Development of a New Dry Powder Aerosol Synthetic Lung Surfactant Product for Neonatal Respiratory Distress Syndrome (RDS) - Part I: In Vitro Testing and Characterization.

PURPOSE: Improving the deep lung delivery of aerosol surfactant therapy (AST) with a dry powder formulation may enable significant reductions in dose while providing improved efficacy. The objective of Part I of this two-part study was to present the development of a new dry powder aerosol synthetic lung surfactant (SLS) product and to characterize performance based on aerosol formation and realistic in vitro airway testing leading to aerosol delivery recommendations for subsequent in vivo animal model experiments. METHODS: A new micrometer-sized SLS excipient enhanced growth (EEG) dry powder formulation was produced via spray drying and aerosolized using a positive-pressure air-jet dry powder inhaler (DPI) intended for aerosol delivery directly to intubated infants with respiratory distress syndrome (RDS) or infant-size test animals. RESULTS: The best-case design (D2) of the air-jet DPI was capable of high emitted dose (> 80% of loaded) and formed a < 2 µm mass median aerodynamic diameter (MMAD) aerosol, but was limited to ≤ 20 mg mass loadings. Testing with a realistic in vitro rabbit model indicated that over half of the loaded dose could penetrate into the lower lung regions. Using the characterization data, a dose delivery protocol was designed in which a 60 mg total loaded dose would be administered and deliver an approximate lung dose of 14.7-17.7 mg phospholipids/kg with a total aerosol delivery period < 5 min. CONCLUSIONS: A high-efficiency aerosol SLS product was designed and tested that may enable an order of magnitude reduction in administered phospholipid dose, and provide rapid aerosol administration to infants with RDS.

Inhalable tobramycin EEG powder formulation for treating Pseudomonas aeruginosa-induced lung infection.

Pulmonary delivery of antibiotics is an effective strategy in treating bacterial lung infection for cystic fibrosis patients, by achieving high local drug concentrations and reducing overall systemic exposure compared to systemic administration. However, the inherent anatomical lung defense mechanisms, formulation characteristics, and drug-device combination determine the treatment efficacy of the aerosol delivery approach. In this study, we prepared a new tobramycin (Tobi) dry powder aerosol using excipient enhanced growth (EEG) technology and evaluated the in vitro and in vivo aerosol performance. We further established a Pseudomonas aeruginosa-induced lung infection rat model using an in-house designed novel liquid aerosolizer device. Notably, novel liquid aerosolizer yields comparable lung infection profiles despite administering 3-times lower P. aeruginosa CFU per rat in comparison to the conventional intratracheal administration. Dry powder insufflator (e.g. Penn-Century DP-4) to administer small powder masses to experimental animals is no longer commercially available. To address this gap, we developed a novel rat air-jet dry powder insufflator (Rat AJ DPI) that can emit 68-70 % of the loaded mass for 2 mg and 5 mg of Tobi-EEG powder formulations, achieving a high rat lung deposition efficiency of 79 % and 86 %, respectively. Rat AJ DPI can achieve homogenous distribution of Tobi EEG powder formulations at both loaded mass (2 mg and 5 mg) over all five lung lobes in rats. We then demonstrated that Tobi EEG formulation delivered by Rat AJ DPI can significantly decrease CFU counts in both trachea and lung lobes at 2 mg (p < 0.05) and 5 mg (p < 0.001) loaded mass compared to the untreated P. aeruginosa-infected group. Tobi EEG powder formulation delivered by the novel Rat AJ DPI showed excellent efficiencies in substantially reducing the P. aeruginosa-induced lung infection in rats.

Development of an effective two-equation turbulence modeling approach for simulating aerosol deposition across a range of turbulence levels.

