Long Acting Ionically Paired Embonate Based Nanocrystals of Donepezil for the Treatment of Alzheimer's Disease: a Proof of Concept Study

Development of nanomedicines for the treatment of Alzheimer's disease: Raison d'être, strategies, challenges and regulatory aspects

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of memory. Presently, AD is challenging to treat with current drug therapy as their delivery to the brain is restricted by the presence of the blood-brain barrier. Nanomedicines, due to their size, high surface volume ratio, and ease of tailoring drug release characteristics, showed their potential to treat AD. The nanotechnology-based formulations for brain targeting are expected to enter the market in the near future. So, regulatory frameworks are required to ensure the quality, safety, and effectiveness of the nanomedicines to treat AD. In this review, we discuss different strategies, in-vitro blood-brain permeation models, in-vivo permeation assessment, and regulatory aspects for the development of nanomedicine to treat AD.

Alzheimer's disease current therapies, novel drug delivery systems and future directions for better disease management

Alzheimer's disease (AD), is a neurodegenerative disorder that escalates with time, exerting a significant impact on physical and mental health and leading to death. The prevalence of AD is progressively rising along with its associated economic burden and necessitates effective therapeutic approaches in the near future. This review paper aims to offer an insightful overview of disease pathogenesis, current FDA-approved drugs, and drugs in different clinical phases. It also explores innovative formulations and drug delivery strategies, focusing on nanocarriers and long-acting medications (LAMs) to enhance treatment efficacy and patient adherence. The review also emphasizes preclinical evidence related to nanocarriers and their potential to improve drug bioavailability, pharmacokinetics, and pharmacodynamics parameters, while also highlighting their ability to minimize systemic side effects. By providing a comprehensive analysis, this review furnishes valuable insights into different pathophysiological mechanisms for future drug development. It aims to inform the development of treatment strategies and innovative formulation approaches for delivering existing molecules in Alzheimer's disease, ultimately striving to improve patient compliance.

Nanotechnology-based Drug Delivery for Alzheimer's and Parkinson's Diseases

The delivery of drugs to the brain is quite challenging in the treatment of the central nervous system (CNS) diseases due to the blood-brain barrier and the blood-cerebrospinal fluid barrier. However, significant developments in nanomaterials employed by nanoparticle drug-delivery systems have substantial potential to cross or bypass these barriers leading to enhanced therapeutic efficacies. Advances in nanoplatform, nanosystems based on lipids, polymers and inorganic materials have been extensively studied and applied in treating Alzheimer's and Parkinson's diseases. In this review, various types of brain drug delivery nanocarriers are classified, summarized, and their potential as drug delivery systems in Alzheimer's and Parkinson's diseases is discussed. Finally, challenges facing the clinical translation of nanoparticles from bench to bedside are highlighted.

Factors affecting the preparation of nanocrystals: characterization, surface modifications and toxicity aspects

INTRODUCTION

The fabrication of well-defined nanocrystals in size and form is the focus of much investigation. In this work, we have critically reviewed several recent instances from the literature that shows how the production procedure affects the physicochemical properties of the nanocrystals.

AREAS COVERED

Scopus, MedLine, PubMed, Web of Science, and Google Scholar were searched for peer-review articles published in the past few years using different key words. Authors chose relevant publications from their files for this review. This review focuses on the range of techniques available for producing nanocrystals. We draw attention to several recent instances demonstrating the impact of various process and formulation variables that affect the nanocrystals' physicochemical properties. Moreover, various developments in the characterization techniques explored for nanocrystals concerning their size, morphology, etc. have been discussed. Last but not least, recent applications, the effect of surface modifications, and the toxicological traits of nanocrystals have also been reviewed.

EXPERT OPINION

The selection of an appropriate production method for the formation of nanocrystals, together with a deep understanding of the relationship between the drug's physicochemical properties, unique features of the various formulation alternatives, and anticipated in-vivo performance, would significantly reduce the risk of failure during human clinical trials that are inadequate.

