A modified USP induction port to characterize nasal spray plume geometry and predict turbinate deposition under flow

What Are the Key Anatomical Features for the Success of Nose-to-Brain Delivery? A Study of Powder Deposition in 3D-Printed Nasal Casts

Nose-to-brain delivery is a promising way to improve the treatment of central nervous system disorders, as it allows the bypassing of the blood-brain barrier. However, it is still largely unknown how the anatomy of the nose can influence the treatment outcome. In this work, we used 3D printing to produce nasal replicas based on 11 different CT scans presenting various anatomical features. Then, for each anatomy and using the Design of Experiments methodology, we characterised the amount of a powder deposited in the olfactory region of the replica as a function of multiple parameters (choice of the nostril, device, orientation angle, and the presence or not of a concomitant inspiration flow). We found that, for each anatomy, the maximum amount of powder that can be deposited in the olfactory region is directly proportional to the total area of this region. More precisely, the results show that, whatever the instillation strategy, if the total area of the olfactory region is below 1500 mm2, no more than 25% of an instilled powder can reach this region. On the other hand, if the total area of the olfactory region is above 3000 mm2, the deposition efficiency reaches 50% with the optimal choice of parameters, whatever the other anatomical characteristics of the nasal cavity. Finally, if the relative difference between the areas of the two sides of the internal nasal valve is larger than 20%, it becomes important to carefully choose the side of instillation. This work, by predicting the amount of powder reaching the olfactory region, provides a tool to evaluate the adequacy of nose-to-brain treatment for a given patient. While the conclusions should be confirmed via in vivo studies, it is a first step towards personalised treatment of neurological pathologies.

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.

Spray coverage analysis of topical sprays formed by cold thermoreversible hydrogels

OBJECTIVE

Sprayable hydrogel formulations are promising topical treatments for skin wounds due to their ability to reduce application pain, prolong drug release, and provide moisture to promote skin healing. These viscoelastic materials, however, present challenges in spray ability which can be overcome using a thermoreversible hydrogels sprayed as lower viscosity liquids at cooler temperatures. The purpose of this research was to evaluate the impact of thermoreversible hydrogel formulation and device characteristics on topical spray patterns and to develop metrics to accurately describe surface coverage.

METHODS

Cold solutions of Pluronic F127 were prepared at 15, 17, and 20% (w/w) and tested to determine their rheological properties. Formulations were sprayed from hand-held atomizing pump dispersers under cold conditions and two distinct areas of their spray patterns analyzed: the concentrated core and the full spray pattern. Traditional analysis of spray patterns was conducted to determine major and minor axes, ovality, and total area. In addition, new scripts were developed to evaluate the concentrated core.

RESULTS

The full spray pattern analysis quantified the total area over which the spray would extend a flat surface, while the concentrated core analysis quantified the continuous region where a drug dose would be concentrated. The combination of formulation viscosity, sprayer nozzle, and spray distance produced spray patterns from highly concentrated to highly dispersed. These parameters can be controlled to generate desired hydrogel spray patterns for application on skin surfaces.

CONCLUSION

The developed metrics provide a basis for topical spray analysis that can inform future product performance.

Factors affecting nasal drug delivery and design strategies for intranasal drug delivery

Intranasal drug delivery system is a non-invasive drug delivery route with the advantages of no first-pass effect, rapid effect and brain targeting. It is a feasible alternative to drug delivery via injection, and a potential drug delivery route for the central nervous system. However, the nasal physiological environment is complex, and the nasal delivery system requires "integration of medicine and device". Its delivery efficiency is affected by many factors such as the features and formulations of drug, delivery devices and nasal cavity physiology. Some strategies have been designed to improve the solubility, stability, membrane permeability and nasal retention time of drugs. These include the use of prodrugs, adding enzyme inhibitors and absorption enhancers to preparations, and new drug carriers, which can eventually improve the efficiency of intranasal drug delivery. This article reviews recent publications and describes the above mentioned aspects and design strategies for nasal intranasal drug delivery systems to provide insights for the development of intranasal drug delivery systems.

