The effect of inlet flow profile and nozzle diameter on drug delivery to the maxillary sinus

Effect of Nasal Inhalation on Drug Particle Deposition and Size Distribution in the Upper Airway: With Soft Mist Inhalers

Delivery of drugs to the lungs is commonly achieved using nasal and/or oral breathing-assisted techniques. The route of inhalation can substantially change the fate of inhaled droplets. The Respimat® Soft Mist™ Inhaler (SMI) is a commercially available efficient inhaler with 40-60% effectiveness. In the present study, we used computational fluid dynamics (CFD) with a custom setup to investigate the effect of a combined oral/nasal inhalation route on the SMI's regional droplet deposition, size distribution, and flow field. Our setup used a modified induction port (MIP) to mimic nasal inhalation inside the human respiratory tract. Six different oral/nasal flow rate ratios inside the MIP were applied (total flow rate of 30 l/min). An overall good agreement was achieved between simulation outcomes and in vitro results. Our results confirmed that the combined inhalation route affects the flow field, altering the MIP's droplet deposition and size distribution. The lowest depositional loss, mainly in the mouth area, was observed at oral/nasal flow rate ratios of O/N = 1 and O/N = 2 with 3% and 7.7% values, respectively. Droplets with a 2-5 µm diameter range showed the highest droplet mass inside the MIP at all combined flow rates. We observed less intense vortexes followed by a lower level of turbulent kinetic energy at the oral/nasal ratio of 1. Increasing the relative humidity (RH) at oral/nasal flow rate ratios of 0.07, 1, and 14 led to an increase in droplet deposition at the outlet of the MIP.

Comparative study of nasal cavity drug delivery efficiency with different nozzles in a 3D printed model

Background

Nasal sprays are widely used in treating nasal and sinus diseases; however, there are very few studies on the drug delivery efficiency of nasal sprays. In this study, the drug delivery efficiency of three different nasal spray devices was evaluated in vitro using a 3D printed cast model of nasal cavity.

Methods

Three nasal spray devices with different nozzles and angles of administration were used in the 3D model of the nasal cavity and paranasal sinuses. The spraying area (SA), maximal spraying distance (MSD), and spraying distribution scores on the nasal septum and lateral nasal wall were recorded.

Results

Different nasal spray devices have their own characteristics, including volume of each spray, SA, and plume angle. The SA of the three nozzles on the nasal septum increased with an increasing angle of administration. When the angle of administration was 50°, each nozzle reached the maximal SA. There was no statistically significant difference in MSD among the three nozzles at the three angles. The total scores for each nozzle using the three different spraying angles were as follows: nozzle A, 40° > 30° > 50°; nozzle B, 30° > 40° > 50°; and nozzle C, 30° > 40° > 50°. The total scores for different nozzles using the same angle were statistically significantly different and the scores for nozzle C were the highest. Nozzle C had the minimum plume angle. None of the three nozzles could effectively delivered drugs into the middle meatus at any angle in this model.

Conclusions

The design of the nozzle affects drug delivery efficiency of nasal spray devices. The ideal angle of administration is 50°. The nozzle with smaller plume angle has higher drug delivery efficiency. Current nasal spray devices can easily deliver drugs to most areas of the nasal cavity, such as the turbinate, nasal septum, olfactory fissure, and nasopharynx, but not the middle meatus. These findings are meaningful for nozzle selection and device improvements.

Parameter characteristics in intranasal drug delivery: A key to targeting medications to the olfactory airspace

BACKGROUND

The nose is a viable pathway for topical drug delivery to the olfactory cleft for treatment of obstructive smell loss and nose-to-brain drug delivery. This study investigates how variations in nasal vestibule morphology influence intranasal spray drug transport to the olfactory cleft and olfactory roof/bulb regions.

METHODS

The unilateral nasal vestibule morphology in three healthy subjects with healthy normal nasal anatomy was classified as Elongated (Subject DN001), Notched (Subject DN002), and Standard (Subject DN003). Computational fluid and particle dynamics modelling were used to simulate nasal airflow and drug particle transport to the olfactory cleft and olfactory roof/bulb regions in each subject-specific nasal cavity. To evaluate highest drug depositions in these regions, the particle transport simulations involved extensive parameter combination analyses: 6 inspiratory flow rates mimicking resting to sniffing (10-50 L/min); 5 spray release locations (Top, Bottom, Central, Lateral, and Medial); 5 head positions (Upright, Tilted Forward, Tilted Back, Supine, and Mygind); 3 particle velocities (1, 5, and 10 m/s); 350,000 μm-particles (1-100 μm) and 346,500 nanoparticles (10-990 nm).

