Nasal delivery as a strategy for the prevention and treatment of COVID-19

Assessment of the effectiveness of intranasal antiviral therapies in preclinical SARS-CoV-2 infection mouse models: a systematic review

INTRODUCTION

Intranasally (IN) administered antiviral therapies have emerged as a promising approach to combating SARS-CoV-2 respiratory tract infections. This systematic review aims to examine published preclinical animal studies that report anti-SARS-CoV-2 effects due to IN-delivered antiviral drugs between 1 December 2019 and 1 March 2025.

METHODS

Our analysis revealed 37 relevant studies out of 792 identified studies. Importantly, 15 out of the 36 selected studies performed prophylactic and post-exposure IN treatments in preclinical animal models.

RESULTS

Our systematic analysis revealed six classes of IN-delivered antiviral therapeutics that significantly improved in vivo survival and reduced target organ viremia with minimal side effects in mice. Antiviral interventions resulted in animal body weight recovery (28 studies), better clinical survival (15 studies) and reduced organ viral loads (infectious viral titers (14 studies) and RNA viral loads (28 studies)). Out of these, one study reported negative outcomes of IN interventions, significant weight loss (one study) and poorer mouse survival (two studies).

CONCLUSIONS

Our systematic analysis revealed a moderate association between IN antiviral therapies and clinical and antiviral efficacy. Although the evidence supports the effectiveness of IN antiviral therapies in preclinical models, translation to clinical efficacy in humans remains uncertain.

PROSPERO REGISTRATION

CRD42024492039.

Evaluation of the duration of new nasal drug interferon α-2b activity in an experimental model system

THIS STUDY AIMED

To develop an adequate system for assessing the duration of IFN antiviral activity in the nasal cavity of animals and to study the antiviral activity of a new IFN drug in the form of a gel in comparison with the known spray form.

METHODS

To assess the duration of the specific activity of IFN, the drugs were administered into the nasal cavity of experimental rats. One, 3, and 4 h after administration, the nasal cavities of the rats were washed out, and the antiviral activity of washed from the nasal cavity (WNC) was analyzed in vitro.

RESULTS

Developed an algorithm to assess the duration of antiviral activity of nasal preparations using a sensitive in vitro test system, in which the analysis of the antiviral activity of WNC made it possible to detect antiviral activity after the administration of nasal forms of IFN-a new variant in the form of a gel in comparison with the IFN spray. It was established that 1 h after the intranasal administration of IFN, the same antiviral activity and IFN concentration is: 266.8 ± 14.0 IU/ml for IFN/spray and 260.2 ± 20.9 IU/ ml for IFN/gel. Three hours after the drugs are administered, their activity decreases but remains at a sufficiently high level: 121.4 ± 5.4 IU/ml for IFN/spray and 88.3 ± 6.2 IU/ml for IFN/gel. Four hours after IFN administration, the concentration of IFN/gel was significantly greater than that of IFN/spray: 39.4 ± 4.9 IU/ml and 10.6 ± 1.0 IU/ml, respectively.

CONCLUSION

The developed system for evaluating the antiviral activity of nasal preparations allows the study of the duration of the local antiviral effect of drugs. The antiviral activity of the IFN nasal preparations persisted for 4 h after their intranasal administration: the concentration of IFN in gel form on the walls of the nasal cavity was significantly greater than that of the IFN spray.

Dry powder formulations of hyperimmune serum

Effective strategies against the spread of respiratory viruses are needed, as tragically demonstrated during the COVID-19 pandemic. Apart from vaccines, other preventive or protective measures are necessary: one promising strategy involves the nasal delivery of preventive or protective agents, targeting the site of initial infection. Harnessing the immune system's ability to produce specific antibodies, a hyperimmune serum, collected from an individual vaccinated against SARS-CoV-2, was formulated as a dry powder for nasal administration. The selection of adequate excipients and process are key to maintaining protein stability and modulating the aerodynamic properties of the powders for reaching the desired respiratory regions. To this end, a hyperimmune serum was formulated with trehalose and mannitol as bulking agents during spray drying, then the ability of the redissolved immunoglobulins to bind Spike protein was verified by ELISA; foetal bovine serum was formulated in the same conditions as a reference. Moreover, a seroneutralization assay against SARS-CoV-2 pseudoviruses generated from different variants of concern was performed. The neutralizing ability of the serum was slightly reduced with respect to the starting serum when trehalose was used as a bulking agent. The powders were loaded in hypromellose capsules and aerosolized employing a nasal insufflator in an in vitro model of the nasal cavity connected to a Next Generation Impactor. The analysis of the powder distribution confirmed that all powders were inhalable and could target, at the same time, the upper and the lower airways. This is a preliminary proof-of-concept that this approach can constitute an effective strategy to provide broad coverage and protection against SARS-CoV-2, and in general against viruses affecting the airway. According to blood availability from donors, pools of hyperimmune sera could be rapidly formulated and administered, providing a simultaneous and timely neutralization of emerging viral variants.

