A New Role of Fine Excipient Materials in Carrier-Based Dry Powder Inhalation Mixtures: Effect on Deagglomeration of Drug Particles During Mixing Revealed

Heparin-azithromycin microparticles show anti-inflammatory effects and inhibit SARS-CoV-2 and bacterial pathogens associated to lung infections

Pulmonary infections are a leading cause of morbidity and mortality worldwide, a situation exacerbated by the COVID-19. Azithromycin (AZM) is used orally to treat pulmonary infections due to its ability to accumulate in lung tissues and immune cells after oral administration. Sulfated polysaccharides, such as heparin, are known to inhibit SARS-CoV-2 entry. This study presents a novel approach focused on developing a dry powder inhaler of AZM-loaded microparticles composed of either heparin or its derivatives. The microparticle formulations exhibited potent antiviral activity against SARS-CoV-2 (IC50 ≤ 95 nM) while retaining superior antibacterial efficacy against Streptococcus pneumoniae and Pseudomonas aeruginosa compared to free AZM (MIC ≤15 μg/mL). Importantly, at bactericidal concentrations, no cytotoxic effects were observed on mammalian cells, including Calu-3 cells and red blood cells. The formulations demonstrated effective alveolar aerodynamic deposition (MMAD ranging from 1 μm to 3 μm) with a Fine Particle Fraction below 5 μm close to 50 %. Adopting a conservative estimate of 20 mL for the pulmonary epithelial lining fluid volume in healthy adults, efficacious local concentrations of sulfated polysaccharides and AZM would be delivered to the lung using this multifaceted strategy which holds promise for the treatment of bacterial pulmonary infections associated with COVID-19.

Fine excipient materials in carrier-based dry powder inhalation formulations: The interplay of particle size and concentration effects

The contributions of fine excipient materials to drug dispersibility from carrier-based dry powder inhalation (DPI) formulations are well recognized, although they are not completely understood. To improve the understanding of these contributions, we investigated the influences of the particle size of the fine excipient materials on characteristics of carrier-based DPI formulations. We studied two particle size grades of silica microspheres, with volume median diameters of 3.31 μm and 8.14 μm, as fine excipient materials. Inhalation formulations, each composed of a lactose carrier material, one of the fine excipient materials (2.5% or 15.0% w/w), and a drug (fluticasone propionate) material (1.5% w/w) were prepared. The physical microstructure, the rheological properties, the aerosolization pattern, and the aerodynamic performance of the formulations were studied. At low concentration, the large silica microspheres had a more beneficial influence on the drug dispersibility than the small silica microspheres. At high concentration, only the small silica microspheres had a beneficial influence on the drug dispersibility. The results reveal influences of fine excipient materials on mixing mechanics. At low concentration, the fine particles improved deaggregation and distribution of the drug particles over the surfaces of the carrier particles. The large silica microspheres were associated with a greater mixing energy and a greater improvement in the drug dispersibility than the small silica microspheres. At high concentration, the large silica microspheres kneaded the drug particles onto the surfaces of the carrier particles and thus impaired the drug dispersibility. As a critical attribute of fine excipient materials in carrier-based dry powder inhalation formulations, the particle size demands robust specification setting.

Critical attributes of fine excipient materials in carrier-based dry powder inhalation formulations: The particle shape and surface properties

The potential of fine excipient materials to improve the aerodynamic performance of carrier-based dry powder inhalation (DPI) formulations is well acknowledged but not fully elucidated. To improve the understanding of this potential, we studied two fine excipient materials: micronized lactose particles and silica microspheres. Inhalation formulations, each composed of a coarse lactose carrier, one of the two fine excipient materials (0.0-15.0 % w/w), and a spray-dried drug (fluticasone propionate) material (1.5 % w/w) were prepared. The physical structure, the flow behavior, the aerosolization behavior, and the aerodynamic performance of the formulations were studied. The two fine excipient materials similarly occupied carrier surface macropores. However, only the micronized lactose particles formed agglomerates and appeared to increase the tensile strength of the formulations. At 2.5 % w/w, the two fine excipient materials similarly improved drug dispersibility, whereas at higher concentrations, the micronized lactose material was more beneficial than the silica microspheres. The findings suggest that fine excipient materials improve drug dispersibility from carrier-based DPI formulations at low concentrations by filling carrier surface macropores and at high concentrations by forming agglomerates and/or enforcing fluidization. The study emphasizes critical attributes of fine excipient materials in carrier-based DPI formulations.

