An evaluation of memantine ER + donepezil for the treatment of Alzheimer’s disease

Pro-cognitive effects of dual tacrine derivatives acting as cholinesterase inhibitors and NMDA receptor antagonists

Therapeutic options for Alzheimer's disease are limited. Dual compounds targeting two pathways concurrently may enable enhanced effect. The study focuses on tacrine derivatives inhibiting acetylcholinesterase (AChE) and simultaneously N-methyl-D-aspartate (NMDA) receptors. Compounds with balanced inhibitory potencies for the target proteins (K1578 and K1599) or increased potency for AChE (K1592 and K1594) were studied to identify the most promising pro-cognitive compound. Their effects were studied in cholinergic (scopolamine-induced) and glutamatergic (MK-801-induced) rat models of cognitive deficits in the Morris water maze. Moreover, the impacts on locomotion in the open field and AChE activity in relevant brain structures were investigated. The effect of the most promising compound on NMDA receptors was explored by in vitro electrophysiology. The cholinergic antagonist scopolamine induced a deficit in memory acquisition, however, it was unaffected by the compounds, and a deficit in reversal learning that was alleviated by K1578 and K1599. K1578 and K1599 significantly inhibited AChE in the striatum, potentially explaining the behavioral observations. The glutamatergic antagonist dizocilpine (MK-801) induced a deficit in memory acquisition, which was alleviated by K1599. K1599 also mitigated the MK-801-induced hyperlocomotion in the open field. In vitro patch-clamp corroborated the K1599-associated NMDA receptor inhibitory effect. K1599 emerged as the most promising compound, demonstrating pro-cognitive efficacy in both models, consistent with intended dual effect. We conclude that tacrine has the potential for development of derivatives with dual in vivo effects. Our findings contributed to the elucidation of the structural and functional properties of tacrine derivatives associated with optimal in vivo pro-cognitive efficacy.

Alzheimer's disease and its treatment-yesterday, today, and tomorrow

Alois Alzheimer described the first patient with Alzheimer's disease (AD) in 1907 and today AD is the most frequently diagnosed of dementias. AD is a multi-factorial neurodegenerative disorder with familial, life style and comorbidity influences impacting a global population of more than 47 million with a projected escalation by 2050 to exceed 130 million. In the USA the AD demographic encompasses approximately six million individuals, expected to increase to surpass 13 million by 2050, and the antecedent phase of AD, recognized as mild cognitive impairment (MCI), involves nearly 12 million individuals. The economic outlay for the management of AD and AD-related cognitive decline is estimated at approximately 355 billion USD. In addition, the intensifying prevalence of AD cases in countries with modest to intermediate income countries further enhances the urgency for more therapeutically and cost-effective treatments and for improving the quality of life for patients and their families. This narrative review evaluates the pathophysiological basis of AD with an initial focus on the therapeutic efficacy and limitations of the existing drugs that provide symptomatic relief: acetylcholinesterase inhibitors (AChEI) donepezil, galantamine, rivastigmine, and the N-methyl-D-aspartate receptor (NMDA) receptor allosteric modulator, memantine. The hypothesis that amyloid-β (Aβ) and tau are appropriate targets for drugs and have the potential to halt the progress of AD is critically analyzed with a particular focus on clinical trial data with anti-Aβ monoclonal antibodies (MABs), namely, aducanumab, lecanemab and donanemab. This review challenges the dogma that targeting Aβ will benefit the majority of subjects with AD that the anti-Aβ MABs are unlikely to be the "magic bullet". A comparison of the benefits and disadvantages of the different classes of drugs forms the basis for determining new directions for research and alternative drug targets that are undergoing pre-clinical and clinical assessments. In addition, we discuss and stress the importance of the treatment of the co-morbidities, including hypertension, diabetes, obesity and depression that are known to increase the risk of developing AD.

