Nasal biocompatible powder of Geraniol oil complexed with cyclodextrins for neurodegenerative diseases: physicochemical characterization and in vivo evidences of nose to brain delivery

Design and development of a chitosan-based nasal powder of dimethyl fumarate-cyclodextrin binary systems aimed at nose-to-brain administration. A stability study

The nasal administration route has been studied for the delivery of active molecules directed to the Central Nervous System, thanks to the anatomical connection between the nasal cavity and the brain. Dimethyl fumarate is used to treat relapsing-remitting multiple sclerosis, with a role as an immunomodulator towards T- T-cells and a cytoprotector towards neurons and glial cells. Its use in therapy is hindered by its low aqueous solubility, and low stability, due to hydrolysis and sublimation at room temperature. To overcome this limitation, in this study we evaluated the feasibility of using two amorphous β-cyclodextrin derivatives, namely hydroxypropyl β-cyclodextrin and methyl β-cyclodextrin, to obtain a nasally administrable powder with a view to nose-to-brain administration. Initially, the interaction product was studied using different analytical methods (differential scanning calorimetry, Fourier transform infrared spectroscopy and powder X-ray diffraction) to detect the occurrence of binary product formation, while phase solubility analysis was used to probe the complexation in solution. The dimethyl fumarate-cyclodextrin binary product showing best solubility and stability properties was subsequently used in the development of a chitosan-based mucoadhesive nasally administrable powder comparing different preparative methods. The best performance in terms of both hydrolytic stability and DMF recovery was achieved by the powder obtained via freeze-drying.

Covalent modification of γ-cyclodextrin with geraniol: An antibacterial agent with good thermal stability, solubility and biocompatibility

Geraniol (Ger) is an essential oil molecule with excellent biological activity. High hydrophobicity and volatility limit its practical application. Cyclodextrins (CDs) are water-soluble cyclic oligosaccharides with hydrophobic cavities. Physical encapsulation of CDs to improve the solubility and stability of essential oil molecules is not satisfactory. Therefore, this study synthesized the γ-CD derivative (γ-CD-Ger) by grafting Ger onto γ-CD using a bromide-mediated method. Compared to the inclusion complexes (γ-CD/Ger) formed by both, the derivatives exhibit better solubility and thermal stability. The derivative has better antibacterial activity when the ratio of γ-CD to Ger was 1:2. In addition, the derivatives did not exhibit cytotoxic and hemolytic properties. These results indicate that this research provides a water-soluble antibacterial agent with a wide range of promising applications and offers new ideas for the application of alcohol hydrophobic molecules in aqueous systems.

Adenosine Encapsulation and Characterization through Layer-by-Layer Assembly of Hydroxypropyl-β-Cyclodextrin and Whey Protein Isolate as Wall Materials

Adenosine, as a water-soluble active substance, has various pharmacological effects. This study proposes a layer-by-layer assembly method of composite wall materials, using hydroxypropyl-β-cyclodextrin as the inner wall and whey protein isolate as the outer wall, to encapsulate adenosine within the core material, aiming to enhance adenosine microcapsules' stability through intermolecular interactions. By combining isothermal titration calorimetry with molecular modeling analysis, it was determined that the core material and the inner wall and the inner wall and the outer wall interact through intermolecular forces. Adenosine and hydroxypropyl-β-cyclodextrin form an optimal 1:1 complex through hydrophobic interactions, while hydroxypropyl-β-cyclodextrin and whey protein isolate interact through hydrogen bonds. The embedding rate of AD/Hp-β-CD/WPI microcapsules was 36.80%, and the 24 h retention rate under the release behavior test was 76.09%. The method of preparing adenosine microcapsules using composite wall materials is environmentally friendly and shows broad application prospects in storage and delivery systems with sustained release properties.

Advances and future perspectives of intranasal drug delivery: A scientometric review

Intranasal drug delivery is as a noninvasive and efficient approach extensively utilized for treating the local, central nervous system, and systemic diseases. Despite numerous reviews delving into the application of intranasal drug delivery across biomedical fields, a comprehensive analysis of advancements and future perspectives remains elusive. This review elucidates the research progress of intranasal drug delivery through a scientometric analysis. It scrutinizes several challenges to bolster research in this domain, encompassing a thorough exploration of entry and elimination mechanisms specific to intranasal delivery, the identification of drugs compatible with the nasal cavity, the selection of dosage forms to surmount limited drug-loading capacity and poor solubility, and the identification of diseases amenable to the intranasal delivery strategy. Overall, this review furnishes a perspective aimed at galvanizing future research and development concerning intranasal drug delivery.