Investigation of powder properties and application aspects impacting nasal deposition of spray-dried powders in a nasal cast

In this study, spray-dried formulations differing in morphology (spherical and wrinkled), surface polarity (hydrophilic and hydrophobic), and size (20-30 µm and 3 µm) were evaluated in a nasal cast to assess their deposition profiles. The objective was to identify how formulation properties and application aspects influence the deposition profile. For this purpose, the formulations were administered at different application angles (45° and 60°), fill weights (20 mg and 40 mg), and airflow rates (0 L/min and 15 L/min) in conjunction with a UDS powder device. The results indicate a more posterior deposition profile for 45° compared to 60° due to increased deposition in the turbinate region; conversely, deposition profiles between fill weights were comparable. Application with simultaneous airflow should be avoided because of an increasing postnasal fraction. No influence of morphology could be observed, but for the surface polarity an influence was apparent, if the powder was applied with a simulated inspiration. In these cases, a hydrophobic formulation was better dispersible than a hydrophilic formulation, which led to an increased postnasal fraction. A particle size for pulmonary application demonstrated comparable results to nasal formulations with respect to the turbinate deposition but exhibited a high postnasal fraction for hydrophobic formulations.

Development of a nasal spray based on cyclodextrin/hydrophobically-modified hydroxypropyl-methyl cellulose for the prevention of viral respiratory infections

The work aims to develop mucoadhesive and thermo-responsive in situ gelling systems, using hydrophobically-modified hydroxypropyl-methyl cellulose (Sangelose, SG) and beta-cyclodextrin (β-CD) derivatives, for preventing viral respiratory infections. Eight SG/CD systems with varying CD concentrations were evaluated for rheological properties, mucoadhesiveness, spreadability and sprayability via nasal devices; cytotoxicity was in vitro investigated on reconstituted nasal epithelia. Additionally, droplet size distribution and spray deposition were assessed for the most promising systems. The addition of β-CD derivatives to SG solution was responsible for a rapid sol-gel transition within a physiological temperature range (29-34 °C). SG/CD systems were characterized by a prevalence of the elastic properties on the viscous ones at 37 °C, functional to the formation of a protective gel barrier on the mucosa. The most promising systems showed sprayability and spreadability suitable for nasal administration, while in vitro tests demonstrated their non-toxicity. All the sprays were characterized by droplets with size >100 μm, functional to avoid droplet exhalation or lung deposition; spray deposition studies confirmed uniform distribution across nasal turbinates, crucial for trapping inhaled particles. In conclusion, a mucoadhesive and thermo-responsive in situ gelling system consisting of SG and β-CD derivatives was successfully developed as promising nasal spray for the prevention of respiratory infections.

Discovery and development of INNA-051, a TLR2/6 agonist for the prevention of complications resulting from viral respiratory infections

Viral respiratory infection is associated with significant morbidity and mortality. The diversity of viruses implicated, coupled with their propensity for mutation, ignited an interest in host-directed antiviral therapies effective across a wide range of viral variants. Toll-like receptors (TLRs) are potential targets for the development of broad-spectrum antivirals given their central role in host immune defenses. Synthetic agonists of TLRs have been shown to boost protective innate immune responses against respiratory viruses. However, clinical success was hindered by short duration of benefit and/or induction of systemic adverse effects. INNA-051, a TLR2/6 agonist, is in development as an intranasal innate immune enhancer for prophylactic treatment in individuals at risk of complications resulting from respiratory viral infections. In vivo animal studies demonstrated the efficacy as prophylaxis against multiple viruses including SARS-CoV-2, influenza, and rhinovirus. Early clinical trials demonstrated an acceptable safety and tolerability profile. Intranasal delivery to the primary site of infection in humans induced a local innate host defense response characterized by innate immune cell infiltration into the nasal epithelium and activation and antiviral response genes. Taken together, the preclinical and clinical data on INNA-051 support further investigation of its use in community infection settings.