FINDINGS

Particle size groups with highest depositions in olfactory cleft: DN001 left = 28.4% at 11-20 μm, right = 75.3% at 6-10 μm; DN002 left = 16.8% at 1-5 μm, right = 45.3% at 30-40 nm; DN003 left = 29.1% at 21-30 μm, right = 15.9% at 6-10 μm. Highest depositions in olfactory roof/bulb: DN001 left = 6.5% at 11-20 μm, right = 26.4% at 11-20 μm; DN002 left = 3.6% at 1-5 μm, right = 2.6% at 1-5 μm; DN003 left = 2.8% at 21-30 μm, right = 1.7% at 31-40 μm.

INTERPRETATION

DN001 (Elongated nasal vestibule) had the most deposition in the olfactory regions. Micron-particles size groups generally had better deposition in the olfactory regions.

Relaxation and creep response of the alveolar lung to diagnosis and treatments for respiratory and lung disorders

BACKGROUND

The lung Extracellular Matrix (ECM) contains a considerable part of the parenchymal cells. It contains three essential components: elastin and collagen within a proteoglycan (PG) viscoelastic network. Elastin provides the lung's elasticity property, a necessity for normal breathing, while collagen prepares structural support and strength, and PGs give stability and cushioning within tissue loading. Bacterial and viral respiratory diseases are dependent on changes in the ECM ingredients, which result in an alteration of the lung tissue strength.

PURPOSE

In the present study, this variation was investigated by changing the volume ratio of the ECM ingredients in the viscoelastic model.

RESULTS

As a result, the relaxation curves continuously declined by reducing the volume ratios of elastin, collagen, and PGs; subsequently, the lung stiffness decreased. Also, the Standard Linear Solid (SLS) model-based results demonstrated excellent accordance with empirical data with only minor deviations. The resting relaxation modulus and the creep modulus for the ECM tissue were 51 kPa and approximately 0.02 kPa, respectively, and the maximum total modulus of elasticity reached 121 kPa.

CONCLUSIONS

Moreover, this model demonstrates individual alveolar mechanical behaviours and adds another pathway to the generalized Kelvin-Voigt and Maxwell models in predicting the progress of lung diseases.

Advancements in acoustic drug delivery for paranasal sinuses: A comprehensive review

Chronic rhinosinusitis (CRS) impacts patients' quality of life and healthcare costs. Traditional methods of drug delivery, such as nasal sprays and irrigation, have limited effectiveness. Acoustic Drug Delivery (ADD) using a nebulizer offers targeted delivery of drug to the sinuses, which may improve the treatment of CRS. This review examines the influence of aerosol particle characteristics, aero-acoustic parameters, inlet flow conditions, and acoustic waves on sinus drug delivery. Key findings reveal that smaller particles improve the ADD efficiency, whereas larger sizes or increased density impair it. The oscillation amplitude of the air plug in the ostium is crucial for the ADD efficiency. Introducing acoustic waves at the NC-sinus system's resonance frequency improves aerosol deposition within sinuses. Future research should address advanced models, optimizing particle characteristics, investigating novel acoustic waveforms, incorporating patient-specific anatomy, and evaluating long-term safety and efficacy. Tackling these challenges, ADD could offer more effective and targeted treatments for sinus-related conditions such as CRS.

Acoustic Aerosol Delivery: Assessing of Various Nasal Delivery Techniques and Medical Devices on Intrasinus Drug Deposition

This study aims to evaluate the impact of the nasal delivery technique and nebulizing technologies (using different frequencies of oscillating airflow) for acoustic aerosol targeting of maxillary sinuses. Sodium fluoride (chemical used as a marker), tobramycin (drug used as a marker) and ^99mTc-DTPA (radiolabel aerosol) were used to assess the intrasinus aerosol deposition on a nasal cast. Two commercial medical devices (PARI SINUS nebulizer and NL11SN ATOMISOR nebulizer) and various nasal delivery techniques (one or two nostrils connected to the aerosol inlet, the patient with the soft palate closed or open during the acoustic administration of the drug, the presence or not of flow resistance in the nostril opposite to the one allowing the aerosol to be administered) were evaluated. The closed soft palate condition showed a significant increase in drug deposition even though no significant difference in the rest of the nasal fossae was noticed. Our results clearly demonstrated a higher intrasinus aerosol deposition (by a factor 2-3; respectively 0.03 ± 0.007% vs. 0.003 ± 0.0002% in the right maxillary sinus and 0.027 ± 0.006% vs. 0.013 ± 0.004% in the left maxillary sinus) using the acoustic airflow generated by the PARI SINUS compared to the NL11SN ATOMISOR. The results clearly demonstrated that the optimal conditions for aerosol deposition in the maxillary sinuses were obtained with a closed soft palate. Thus, the choice of the nebulizing technology (and mainly the frequency of the pulsating aerosol generated) and also the recommendation of the best nasal delivery technique are key factors to improve intrasinus aerosol deposition.