Evolving therapeutic interventions for the management and treatment of Alzheimer's disease

Alzheimer's Disease (AD) patients experience diverse symptoms, including memory loss, cognitive impairment, behavioral abnormalities, mood changes, and mental issues. The fundamental objective of this review is to discuss novel therapeutic approaches, with special emphasis on recently approved marketed formulations for the treatment of AD, especially Aducanumab, the first FDA approved moiety that surpasses the blood-brain barrier (BBB) and reduces amyloid plaques in the brain, thereby reducing associated cognitive decline. However, it is still in the phase IV trial and is to be completed by 2030. Other drugs such as lecanemab are also under clinical trial and has recently been approved by the FDA and is also discussed here. In this review, we also focus on active and passive immunotherapy for AD as well as several vaccines, such as amyloid-beta epitope-based vaccines, amyloid-beta DNA vaccines, and stem cell therapy for AD, which are in clinical trials. Furthermore, ongoing pre-clinical trials associated with AD and other novel strategies such as curcumin-loaded nanoparticles, Crispr/ cas9, precision medicine, as well as some emerging therapies like anti-sense therapy are also highlighted. Additionally, we discuss some off-labeled drugs like non-steroidal anti-inflammatory drugs (NSAID), anti-diabetic drugs, and lithium, which can manage symptoms of AD and different non-pharmacological approaches are also covered which can help to manage AD. In summary, we have tried to cover all the therapeutic interventions which are available for the treatment and management of AD under sections approved, clinical phase, pre-clinical phase or futuristic interventions, off-labelled drugs, and non-pharmacological interventions for AD, offering positive findings and well as challenges that remain.

Evaluation of binding mechanism of dietary phytochemical, capsaicin, with human transferrin: targeting neurodegenerative diseases therapeutics

Human transferrin (htf) plays a crucial role in regulating the balance of iron within brain cells; any disruption directly contributes to the development of Neurodegenerative Diseases (NDs) and other related pathologies, especially Alzheimer's Disease (AD). In recent times, a transition towards natural compounds is evident to treat diseases and this shift is mainly attributed to their broad therapeutic potential along with minimal side effects. Capsaicin, a natural compound abundantly found in red and chili peppers, possess neuroprotective potential. The current work targets to decipher the interaction mechanism of capsaicin with htf using experimental and computational approaches. Molecular docking analysis revealed that capsaicin occupies the iron binding pocket of htf, with good binding affinity. Further, the binding mechanism was investigated atomistically using Molecular dynamic (MD) simulation approach. The results revealed no significant alterations in the structure of htf implying the stability of the complex. In silico observations were validated by fluorescence binding assay. Capsaicin binds to htf with a binding constant (K) of 3.99 × 106 M-1, implying the stability of the htf-capsaicin complex. This study lays a platform for potential applications of capsaicin in treatment of NDs in terms of iron homeostasis.

Neuroprotective effect of chrysophanol in Alzheimer disease via modulating the Ca2+/EGFR-PLCγ pathway

Chrysophanol (CHR) is an anthraquinone compound found in rhubarb, and it possesses neuroprotective properties. The purpose of this study was to gain a better understanding of its role in Alzheimer's disease (AD). In vivo study, D-galactose combined with intracerebral injection of β-protein 25-35(Aβ25-35) were used to establish AD model rats. In vitro study, Aβ25-35 was used to induce AD model cells. Our results indicated that CHR improves learning and memory in AD model rats and provides protection against neuronal damage in both AD model rats and cells. Additionally, we observed that CHR suppressed the protein expression of p-tau, EGFR, PLCγ, IP3R, and CAM, as well as the mRNA levels of tau, EGFR, PLCγ, IP3R, and CAM. Furthermore, we have confirmed that CHR inhibited the fluorescence expression of calcium ions (Ca2+). In conclusion, the CHR may exert neuroprotective effects in AD by reducing tau phosphorylation through the Ca2+/EGFR-PLCγ pathway.

The role of N-methyl-D-aspartate glutamate receptors in Alzheimer's disease: From pathophysiology to therapeutic approaches

N-Methyl-D-aspartate glutamate receptors (NMDARs) are involved in multiple physiopathological processes, including synaptic plasticity, neuronal network activities, excitotoxic events, and cognitive impairment. Abnormalities in NMDARs can initiate a cascade of pathological events, notably in Alzheimer's disease (AD) and even other neuropsychiatric disorders. The subunit composition of NMDARs is plastic, giving rise to a diverse array of receptor subtypes. While they are primarily found in neurons, NMDAR complexes, comprising both traditional and atypical subunits, are also present in non-neuronal cells, influencing the functions of various peripheral tissues. Furthermore, protein-protein interactions within NMDAR complexes has been linked with Aβ accumulation, tau phosphorylation, neuroinflammation, and mitochondrial dysfunction, all of which potentially served as an obligatory relay of cognitive impairment. Nonetheless, the precise mechanistic link remains to be fully elucidated. In this review, we provided an in-depth analysis of the structure and function of NMDAR, investigated their interactions with various pathogenic proteins, discussed the current landscape of NMDAR-based therapeutics, and highlighted the remaining challenges during drug development.