Localized delivery of therapeutics impact laryngeal mechanics, local inflammatory response, and respiratory microbiome following upper airway intubation injury in swine

BACKGROUND

Laryngeal injury associated with traumatic or prolonged intubation may lead to voice, swallow, and airway complications. The interplay between inflammation and microbial population shifts induced by intubation may relate to clinical outcomes. The objective of this study was to investigate laryngeal mechanics, tissue inflammatory response, and local microbiome changes with laryngotracheal injury and localized delivery of therapeutics via drug-eluting endotracheal tube.

METHODS

A simulated traumatic intubation injury was created in Yorkshire crossbreed swine under direct laryngoscopy. Endotracheal tubes electrospun with roxadustat or valacyclovir- loaded polycaprolactone (PCL) fibers were placed in the injured airway for 3, 7, or 14 days (n = 3 per group/time and ETT type). Vocal fold stiffness was then evaluated with normal indentation and laryngeal tissue sections were histologically examined. Immunohistochemistry and inflammatory marker profiling were conducted to evaluate the inflammatory response associated with injury and ETT placement. Additionally, ETT biofilm formation was visualized using scanning electron microscopy and micro-computed tomography, while changes in the airway microbiome were profiled through 16S rRNA sequencing.

RESULTS

Laryngeal tissue with roxadustat ETT placement had increasing localized stiffness outcomes over time and histological assessment indicated minimal epithelial ulceration and fibrosis, while inflammation remained severe across all timepoints. In contrast, vocal fold tissue with valacyclovir ETT placement showed no significant changes in stiffness over time; histological analysis presented a reduction in epithelial ulceration and inflammation scores along with increased fibrosis observed at 14 days. Immunohistochemistry revealed a decline in M1 and M2 macrophage markers over time for both ETT types. Among the cytokines, IL-8 levels differed significantly between the roxadustat and valacyclovir ETT groups, while no other cytokines showed statistically significant differences. Additionally, increased biofilm formation was observed in the coated ETTs with notable alterations in microbiota distinctive to each ETT type and across time.

CONCLUSION

The injured and intubated airway resulted in increased laryngeal stiffness. Local inflammation and the type of therapeutic administered impacted the bacterial composition within the upper respiratory microbiome, which in turn mediated local tissue healing and recovery.

Curcumin and quercetin co-encapsulated in nanoemulsions for nasal administration: A promising therapeutic and prophylactic treatment for viral respiratory infections

One of the most frequent causes of respiratory infections are viruses. Viruses reaching the airways can be absorbed by the human body through the respiratory mucosa and mainly infect lung cells. Several viral infections are not yet curable, such as coronavirus-2 (SARS-CoV-2). Furthermore, the side effect of synthetic antiviral drugs and reduced efficacy against resistant variants have reinforced the search for alternative and effective treatment options, such as plant-derived antiviral molecules. Curcumin (CUR) and quercetin (QUE) are two natural compounds that have been widely studied for their health benefits, such as antiviral and anti-inflammatory activity. However, poor oral bioavailability limits the clinical applications of these natural compounds. In this work, nanoemulsions (NE) co-encapsulating CUR and QUE designed for nasal administration were developed as promising prophylactic and therapeutic treatments for viral respiratory infections. The NEs were prepared by high-pressure homogenization combined with the phase inversion temperature technique and evaluated for their physical and chemical characteristics. In vitro assays were performed to evaluate the nanoemulsion retention into the porcine nasal mucosa. In addition, the CUR and QUE-loaded NE antiviral activity was tested against a murine β-COV, namely MHV-3. The results evidenced that CUR and QUE loaded NE had a particle size of 400 nm and retention in the porcine nasal mucosa. The antiviral activity of the NEs showed a percentage of inhibition of around 99 %, indicating that the developed NEs has interesting properties as a therapeutic and prophylactic treatment against viral respiratory infections.