Pharmaceutical aerosol systems present a significant challenge to computational fluid dynamics (CFD) modeling based on the need to capture multiple levels of turbulence, frequent transition between laminar and turbulent flows, anisotropic turbulent particle dispersion, and near-wall particle transport phenomena often within geometrically complex systems over multiple time scales. Two-equation turbulence models, such as the k-ω family of approximations, offer a computationally efficient solution approach, but are known to require the use of near-wall (NW) corrections and eddy interaction model (EIM) modifications for accurate predictions of aerosol deposition. The objective of this study was to develop an efficient and effective two-equation turbulence modeling approach that enables accurate predictions of pharmaceutical aerosol deposition across a range of turbulence levels. Key systems considered were the traditional aerosol deposition benchmark cases of a 90-degree bend (Re=6,000) and a vertical straight section of pipe (Re=10,000), as well as a highly complex case of direct-to-infant (D2I) nose-to-lung pharmaceutical aerosol delivery from an air-jet dry powder inhaler (DPI) including a patient interface and infant nasal geometry through mid-trachea (500

Advancement of a high-dose infant air-jet dry powder inhaler (DPI) with passive cyclic loading: Performance tuning for different formulations.

There is a current medical need for a dry powder aerosol delivery device that can be used to efficiently and consistently administer high dose therapeutics, such as inhaled antibiotics, surfactants and antivirals, to the lungs of infants. This study considered an infant air-jet dry powder inhaler (DPI) that could be actuated multiple times with minimal user interaction (i.e., a passive cyclic loading strategy) and focused on the development of a metering system that could be tuned for individual powder formulations to maintain high efficiency lung delivery. The metering system consisted of a powder delivery tube (PDT) connecting a powder reservoir with an aerosolization chamber and a powder supporting shelf that held a defined formulation volume. Results indicated that the metering system could administer a consistent dose per actuation after reaching a steady state condition. Modifications of the PDT diameter and shelf volume provided a controllable approach that could be tuned to maximize lung delivery efficiency for three different formulations. Using optimized metering system conditions for each formulation, the infant air-jet DPI was found to provide efficient and consistent lung delivery of aerosols (∼45% of loaded dose) based on in vitro testing with a preterm nose-throat model and limited dose/actuation to <5 mg.

Effects of different mesh nebulizer sources on the dispersion of powder formulations produced with a new small-particle spray dryer.

The objective of this study was to explore the aerosolization performance of powders produced with different mesh nebulizer sources in the initial design of a new small-particle spray dryer system. An aqueous excipient enhanced growth (EEG) model formulation was spray dried using different mesh sources and the resulting powders were characterized based on (i) laser diffraction, (ii) aerosolization with a new infant air-jet dry powder inhaler, and (iii) aerosol transport through an infant nose-throat (NT) model ending with a tracheal filter. While few differences were observed among the powders, the medical-grade Aerogen Solo (with custom holder) and Aerogen Pro mesh sources were selected as lead candidates that produced mean fine particle fractions <5 µm and <1 µm in ranges of 80.6-77.4% and 13.1-16.0%, respectively. Improved aerosolization performance was achieved at a lower spray drying temperature. Lung delivery efficiencies through the NT model were in the range of 42.5-45.8% for powders from the Aerogen mesh sources, which were very similar to previous results with a commercial spray dryer. Ultimately, a custom spray dryer that can accept meshes with different characteristics (e.g., pore sizes and liquid flow rates) will provide particle engineers greater flexibility in producing highly dispersible powders with unique characteristics.

New Air-Jet Dry Powder Insufflator for High-Efficiency Aerosol Delivery to Rats.

Pulmonary deposition of lung-targeted therapeutic aerosols can achieve direct drug delivery to the site of action, thereby enhancing the efficacy and reducing systemic exposure. In this study, we investigated the in vitro and in vivo aerosol performance of the novel small animal air-jet dry powder insufflator (Rat AJ DPI) using spray-dried albuterol excipient-enhanced-growth (EEG) powder as a model formulation. The in vitro aerosolization performance of the optimized albuterol EEG powder was first assessed using the Rat AJ DPI. The performance of Rat AJ DPI to deliver albuterol EEG aerosol to rat lungs was then compared to that of the Penn-Century Insufflator. Albuterol EEG powders dispersed using the Rat AJ DPI demonstrated narrow unimodal aerosol size distribution profiles, which were independent of the loaded powder dose (1, 2, and 5 mg). In addition, the span value for Rat AJ DPI (5 mg powder mass) was 1.32, which was 4.2-fold lower than that for Penn-Century insufflator (5 mg powder mass). At a higher loaded mass of 5 mg, the Rat AJ DPI delivered significantly larger doses to rat lungs compared with the Penn-Century DPI. The Rat AJ DPI with hand actuation delivered approximately 85% of the total emitted dose (2 and 5 mg loadings), which was comparatively higher than that for Penn-Century DPI (approximately 75%). In addition, percentage deposition in each of the lung lobes for the Rat AJ DPI was observed to be independent of the administration dose (2 and 5 mg loadings) with coefficients of variation below 12%, except in the right middle lobe. Automatic actuation of a 5 mg powder mass using the Rat AJ DPI demonstrated a similar delivered dose compared to manual actuation of the same dose, with 82% of the total emitted dose reaching the lung lobes. High-efficiency delivery of the aerosol to the lobar lung region and low sensitivity of the interlobar delivery efficiency to the loaded dose highlight the suitability of the new air-jet DPI for administering therapeutic pharmaceutical aerosols to small test animals.