Chitosan-Based Thermogelling System for Nose-to-Brain Donepezil Delivery: Optimising Formulation Properties and Nasal Deposition Profile

Donepezil nasal delivery strategies are being continuously investigated for advancing therapy in Alzheimer's disease. The aim of this study was to develop a chitosan-based, donepezil-loaded thermogelling formulation tailored to meet all the requirements for efficient nose-to-brain delivery. A statistical design of the experiments was implemented for the optimisation of the formulation and/or administration parameters, with regard to formulation viscosity, gelling and spray properties, as well as its targeted nasal deposition within the 3D-printed nasal cavity model. The optimised formulation was further characterised in terms of stability, in vitro release, in vitro biocompatibility and permeability (using Calu-3 cells), ex vivo mucoadhesion (using porcine nasal mucosa), and in vivo irritability (using slug mucosal irritation assay). The applied research design resulted in the development of a sprayable donepezil delivery platform characterised by instant gelation at 34 °C and olfactory deposition reaching a remarkably high 71.8% of the applied dose. The optimised formulation showed prolonged drug release (t_1/2 about 90 min), mucoadhesive behaviour, and reversible permeation enhancement, with a 20-fold increase in adhesion and a 1.5-fold increase in the apparent permeability coefficient in relation to the corresponding donepezil solution. The slug mucosal irritation assay demonstrated an acceptable irritability profile, indicating its potential for safe nasal delivery. It can be concluded that the developed thermogelling formulation showed great promise as an efficient donepezil brain-targeted delivery system. Furthermore, the formulation is worth investigating in vivo for final feasibility confirmation.

In vitro Evaluation of Paliperidone Palmitate Loaded Cubosomes Effective for Nasal-to-Brain Delivery

Introduction

This work aimed to develop chitosan-coated cubosomal nanoparticles intended for nose-to-brain delivery of paliperidone palmitate. They were compared with standard and cationic cubosomal nanoparticles. This comparison relies on numerous classical in vitro tests and powder deposition within a 3D-printed nasal cast.

Methods

Cubosomal nanoparticles were prepared by a Bottom-up method followed by a spray drying process. We evaluated their particle size, polydispersity index, zeta-potential, encapsulation efficiency, drug loading, mucoaffinity properties and morphology. The RPMI 2650 cell line was used to assess the cytotoxicity and cellular permeation. An in vitro deposition test within a nasal cast completed these measurements.

Results

The selected chitosan-coated cubosomal nanoparticles loaded with paliperidone palmitate had a size of 305.7 ± 22.54 nm, their polydispersity index was 0.166 ± 0.022 and their zeta potential was +42.4 ± 0.2 mV. This formulation had a drug loading of 70% and an encapsulation efficiency of 99.7 ± 0.1%. Its affinity with mucins was characterized by a ΔZP of 20.93 ± 0.31. Its apparent permeability coefficient thought the RPMI 2650 cell line was 3.00E-05 ± 0.24E-05 cm/s. After instillation in a 3D-printed nasal cast, the fraction of the injected powder deposited in the olfactory region reached 51.47 ± 9.30% in the right nostril and 41.20 ± 4.59% in the left nostril, respectively.

Conclusion

The chitosan coated cubosomal formulation seems to be the most promising formulation for nose-to-brain delivery. Indeed, it has a high mucoaffinity and a significantly higher apparent permeability coefficient than the two other formulations. Finally, it reaches well the olfactory region.

Instillation of a Dry Powder in Nasal Casts: Parameters Influencing the Olfactory Deposition With Uni- and Bi-Directional Devices

Nose-to-brain delivery is a promising way to reach the central nervous system with therapeutic drugs. However, the location of the olfactory region at the top of the nasal cavity complexifies this route of administration. In this study, we used a 3D-printed replica of a nasal cavity (a so-called “nasal cast”) to reproduce in vitro the deposition of a solid powder. We considered two different delivery devices: a unidirectional device generating a classical spray and a bidirectional device that relies on the user expiration. A new artificial mucus also coated the replica. Five parameters were varied to measure their influence on the powder deposition pattern in the olfactory region of the cast: the administration device, the instillation angle and side, the presence of a septum perforation, and the flow rate of possible concomitant inspiration. We found that the unidirectional powder device is more effective in targeting the olfactory zone than the bi-directional device. Also, aiming the spray nozzle directly at the olfactory area is more effective than targeting the center of the nasal valve. Moreover, the choice of the nostril and the presence of a perforation in the septum also significantly influence the olfactory deposition. On the contrary, the inspiratory flow has only a minor effect on the powder outcome. By selecting the more efficient administration device and parameters, 44% of the powder can reach the olfactory region of the nasal cast.

