The Upper Nasal Space: Option for Systemic Drug Delivery, Mucosal Vaccines and "Nose-to-Brain"

The nasal route for nose-to-brain drug delivery: advanced nasal formulations for CNS disorders

INTRODUCTION

The nasal route offers a feasible alternative to oral and/or parenteral administration, providing a noninvasive route to achieve nose-to-brain drug delivery involving the olfactory and trigeminal nerves, and facilitating local or systemic drug action. Conventional liquid nasal dosage forms have not managed to bridge the gaps of precise dosing and targeted central nervous system (CNS) delivery, while more sophisticated formulation approaches are being explored for brain targeting, aiming to enhance bioavailability and therapeutic efficacy.

AREAS COVERED

This review focuses on preclinical and clinical evaluation of microemulsions, in-situ gels, nasal powders, and nanocarrier-based formulations. Key pharmacokinetic and pharmacodynamic findings are discussed to evaluate their potential and limitations in improving drug bioavailability and CNS targeting. The existing regulatory framework for approval of products for nose-to-brain drug delivery is also addressed and relative hurdles are discussed.

EXPERT OPINION

While nasal drug delivery holds great promise for CNS therapeutics, key challenges remain, including formulation stability, mucosal permeability, patient adherence. Future research should prioritize improving targeting efficiency, overcoming mucociliary clearance, developing user-friendly pharmaceutical products. Personalized medicine and smart delivery systems could further enhance drug targeting and minimize side effects. Continued research and regulatory advancements are essential to fully realize nasal delivery's perspective in CNS therapeutics.

Uniform Spray Dried Loxapine Microparticles Potentially for Nasal Delivery: Exploring Discriminatory In Vitro Release Evaluation Methods

This study aimed to develop suitable in vitro evaluation methods for the release behavior of nasal powders (NPs). We synthesized a range of standardized microparticles with adjustable size and morphology by co-spray-drying loxapine succinate (LOX) and gelatin (GEL) using an ethanol/water solvent mixture in a self-designed micro-fluidic jet spray dryer (MFJSD). The influence of the LOX/GEL mass ratio and solvent composition on particle characteristics, including size, morphology, and crystalline properties, was systematically investigated. In vitro release profiles of NPs were thoroughly assessed across different release medium, apparatus, and membranes. The modified Transwell® system, utilizing simulated nasal electrolyte solution (SNES) as the release medium, was identified as the most effective in distinguishing the performance of microparticles with diverse attributes. Furthermore, the impact of particle size, morphology, and crystalline properties on in vitro release profiles was discussed. This research presents a robust methodology for the in vitro evaluation of NPs release profiles and provides a practical approach for the rational fabrication of high-quality NPs products.

Mannose and Lactobionic Acid in Nasal Vaccination: Enhancing Antigen Delivery via C-Type Lectin Receptors

BACKGROUND/OBJECTIVES

Nasal vaccines are a promising strategy for enhancing mucosal immune responses and preventing diseases at mucosal sites by stimulating the secretion of secretory IgA, which is crucial for early pathogen neutralization. However, designing effective nasal vaccines is challenging due to the complex immunological mechanisms in the nasal mucosa, which must balance protection and tolerance against constant exposure to inhaled pathogens. The nasal route also presents unique formulation and delivery hurdles, such as the mucous layer hindering antigen penetration and immune cell access.

METHODS

This review focuses on cutting-edge approaches to enhance nasal vaccine delivery, particularly those targeting C-type lectin receptors (CLRs) like the mannose receptor and macrophage galactose-type lectin (MGL) receptor. It elucidates the roles of these receptors in antigen recognition and uptake by antigen-presenting cells (APCs), providing insights into optimizing vaccine delivery.

RESULTS

While a comprehensive examination of targeted glycoconjugate vaccine development is outside the scope of this study, we provide key examples of glycan-based ligands, such as lactobionic acid and mannose, which can selectively target CLRs in the nasal mucosa.

CONCLUSIONS

With the rise of new viral infections, this review aims to facilitate the design of innovative vaccines and equip researchers, clinicians, and vaccine developers with the knowledge to enhance immune defenses against respiratory pathogens, ultimately protecting public health.

