Spray Pattern and Droplet Size Analyses for High-Shear Viscosity Determination of Aqueous Suspension Corticosteroid Nasal Sprays

Toward a Radically Simple Multi-Modal Nasal Spray for Preventing Respiratory Infections

Nasal sprays for pre-exposure prophylaxis against respiratory infections show limited protection (20-70%), largely due to their single mechanism of action-either neutralizing pathogens or blocking their entry at the nasal lining, and a failure to maximize the capture of respiratory droplets, allowing them to potentially rebound and reach deeper airways. This report introduces the Pathogen Capture and Neutralizing Spray (PCANS), which utilizes a multi-modal approach to enhance efficacy. PCANS coats the nasal cavity, capturing large respiratory droplets from the air, and serving as a physical barrier against a broad spectrum of viruses and bacteria, while rapidly neutralizing them with over 99.99% effectiveness. The formulation consists of excipients identified from the FDA's Inactive Ingredient Database and Generally Recognized as Safe list to maximize efficacy for each step in the multi-modal approach. PCANS demonstrates nasal retention for up to 8 hours in mice. In a severe Influenza A mouse model, a single pre-exposure dose of PCANS leads to a >99.99% reduction in lung viral titer and ensures 100% survival, compared to 0% in the control group. PCANS suppresses pathological manifestations and offers protection for at least 4 hours. This data suggest PCANS as a promising daily-use prophylactic against respiratory infections.

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.

In situ hydrogel containing diazepam-loaded nanostructured lipid carriers (DZP-NLC) for nose-to-brain delivery: development, characterization and deposition studies in a 3D-printed human nasal cavity model

The nasal route has been investigated as a promising alternative for drug delivery to the central nervous system, avoiding passage through the blood-brain barrier and improving bioavailability. In this sense, it is necessary to develop and test the effectiveness of new formulations proposed for the management of neurological disorders. Thereby, the aim of this work was to develop and characterize an ion sensitive in situ hydrogel containing diazepam-loaded nanostructured lipid carriers (DZP-NLC) for nasal delivery in the treatment of epilepsy. Physical characterization of the developed formulations was performed and included the evaluation of rheological features, particle size, polydispersity index (PDI) and zeta potential (ZP) of an in situ hydrogel containing DZP-NLC. Afterwards, in vitro drug release, in vitro mucoadhesion and biocompatibility studies with RPMI 2650 nasal cells were performed. The in situ hydrogel containing DZP-NLC was aerosolized with a nasal spray device specifically designed for nose-to-brain delivery (VP7 multidose spray pump with a 232 N2B actuator) and characterized for droplet size distribution and spray cone angle. Finally, the deposition pattern of this hydrogel was evaluated in a 3D-printed human nasal cavity model. The developed in situ hydrogel containing DZP-NLC presented adequate characteristics for nasal administration, including good gelling ability, mucoadhesiveness and prolonged drug release. In addition, after inclusion in the hydrogel net, the particle size (81.79 ± 0.53 nm), PDI (0.21 ± 0.10) and ZP (-30.90 ± 0.10 mV), of the DZP-NLC remained appropriate for nose-to-brain delivery. Upon aerosolization in a nasal spray device, a suitable spray cone angle (22.5 ± 0.2°) and adequate droplet size distribution (Dv (90) of 317.77 ± 44.12 µm) were observed. Biocompatibility studies have shown that the developed formulation is safe towards RPMI 2650 cells in concentrations up to 100 μg/mL. Deposition studies on a 3D-printed human nasal cavity model revealed that the best nasal deposition profile was obtained upon formulation administration without airflow and at an angle from horizontal plane of 75°, resulting in 47% of administered dose deposited in the olfactory region and 89% recovery. The results of this study suggested that the intranasal administration of the developed in situ hydrogel containing DZP-NLC could be a promising alternative to the conventional treatments for epilepsy.

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.

