moreover, time-sliced measurements were used to monitor the PDPs in real-time. The Next Generation Impactor (NGI) was applied to determine the aerosolization performance of the model DPIs. The release profiles of the drug particles, drug aggregations and carriers were obtained by MMSH in real-time. Each PDP of the DPIs was analyzed in detail. Moreover, a positive correlation was established between the total release amount of drug particles and the fine particle fraction (FPF) values (R 2 = 0.9898). The innovative MMSH was successfully developed and was capable of illustrating the PDPs and the mechanism of carrier-based DPIs, providing a theoretical basis for the design and optimization of carrier-based DPIs.

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.

Physical stability of dry powder inhaler formulations

Introduction: Dry powder inhalers (DPIs) are popular for pulmonary drug delivery. Various techniques have been employed to produce inhalation drug particles and improve the delivery efficiency of DPI formulations. Physical stability of these DPI formulations is critical to ensure the delivery of a reproducible dose to the airways over the shelf-life.Areas covered: This review focuses on the impact of solid-state stability on aerosolization performance of DPI drug particles manufactured by powder production approaches and particle-engineering techniques. It also highlights the different analytical tools that can be used to characterize the physical instability originating from production and storage.Expert opinion: A majority of the DPI literature focuses on the effects of physico-chemical properties such as size, morphology, and density on aerosolization. While little has been reported on the physical stability, particularly the stability of engineered drug particles for use in DPIs. Literature data have shown that different particle-engineering methods and storage conditions may cause physical instability of dry powders for inhalation and can significantly change the aerosol performance. A systematic examination of physical instability mechanisms in DPI formulations is necessary during formulation development in order to select the optimum formulation with satisfactory stability. In addition, the use of appropriate characterization tools is critical to detect and understand physical instability during the development of DPI formulations.