Establishing quantitative relationships between changes in nasal spray in vitro metrics and drug delivery to the posterior nasal region.

Nasal sprays are typically characterized using in vitro spray metrics such as spray cone angle and droplet size distribution. It is currently not clear how these in vitro metrics correlate with regional nasal deposition, and these relationships could help explain the impact of product differences. In this study, the effects of changes in spray cone angle, spray velocity, spray ovality and droplet size distribution on regional nasal deposition were analyzed using a validated computational fluid dynamics model in recently developed adult characteristic nasal airway anatomies. The impact of the spray on the surrounding air phase was included. Results indicated that changes in spray cone angle largely influenced the nasal posterior deposition (PD) of the drug. Changes in the plume ovality and characteristic droplet size moderately influenced PD, but the results were dependent on the insertion conditions and nasal geometry. Changes in spray velocity and uniformity constant of the droplet size distribution had only minimal influence on PD. The rank order of metrics having the greatest to least impact on PD was cone angle ≫ plume ovality ≫ characteristic droplet size ≫ velocity ≫ size distribution uniformity constant. Overall, results from this study established quantitative relationships for predicting expected changes in PD.

Airway mucus in pulmonary diseases: Muco-adhesive and muco-penetrating particles to overcome the airway mucus barriers.

Airway mucus is a complex viscoelastic gel that provides a defensive physical barrier and shields the airway epithelium by trapping inhaled foreign pathogens and facilitating their removal via mucociliary clearance (MCC). In patients with respiratory diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), non-CF bronchiectasis, and asthma, an increase in crosslinking and physical entanglement of mucin polymers as well as mucus dehydration often alters and typically reduces mucus mesh network pore size, which reduces neutrophil migration, decreases pathogen capture, sustains bacterial infection, and accelerates lung function decline. Conventional aerosol particles containing hydrophobic drugs are rapidly captured and removed by MCC. Therefore, it is critical to design aerosol delivery systems with the appropriate size and surface chemistry that can improve drug retention and absorption with the goal of increased efficacy. Biodegradable muco-adhesive particles (MAPs) and muco-penetrating particles (MPPs) have been engineered to achieve effective pulmonary delivery and extend drug residence time in the lungs. MAPs can be used to target mucus as they get trapped in airway mucus by steric obstruction and/or adhesion. MPPs avoid muco-adhesion and are designed to have a particle size smaller than the mucus network, enhancing lung retention of particles as well as transport to the respiratory epithelial layer and drug absorption. In this review, we aim to provide insight into the composition of airway mucus, rheological characteristics of airway mucus in healthy and diseased subjects, the most recent techniques to study the flow dynamics and particle diffusion in airway mucus (in particular, multiple particle tracking, MPT), and the advancements in engineering MPPs that have contributed to improved airway mucus penetration, lung distribution, and retention.

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.

In Vitro Evaluation of Nebulized Pharmaceutical Aerosol Delivery to the Lungs Using a New Heated Dryer System (HDS).