Importance of Spray–Wall Interaction and Post-Deposition Liquid Motion in the Transport and Delivery of Pharmaceutical Nasal Sprays

Nasal sprays, which produce relatively large pharmaceutical droplets and have high momentum, are primarily used to deliver locally acting drugs to the nasal mucosa. Depending on spray pump administration conditions and insertion angles, nasal sprays may interact with the nasal surface in ways that creates complex droplet–wall interactions followed by significant liquid motion after initial wall contact. Additionally, liquid motion can occur after deposition as the spray liquid moves in bulk along the nasal surface. It is difficult or impossible to capture these conditions with commonly used computational fluid dynamics (CFD) models of spray droplet transport that typically employ a deposit-on-touch boundary condition. Hence, an updated CFD framework with a new spray–wall interaction (SWI) model in tandem with a post-deposition liquid motion (PDLM) model was developed and applied to evaluate nasal spray delivery for Flonase and Flonase Sensimist products. For both nasal spray products, CFD revealed significant effects of the spray momentum on surface liquid motion, as well as motion of the surface film due to airflow generated shear stress and gravity. With Flonase, these factors substantially influenced the final resting place of the liquid. For Flonase Sensimist, anterior and posterior liquid movements were approximately balanced over time. As a result, comparisons with concurrent in vitro experimental results were substantially improved for Flonase compared with the traditional deposit-on-touch boundary condition. The new SWI-PDLM model highlights the dynamicenvironment that occurs when a nasal spray interacts with a nasal wall surface and can be used to better understand the delivery of current nasal spray products as well as to develop new nasal drug delivery strategies with improved regional targeting.

Enhanced Delivery of Neuroactive Drugs via Nasal Delivery with a Self-Healing Supramolecular Gel

This paper reports the use of a self-assembling hydrogel as a delivery vehicle for the Parkinson's disease drug l-DOPA. Based on a two-component combination of an l-glutamine amide derivative and benzaldehyde, this gel has very soft rheological properties and self-healing characteristics. It is demonstrated that the gel can be formulated to encapsulate l-DOPA. These drug-loaded gels are characterized, and rapid release of the drug is obtained from the gel network. This drug-loaded hydrogel has appropriate rheological characteristics to be amenable for injection. This system is therefore tested as a vehicle for nasal delivery of neurologically-active drugs-a drug delivery strategy that can potentially avoid first pass liver metabolism and bypass the blood-brain barrier, hence enhancing brain uptake. In vitro tests indicate that the gel has biocompatibility with respect to nasal epithelial cells. Furthermore, animal studies demonstrate that the nasal delivery of a gel loaded with 3 H-labeled l-DOPA out-performed a simple intranasal l-DOPA solution. This is attributed to longer residence times of the gel in the nasal cavity resulting in increased blood and brain concentrations. It is demonstrated that the likely routes of brain penetration of intranasally-delivered l-DOPA gel involve the trigeminal and olfactory nerves connecting to other brain regions.

Rheological characterization of polymeric solutions used in spray drying process

The present works contributes with a rheological characterization of the most commonly used polymers and solvents to formulate amorphous solid dispersions by means of spray drying process: copovidone, hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMCAS) and a copolymer of methacrylic acid and methyl methacrylate (1:1 ratio and commercially known as Eudragit L100). The organic-based solutions are characterized in terms of surface tension, shear viscosity and relaxation time. HPMC and HPMCAS solutions exhibit shear thinning behaviour, i.e. decrease of shear viscosity with the increasing shear rate imposed, while the samples with Eudragit L100 can be considered Boger fluids, showing a constant viscosity but maintaining its viscoelastic character. Under uniaxial extensional flow, these polymers solutions exhibit a viscoelastic behavior with an increasing relaxation time with an increasing concentration, and in some cases showed a 'beads-on-string' effect. In contrast, copovidone showed a Newtonian fluid behavior, with the absence of elasticity. The fundamental understanding and characterization of the present work may be further applied to atomization modelling and support and expedite spray drying process development.

In vitro evaluation of regional nasal drug delivery using multiple anatomical nasal replicas of adult human subjects and two nasal sprays

Quantifying drug delivery to the site of action using locally-acting nasal suspension sprays is a challenging but important step toward understanding bioequivalence (BE) between test and reference products. The main objective of this study was to investigate the in vitro deposition pattern of two common but different locally-acting nasal suspension sprays using multiple nasal cavities. Twenty anatomically accurate nasal replicas were developed from high-resolution sinonasal computed tomography scans of adults with healthy nasal airways. The airways were segmented into two regions of anterior and posterior to the internal nasal valve. Both sides of the septum were considered separately; hence, 40 nasal cavities were studied. The positioning of the spray nozzle in all 40 cavities was characterized by the head angle, coronal angle, and the insertion depth. Despite using a controlled protocol to minimize the anterior losses, a wide range of variability in posterior drug delivery was observed. The observed intersubject variability using this in vitro method may have important implications for understanding BE of locally-acting nasal suspension sprays.

