Publications by authors named "Habib Aminfar"

5 Publications

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Flow Structure and Particle Deposition Analyses for Optimization of a Pressurized Metered Dose Inhaler (pMDI) in a Model of Tracheobronchial Airway.

Eur J Pharm Sci 2021 Sep 12;164:105911. Epub 2021 Jun 12.

Institute of Lung Biology and Disease, Helmholtz Zentrum München- German Research Centre for Environmental Health, Neuherberg, Germany; Comprehensive Pneumology Center, Member of the German Center for Lung Research, Max-Lebsche-Platz 31, Munich 81377, Germany. Electronic address:

Inhalation therapy plays an important role in management or treatment of respiratory diseases such asthma and chronic obstructive pulmonary diseases (COPDs). For decades, pressurized metered dose inhalers (pMDIs) have been the most popular and prescribed drug delivery devices for inhalation therapy. The main objectives of the present computational work are to study flow structure inside a pMDI, as well as transport and deposition of micron-sized particles in a model of human tracheobronchial airways and their dependence on inhalation air flow rate and characteristic pMDI parameters. The upper airway geometry, which includes the extrathoracic region, trachea, and bronchial airways up to the fourth generation in some branches, was constructed based on computed tomography (CT) images of an adult healthy female. Computational fluid dynamics (CFD) simulation was employed using the k-ω model with low-Reynolds number (LRN) corrections to accomplish the objectives. The deposition results of the present study were verified with the in vitro deposition data of our previous investigation on pulmonary drug delivery using a hollow replica of the same airway geometry as used for CFD modeling. It was found that the flow structure inside the pMDI and extrathoracic region strongly depends on inhalation flow rate and geometry of the inhaler. In addition, regional aerosol deposition patterns were investigated at four inhalation flow rates between 30 and 120 L/min and for 60 L/min yielding highest deposition fractions of 24.4% and 3.1% for the extrathoracic region (EX) and the trachea, respectively. It was also revealed that particle deposition was larger in the right branches of the bronchial airways (right lung) than the left branches (left lung) for all of the considered cases. Also, optimization of spray characteristics showed that the optimum values for initial spray velocity, spray cone angle and spray duration were 100 m/s, 10° and 0.1 sec, respectively. Moreover, spray cone angle, more than any other of the investigated pMDI parameters can change the deposition pattern of inhaled particles in the airway model. In conclusion, the present investigation provides a validated CFD model for particle deposition and new insights into the relevance of flow structure for deposition of pMDI-emitted pharmaceutical aerosols in the upper respiratory tract.
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http://dx.doi.org/10.1016/j.ejps.2021.105911DOI Listing
September 2021

Dry powder inhaler aerosol deposition in a model of tracheobronchial airways: Validating CFD predictions with in vitro data.

Int J Pharm 2020 Sep 11;587:119599. Epub 2020 Jul 11.

Biotechnology Research Center, Student Research Committee, and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.

Effective drug delivery into the lungs plays an important role in management of pulmonary diseases that affect millions all around the world. The main objective of this investigation is to study airflow structure, as well as transport and deposition of micron-size particles at different inhalation flow rates in a realistic model of human tracheobronchial airways. The airway model was developed based on computed tomography (CT) images of a healthy 48-years-old female, which includes extrathoracic, trachea, and bronchial airways up to fourth generations. Computational fluid dynamics (CFD) simulations were performed to predict transport and deposition of inhaled particles and the results were compared to our previous in vitro experiments. Airflow structure was studied through velocity contours and streamlines in the extrathoracic region, where the onset of turbulence, reverse flow and subsequently vortex formation, and laryngeal jet are found to be critical phenomenons in the formation of airflow and deposition patterns. The deposition data was presented by deposition efficiency (DE) and deposition fraction (DF) against impaction parameter and Stokes number. At all of the inhalation flow rates, highest values of deposition fractions were devoted to the mouth-throat (MT), tracheobronchial tree (TB), and trachea (Tra), respectively (At 60 L/min: MT = 6.7%, TB = 5.3%, Tra = 1.9%). The numerical deposition data showed a good agreement with the experimental deposition data in most of the airway regions (e.g. less than 10% difference between the deposition fractions in the tracheobronchial region). Enhancing inhalation flow rate in all of the airway regions led to an uptrend in deposition rate due to the increase of particles inertia and turbulence level. In addition, the increase of particle deposition with enhancing inhalation flow rate in all of the sections including extrathoracic, trachea, and tracheobronchial tree suggesting that inertial impaction is the dominant deposition mechanism due to the increase of inertial force. In conclusion, the validated CFD model provided an opportunity to cover the limitations of our previous experimental investigation on aerosol deposition of commercial inhalers and became an efficient method for further studies.
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http://dx.doi.org/10.1016/j.ijpharm.2020.119599DOI Listing
September 2020

Implementation of magnetic field force in molecular dynamics algorithm: NAMD source code version 2.12.