The objective of this study was to develop a new heated dryer system (HDS) for high efficiency lung delivery of nebulized aerosol and demonstrate performance with realistic in vitro testing for trans-nasal aerosol administration simultaneously with high-flow nasal cannula (HFNC) therapy and separately for direct oral inhalation (OI) of the aerosol. With the HDS-HFNC and HDS-OI platforms, new active synchronization control routines were developed to sense subject inhalation and coordinate drug aerosol delivery. In vitro experiments were conducted to predict regional drug loss and lung delivery efficiency in systems that included the HDS with various patient interfaces, realistic airway models, and simulated breathing waveforms. For the HDS-HFNC platform and a repeating breathing waveform, total system loss was < 10%, extrathoracic deposition was approximately 6%, and best-case lung delivery efficiency was 75-78% of nebulized dose. Inclusion of randomized breathing with the HFNC system decreased lung delivery efficiency by ~ 10% and had no impact on nasal depositional loss. For the HDS-OI platform and best-case mouthpiece, total system loss was < 8%, extrathoracic deposition was < 1%, and lung delivery efficiency was > 90% of nebulized dose. Normal vs. deep randomized oral inhalation had little impact on performance of the HDS-OI platform and environmental aerosol loss was negligible. In conclusion, both platforms demonstrated the potential for high efficiency lung delivery of the aerosol with the HDS-OI platform having the added advantages of nearly eliminating extrathoracic deposition, being insensitive to breathing waveform, and preventing environmental aerosol loss.

Development of a High-Dose Infant Air-Jet Dry Powder Inhaler (DPI) with Passive Cyclic Loading of the Formulation.

PURPOSE: The objective of this study was to incorporate a passive cyclic loading strategy into the infant air-jet dry powder inhaler (DPI) in a manner that provides high efficiency aerosol lung delivery and is insensitive to powder mass loadings and the presence of downstream pulmonary mechanics. METHODS: Four unique air-jet DPIs were initially compared and the best performing passive design (PD) was selected for sensitivity analyses. A single preterm in vitro nose-throat (NT) model, air source, and nasal interface were utilized throughout. While the majority of analyses were evaluated with a model spray-dried excipient enhanced growth (EEG) formulation, performance of a Surfactant-EEG formulation was also explored for the lead DPI design. RESULTS: Two devices, PD-2 and PD-3, evaluated in the preterm model achieved an estimated lung delivery efficiency of 60% with the model EEG formulation, and were not sensitive to the loaded dose (10-30 mg of powder). The PD-3 device was also unaffected by the presence of downstream pulmonary mechanics (infant lung model) and had only a minor sensitivity to tripling the volume of the powder reservoir. When using the Surfactant-EEG formulation, increasing the actuation flow rate from 1.7 to 4.0 L/min improved lung delivery by nearly 10%. CONCLUSIONS: The infant air-jet DPI platform was successfully modified with a passive cyclic loading strategy and capable of providing an estimated > 60% lung delivery efficiency of a model spray-dried formulation with negligible sensitivity to powder mass loading in the range of 10-30 mg and could be scaled to deliver much higher doses.

Anatomically realistic nasal replicas capturing the range of nasal spray drug delivery in adults.

To improve the relationships between commonly conducted in vitro studies for locally-acting nasal spray drug products with in vivo regional deposition, this study developed a set of in vitro adult nasal geometries that captured the range of nasal drug delivery to the region posterior to internal nasal valve (INV), also known as posterior delivery (PD), and evaluated their performance with existing in vivo data. The PD of fluticasone propionate (FP) and fluticasone furoate (FF) in 40 nasal cavities was statistically analyzed to identify three airway models representing the low, mean, and high PD in adults. The models were also externally validated by comparing the in vitro nasal deposition from a different drug product (mometasone furoate (MF)) with the relevant in vivo data. The three selected geometries represented the low, mean, and high PD with multiple nasal sprays. They were verified in terms of reproducibility of in vitro data and validated by showing a reasonable agreement with preexisting in vivo MF PD despite differences in administration and defining the regions. The three models are envisioned to potentially facilitate the development of locally-acting nasal sprays and provide a better understanding of how in vitro metrics relate to in vivo regional nasal deposition.

Characterizing the Effects of Nasal Prong Interfaces on Aerosol Deposition in a Preterm Infant Nasal Model.