Characterizing regional drug delivery within the nasal airways

INTRODUCTION

The nose has been receiving increased attention as a route for drug delivery. As the site of deposition constitutes the first point of contact of the body with the drug, characterization of the regional deposition of intranasally delivered droplets or particles is paramount to formulation and device design of new products.

AREAS COVERED

This review article summarizes the recent literature on intranasal regional drug deposition evaluated in vivo, in vitro and in silico, with the aim of correlating parameters measured in vitro with formulation and device performance. We also highlight the relevance of regional deposition to two emerging applications: nose-to-brain drug delivery and intranasal vaccines.

EXPERT OPINION

As in vivo studies of deposition can be costly and time-consuming, researchers have often turned to predictive in vitro and in silico models. Variability in deposition is high due in part to individual differences in nasal geometry, and a complete predictive model of deposition based on spray characteristics remains elusive. Carefully selected or idealized geometries capturing population average deposition can be useful surrogates to in vivo measurements. Continued development of in vitro and in silico models may pave the way for development of less variable and more effective intranasal drug products.

Cyclosporine A micellar nasal spray characterization and antiviral action against SARS-CoV-2

The upper airways represent the point of entrance from where Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection spreads to the lungs. In the present work, α-tocopheryl-polyethylene-glycol succinate (TPGS) micelles loaded with cyclosporine A (CSA) were developed for nasal administration to prevent or treat the viral infection in the very first phases. The behavior of the micelles in presence of simulated nasal mucus was investigated in terms of stability and mucopenetration rate, evidencing long-term stability and fast diffusion across the glycoproteins matrix. Moreover, the spray characteristics of the micellar formulation and deposition profile in a silicon nasal model were studied using three nasal spray devices. Results allowed to identify the nasal spray pump (BiVax, Aptar) able to provide the wider and uniform deposition of the nasal cavity. The cyclosporine A micelles antiviral activity against SARS-CoV-2 was tested on the Omicron BA.1 variant using Vero E6 cells with protocols simulating treatment before, during and after the infection of the upper airways. Complete viral inactivation was observed for the cyclosporine-loaded micelles while a very low activity was evidenced for the non-formulated drug, suggesting a synergistic activity of the drug and the formulation. In conclusion, this work showed that the developed cyclosporine A-loaded micellar formulations have the potential to be clinically effective against a wide spectrum of coronavirus variants.

Use of a point-of-care test to rapidly assess levels of SARS-CoV-2 nasal neutralising antibodies in vaccines and breakthrough infected individuals

Despite SARS-CoV-2 vaccines eliciting systemic neutralising antibodies (nAbs), breakthrough infections still regularly occur. Infection helps to generate mucosal immunity, possibly reducing disease transmission. Monitoring mucosal nAbs is predominantly restricted to lab-based assays, which have limited application to the public. In this multi-site study, we used lateral-flow surrogate neutralisation tests to measure mucosal and systemic nAbs in vaccinated and breakthrough infected individuals in Australia and Singapore. Using three lateral flow assays to detect SARS-CoV-2 nAbs, we demonstrated that nasal mucosal nAbs were present in 71.4 (95% CI 56.3-82.9%) to 85.7% (95% CI 71.8-93.7%) of individuals with breakthrough infection (positivity rate was dependent upon the type of test), whereas only 20.7 (95% CI 17.1-49.4%) to 34.5% (95% CI 19.8-52.7%) of vaccinated individuals without breakthrough infection had detectible nasal mucosal nAbs. Of the individuals with breakthrough infection, collective mucosal anti-S antibody detection in confirmatory assays was 92.9% (95% CI 80.3-98.2%) of samples, while 72.4% (95% CI 54.1-85.5%) of the vaccinated individuals who had not experienced a breakthrough infection were positive to anti-S antibody. All breakthrough infected individuals produced systemic anti-N antibodies; however, these antibodies were not detected in the nasal cavity. Mucosal immunity is likely to play a role in limiting the transmission of SARS-CoV-2 and lateral flow neutralisation tests provide a rapid readout of mucosal nAbs at the point-of-care.