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Jubaer H, Thomas M, Farkas D, Kolanjiyil AV, Momin MA, Hindle M, Longest W. Development of an effective two-equation turbulence modeling approach for simulating aerosol deposition across a range of turbulence levels. J Aerosol Sci 2024; 175:106262. [PMID: 38164243 PMCID: PMC10698304 DOI: 10.1016/j.jaerosci.2023.106262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 01/03/2024]
Abstract
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 (R e = 6,000 ) and a vertical straight section of pipe (R e = 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 < R e < 7,000 ). Of the k - ω family of models, the low Reynolds number (LRN) shear stress transport (SST) approach was determined to provide the best agreement with experimental aerosol deposition data in the D2I system, based on an improved simulation of turbulent jet flow that frequently occurs in DPIs. Considering NW corrections, a new correlation was developed to quantitatively predict best regional values of the y + l i m i t , within which anisotropic NW turbulence is approximated. Considering EIM modifications, a previously described drift correction approach was implemented in pharmaceutical aerosol simulations for the first time. Considering all model corrections and modifications applied to the D2I system, regional relative errors in deposition fractions between CFD predictions and new experimental data were improved from 19-207% (no modifications) to 2-15% (all modifications) with a notable decrease in computational time (up to ∼15%). In conclusion, the highly efficient two-equation k - ω models with physically realistic corrections and modifications provided a viable, efficient and accurate approach to simulate the transport and deposition of pharmaceutical aerosols in complex airway systems that include laminar, turbulent and transitional flows.
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Affiliation(s)
- Hasan Jubaer
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Morgan Thomas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Dale Farkas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Arun V. Kolanjiyil
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Mohammad A.M. Momin
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
| | - Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
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Howe C, Momin MAM, Aladwani G, Strickler S, Hindle M, Longest W. Advancement of a high-dose infant air-jet dry powder inhaler (DPI) with passive cyclic loading: Performance tuning for different formulations. Int J Pharm 2023; 643:123199. [PMID: 37406945 PMCID: PMC10530264 DOI: 10.1016/j.ijpharm.2023.123199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/22/2023] [Accepted: 07/01/2023] [Indexed: 07/07/2023]
Abstract
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.
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Affiliation(s)
- Connor Howe
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 W Main Street, PO Box 843015, Richmond, VA 23284, USA.
| | - Mohammad A M Momin
- Department of Pharmaceutics, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980533, Richmond, VA 23284, USA.
| | - Ghali Aladwani
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 W Main Street, PO Box 843015, Richmond, VA 23284, USA.
| | - Sarah Strickler
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 W Main Street, PO Box 843015, Richmond, VA 23284, USA.
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980533, Richmond, VA 23284, USA.
| | - Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 W Main Street, PO Box 843015, Richmond, VA 23284, USA; Department of Pharmaceutics, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980533, Richmond, VA 23284, USA.
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Aladwani G, Momin MAM, Spence B, Farkas DR, Bonasera S, Hassan A, Hindle M, Longest W. Effects of different mesh nebulizer sources on the dispersion of powder formulations produced with a new small-particle spray dryer. Int J Pharm 2023; 642:123138. [PMID: 37307962 PMCID: PMC10527815 DOI: 10.1016/j.ijpharm.2023.123138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/07/2023] [Accepted: 06/09/2023] [Indexed: 06/14/2023]
Abstract
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.
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Affiliation(s)
- Ghali Aladwani
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - Mohammad A M Momin
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States
| | - Benjamin Spence
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - Dale R Farkas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - Serena Bonasera
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States
| | - Amr Hassan
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States
| | - Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States; Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States.
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Howe C, Momin MAM, Aladwani G, Hindle M, Longest PW. Development of a High-Dose Infant Air-Jet Dry Powder Inhaler (DPI) with Passive Cyclic Loading of the Formulation. Pharm Res 2022; 39:3317-3330. [PMID: 36253630 PMCID: PMC10561662 DOI: 10.1007/s11095-022-03409-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 09/29/2022] [Indexed: 12/27/2022]
Abstract
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.
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Affiliation(s)
- Connor Howe
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Mohammad A M Momin
- Department of Pharmaceutics, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980533, Richmond, VA, 23284, USA
| | - Ghali Aladwani
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980533, Richmond, VA, 23284, USA
| | - P Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA.
- Department of Pharmaceutics, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980533, Richmond, VA, 23284, USA.
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Bass K, Momin MAM, Howe C, Aladwani G, Strickler S, Kolanjiyil AV, Hindle M, DiBlasi RM, Longest W. Characterizing the Effects of Nasal Prong Interfaces on Aerosol Deposition in a Preterm Infant Nasal Model. AAPS PharmSciTech 2022; 23:114. [PMID: 35441324 DOI: 10.1208/s12249-022-02259-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 03/20/2022] [Indexed: 11/30/2022] Open
Abstract
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.
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Howe C, Momin MAM, Bass K, Aladwani G, Bonasera S, Hindle M, Longest PW. In Vitro Analysis of Nasal Interface Options for High-Efficiency Aerosol Administration to Preterm Infants. J Aerosol Med Pulm Drug Deliv 2022; 35:196-211. [PMID: 35166601 PMCID: PMC9416545 DOI: 10.1089/jamp.2021.0057] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
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.
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Affiliation(s)
- Connor Howe
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Mohammad A M Momin
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Karl Bass
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Ghali Aladwani
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Serena Bonasera
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Philip Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA.,Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia, USA
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Longest W, Hassan A, Farkas D, Hindle M. Computational Fluid Dynamics (CFD) Guided Spray Drying Recommendations for Improved Aerosol Performance of a Small-Particle Antibiotic Formulation. Pharm Res 2022; 39:295-316. [PMID: 35147870 DOI: 10.1007/s11095-022-03180-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/24/2022] [Indexed: 12/14/2022]
Abstract
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.
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