Sodium hyaluronate dry powder inhalation in combination with sodium cromoglycate prepared using optimized spray drying conditions

Sodium hyaluronate (SHA) is an anti-inflammatory and protective agent against bronchoconstriction, and sodium cromoglicate (SCG) prevents exercise-induced bronchoconstriction and inflammation. Based on the pharmacological properties of both substances, this study aimed to develop a dry powder inhaler (DPI) of SHA alone and in combination with SCG. The target of the study was to develop flowable formulations without any surfactants by using the spray drying method. To obtain respirable SHA and SCG:SHA particles, variables of the spray dryer, such as inlet temperature, atomized air flow, and feed solution, were changed. The particles 1-8 μm in size were produced with high yield by spray drying and increasing the ethanol percentage of the feed solution (60%), which is the most remarkable parameter. After that, physicochemical characterizations were performed. The aerosol performance of DPI formulations prepared using lactose was evaluated using Handihaler® DPI. The fine particle fraction (FPF) was 36% for the SHA formulation, whereas it was 52 and 53% for SCG and SHA, respectively, in the SCG:SHA formulation. Consequently, both particles were produced reproducibly by spray drying, and inhaled SHA and SCG:SHA dry powder formulations were developed due to their high FPF and flowability with lactose.

Recent developments in lactose blend formulations for carrier-based dry powder inhalation

Lactose is the most commonly used excipient in carrier-based dry powder inhalation (DPI) formulations. Numerous inhalation therapies have been developed using lactose as a carrier material. Several theories have described the role of carriers in DPI formulations. Although these theories are valuable, each DPI formulation is unique and are not described by any single theory. For each new formulation, a specific development trajectory is required, and the versatility of lactose can be exploited to optimize each formulation. In this review, recent developments in lactose-based DPI formulations are discussed. The effects of varying the material properties of lactose carrier particles, such as particle size, shape, and morphology are reviewed. Owing to the complex interactions between the particles in a formulation, processing adhesive mixtures of lactose with the active ingredient is crucial. Therefore, blending and filling processes for DPI formulations are also reviewed. While the role of ternary agents, such as magnesium stearate, has increased, lactose remains the excipient of choice in carrier-based DPI formulations. Therefore, new developments in lactose-based DPI formulations are crucial in the optimization of inhalable medicine performance.

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.

Insights into the potential of rheological measurements in development of dry powder inhalation formulations

Study of flow is a key to development of dry powder inhalation formulations. Various static (bulk) and dynamic rheological measurements are used to study different aspects of powder flow and packing. Among rheological measurements, the permeability and the fluidization energy are, conceptually, most relevant to dispersion of dry powder inhalation formulations. The aim of the current study was to test the robustness and the range of applications of the two measurements, among other rheological measurements. To this end, we prepared and studied a series of ternary, carrier-based dry powder inhalation formulations. The formulations were mixtures of coarse-fine excipient (α-lactose monohydrate) blends, with different fine excipient concentrations (0.0-15.0 % w/w), and a spray-dried drug (fluticasone propionate) material. The excipient blends were characterized in terms of morphology, size, crystallinity and rheological properties. The formulations were evaluated in vitro using a low resistance inhalation device, the Cyclohaler®, and a high resistance inhalation device, the Handihaler®. The study design aimed to complement literature data. Bulk rheological measurements, specifically the bulk density, the compressibility, and the permeability, exhibited satisfactory precision and could demonstrate changes in powder composition and structure. They hold a potential for use as critical material attributes to aid monitoring and optimization of carrier-based dry powder inhalation formulations in quality-by-design systems. On the other hand, dynamic rheological measurements, specifically the basic flowability energy, the specific energy, and the fluidization energy, generally exhibited high variability, which obscured interpretation of the measurements and implied heterogeneous powder structures. The fluidization energy could, nevertheless, convey structural changes taking place during powder fluidization.