Microwave-assisted enzymatic synthesis of geraniol esters in solvent-free systems: optimization of the reaction parameters, purification and characterization of the products, and biocatalyst reuse

Various geraniol esters act as insect pheromones and display pharmacological activities, especially as neuroprotective agents. Therefore, the search for synthetic strategies alternative to traditional chemical synthesis could help designing ecofriendly routes for the preparation of such bioactive compounds. Hence, this work aims at the microwave-assisted enzymatic synthesis of geranyl esters in solvent-free systems. The process variables were optimized for the synthesis of geranyl acetoacetate, achieving 85% conversion after 60 min using a 1:5 substrates molar ratio (ester to geraniol), 80 °C and 8.4% of Lipozyme 435 lipase without removal of the co-produced methanol. On the other hand, a 95% conversion was reached after 30 min using 1:6 substrates molar ratio, 70 °C and 7% lipase in the presence of 5Å molecular sieves for the methanol capture. In addition, the lipase showed good reusability, maintaining the same activity for five reaction cycles. Finally, under the above optimized conditions, other geraniol esters were successfully synthetized such as the geranyl butyrate (98%), geranyl hexanoate (99%), geranyl octanoate (98%), and geranyl (R)-3-hydroxybutyrate (56%). These results demonstrate the microwave-assisted lipase-catalyzed transesterification in a solvent-free system as an excellent and sustainable catalytic methodology to produce geraniol esters.

Evaluation of Brain Targeting and Antipsychotic Activity of Nasally Administrated Ziprasidone Lipid-Polymer Hybrid Nanocarriers

The feasibility of using lipid-polymer hybrid (LPH) nanocarriers as a potential platform for the intranasal delivery of ziprasidone (ZP), a second-generation antipsychotic, was explored. Different ZP-loaded LPH composed of a PLGA core and cholesterol-lecithin lipid coat were prepared using a single step nano-precipitation self-assembly technique. Modulation of polymer, lipid and drug amounts, as well as stirring-speed-optimized LPH with a particle size of 97.56 ± 4.55 nm and a ZP entrapment efficiency (EE%) of 97.98 ± 1.22%. The brain deposition and pharmacokinetics studies proved the efficiency of LPH to traverse the blood-brain barrier (BBB) following intranasal delivery with a 3.9-fold increase in targeting efficiency compared to the intravenous (IV) ZP solution with a direct nose-to-brain transport percentage (DTP) of 74.68%. The ZP-LPH showed enhanced antipsychotic activity in terms of animals' hypermobility over an IV drug solution in schizophrenic rats. The obtained results showed that the fabricated LPH was able to improve ZP brain uptake and proved its antipsychotic efficiency.

Conjugation, Prodrug, and Co-Administration Strategies in Support of Nanotechnologies to Improve the Therapeutic Efficacy of Phytochemicals in the Central Nervous System

Phytochemicals, produced as secondary plant metabolites, have shown interesting potential therapeutic activities against neurodegenerative diseases and cancer. Unfortunately, poor bioavailability and rapid metabolic processes compromise their therapeutic use, and several strategies are currently proposed for overcoming these issues. The present review summarises strategies for enhancing the central nervous system's phytochemical efficacy. Particular attention has been paid to the use of phytochemicals in combination with other drugs (co-administrations) or administration of phytochemicals as prodrugs or conjugates, particularly when these approaches are supported by nanotechnologies exploiting conjugation strategies with appropriate targeting molecules. These aspects are described for polyphenols and essential oil components, which can improve their loading as prodrugs in nanocarriers, or be part of nanocarriers designed for targeted co-delivery to achieve synergistic anti-glioma or anti-neurodegenerative effects. The use of in vitro models, able to simulate the blood-brain barrier, neurodegeneration or glioma, and useful for optimizing innovative formulations before their in vivo administration via intravenous, oral, or nasal routes, is also summarised. Among the described compounds, quercetin, curcumin, resveratrol, ferulic acid, geraniol, and cinnamaldehyde can be efficaciously formulated to attain brain-targeting characteristics, and may therefore be therapeutically useful against glioma or neurodegenerative diseases.