Investigating molecular interactions between human transferrin and resveratrol through a unified experimental and computational approach: Role of natural compounds in Alzheimer's disease therapeutics

Disruptions to iron metabolism and iron homeostasis have emerged as significant contributors to the development and progression of Alzheimer's disease (AD). Human transferrin plays a key part in maintaining iron equilibrium throughout the body, highlighting its importance in AD. Many plant-derived compounds and dietary constituents show promise for preventing AD. Polyphenols that are abundant in fruits, vegetables, teas, coffee, and herbs possess neuroprotective attributes. Resveratrol is a natural polyphenol present in various plant sources like grapes, berries, peanuts, and red wine that has garnered research interest due to its wide range of biological activities. Notably, resveratrol exhibits neuroprotective effects that may help prevent or treat AD through multiple mechanisms. In the present study, we employed a combination of molecular docking and all-atom molecular dynamic simulations (MD) along with experimental approaches to unravel the intricate interactions between transferrin and resveratrol deciphering the binding mechanism. Through molecular docking analysis, it was determined that resveratrol occupies the iron binding pocket of transferrin. Furthermore, MD simulations provided a more profound insight into the stability and conformational dynamics of the complex suggesting that the binding of resveratrol introduced localized flexibility, while maintaining overall stability. The spectroscopic observations yielded clear evidence of substantial binding between resveratrol and transferrin, confirming the computational findings. The identified binding mechanism and conformational stability hold potential for advancing the development of innovative therapeutic approaches targeting AD through resveratrol, particularly concerning iron homeostasis. These insights serve as a platform for considering the natural compounds in the realm of AD therapeutics.

Advances in the Study of the Pathology and Treatment of Alzheimer's Disease and Its Association with Periodontitis

Alzheimer's disease (AD) has become one of the leading causes of health problems in the elderly, and studying its causes and treatments remains a serious challenge for researchers worldwide. The two main pathological features of Alzheimer's disease are the extracellular deposition of β-amyloid (Aβ) to form senile plaques and the intracellular aggregation of hyperphosphorylated Tau protein to form neurofibrillary tangles (NFTs). Researchers have proposed several hypotheses to elucidate the pathogenesis of AD, but due to the complexity of the pathophysiologic factors involved in the development of AD, no effective drugs have been found to stop the progression of the disease. Currently, the mainstay drugs used to treat AD can only alleviate the patient's symptoms and do not have a therapeutic effect. As researchers explore interactions among diseases, much evidence suggests that there is a close link between periodontitis and AD, and that periodontal pathogenic bacteria can exacerbate Aβ deposition and Tau protein hyperphosphorylation through neuroinflammatory mechanisms, thereby advancing the pathogenesis of AD. This article reviews recent advances in the pathogenesis of AD, available therapeutic agents, the relevance of periodontitis to AD, and mechanisms of action.

Basic information about memantine and its treatment of Alzheimer's disease and other clinical applications

Memantine is a noncompetitive moderate-affinity strong voltage-dependent N-methyl-D-aspartate receptor antagonist. It has been used to treat Alzheimer's disease (AD) since 1989. In 2018, it became the second most commonly used drug for the treatment of dementia in the world. AD is nonreversible, and memantine can only relieve the symptoms of AD but not cure it. Over the past half-century, memantine's research and clinical application have been extensively developed. In this review, the basic composition of memantine, the mechanism and limitations of memantine in the treatment of AD, memantine combination therapy, comparison of memantine with other drugs for AD, and clinical studies of memantine in other diseases are reviewed to provide a valuable reference for further research and application of memantine for the treatment of AD.