Recent Advancements in Nanomaterials: A Promising Way to Manage Neurodegenerative Disorders

Neurodegenerative diseases (NDs) such as dementia, Alzheimer's disease, Parkinson's disease, frontotemporal dementia, and amyotrophic lateral sclerosis are some of the most prevalent disorders currently afflicting healthcare systems. Many of these diseases share similar pathological hallmarks, including elevated oxidative stress, mitochondrial dysfunction, protein misfolding, excitotoxicity, and neuroinflammation, all of which contribute to the deterioration of the nervous system's structure and function. The development of diagnostic and therapeutic materials in the monitoring and treatment of these diseases remains challenging. One of the biggest challenges facing therapeutic and diagnostic materials is the blood-brain barrier (BBB). The BBB is a multifunctional membrane possessing a plethora of biochemical, cellular, and immunological features that ensure brain homeostasis by preventing the entry and accumulation of unwanted compounds. With regards to neurodegenerative diseases, the recent application of tailored nanomaterials (nanocarriers and nanoparticles) has led to advances in diagnostics and therapeutics. In this review, we provide an overview of commonly used nanoparticles and their applications in NDs, which may offer new therapeutic strategies for the prevention and treatment of neurodegenerative diseases.

Therapeutic Potential of Nanomedicine in Management of Alzheimer's Disease and Glioma

Neoplasm (Glioblastoma) and Alzheimer's disease (AD) comprise two of the most chronic psychological ailments. Glioblastoma is one of the aggressive and prevalent malignant diseases characterized by rapid growth and invasion resulting from cell migration and degradation of extracellular matrix. While the latter is characterized by extracellular plaques of amyloid and intracellular tangles of tau proteins. Both possess a high degree of resistance to treatment owing to the restricted transport of corresponding drugs to the brain protected by the blood-brain barrier (BBB). Development of optimized therapies using advanced technologies is a great need of today. One such approach is the designing of nanoparticles (NPs) to facilitate the drug delivery at the target site. The present article elaborates the advances in nanomedicines in treatment of both AD as well as Gliomas. The intention of this review is to provide an overview of different types of NPs with their physical properties emphasizing their importance in traversing the BBB and hitting the target site. Further, we discuss the therapeutic applications of these NPs along with their specific targets. Multiple overlapping factors with a common pathway in development of AD and Glioblastoma are discussed in details that will assist the readers in developing the conceptual approach to target the NP for an aging population in the given circumstances with limitations of currently designed NPs, and the challenges to meet and the future perspectives.

Comparison of in vivo behaviors of intramuscularly long-acting celecoxib nanosuspensions with different particle sizes for the postoperative pain treatment

Celecoxib (CXB) has a good analgesic effect on postoperative acute pain, but clinically its compliance is compromised because of frequent administration. Therefore, the development of injectable celecoxib nanosuspensions (CXB-NS) for long-acting analgesic effects is highly desirable. However, how the particle size affects the in vivo behaviors of CXB-NS remains unclear. Herein, CXB-NS with different sizes were prepared by the wet-milling method. Following intramuscular (i.m.) injection in rats (50 mg/kg), all CXB-NS achieved sustained systemic exposure and long-acting analgesic effects. More importantly, CXB-NS showed size-dependent pharmacokinetic profiles and analgesic effects, and the smallest CXB-NS (about 0.5 μm) had the highest C_max, T_1/2, and AUC_0-240h and the strongest analgesic effects on incision pain. Therefore, small sizes are preferred for long action by i.m. injection, and the CXB-NS developed in this study were alternative formulations for the treatment of postoperative acute pain.

Facile Technology for Extemporaneous Preparation of Long-Acting Injectable Microparticulate Suspensions at the Patient Side

In this study, we present an innovative and facile in situ approach for extemporaneous preparation of sterile microparticles. An amazingly simple approach, in situ technology circumvents the stability, and scale up challenges as well as sterilization issues associated with long-acting particulate systems. Monophasic preconcentrates of donepezil base (DPZ), a model drug with a biodegradable polymer poly (DL-lactide-co-glycolide) (PLGA), with stabilizer were prepared by simple solution and sterilized by filtration (0.22 micron). The sterile preconcentrates when added to aqueous dextrose solution (total volume < 3 mL) generated ready-to-inject DPZ PLGA microparticles (DPZ-PLGA-MP) with high reproducibility, entrapment efficiency (> 80%), and size ~ 80 micron. DPZ micro suspension (DPZ-MS) with high precipitation efficiency (> 90%) and size ~ 80 micron was obtained in a similar manner omitting PLGA. XRD and DSC study confirmed decreased crystallinity in the presence of PLGA. No interaction between PLGA and DPZ was evident in the FTIR study. The microparticulate dispersions exhibited good in vitro injectability when tested using the texture analyzer (force < 5 N). When evaluated using the dialysis bag method (Himedia 12-14 kDa molecular weight cutoff), both microparticulate formulations exhibited controlled release up to 1 week in vitro. Further, low burst release of ~ 10% at the end of 6 h in the ex vivo chicken muscle study proposes great promise. Our data propose the facile extemporaneous generation of microparticles as a practical and promising approach for development of long-acting injectables. This facile approach could serve as platform technology for other drug candidates.