How to characterize a nasal product. The state of the art of in vitro and ex vivo specific methods

Nasal delivery offers many benefits over other conventional routes of delivery (e.g. oral or intravenous administration). Benefits include, among others, a fast onset of action, non-invasiveness and direct access to the central nervous system. The nasal cavity is not only limited to local application (e.g. rhinosinusitis) but can also provide direct access to other sites in the body (e.g. the central nervous system or systemic circulation). However, both the anatomy and the physiology of the nose impose their own limitations, such as a small volume for delivery or rapid mucociliary clearance. To meet nasal-specific criteria, the formulator has to complete a plethora of tests, in vitro and ex vivo, to assess the efficacy and tolerance of a new drug-delivery system. Moreover, depending on the desired therapeutic effect, the delivery of the drug should target a specific pathway that could potentially be achieved through a modified release of this drug. Therefore, this review focuses on specific techniques that should be performed when a nasal formulation is developed. The review covers both the tests recommended by regulatory agencies (e.g. the Food and Drug Administration) and other complementary experiments frequently performed in the field.

Development of coated liposomes loaded with ghrelin for nose-to-brain delivery for the treatment of cachexia

The aim of the present study was to develop a ghrelin-containing formulation based on liposomes coated with chitosan intended for nose–brain delivery for the treatment of cachexia. Among the three types of liposomes developed, anionic liposomes provided the best results in terms of encapsulation efficiency (56%) and enzymatic protection against trypsin (20.6% vs 0% for ghrelin alone) and carboxylesterase (81.6% vs 17.2% for ghrelin alone). Ghrelin presented both electrostatic and hydrophobic interactions with the anionic lipid bilayer, as demonstrated by isothermal titration calorimetry. Then, anionic liposomes were coated with N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride. The coating involved a size increment from 146.9±2.7 to 194±6.1 nm, for uncoated and coated liposomes, respectively. The ζ-potential was similarly increased from -0.3±1.2 mV to 6±0.4 mV before and after coating, respectively. Chitosan provided mucoadhesion, with an increase in mucin adsorption of 22.9%. Enhancement of permeation through the Calu3 epithelial monolayer was also observed with 10.8% of ghrelin recovered in the basal compartment in comparison to 0% for ghrelin alone. Finally, aerosols generated from two nasal devices (VP3 and SP270) intended for aqueous dispersion were characterized with either coated or uncoated liposomes. Contrarily to the SP270 device, VP3 device showed minor changes between coated and uncoated liposome aerosols, as shown by their median volume diameters of 38.4±5.76 and 37.6±5.74 µm, respectively. Overall, the results obtained in this study show that the developed formulation delivered by the VP3 device can be considered as a potential candidate for nose–brain delivery of ghrelin.

The Enhancement of Nasal Drug Absorption From Powder Formulations by the Addition of Sodium Carboxymethyl Cellulose

For nasal drug absorption, powder formulations can be expected to provide many advantages. The first aim of this study was to examine drug absorption following nasal administration of powder formulations in rats. Pharmaceutical excipients are typically added to most powder formulations. The second aim was to investigate the change in nasal drug absorption of powder formulations in the presence of sodium carboxymethyl cellulose (CMC-Na). Model drugs used were norfloxacin (NFX), warfarin (WF), and piroxicam (PXC). The absorption from bulk powders is different from that of solutions. The absorption of PXC and WF from powder formulations was enhanced compared to those of the other solutions, while that of NFX, which has a low solubility, was decreased, suggesting that the nasal absorption of many drugs, except poorly soluble drugs, is enhanced when they are administered as powder formulations. CMC-Na enhanced the absorption of NFX and PXC. The presence of CMC-Na slightly decreased the absorption of WF. In vitro transepithelial transport from the powder formulation was not affected by the presence of CMC-Na. Furthermore, the nasal retention of the powder formulation was significantly increased in the presence of CMC-Na. In conclusion, the nasal absorption of many drugs, except those that are poorly soluble, can be increased by administering them as a powder formulation and the nasal absorption of the formulation is enhanced further in the presence of CMC-Na.

Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption

The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na) as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4) and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control) was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules.