Microbiota-gut-brain axis and related therapeutics in Alzheimer's disease: prospects for multitherapy and inflammation control

Alzheimer's disease (AD) is the most common type of dementia in the elderly and causes neurodegeneration, leading to memory loss, behavioral disorder, and psychiatric impairment. One potential mechanism contributing to the pathogenesis of AD may be the imbalance in gut microbiota, local and systemic inflammation, and dysregulation of the microbiota-gut-brain axis (MGBA). Most of the AD drugs approved for clinical use today are symptomatic treatments that do not improve AD pathologic changes. As a result, researchers are exploring novel therapeutic modalities. Treatments involving the MGBA include antibiotics, probiotics, transplantation of fecal microbiota, botanical products, and others. However, single-treatment modalities are not as effective as expected, and a combination therapy is gaining momentum. The purpose of this review is to summarize recent advances in MGBA-related pathological mechanisms and treatment modalities in AD and to propose a new concept of combination therapy. "MGBA-based multitherapy" is an emerging view of treatment in which classic symptomatic treatments and MGBA-based therapeutic modalities are used in combination. Donepezil and memantine are two commonly used drugs in AD treatment. On the basis of the single/combined use of these two drugs, two/more additional drugs and treatment modalities that target the MGBA are chosen based on the characteristics of the patient's condition as an adjuvant treatment, as well as the maintenance of good lifestyle habits. "MGBA-based multitherapy" offers new insights for the treatment of cognitive impairment in AD patients and is expected to show good therapeutic results.

Photobiomodulation in Alzheimer's Disease-A Complementary Method to State-of-the-Art Pharmaceutical Formulations and Nanomedicine?

Alzheimer's disease (AD), as a neurodegenerative disorder, usually develops slowly but gradually worsens. It accounts for approximately 70% of dementia cases worldwide, and is recognized by WHO as a public health priority. Being a multifactorial disease, the origins of AD are not satisfactorily understood. Despite huge medical expenditures and attempts to discover new pharmaceuticals or nanomedicines in recent years, there is no cure for AD and not many successful treatments are available. The current review supports introspection on the latest scientific results from the specialized literature regarding the molecular and cellular mechanisms of brain photobiomodulation, as a complementary method with implications in AD. State-of-the-art pharmaceutical formulations, development of new nanoscale materials, bionanoformulations in current applications and perspectives in AD are highlighted. Another goal of this review was to discover and to speed transition to completely new paradigms for the multi-target management of AD, to facilitate brain remodeling through new therapeutic models and high-tech medical applications with light or lasers in the integrative nanomedicine of the future. In conclusion, new insights from this interdisciplinary approach, including the latest results from photobiomodulation (PBM) applied in human clinical trials, combined with the latest nanoscale drug delivery systems to easily overcome protective brain barriers, could open new avenues to rejuvenate our central nervous system, the most fascinating and complex organ. Picosecond transcranial laser stimulation could be successfully used to cross the blood-brain barrier together with the latest nanotechnologies, nanomedicines and drug delivery systems in AD therapy. Original, smart and targeted multifunctional solutions and new nanodrugs may soon be developed to treat AD.

Brain-neuron targeted nanoparticles for peptide synergy therapy at dual-target of Alzheimer's disease

Since the complex interactions of multiple mechanisms involved in Alzheimer's disease (AD) preclude the monotherapeutic approaches from clinical application, combination therapy has become an attractive strategy for AD treatment. However, to be emphasized, the realization of the edges of combination therapy greatly depends on the reasonable choice of targets and the rational design of combination scheme. Acknowledgedly, amyloid plaques and hyperphosphorylated tau (p-tau) are two main hallmarks in AD with close pathological correlations, implying the hopeful prospect of combined intervention in them for AD treatment. Herein, we developed the nano-combination system, neuron-targeting PEG-PLA nanoparticles (CT-NP) loading two peptide drugs H102, a β-sheet breaker acting on Aβ, and NAP, a microtubule stabilizer acting on p-tau. Compared with free peptide combination, nano-combination system partly aligned the in vivo behaviors of combined peptides and enhanced peptide accumulation in lesion neurons by the guidance of targeting peptide CGN and Tet1, facilitating the therapeutic performance of peptide combination. Further, to maximize the therapeutic potential of nano-combination system, the combination ratio and mode were screened by the quantitative evaluation with combination index and U test, respectively, in vitro and in vivo. The results showed that the separated-loading CT-NP at the combination molar ratio of 2:1 (H102:NAP), CT-NP/H102 + CT-NP/NAP(2:1), generated the strongest synergistic therapeutic effects on Aβ, p-tau and their linkage, and effectually prevented neuroinflammation, reversed the neuronal damage and restored cognitive performance in 3 × Tg-AD transgenic mice. Our studies provide critical data on the effectiveness of nano-combination therapy simultaneously intervening in Aβ and p-tau, confirming the promising application of nano-combination strategy in AD treatment.