Characterization of excipients to improve pharmaceutical properties of sirolimus in the supercritical anti-solvent fluidized process

Enhanced drug release and bioavailability of poorly soluble active pharmaceutical ingredient (API) can be achieved via a fluidized bed coating integrated with supercritical anti-solvent (SAS-FB) - a process of precipitating drug particles onto carrier granules. However, in the absence of excipients, SAS-FB often results in crystalline of the API on the surface of carriers, limiting the improvement of pharmaceutical properties. Co-processing with excipients is considered an effective approach to improve drug release in the SAS-FB process. Our study used sirolimus, an immune suppressive agent, as the model API to characterize excipients for their effect on pharmaceutical properties in the SAS-FB process. We show that co-precipitation of excipients and sirolumus impacts on carrier specific surface area and drug yield. Among the tested excipients, formulation containing polyvinylpyrrolidone K30 achieved the highest drug yield. Importantly, compared with Rapamune® tablet, our optimized formulation displayed a superior in vivo oral bioavailability by 3.05-fold in Sprague-Dawley rats and 3.99-fold in beagle dogs. A series of characterization of the processed API was performed to understand the mechanism by which excipients contributed to drug dissolution properties. Our study provides a useful guidance for the use of excipients in the SAS-FB technology to improve pharmaceutical properties of sirolimus and other poorly soluble drugs.

Dry powder inhaler formulation comparison: Study of the role of particle deposition pattern and dissolution

The composition, morphology and dissolution profile of particles and micro-sized agglomerates delivered upon inhalation may have a significant impact on the product clinical effect. However, although several efforts are ongoing, a methodology that considers deposition structures and dissolution performance evaluation in a biorelevant set-up is not yet standardized. The goal of this work is to apply a collection and dissolution methodology able to discriminate dry powder inhaler (DPI) formulations in terms of deposition structures and dissolution profile in vitro. Hence, Fluticasone Propionate (FP) engineered particles and formulated products (used as a case study) were collected employing a breath simulator and characterized regarding (i) aerodynamic particle size distribution; (ii) deposited microstructures; and (iii) dissolution/absorption profiles using the DissolvIt® bio-relevant dissolution equipment. The results indicated that the particle engineering technology had an impact on the generated and deposited microstructures, here associated to the differences on surface properties of jet milled and wet polished particles quantified by the specific surface area. Differences on surface properties modulate particle interactions, resulting in agglomerates of drug substance and excipient upon actuation with significant different morphologies, observed by microscope, as well as quantified by Marple cascade impactor. These observations allow for a further understanding of the DPI aerosolization and deposition mechanisms. The dissolution and absorption assessment indicates that the presence of lactose may accelerate the drug substance dissolution kinetics, and the FP dissolution can be significantly enhanced when formulated as a spray-dried dispersion particle. Ultimately, the results suggest dissolution testing can be an essential tool to both optimize an innovator DPI and de-risk generics development.

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.

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.

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.

Microstructural characterization of carrier-based dry powder inhalation excipients: Insights and guidance

The growing interest in development of dry powder inhalation (DPI) products raises a need for development of standard testing methods and specifications for DPI excipients. The pharmaceutical industry, meanwhile, yet lacks compendial guidance on this topic. Despite of the complexity of interactions taking place in DPI systems and the large number and variety of interplaying factors, understanding of key determinants of performance (critical quality attributes) of DPI excipients have considerably developed over the past years. In light of the current knowledge in this area, this article provides technical guidance and insights on testing and quality control of carrier-based-DPI excipients. These excipients are, typically, blends of coarse, carrier particles and fine, performance-modulating particles. The article explores techniques used for measurement of key microstructural attributes, namely the particle size distribution, the porosity and the particle surface roughness, the particle shape, rheological properties, and the permeability, of these excipients. The technical relevance of each measurement to the functionality of the excipients is critically discussed. In this regard, caveats concerning use of some measurements and data analysis procedures are raised. The guidance lends itself for compendial adoption.

Assessing Aerosol Performance of a Dry Powder Carrier Formulation with Increasing Doses Using a Novel Inhaler

This study aims to investigate the implications of loaded formulation mass on aerosol performance using a reservoir novel dry powder inhaler containing a custom dosing cup to deliver carrier-based formulation to the lungs. A 3D printed dosing cup with volume size of 133.04 mm³ was manufactured to allow for the progressive loading of different carrier formulation masses of 1% beclomethasone dipropionate BDP (w/w) formulation (10 to 60 mg, with increments of 10 mg), in a novel customizable DPI device. Scanning electron micrographs were used to investigate BDP detachment from carrier particles post-aerosolisation and particle deposition on the USP induction port. The subsequent aerosol performance analysis was performed using the next generation impactor (NGI). Incrementally increasing the loading mass to 60 mg led to decreases in BDP detachment from carrier particles, resulting in significant decreases in aerosol performance. Increases in loading dose mass led to progressively decreased detachment of BDP from the carrier and the overall aerosol performance in comparison to the initial mass of 10 mg. These results are likely to be due to a decrease in void volume within the dosing cup with increased loading mass leading to altered airflow, decreased impaction forces and the possibility of a significant quantity of large carrier particles introducing a 'sweeping' effect on the inhaler inner surface. This study has shown that despite the decreased BDP detachment from the carrier and decreased aerosol performance, the dose delivered to the lung still increased due to the higher loaded dose.