In situ gelling nanosuspension as an advanced platform for fluticasone propionate nasal delivery

In this work we present the development of in situ gelling nanosuspension as advanced form for fluticasone propionate nasal delivery. Drug nanocrystals were prepared by wet milling technique. Incorporation of drug nanocrystals into polymeric in situ gelling system with pectin and sodium hyaluronate as constitutive polymers was fine-tuned attaining appropriate formulation surface tension, viscosity and gelling ability. Drug nanonisation improved the release profile and enhanced formulation mucoadhesive properties. QbD approach combining formulation and administration parameters resulted in optimised nasal deposition profile, with 51.8% of the dose deposited in the middle meatus, the critical region in the treatment of rhinosinusitis and nasal polyposis. Results obtained in biocompatibility and physico-chemical stability studies confirmed the leading formulation potential for safe and efficient nasal corticosteroid delivery.

Management of acute upper respiratory tract infection: the role of early intervention

INTRODUCTION

Upper respiratory tract infection (URTI) is an illness caused by an acute infection by viruses or bacteria of the nose, sinuses, pharynx, and larynx. Most URTIs are short, mild, and self-limiting, but some can lead to serious complications, resulting in heavy social and economic burden on individuals and society.

AREAS COVERED

This article presents the management guidelines and consensus established through the Delphi method during an expert roundtable conducted in November 2020 and results of a targeted literature review.

EXPERT OPINION

The current acute URTI management strategies aim toward symptom alleviation and prevention of URTI virus transmission. The effectiveness of these strategies is highly increased with early intervention, administered prior to the peaking of viral shedding. This reduces the chances of developing a full-blown acute URTI, decreases symptom severity, and reduces viral transmission. Mucoadhesive gel nasal sprays have shown promising results for early intervention of acute URTI. They act by creating a barrier that can trap virus particles, thereby preventing invasion of the mucosa by the virus. Additionally, they deliver broad spectrum activity that is effective against a wide variety of pathogens that cause acute URTI. Acute URTI warrants greater attention and proactive management in reducing its burden.

The importance of pre-formulation studies and of 3D-printed nasal casts in the success of a pharmaceutical product intended for nose-to-brain delivery

This review aims to cement three hot topics in drug delivery: (a) the pre-formulation of new products intended for nose-to-brain delivery; (b) the development of nasal casts for studying the efficacy of potential new nose-to-brain delivery systems at the early of their development (pre-formulation); (c) the use of 3D printing based on a wide variety of materials (transparent, biocompatible, flexible) providing an unprecedented fabrication tool towards personalized medicine by printing nasal cast on-demand based on CT scans of patients. This review intends to show the links between these three subjects. Indeed, the pathway selected to administrate the drug to the brain not only influence the formulation strategies to implement but also the design of the cast, to get the most convincing measures from it. Moreover, the design of the cast himself influences the choice of the 3D-printing technology, which, in its turn, bring more constraints to the nasal replica design. Consequently, the formulation of the drug, the cast preparation and its realisation should be thought of as a whole and not separately.

In Vitro Evaluation of Nasal Aerosol Depositions: An Insight for Direct Nose to Brain Drug Delivery

The nasal cavity is an attractive route for both local and systemic drug delivery and holds great potential for access to the brain via the olfactory region, an area where the blood–brain barrier (BBB) is effectively absent. However, the olfactory region is located at the roof of the nasal cavity and only represents ~5–7% of the epithelial surface area, presenting significant challenges for the deposition of drug molecules for nose to brain drug delivery (NTBDD). Aerosolized particles have the potential to be directed to the olfactory region, but their specific deposition within this area is confounded by a complex combination of factors, which include the properties of the formulation, the delivery device and how it is used, and differences in inter-patient physiology. In this review, an in-depth examination of these different factors is provided in relation to both in vitro and in vivo studies and how advances in the fabrication of nasal cast models and analysis of aerosol deposition can be utilized to predict in vivo outcomes more accurately. The challenges faced in assessing the nasal deposition of aerosolized particles within the paediatric population are specifically considered, representing an unmet need for nasal and NTBDD to treat CNS disorders.