Benefits and limitations of nanomedicine treatment of brain cancers and age-dependent neurodegenerative disorders

The treatment of central nervous system (CNS) malignancies, including brain cancers, is limited by a number of obstructions, including the blood-brain barrier (BBB), the heterogeneity and high invasiveness of tumors, the inaccessibility of tissues for early diagnosis and effective surgery, and anti-cancer drug resistance. Therapies employing nanomedicine have been shown to facilitate drug penetration across the BBB and maintain biodistribution and accumulation of therapeutic agents at the desired target site. The application of lipid-, polymer-, or metal-based nanocarriers represents an advanced drug delivery system for a growing group of anti-cancer chemicals. The nanocarrier surface is designed to contain an active ligand (cancer cell marker or antibody)-binding structure which can be modified to target specific cancer cells. Glioblastoma, ependymoma, neuroblastoma, medulloblastoma, and primary CNS lymphomas were recently targeted by easily absorbed nanocarriers. The metal- (such as transferrin drug-loaded systems), polymer- (nanocapsules and nanospheres), or lipid- (such as sulfatide-containing nanoliposomes)-based nano-vehicles were loaded with apoptosis- and/or ferroptosis-stimulating agents and demonstrated promising anti-cancer effects. This review aims to discuss effective nanomedicine approaches designed to overcome the current limitations in the therapy of brain cancers and age-dependent neurodegenerative disorders. To accent current obstacles for successful CNS-based cancer therapy, we discuss nanomedicine perspectives and limitations of nanodrug use associated with the specificity of nervous tissue characteristics and the effects nanocarriers have on cognition.

Therapeutic nanotechnologies for Alzheimer's disease: a critical analysis of recent trends and findings

Alzheimer's Disease (AD) is an irreversible neurodegenerative disease for which no disease modifying therapies are presently available. Besides the identification of pathological targets, AD presents numerous clinical and pharmacological challenges such as efficient active delivery to the central nervous system, cell targeting, and long-term dosing. Nanoparticles have been explored to overcome some of these challenges as drug delivery vehicles or drugs themselves. However, early promises have failed to materialize as no nanotechnology-based product has been able to reach the market and very few have moved past preclinical stages. In this review, we perform a critical analysis of the past decade's research on nanomedicine-based therapies for AD at the preclinical and clinical stages. The main obstacles to nanotechnology products and the most promising approaches were also identified, including renewed promise with gene editing, gene modulation, and vaccines.

Drug Nanocrystals: Focus on Brain Delivery from Therapeutic to Diagnostic Applications

The development of new drugs is often hindered by low solubility in water, a problem common to nearly 90% of natural and/or synthetic molecules in the discovery pipeline. Nanocrystalline drug technology involves the reduction in the bulk particle size down to the nanosize range, thus modifying its physico-chemical properties with beneficial effects on drug bioavailability. Nanocrystals (NCs) are carrier-free drug particles surrounded by a stabilizer and suspended in an aqueous medium. Due to high drug loading, NCs maintain a potent therapeutic concentration to produce desirable pharmacological action, particularly useful in the treatment of central nervous system (CNS) diseases. In addition to the therapeutic purpose, NC technology can be applied for diagnostic scope. This review aims to provide an overview of NC application by different administration routes, especially focusing on brain targeting, and with a particular attention to therapeutic and diagnostic fields. NC therapeutic applications are analyzed for the most common CNS pathologies (i.e., Parkinson’s disease, psychosis, Alzheimer’s disease, etc.). Recently, a growing interest has emerged from the use of colloidal fluorescent NCs for brain diagnostics. Therefore, the use of NCs in the imaging of brain vessels and tumor cells is also discussed. Finally, the clinical effectiveness of NCs is leading to an increasing number of FDA-approved products, among which the NCs approved for neurological disorders have increased.