Physico-Chemical Characterization and Initial Evaluation of Carboxymethyl Chitosan-Hyaluronan Hydrocolloid Systems with Insulin Intended for Intranasal Administration

The nasal route of administration can bypass the blood-brain barrier in order to obtain a higher concentration in the brain, thus offering a feasible alternative route of administration for diseases associated with the central nervous system. The advantages of the intranasal administration and the potential favorable therapeutic effects of intranasally administered insulin led to the formulation of carboxymethyl chitosan (CMC) and sodium hyaluronate (NaHA) hydrocolloidal systems with insulin for nasal administration, targeting nose-to-brain delivery and the initial assessment of these systems. The influence of the formulation variables on the response parameters defined as surface properties, rheology, and in vitro release of insulin were analyzed using experimental design and statistical programs (Modde and Minitab software). The systems recorded good wetting and adhesion capacity, allowing the spread of the hydrocolloidal systems on the nasal mucosa. The samples had a pseudoplastic flow and the rapid release of the insulin was according to our objective. According to the physico-chemical characterization and preliminary assessment, these formulations are appropriate for administration on the nasal mucosa, but further studies are necessary to demonstrate the beneficial therapeutic actions and the safety of using intranasal insulin.

Ex vivo propofol permeation across nasal mucosa: A proof-of-concept study for outpatient light sedation via nasal route

Background and Purpose

Aiming to achieve light sedation via intranasal administration, this study showed that propofol (PPF) did not permeate across the rabbit nasal mucosa ex vivo from its marketed emulsion for injection.

Experimental approach

Dilution of the emulsion with methyl-β-cyclodextrin in saline solution increased propofol solubility in water and diffusion across the nasal epithelium.

Key results and conclusion

Despite these positive effects of the cyclodextrin, the amount of PPF permeated was minimal in 3 h, exceeding the formulation residence time in the nose. These results highlight the key role of formulation and the need for innovation in solubility and transmucosal transport enhancement techniques to optimize drug delivery and therapeutic efficacy.

Development and Optimization of Nasal Composition of a Neuroprotective Agent for Use in Neonatology after Prenatal Hypoxia

The intranasal route of drug administration is characterized by high bioavailability and is considered promising for rapid delivery of drugs with systemic action to the central nervous system (CNS), bypassing the blood-brain barrier. This is particularly important for the use of neuroprotective drugs in the treatment of brain tissue damage in infants caused by the effects of intrauterine hypoxia. The creation of new dosage forms for neonatology using mathematical technologies and special software in pharmaceutical development allows for the creation of cerebroprotective drugs with controlled pharmaco-technological properties, thus reducing time and resources for necessary research. We developed a new nasal gel formulation with Angiolin using a Box-Behnken experiment design for the therapy of prenatal CNS damage. It was found that the consistency characteristics of the nasal gel were significantly influenced by the gelling agent and mucoadhesive component-sodium salt of carboxymethylcellulose. We optimized the composition of nasal gel formulation with Angiolin using the formed models and relationships between the factors. The optimized nasal gel composition demonstrated satisfactory thixotropic properties. The 1% gel for neuroprotection with Angiolin, developed for intranasal administration, meets all safety requirements for this group of drug forms, showing low toxicity and no local irritant or allergic effects.

Correction: Shrewsbury, S.B. The Upper Nasal Space: Option for Systemic Drug Delivery, Mucosal Vaccines and "Nose-to-Brain". Pharmaceutics 2023, 15, 1720

In the original publication [...].

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.

Long-acting anti-inflammatory injectable DEX-Gel with sustained release and self-healing properties regulates TH1/TH2 immune balance for minimally invasive treatment of allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is a prevalent immune-related allergic disease, and corticosteroid nasal sprays serve as the primary treatment for this patient population. However, their short duration of efficacy and frequent administration pose challenges, leading to drug wastage and potential adverse effects. To overcome these limitations, we devised a novel approach to formulate DEX-Gel by incorporating dexamethasone (DEX) into a blend of Pluronic F127, stearic acid (SA), and polyethylene glycol 400 (PEG400) to achieve sustained-release treatment for AR.