Innovating on Inhaled Bioequivalence: A Critical Analysis of the Current Limitations, Potential Solutions and Stakeholders of the Process

Orally inhaled drug products (OIDPs) are an important group of medicines traditionally used to treat pulmonary diseases. Over the past decade, this trend has broadened, increasing their use in other conditions such as diabetes, expanding the interest in this administration route. Thus, the bioequivalence of OIDPs is more important than ever, aiming to increase access to affordable, safe and effective medicines, which translates into better public health policies. However, regulatory agencies leading the bioequivalence process are still deciding the best approach for ensuring a proposed inhalable product is bioequivalent. This lack of agreement translates into less cost-effective strategies to determine bioequivalence, discouraging innovation in this field. The Next-Generation Impactor (NGI) is an example of the slow pace at which the inhalation field evolves. The NGI was officially implemented in 2003, being the last equipment innovation for OIDP characterization. Even though it was a breakthrough in the field, it did not solve other deficiencies of the BE process such as dissolution rate analysis on physiologically relevant conditions, being the last attempt of transferring technology into the field. This review aims to reveal the steps required for innovation in the regulations defining the bioequivalence of OIDPs, elucidating the pitfalls of implementing new technologies in the current standards. To do so, we collected the opinion of experts from the literature to explain these trends, showing, for the first time, the stakeholders of the OIDP market. This review analyzes the stakeholders involved in the development, improvement and implementation of methodologies that can help assess bioequivalence between OIDPs. Additionally, it presents a list of methods potentially useful to overcome some of the current limitations of the bioequivalence standard methodologies. Finally, we review one of the most revolutionary approaches, the inhaled Biopharmaceutical Classification System (IBCs), which can help establish priorities and order in both the innovation process and in regulations for OIDPs.

Liquid Film Translocation Significantly Enhances Nasal Spray Delivery to Olfactory Region: A Numerical Simulation Study

Previous in vivo and ex vivo studies have tested nasal sprays with varying head positions to enhance the olfactory delivery; however, such studies often suffered from a lack of quantitative dosimetry in the target region, which relied on the observer’s subjective perception of color changes in the endoscopy images. The objective of this study is to test the feasibility of gravitationally driven droplet translocation numerically to enhance the nasal spray dosages in the olfactory region and quantify the intranasal dose distribution in the regions of interest. A computational nasal spray testing platform was developed that included a nasal spray releasing model, an airflow-droplet transport model, and an Eulerian wall film formation/translocation model. The effects of both device-related and administration-related variables on the initial olfactory deposition were studied, including droplet size, velocity, plume angle, spray release position, and orientation. The liquid film formation and translocation after nasal spray applications were simulated for both a standard and a newly proposed delivery system. Results show that the initial droplet deposition in the olfactory region is highly sensitive to the spray plume angle. For the given nasal cavity with a vertex-to-floor head position, a plume angle of 10° with a device orientation of 45° to the nostril delivered the optimal dose to the olfactory region. Liquid wall film translocation enhanced the olfactory dosage by ninefold, compared to the initial olfactory dose, for both the baseline and optimized delivery systems. The optimized delivery system delivered 6.2% of applied sprays to the olfactory region and significantly reduced drug losses in the vestibule. Rheological properties of spray formulations can be explored to harness further the benefits of liquid film translocation in targeted intranasal deliveries.

In vitro - in vivo correlation of intranasal drug deposition

In vitro - in vivo correlation (IVIVC) allows prediction of in vivo drug deposition from a nasally inhaled drug based on in vitro drug measurements. In vitro measurements include physical particle characterization and, more recently, deposition studies using anatomical models. Currently, there is a lack of IVIVC for deposition measurements in anatomical models, especially for deposition patterns in various nasal cavity regions. Therefore, improvement of in vitro and in vivo measurement methods and knowledge about nasal deposition mechanisms should help IVIVC in the future.

Innovative sprayable in situ gelling fluticasone suspension: Development and optimization of nasal deposition

The aim of this study was to develop an innovative in situ gelling suspension for effective nasal delivery of fluticasone. Pectin, gellan gum and sodium hyaluronate were used as gelling/thickening agents, and Tween 80 as a suspending agent. The influence of the formulation and/or administration parameters on formulation sprayability and nasal deposition was explored with an appropriate experimental design with the range for parameters in the design obtained from previous research and domain knowledge. All formulations exhibited appropriate sprayability and instant gelation upon mixing with simulated nasal fluid exhibiting weak gel properties convenient for nasal delivery. Targeted turbinate deposition depended on administration and formulation parameters, including their interactions. Decrease in the administration angle from horizontal plane, increase in inspiratory flow and presence of sodium hyaluronate significantly increased deposition in turbinate region. Parameters in interactions included concentration of polymers, surfactant and fluticasone, as well as administration angle. Selected formulations with high turbinate deposition exhibited significant increase in viscosity upon gelation, showing potential to prolong the drug retention at the nasal mucosa. The highest effect on the gel viscosity, strength and fluticasone release profile was observed for gellan gum, thus recognised as crucial parameter for the optimisation of overall therapeutic effect.

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.