Amalgamated Microneedle Array Bearing Ribociclib-Loaded Transfersomes Eradicates Breast Cancer via CD44 Targeting

HR+/HER2- metastatic breast cancer (MBC) is one of the most common and life-threatening conditions diagnosed in women. The endocrine therapy using an orally active CDK4/6 inhibitor, ribociclib (RB), is the most intriguing approach for treating HR+/HER2- MBC. However, the repeated three to six cycles of multiple dosing and non-targeted distribution of RB led to severe neutropenia; hepatobiliary, gastrointestinal, and renal toxicities, and QT interval prolongation. Here, a novel organic solvent-free HA-PVA-PVP (hyaluronic acid-polyvinyl alcohol-polyvinyl pyrrolidone) composed of a microneedle (MN) array is formulated to deliver RB, integrated with amphiphilic conjugated polymer (HA-GMS)-anchored ultradeformable transfersomes. This unique MN array efficiently crafts microchannels in the skin, allowing HA-RB-Ts to internalize into the tumor cells through lymphatic and systemic absorption and interact with CD44 both spatially and temporally with an amplification of drug release time up to 6-folds. The pharmacokinetic and tissue distribution studies portray drug concentrations within the therapeutic window as long as 48 h, facilitating thrice-a-week frequency with the lower dose, and rule out severe toxicities, with a significant reduction in 8.3-fold RB concentration in vital organs that ultimately enhances the survival rate. Thus, the novel MN system pursues a unique embeddable feature and offers an effective, self-administrable, biodegradable, and chronic treatment option for patients requiring long-term cancer treatments.

Nanotechnology-based drug delivery for central nervous system disorders

Drug delivery to central nervous system (CNS) diseases is very challenging since the presence of the innate blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier that impede drug delivery. Among new strategies to overcome these limitations and successfully deliver drugs to the CNS, nanotechnology-based drug delivery platform, offers potential therapeutic approach for the treatment of some common neurological disorders like Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease. This review aimed to highlight advances in research on the development of nano-based therapeutics for their implications in therapy of CNS disorders. The challenges during clinical translation of nanomedicine from bench to bed side is also discussed.

An Update on the Routes for the Delivery of Donepezil

Dementia is a significant public health problem in the 21st century. Alzheimer's disease (AD) is an essential factor in dementia. Currently, the drugs used for the treatment of AD are mainly acetylcholine inhibitors (AChEIs). As an AChEI, donepezil (DP) can improve patients' cognitive ability with low side effects and has been accepted by most patients and doctors. For AD patients, the dosage regimen is also crucial due to aging and diseases. Although there are DP oral tablets on the market, there are still many problems to be solved. At present, more and more research is conducted to optimize the route of administration of DP to improve the self-administration of patients. The research fields of DP administration include oral administration, injection administration, intranasal administration, and transdermal administration. This Review is to present the development of different DP administrations and evaluates the advantages and limitations of those works, hoping to optimize the DP dosage regimen for AD patients.

Intranasal Insulin Enhances Intracerebroventricular Streptozotocin-Induced Decrease in Olfactory Discriminative Learning via Upregulation of Subventricular Zone-Olfactory Bulb Neurogenesis in the Rat Model

Olfactory perception and learning play a vital role in the animal's entire life for habituation and survival. Insulin and insulin receptor signaling is well known to modulate the olfactory function and is also involved in the regulation of neurogenesis. A very high density of insulin receptors is present in the olfactory bulb (OB), the brain area involved in the olfactory function, where active adult neurogenesis also takes place. Hence, our study was aimed to explore the effect of intranasal insulin treatment and the involvement of the subventricular zone-olfactory bulb (SVZ-OB) neurogenesis on olfactory discriminative learning and memory in intracerebroventricular streptozotocin (ICV STZ) rat model. Our findings revealed that intranasal insulin treatment significantly increased ICV STZ-induced decrease in the olfactory discriminative learning. No significant change was observed in the post-treatment olfactory memory upon ICV STZ and intranasal insulin treatment. ICV STZ also caused a substantial decline in the SVZ-OB neurogenesis, as indicated by the reduction in the number of 5-bromo-2'-deoxyuridine (BrdU+) cells, BrdU+ Nestin+ cells, and Doublecortin (DCX+) cells, which was reversed by intranasal insulin treatment. Intranasal insulin treatment also increased the number of immature neurons reaching the olfactory bulb (OB) as indicated by an increase in the DCX expression in the OB as compared to the ICV STZ administered group. ICV STZ administration also resulted in the modulation of the expression of the genes regulating postnatal SVZ-OB neurogenesis like Mammalian achaete scute homolog 1 (Mash 1), Neurogenin 2 (Ngn 2), Neuronal differentiation 1 (Neuro D1), and T box brain protein 2 (Tbr 2). Intranasal insulin treatment reverted these changes in gene expression, which might be responsible for the observed increase in the SVZ-OB neurogenesis and hence the olfactory discriminative learning.