RESULTS

Following endoscopic injection into the nasal mucosa of AR rats, DEX-Gel exhibited sustained release over a 14-day period. In vivo trials employing various assays, such as flow cytometry (FC), demonstrated that DEX-Gel not only effectively managed allergic symptoms but also significantly downregulated helper T-cells (TH) 2 and TH2-type inflammatory cytokines (e.g., interleukins 4, 5, and 13). Additionally, the TH1/TH2 cell ratio was increased.

CONCLUSION

This innovative long-acting anti-inflammatory sustained-release therapy addresses the TH1/TH2 immune imbalance, offering a promising and valuable approach for the treatment of AR and other inflammatory nasal diseases.

Research progress in brain-targeted nasal drug delivery

The unique anatomical and physiological connections between the nasal cavity and brain provide a pathway for bypassing the blood-brain barrier to allow for direct brain-targeted drug delivery through nasal administration. There are several advantages of nasal administration compared with other routes; for example, the first-pass effect that leads to the metabolism of orally administered drugs can be bypassed, and the poor compliance associated with injections can be minimized. Nasal administration can also help maximize brain-targeted drug delivery, allowing for high pharmacological activity at lower drug dosages, thereby minimizing the likelihood of adverse effects and providing a highly promising drug delivery pathway for the treatment of central nervous system diseases. The aim of this review article was to briefly describe the physiological structures of the nasal cavity and brain, the pathways through which drugs can enter the brain through the nose, the factors affecting brain-targeted nasal drug delivery, methods to improve brain-targeted nasal drug delivery systems through the application of related biomaterials, common experimental methods used in intranasal drug delivery research, and the current limitations of such approaches, providing a solid foundation for further in-depth research on intranasal brain-targeted drug delivery systems (see Graphical Abstract).

Nose-to-Heart Approach: Unveiling an Alternative Route of Acute Treatment

Intranasal (IN) administration has emerged as a novel approach for rapid systemic absorption, with potential applicability in the management of acute cardiovascular events. This review explores the evolution of IN cardiovascular pharmacotherapy, emphasizing its potential in achieving systemic effects and bypassing the first-pass metabolism associated with oral administration. The extensive vascularization of nasal mucosa and a porous endothelial basement membrane facilitate efficient drug absorption into the bloodstream. The IN route ensures a critical swift onset of action, which allows self-administration in at-home settings. For instance, etripamil nasal spray, a first-in-class formulation, exemplifies the therapeutic potential of this approach in the treatment of spontaneous supraventricular tachycardia. The review critically assesses studies on IN formulations for angina, acute myocardial infarction, hypertensive episodes, and cardiac arrhythmias. Preclinical evaluations of beta-blockers, calcium-channel blockers, and antianginal drugs demonstrate the feasibility of IN administration for acute cardiovascular events. A small number of clinical trials have revealed promising results, emphasizing the superiority of IN drug delivery over oral administration in terms of bioavailability and onset of action. Unambiguously, the limited clinical trials and patient enrollment pose challenges in generalizing experimental outcomes. However, the nose-to-heart approach has clinical potential.

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

INTRODUCTION

The upper respiratory tract is a major route of infection for COVID-19 and other respiratory diseases. Thus, it appears logical to exploit the nose as administration site to prevent, fight, or minimize infectious spread and treat the disease. Numerous nasal products addressing these aspects have been considered and developed for COVID-19.

AREAS COVERED

This review gives a comprehensive overview of the different approaches involving nasal delivery, i.e., nasal vaccination, barrier products, and antiviral pharmacological treatments that have led to products on the market or under clinical evaluation, highlighting the peculiarities of the nose as application and absorption site and pointing at key aspects of nasal drug delivery.

EXPERT OPINION

From the analysis of nasal delivery strategies to prevent or fight COVID-19, it emerges that, especially for nasal immunization, formulations appear the same as originally designed for parenteral administration, leading to suboptimal results. On the other hand, mechanical barrier and antiviral products, designed to halt or treat the infection at early stage, have been proven effective but were rarely brought to the clinics. If supported by robust and targeted product development strategies, intranasal immunization and drug delivery can represent valid and sometimes superior alternatives to more conventional parenteral and oral medications.