J Mol Model 2020 Apr 20;26(5):106. Epub 2020 Apr 20.

Faculty of Chemical and Petroleum Engineering, University of Tabriz, Tabriz, Iran.

The external fields, such as the magnetic force, have made advances in many industrial and biotechnology applications during the past century, although the changes in the structure of materials under the impact of the electromagnetic fields have not entirely been clear yet. The molecular simulation technique by providing extensive data from the configuration and orientations of the atoms is becoming the effective useful tool for scientists in a wide range of research areas. This paper presents an extended velocity Verlet algorithm inside the Nanoscale Molecular Dynamics (NAMD) package that enhances the NAMD features with the capability to compute the magnetic field force. We described how this novel feature has been implemented inside the package. Moreover, the results are reported for the rotation of a charged particle, and the thermo-physical properties of water in the presence of a magnetic field confirming how this developed NAMD source code provides accurate measurements compared with other available data.
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http://dx.doi.org/10.1007/s00894-020-4349-0DOI Listing
April 2020

Development of human respiratory airway models: A review.

Eur J Pharm Sci 2020 Mar 21;145:105233. Epub 2020 Jan 21.

Drug Applied Research Center, Tabriz University of Medical Science, Tabriz, Iran.

Pulmonary drug delivery has gained great interest as an important subject of research over the past decades given the lung diseases which are affecting millions of people suffer from these diseases. Drug delivery into the respiratory system is influenced by many anatomical and physiological factors such as lung morphometry, breathing patterns, fluid dynamics, particle properties, etc. The respiratory airway structure is one of these parameters which greatly influences the deposition pattern of inhaled drug particles. There have been a wide variety of major morphometric studies, conducted using cadavers to increase an understanding of the respiratory airway anatomy and provide important information for developing realistic airway models. Casting as one of the first methods, was utilized for morphometric studies providing a hollow model for in vitro investigations. The above-mentioned morphometric data were utilized to describe the first idealized airway model as a simple symmetric description of the branching airways, later followed by more realistic asymmetric models. However, even these asymmetric airway models were not good enough to reflect the anatomical complexities of the human respiratory airway and contained several major limitations which made them inefficient. Further attempts alongside with the progress of technology led to introduction of the stochastic and image-based models which provided more realistic and efficient tools for numerical and experimental investigations. The main objective of this study is to provide a comprehensive review about the development of different perspectives of the respiratory airway modeling over the past decades. The following sections will present useful information about anatomy of the human respiratory tract, and different viewpoints of the respiratory airway modeling, including their historical routes, strengths, and deficiencies.
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http://dx.doi.org/10.1016/j.ejps.2020.105233DOI Listing
March 2020

Experimental investigation of aerosol deposition through a realistic respiratory airway replica: An evaluation for MDI and DPI performance.

Int J Pharm 2019 Jul 23;566:157-172. Epub 2019 May 23.

Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran. Electronic address:

Purpose: In the present work, a comparison between MDI and DPI for evaluating performance of the devices were carried out by experimentally investigating the deposition parameters through a realistic airway replica.

Methods: Computed tomography (CT) images of the respiratory airway of a healthy subject were used to develop the realistic model. The airway replica was included extrathoracic, trachea, and tracheobronchial tree up to fourth generations which was fabricated by rapid prototyping. Afterward, in vitro experiments were performed to validate the airway model by comparing the total deposition (G0 to G3) of present replica with available data in the literature. Drug deposition (Salbutamol) in the model was measured by determining concentration of the segments sample by High Performance Liquid Chromatography (HPLC) assay.

Results: Deposition parameters were used for investigating the deposition patterns of the inhaled particles. Results showed that inertial impaction is the dominant mechanism in the most regions of the replica. It was found that the MDI delivered more drug to the tracheobronchial tree compared to the DPI for three different flow rate.

Conclusion: The developed realistic respiratory airways model provided an opportunity to more accurately evaluate the performance of drug delivery devices and studying mechanisms of the drug deposition.
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http://dx.doi.org/10.1016/j.ijpharm.2019.05.058DOI Listing
July 2019
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