Hydrophobic ion pairing: encapsulating small molecules, peptides, and proteins into nanocarriers

Hydrophobic ion pairing has emerged as a method to modulate the solubility of charged hydrophilic molecules ranging in class from small molecules to large enzymes. Charged hydrophilic molecules are ionically paired with oppositely-charged molecules that include hydrophobic moieties; the resulting uncharged complex is water-insoluble and will precipitate in aqueous media. Here we review one of the most prominent applications of hydrophobic ion pairing: efficient encapsulation of charged hydrophilic molecules into nano-scale delivery vehicles - nanoparticles or nanocarriers. Hydrophobic complexes are formed and then encapsulated using techniques developed for poorly-water-soluble therapeutics. With this approach, researchers have reported encapsulation efficiencies up to 100% and drug loadings up to 30%. This review covers the fundamentals of hydrophobic ion pairing, including nomenclature, drug eligibility for the technique, commonly-used counterions, and drug release of encapsulated ion paired complexes. We then focus on nanoformulation techniques used in concert with hydrophobic ion pairing and note strengths and weaknesses specific to each. The penultimate section bridges hydrophobic ion pairing with the related fields of polyelectrolyte coacervation and polyelectrolyte-surfactant complexation. We then discuss the state of the art and anticipated future challenges. The review ends with comprehensive tables of reported hydrophobic ion pairing and encapsulation from the literature.

In Depth Analysis of Pressure-Sensitive Adhesive Patch-Assisted Delivery of Memantine and Donepezil Using Physiologically Based Pharmacokinetic Modeling and in Vitro/in Vivo Correlations

The objective of this work was to evaluate the feasibility of transdermal delivery of two widely prescribed dementia drugs for the Alzheimer's disease. In this regard, the drug in adhesive patches of memantine (ME) co-loaded with donepezil (DO) was prepared using an ethylene vinyl acetate polymer and characterized for drug content, the crystallinity of drugs in the polymer matrix, and in vitro permeation. To understand the different physical and chemical processes underlying the percutaneous absorption, it is required to employ a comprehensive model that accounts for the anatomy and physiology of the skin. A transdermal physiologically based pharmacokinetic (TPBPK) model was developed and was integrated in a compartmental pharmacokinetic model to predict the plasma drug concentrations in rats. The model predictions showed a good fit with the experimental data, as evaluated by the prediction error calculated for both drugs. It was evident from the simulations that the drug diffusivity and partition coefficient in the polymer matrix are the critical parameters that affect the drug release from the vehicle and subsequently influence the in vivo pharmacokinetic profile. Moreover, a correlation function was built between the in vitro permeation data and in vivo absorption for both ME and DO. A good point-to-point in vitro/in vivo correlation (IVIVC, Level A correlation) was achieved by predicting the plasma concentrations with convolution for the entire study duration. The results of our study suggested that the implementation of mechanistic modeling along with IVIVC can be a valuable tool to evaluate the relative effects of formulation variables on the bioavailability from transdermal delivery systems.

Multifunctional Glycoconjugate Assisted Nanocrystalline Drug Delivery for Tumor Targeting and Permeabilization of Lysosomal-Mitochondrial Membrane

Nanotechnology has emerged as the most successful strategy for targeting drug payloads to tumors with the potential to overcome the problems of low concentration at the target site, nonspecific distribution, and untoward toxicities. Here, we synthesized a novel polymeric conjugate comprising chondroitin sulfate A and polyethylene glycol using carbodiimide chemistry. We further employed this glycoconjugate possessing the propensity to provide stability, stealth effects, and tumor targeting via CD44 receptors, all in one, to develop a nanocrystalline system of docetaxel (DTX@CSA-NCs) with size < 200 nm, negative zeta potential, and 98% drug content. Taking advantage of the enhanced permeability and retention effect coupled with receptor mediated endocytosis, the DTX@CSA-NCs cross the peripheral tumor barrier and penetrate deeper into the cells of tumor mass. In MDA-MB-231 cells, this enhanced cellular uptake was observed to exhibit a higher degree of cytotoxicity and arrest in the G2 phase in a time dependent fashion. Acting via a mitochondrial-lysosomotropic pathway, DTX@CSA-NCs disrupted the membrane potential and integrity and outperformed the clinically used formulation. Upon intravenous administration, the DTX@CSA-NCs showed better pharmacokinetic profile and excellent 4T1 induced tumor inhibition with significantly less off target toxicity. Thus, this glycoconjugate stabilized nanocrystalline formulation has the potential to take nano-oncology a step forward.