[Russian experience in using a combination of fixed doses of donepezil and memantine in the treatment of Alzheimer's disease as an observational non-interventional multicenter program]

OBJECTIVE

To evaluate the efficacy, safety, and compliance to therapy with Mioreol, first used as part of routine clinical practice in patients with moderate-to-severe dementia due to AD.

MATERIAL AND METHODS

The study was conducted as a non-interventional observational program. The work was performed on a group of 48 patients with moderate-to-severe AD aged from 60 to 90 years (median age 74 [69; 77]). The therapeutic dose of Mioreol was 10 mg donepezil + 20 mg memantine, the drug was taken orally, once a day at the same time, regardless of meals. The duration of the course of therapy was 24 weeks. The effects of the drug were assessed using the MMSE, ADAS-Cog, NPI, and CGI scales before the start of therapy and by the end of 12 and 24 weeks of treatment.

RESULTS

The use of Mioreol in six-month therapy of AD patients with moderate-to-severe dementia improved not only cognitive but also a wide range of non-cognitive mental disorders. There was an improvement in the CGI-C scale in more than 50% of included patients, positive dynamics on the ADAS-cog scale (6.5 points reduction in total score) and reduction of non-cognitive mental disorders on the NPI scale (4 points reduction in total score).

CONCLUSION

Fixed-dose combination therapy with Mioreol is an effective and well-tolerated treatment option for patients with moderate-to-severe AD. A combination of fixed-dose therapeutic doses of donepezil and memantine is potentially more appropriate than the simultaneous use of two recommended drugs for the treatment of AD, which will improve treatment adherence in patients with moderate to severe AD.

Molecular mechanisms of Alzheimer's disease: From therapeutic targets to promising drugs

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment so widespread that it interferes with a person's ability to complete daily activities. AD is becoming increasingly common, and it is estimated that the number of patients will reach 152 million by 2050. Current treatment options for AD are symptomatic and have modest benefits. Therefore, considering the human, social, and economic burden of the disease, the development of drugs with the potential to alter disease progression has become a global priority. In this review, the molecular mechanisms involved in the pathology of AD were evaluated as therapeutic targets. The main aim of the review is to focus on new knowledge about mitochondrial dysfunction, oxidative stress, and neuronal transmission in AD, as well as a range of cellular signaling mechanisms and associated treatments. Important molecular interactions leading to AD were described in amyloid cascade and in tau protein function, oxidative stress, mitochondrial dysfunction, cholinergic and glutamatergic neurotransmission, cAMP-regulatory element-binding protein (CREB), the silent mating type information regulation 2 homolog 1 (SIRT-1), neuroinflammation (glial cells), and synaptic alterations. This review summarizes recent experimental and clinical research in AD pathology and analyzes the potential of therapeutic applications based on molecular disease mechanisms.

Pharmacological Management of Dysphagia in Patients with Alzheimer's Disease: A Narrative Review

Alzheimer's disease (AD) and dysphagia are important health and socioeconomic problems in the aging population. Currently, the medical treatment of dysphagia in AD patients remains insufficient, and there are significant gaps in the management and clinical needs to postpone tube feeding. Literatures published over the last 30 years were searched in the PubMed and Embase databases. All relevant and promising pharmacological management studies were included. Because of the heterogeneity in design and methodology, only narrative reports were mentioned. Nine studies were included with two case reports, two case series, and two observational and three randomized controlled trials. The key approaches and clinical problems related to dysphagia include onset pattern, dementia stage, review of offending drugs and polypharmacy, and comorbidities (cerebrovascular disease, hypertension, parkinsonism, depression, and anorexia). The corresponding strategies of pharmacological treatments are further proposed and discussed comprehensively, with transient receptor potential channel modulators as promising treatment. With the integration of adequate and potential pharmacomanagement, AD patients with dysphagia can achieve a good prognosis and postpone tube feeding to maintain a better quality of life. More rigorous studies are needed to verify the effectiveness of innovative strategies and develop targets for neurostimulation.