Effect of Dosing Cup Size on the Aerosol Performance of High-Dose Carrier-Based Formulations in a Novel Dry Powder Inhaler

This study investigated how varying the dosing cup size of a novel reservoir dry powder inhaler (DPI) affects the detachment of a micronized active pharmaceutical ingredient from larger carrier particles, and the aerosol performance of a DPI carrier formulation. Three different-sized dosing cups were designed: 3D printed with cup volumes of 16.26 mm³, 55.99 mm³, and 133.04 mm³, and tested with five different carrier type formulations with beclomethasone dipropionate (BDP) concentrations between 1% and 30% (w/w). The morphology of the BDP attached to the carrier was investigated using scanning electron microscopy and the aerosol performance using the Next Generation Impactor. Increasing the volume of the dosing cup led to a reduction of BDP deposition in the Next Generation Impactor preseparator, and an increase in BDP detachment from the carrier was observed, leading to increased aerosol performance. The decreased amount of BDP attached to carrier after aerosolization was attributed to the increased dosing cup void volume. This may enable greater particle-particle and particle-wall collisions, with greater BDP detachment from the carrier and deagglomeration of smaller agglomerates. The dosing cup volume was observed to have significant influence on particle dispersion and the overall aerosol performance of a DPI.

Dosing challenges in respiratory therapies

The pulmonary route of administration has been commonly used for local lung conditions such as asthma and chronic obstructive pulmonary disease (COPD). Recently, with the advent of new technologies available for both formulation and device design, molecules usually delivered at high doses, such as antibiotics and insulin to treat cystic fibrosis (CF) and diabetes, respectively, can now be delivered by inhalation as a dry powder. These molecules are generally delivered in milligrams instead of traditional microgram quantities. High dose delivery is most commonly achieved via dry powder inhalers (DPIs), breath activated devices designed with a formulated powder containing micronized drug with aerodynamic diameters between 1 and 5 µm. The powder formulation may also contain other excipients and/or carrier particles to improve the flowability and aerosol dispersion of the powder. A drawback with high doses is that the formulation contains a great number of fine particles, leading to a greater degree of cohesive forces, producing strongly bound agglomerates. With greater cohesive forces holding fine particles together, higher dispersion forces are needed for efficient de-agglomeration and aerosolisation. This requirement of greater dispersion forces has led to different dry powder formulations and vastly different inhaler designs. The purpose of this review is to evaluate the different formulation types, various DPI devices currently available, and how these affect the aerosolisation process and delivery of high dosed inhalable dry powder formulations to the lungs.

The Relationship Between the Permeability and the Performance of Carrier-Based Dry Powder Inhalation Mixtures: New Insights and Practical Guidance

The permeability of a powder bed reflects its particle size distribution, shape, packing, porosity, cohesivity, and tensile strength in a manner relevant to powder fluidization. The relationship between the permeability and the performance of carrier-based dry powder inhalation (DPI) mixtures has, however, aroused controversy. The current study sought to gain new insights into the relationship and to explore its potential applications. We studied eight lactose materials as DPI carriers. The carriers covered a broad permeability range of 0.42-13.53 D and moreover differed in particle size distribution, particle shape, crystal form, and/or porosity. We evaluated the performance of inhalation mixtures of each of these carriers and fluticasone propionate after aerosolization from an Aerolizer®, a model turbulent-shear inhaler, at a flow rate of 60 L/min. Starting from the high permeability side, the inhalation mixture performance increased as the carrier permeability decreased until optimum performance was reached at permeability of ~ 3.2 D. Increased resistance to air flow strengthens aerodynamic dispersion forces. The inhalation mixture performance then decreased as the carrier permeability further decreased. Very high resistance to air flow restricts powder dispersion. The permeability accounted for effects of carrier size, shape, and macroporosity on the performance. We confirmed the relationship by analysis of two literature permeability-performance datasets, representing measurements that differ from ours in terms of carrier grades, drug, technique used to determine permeability, turbulent-shear inhaler, and/or aerosolization flow rate. Permeability provides useful information that can aid development of DPI mixtures for turbulent-shear inhalers. A practical guidance is provided.