Analytical challenges and regulatory requirements for nasal drug products in europe and the u.s

Nasal drug delivery can be assessed by a variety of means and regulatory agencies, e.g., the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have published a set of guidelines and regulations proposing in vitro test methods for the characterization of nasal drug products. This article gives a summary of the FDA and EMA requirements regarding the determination of droplet size distribution (DSD), plume geometry, spray pattern and shot weights of solution nasal sprays and discusses the analytical challenges that can occur when performing these measurements. In order to support findings from the literature, studies were performed using a standard nasal spray pump and aqueous model formulations. The aim was to identify possible method-, device- and formulation-dependent influencing factors. The literature review, as well as the results from the studies show that DSD, plume geometry and spray pattern are influenced by, e.g., the viscosity of the solution, the design of the device and the actuation parameters, particularly the stroke length, actuation velocity and actuation force. The dominant factor influencing shot weights, however, is the adjustment of the actuation parameters, especially stroke length and actuation velocity. Consequently, for routine measurements assuring, e.g., the quality of a solution nasal spray or, for in vitro bioequivalence studies, the critical parameters, have to be identified and considered in method development in order to obtain reproducible and reliable results.

Effect of formulation- and administration-related variables on deposition pattern of nasal spray pumps evaluated using a nasal cast

PURPOSE

To systematically evaluate the effect of formulation- and administration-related variables on nasal spray deposition using a nasal cast.

METHODS

Deposition pattern was assessed by uniformly coating a transparent nose model with Sar-Gel®, which changes from white to purple on contact with water. Sprays were subsequently discharged into the cast, which was then digitally photographed. Images were quantified using Adobe® Photoshop. The effects of formulation viscosity (which influences droplet size), simulated administration techniques (head orientation, spray administration angle, spray nozzle insertion depth), spray pump design and metering volume on nasal deposition pattern were investigated.

RESULTS

There was a significant decrease in the deposition area associated with sprays of increasing viscosity. This appeared to be mediated by an increase in droplet size and a narrowing of the spray plume. Administration techniques and nasal spray pump design also had a significant effect on the deposition pattern.

CONCLUSIONS

This simple color-based method provides quantitative estimates of the effects that different formulation and administration variables may have on the nasal deposition area, and provides a rational basis on which manufacturers of nasal sprays can base their patient instructions or post approval changes when it is impractical to optimize these using a clinical study.

Characterization of stability and nasal delivery systems for immunization with nanoemulsion-based vaccines

BACKGROUND

Many infectious diseases that cause significant morbidity and mortality, especially in the developing world, could be preventable through vaccination. The effort to produce safe, thermally stable, and needle-free mucosal vaccines has become increasingly important for global health considerations. We have previously demonstrated that a thermally stable nanoemulsion, a mucosal adjuvant for needle-free nasal immunization, is safe and induces protective immunity with a variety of antigens, including recombinant protein. The successful use of nanoemulsion-based vaccines, however, poses numerous challenges. Among the challenges is optimization of the formulation to maintain thermal stability and potency and another is accuracy and efficiency of dispensing the vaccines to the nasal mucosa in the anterior and turbinate region of the nasal cavity or potentially to the nasopharynx-associated lymphoid tissue.

METHODS

We have examined the effects of different diluents [phosphate-buffered saline (PBS) and 0.9% NaCl] on the stability and potency of nanoemulsion-based vaccines. In addition, we have determined the efficiency of delivering them using commercially available nasal spray devices (Pfeiffer SAP-62602 multidose pump and the BD Hypak SCF 0.5 ml unit dose Accuspray(TM)).

RESULTS

We report the stability and potency of PBS-diluted ovalbumin-nanomeulsion mixtures for up to 8 months and NaCl-diluted mixtures up to 6 months when stored at room temperature. Significant differences in spray characteristics including droplet size, spray angle, plume width, and ovality ratios were observed between the two pumps. Further, we have demonstrated that the nanoemulsion-based vaccines are not physically or chemically altered and retain potency following actuation with nasal spray devices. Using either device, the measured spray characteristics suggest deposition of nanoemulsion-based vaccines in inductive tissues located in the anterior region of the nasal cavity.

CONCLUSIONS

The results of this study suggest that nanoemulsion-based vaccines do not require specially engineered delivery devices and support their potential use as nasopharyngeal vaccine adjuvants.