Differences in treatment for Alzheimer's disease between urban and rural areas in China

Introduction

In China, the increasing number of people with Alzheimer's disease (AD) poses a great challenge to families and the country. Economic and cultural differences cause a urban-rural gap in medical resources. This multicenter survey aimed to investigate the real-world practice of disease treatment among people with AD.

Methods

People with AD and their caregivers from 30 provincial regions in mainland China were enrolled from October 2020 to December 2020 to be surveyed for their treatment experience. Logistic regression was used to explore the factors that influence medication adherence in all areas, urban areas, and rural areas.

Results

In this survey, 1,427 participants came from urban areas, and 539 participants came from rural areas. Patients in urban areas were older (mean age 74 vs. 70, p = 0.001), less frequently had mild AD (36.0 vs. 52.1%, p < 0.001), and more often were cared for at professional institutions (8.8 vs. 3.2%, p < 0.001). In terms of pharmacotherapy, 77.8% of people accepted taking lifelong medication, whereas 61.3% of patients insisted on taking medications. Although 72.0% of rural people believed in taking lifelong medication, only 30.0% adhered to drug use. The major factors that influenced medication adherence for all patients with AD were regional distribution (p < 0.001, OR = 6.18, 95% CI: 4.93–7.74) and family earnings (p = 0.003, OR = 1.22, 95% CI: 1.07–1.38). In rural areas, family earnings (p = 0.008, OR = 1.44, 95% CI: 1.10–1.89) and severity of AD (p = 0.033, OR = 1.31, 95% CI: 1.02–1.68) were the main factors. Family earnings (p = 0.038, OR = 1.16, 95% CI: 1.01–1.34) was the only factor among urban areas. Among all non-pharmaceutical activities except for cognitive intervention, the participation rates of rural patients were significantly higher than those of urban patients (p < 0.05).

Conclusion

Although national progress has been made in the public awareness of disease treatment, adequate diagnosis and medication adherence need to be prompted, especially in rural areas. Furthermore, lifelong treatment should be improved based on regional characteristics through the joint efforts of the government, health workers, and social volunteers.

Efficacy and safety of 3-n-butylphthalide for the treatment of cognitive impairment: A systematic review and meta-analysis

Background

Current evidence for the efficacy of pharmacological treatment in improving cognitive function is absent. Recent studies have reported that 3‐n‐butylphthalide (NBP) has a positive effect on improving cognitive impairment; however, its clinical efficacy and safety is unclear. Therefore, we conducted a meta‐analysis to assess its efficacy and safety for cognitive impairment.

Methods

We systematically searched the PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus databases, and two reviewers independently screened and extracted the data from included studies. We synthesized the data using the Review Manager Software version 5.3.

Results

We included six randomized clinical trials (RCTs), encompassing 851 patients with cognitive impairment. The results showed that NBP improved cognitive impairment. Specifically, the clinical efficacy was better than that in the control group, with better performance in improving the Mini‐Mental State Examination and the Montreal Cognitive Assessment scores, while decreasing the Alzheimer's Disease Assessment Scale‐Cognitive subscale and the Clinician's Interview‐Based Impression of Change plus caregiver input scores. There was no significant difference in the incidence of adverse events between both groups.

Conclusion

The NBP is effective and safe in improving cognitive impairment; however, more high‐quality RCTs are needed to confirm these findings.

Therapeutic Approach to Alzheimer’s Disease: Current Treatments and New Perspectives

Alzheimer’s disease (AD) is the most common cause of dementia. The pathophysiology of this disease is characterized by the accumulation of amyloid-β, leading to the formation of senile plaques, and by the intracellular presence of neurofibrillary tangles based on hyperphosphorylated tau protein. In the therapeutic approach to AD, we can identify three important fronts: the approved drugs currently available for the treatment of the disease, which include aducanumab, donepezil, galantamine, rivastigmine, memantine, and a combination of memantine and donepezil; therapies under investigation that work mainly on Aβ pathology and tau pathology, and which include γ-secretase inhibitors, β-secretase inhibitors, α-secretase modulators, aggregation inhibitors, metal interfering drugs, drugs that enhance Aβ clearance, inhibitors of tau protein hyperphosphorylation, tau protein aggregation inhibitors, and drugs that promote the clearance of tau, and finally, other alternative therapies designed to improve lifestyle, thus contributing to the prevention of the disease. Therefore, the aim of this review was to analyze and describe current treatments and possible future alternatives in the therapeutic approach to AD.