The objective of this study was to characterize the effects of multiple nasal prong interface configurations on nasal depositional loss of pharmaceutical aerosols in a preterm infant nose-throat (NT) airway model. Benchmark in vitro experiments were performed in which a spray-dried powder formulation was delivered to a new preterm NT model with a positive-pressure infant air-jet dry powder inhaler using single- and dual-prong interfaces. These results were used to develop and validate a computational fluid dynamics (CFD) model of aerosol transport and deposition in the NT geometry. The validated CFD model was then used to explore the NT depositional characteristic of multiple prong types and configurations. The CFD model highlighted a turbulent jet effect emanating from the prong(s). Analysis of NT aerosol deposition efficiency curves for a characteristic particle size and delivery flowrate (3 µm and 1.4 L/min (LPM)) revealed little difference in NT aerosol deposition fraction (DF) across the prong insertion depths of 2-5 mm (DF = 16-24%) with the exception of a single prong with 5-mm insertion (DF = 36%). Dual prongs provided a modest reduction in deposition vs. a single aerosol delivery prong at the same flow for insertion depths < 5 mm. The presence of the prongs increased nasal depositional loss by absolute differences in the range of 20-70% compared with existing correlations for ambient aerosols. In conclusion, the use of nasal prongs was shown to have a significant impact on infant NT aerosol depositional loss prompting the need for prong design alterations to improve lung delivery efficiency.

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.

Computational Fluid Dynamics (CFD) Guided Spray Drying Recommendations for Improved Aerosol Performance of a Small-Particle Antibiotic Formulation.

PURPOSE: The objective of this study was to implement computational fluid dynamics (CFD) simulations and aerosol characterization experiments to determine best-case spray drying conditions of a tobramycin excipient enhanced growth (Tobi-EEG) formulation for use in a pediatric air-jet dry powder inhaler (DPI). METHODS: An iterative approach was implemented in which sets of spray drying conditions were explored using CFD simulations followed by lead candidate selection, powder production and in vitro aerosol testing. CFD simulations of a small-particle spray dryer were performed to capture droplet drying parameters and surface-averaged temperature and relative humidity (RH) conditions in the powder collection region. In vitro aerosol testing was performed for the selected powders using the pediatric air-jet DPI, cascade impaction, and aerosol transport through a pediatric mouth-throat (MT) model to a tracheal filter. RESULTS: Based on comparisons of CFD simulations and in vitro powder performance, recommended drying conditions for small-particle powders with electrostatic collection include: (i) reducing the CFD-predicted drying parameters of κavg and κmax to values below 3 µm2/ms and 114 µm2/ms, respectively; (ii) maintaining the Collector Surface RH within an elevated range, which for the Tobi-EEG formulation with l-leucine was 20-30 %RH; and (iii) ensuring that particles reaching the collector were fully dried, based on a mass fraction of solute CFD parameter. CONCLUSIONS: Based on the newly recommended spray dryer conditions for small particle aerosols, delivery performance of the lead Tobi-EEG formulation was improved resulting in >60% of the DPI loaded dose passing through the pediatric MT model.

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.

Performance of Low Air Volume Dry Powder Inhalers (LV-DPI) when Aerosolizing Excipient Enhanced Growth (EEG) Surfactant Powder Formulations.

Efficient delivery of dry powder aerosols dispersed with low volumes of air is challenging. This study aims to develop an efficient dry powder inhaler (DPI) capable of delivering spray-dried Survanta-EEG powders (3-10 mg) with a low volume (3 mL) of dispersion air. A series of iterative design modifications were made to a base low air volume actuated DPI. The modifications included the replacement of the original capsule chamber with an integral dose containment chamber, alteration of the entrainment air flow path through the device (from single-sided (SS) to straight through (ST)), change in the number of air inlet holes (from one to three), varying the outlet delivery tube length (45, 55, and 90 mm) and internal diameter (0.60, 0.89, and 1.17 mm). The modified devices were evaluated by determining the influence of the modifications and powder fill mass on aerosol performance of spray-dried Survanta-EEG powders. The optimal DPI was also evaluated for its ability to aerosolize a micronized powder. The optimized dose containment unit DPI had a 0.21 mL powder chamber, ST airflow path, three-0.60 mm air inlet holes, and 90 mm outlet delivery tube with 0.89 mm internal diameter. The powder dispersion characteristics of the optimal device were independent of fill mass with good powder emptying in one 3 mL actuation. At 10 mg fill mass, this device had an emitted mass of 5.3 mg with an aerosol Dv50 of 2.7 µm. After three 3 mL actuations, >85% of the spray-dried powder was emitted from the device. The emitted mass of the optimal device with micronized albuterol sulfate was >72% of the nominal fill mass of 10 mg in one 3 mL actuation. Design optimization produced a DPI capable of efficient performance with a dispersion air volume of 3 mL to aerosolize Survanta-EEG powders.

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.

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.