Phytochemicals and Cancer Treatment: Cell-Derived and Biomimetic Vesicles as Promising Carriers

The majority of anticancer agents currently used derive from natural sources: plants, frequently the ones employed in traditional medicines, are an abundant source of mono- and diterpenes, polyphenols, and alkaloids that exert antitumor activity through diverse mechanisms. Unfortunately, many of these molecules are affected by poor pharmacokinetics and limited specificity, shortcomings that may be overcome by incorporating them into nanovehicles. Cell-derived nanovesicles have recently risen to prominence, due to their biocompatibility, low immunogenicity and, above all, targeting properties. However, due to difficult scalability, the industrial production of biologically-derived vesicles and consequent application in clinics is difficult. As an efficient alternative, bioinspired vesicles deriving from the hybridization of cell-derived and artificial membranes have been conceived, revealing high flexibility and appropriate drug delivery ability. In this review, the most recent advances in the application of these vesicles to the targeted delivery of anticancer actives obtained from plants are presented, with specific focus on vehicle manufacture and characterization, and effectiveness evaluation performed through in vitro and in vivo assays. The emerging overall outlook appears promising in terms of efficient drug loading and selective targeting of tumor cells, suggesting further engrossing developments in the future.

Anomalous Properties of Cyclodextrins and Their Complexes in Aqueous Solutions

Cyclodextrins (CDs) are cyclic oligosaccharides that emerged as industrial excipients in the early 1970s and are currently found in at least 130 marketed pharmaceutical products, in addition to numerous other consumer products. Although CDs have been the subject of close to 100,000 publications since their discovery, and although their structure and properties appear to be trivial, CDs are constantly surprising investigators by their unique physicochemical properties. In aqueous solutions, CDs are solubilizing complexing agents of poorly soluble drugs while they can also act as organic cosolvents like ethanol. CDs and their complexes self-assemble in aqueous solutions to form both nano- and microparticles. The nanoparticles have diameters that are well below the wavelength of visible light; thus, the solutions appear to be clear. However, the nanoparticles can result in erroneous conclusions and misinterpretations of experimental results. CDs can act as penetration enhancers, increasing drug permeation through lipophilic membranes, but they do so without affecting the membrane barrier. This review is an account of some of the unexpected results the authors have encountered during their studies of CDs as pharmaceutical excipients.

Alternative Methotrexate Oral Formulation: Enhanced Aqueous Solubility, Bioavailability, Photostability, and Permeability

The poor aqueous solubility and/or permeability and thereby limited bioavailability largely restricts the pharmaco-therapeutic implications of potent anticancer drugs such as methotrexate (MTX). Furthermore, MTX’s inherently unstable nature makes it difficult to develop a viable oral formulation. In this study we developed the spray-dried amorphous inclusion complexes of MTX with native β-cyclodextrin (β-CD) and its derivatives, namely HP-β-CD, M-β-CD, and DM-β-CD to enhance the aqueous solubility, photostability, permeability, and oral bioavailability of MTX in rats. Our findings show that the 1:1 stoichiometry ratio of MTX and CDs improves the aqueous solubility, stability, and pharmacokinetic profiles of the drug, the better results being obtained particularly with DM-β-CD as a host, which has a higher complexation ability with the drug compared to other β-CDs. Specifically, the pharmacokinetic analysis demonstrated 2.20- and 3.29-fold increments in AUC and Cmax, respectively, in comparison to free MTX. Even though the absorptive permeability of MTX and MTX/DM-β-CD inclusion complexes was similar, the efflux of the absorbed MTX from ICs was significantly lower compared to the free MTX (4.6- vs. 8.0-fold). Furthermore, the physicochemical characterization employing SEM, DSC, and PXRD confirmed the transformation of crystalline MTX to its amorphous state. In solution, ¹H NMR studies revealed that MTX embedded into the DM-β-CD cavity resulting in both H-3 and H-5 chemical shifts implied the presence of intermolecular interaction between the drug and CD moiety. It was, therefore, evident that an MTX IC could be a successful oral formulation technique, preventing MTX degradation and enhancing its pharmacologically relevant properties.

Formulation and In Vitro Characterization of a Vacuum-Dried Drug–Polymer Thin Film for Intranasal Application

Intranasal drug applications show significant therapeutic potential for diverse pharmaceutical modalities. Because the formulation applied to the nasal cavity is discharged to the pharyngeal side by mucociliary clearance, the formulation should be dissolved effectively in a limited amount of mucus within its retention time in the nasal cavity. In this study, to develop novel formulations with improved dissolution behavior and compatibility with the intranasal environment, a thin-film formulation including drug and polymer was prepared using a vacuum-drying method. The poorly water-soluble drugs ketoprofen, flurbiprofen, ibuprofen, and loxoprofen were dissolved in a solvent comprising water and methanol, and evaporated to obtain a thin film. Physical analyses using differential scanning calorimetry (DSC), powder X-ray diffraction analysis (PXRD), and scanning electron microscopy SEM revealed that the formulations were amorphized in the film. The dissolution behavior of the drugs was investigated using an in vitro evaluation system that mimicked the intranasal physiological environment. The amorphization of drugs formulated with polymers into thin films using the vacuum-drying method improved the dissolution rate in artificial nasal fluid. Therefore, the thin film developed in this study can be safely and effectively used for intranasal drug application.

Utilization of Polymeric Micelles as a Lucrative Platform for Efficient Brain Deposition of Olanzapine as an Antischizophrenic Drug via Intranasal Delivery

Schizophrenia is a mental disorder characterized by alterations in cognition, behavior and emotions. Oral olanzapine (OZ) administration is extensively metabolized (~up to 40% of the administrated dose). In addition, OZ is a P-glycoproteins substrate that impairs the blood–brain barrier (BBB) permeability. To direct OZ to the brain and to minimize its systemic side effects, the nasal pathway is recommended. OZ-loaded polymeric micelles nano-carriers were developed using suitable biodegradable excipients. The developed micelles were physicochemically investigated to assess their appropriateness for intranasal delivery and the potential of these carriers for OZ brain targeting. The selected formula will be examined in vivo for improving the anti-schizophrenic effects on a schizophrenia rat model. The binary mixture of P123/P407 has a low CMC (0.001326% w/v), which helps in maintaining the formed micelles’ stability upon dilution. The combination effect of P123, P407 and TPGS led to a decrease in micelle size, ranging between 37.5–47.55 nm and an increase in the EE% (ranging between 68.22–86.84%). The selected OZ–PM shows great stability expressed by a suitable negative charge zeta potential value (−15.11 ± 1.35 mV) and scattered non-aggregated spherical particles with a particle size range of 30–40 nm. OZ–PM maintains sustained drug release at the application site with no nasal cytotoxicity. In vivo administration of the selected OZ–PM formula reveals improved CNS targeting and anti-schizophrenia-related deficits after OZ nasal administration. Therefore, OZ–PM provided safe direct nose-to-brain transport of OZ after nasal administration with an efficient anti-schizophrenic effect.

Versatile Nasal Application of Cyclodextrins: Excipients and/or Actives?

Cyclodextrins (CDs) are oligosaccharides widely used in the pharmaceutical field. In this review, a detailed examination of the literature of the last two decades has been made to understand the role of CDs in nasal drug delivery systems. In nasal formulations, CDs are used as pharmaceutical excipients, as solubilizers and absorption promoters, and as active ingredients due to their several biological activities (antiviral, antiparasitic, anti-atherosclerotic, and neuroprotective). The use of CDs in nasal formulations allowed obtaining versatile drug delivery systems intended for local and systemic effects, as well as for nose-to-brain transport of drugs. In vitro and in vivo models currently employed are suitable to analyze the effects of CDs in nasal formulations. Therefore, CDs are versatile pharmaceutical materials, and due to the continual synthesis of new CDs derivatives, the research on the new nasal applications is an interesting field evolving in the coming years, to which Italian research will still contribute.

Targeting Systems to the Brain Obtained by Merging Prodrugs, Nanoparticles, and Nasal Administration

About 40 years ago the lipidization of hydrophilic drugs was proposed to induce their brain targeting by transforming them into lipophilic prodrugs. Unfortunately, lipidization often transforms a hydrophilic neuroactive agent into an active efflux transporter (AET) substrate, with consequent rejection from the brain after permeation across the blood brain barrier (BBB). Currently, the prodrug approach has greatly evolved in comparison to lipidization. This review describes the evolution of the prodrug approach for brain targeting considering the design of prodrugs as active influx substrates or molecules able to inhibit or elude AETs. Moreover, the prodrug approach appears strategic in optimization of the encapsulation of neuroactive drugs in nanoparticulate systems that can be designed to induce their receptor-mediated transport (RMT) across the BBB by appropriate decorations on their surface. Nasal administration is described as a valuable alternative to obtain the brain targeting of drugs, evidencing that the prodrug approach can allow the optimization of micro or nanoparticulate nasal formulations of neuroactive agents in order to obtain this goal. Furthermore, nasal administration is also proposed for prodrugs characterized by peripheral instability but potentially able to induce their targeting inside cells of the brain.