[Comparative clinical study of the pharmacokinetics and bioequivalence of the combined drug Mioreol and the combined use of mono-drugs containing donepezil and memantine]

OBJECTIVE

The study of bioequivalence and safety of the fixed combination of the drug Mioreol (Donepezil + Memantine, 10 mg + 20 mg) in relation to the combined use of Yasnal 10 mg and Akatinol Memantin 20 mg.

MATERIAL AND METHODS

The safety analysis study included 36 male (n=8) and female (n=10) subjects, sexes (age 26.3±7.1 years, body mass index (BMI) 23.0±2.8 kg/m²). In the study for the analysis of pharmacokinetics - 31 male (n=8) and female (n=10) persons (age 26.5±7.9 years, BMI 23.5±3.1 kg/m²). The method used high performance liquid chromatography with tandem mass spectrometric detection. Pharmacokinetic analysis was carried out using Phoenix WinNonlin software («CERTARA», Pharsight, USA) v. 8.2. Statistical analysis of the obtained data was performed based on the assumption of a lognormal distribution of parameters AUC_0-72 and C_max.

RESULTS

Geometric mean ratio for key pharmacokinetic parameters (AUC_0-t, AUC_0-####sub/sub#### and C_max) donepezil and memantine are close to 100% and 90%, measuring ranges are within acceptable limits for bioequivalent drugs range (80-125%) for both active ingredients. Within-subject variability (CVintra) for donepezil was 9.34% (C_max), 6.12% (AUC_0-t), and for memantine - 8.13% (C_max), 6.67% (AUC_0-t).

The average profiles of the pharmacokinetic curves of donepezil and memantine when taking the test drug and the combination of comparator drugs have similar forms. Fixed combination Mioreol (Donepezil + Memantine, drug, 10 mg + 20 mg) and Yasnal preparations 10 mg (Krka JSC, d.d., Novo Mesto) and Akatinol Memantine 20 mg («Merz Pharma GmbH and Co. KGaA», Germany) when taken together are bioequivalent.

CONCLUSION

The results of the study allow us to recommend Mioreol for further clinical study and wide practical application.

Memantine-Derived Schiff Bases as Transdermal Prodrug Candidates

Condensation reactions of salicylaldehyde, 2-pyridinecarboxaldehyde, and pyridoxaldehyde with memantine (Me) produced novel memantine-derived Schiff bases (1-3). Speciation predictions and calculations of Log P, Log D, and of the percentage (%) of neutral species for (1-3) were carried out. In comparison with Me, the Schiff bases presented increased log P and log D in all cases and pH values, suggesting higher hydrophobicity. The determined solubilities in n-octanol were 34.7 mg/mL for memantine hydrochloride and 67.3 mg/mL for (3). According to the molecular weights and calculated logP, compounds (1-3) are suitable for transdermal administration, especially compound (3). In addition, hydrolysis of 3 with the release of pyridoxal, a daily cofactor in human metabolism, was observed. The results suggested that 3 is the most promising compound and that formation of the pyridoxal Schiff base with Me might be an effective strategy to obtain a prodrug candidate with increased lipophilicity, which would be able to passively cross biological barriers during transdermal delivery and might have applications in the treatment of Alzheimer's disease and other neurological disorders.

Breaker peptides against amyloid-β aggregation: a potential therapeutic strategy for Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, for which blocking the early steps of extracellular misfolded amyloid-β (Aβ) aggregation is a promising therapeutic approach. However, the pathological features of AD progression include the accumulation of intracellular tau protein, membrane-catalyzed cell death and the abnormal deposition of Aβ. Here, we focus on anti-amyloid breaker peptides derived from the Aβ sequence and non-Aβ-based peptides containing both natural and modified amino acids. Critical aspects of the breaker peptides include N-methylation, conformational restriction through cyclization, incorporation of unnatural amino acid, fluorinated molecules, polymeric nanoparticles and PEGylation. This review confers a general idea of such breaker peptides with in vitro and in vivo studies, which may advance our understanding of AD pathology and develop an effective treatment strategy against AD.

Industry Payments to Physicians and Prescribing Branded Memantine and Donepezil Combination

Background

Once-daily extended-released memantine with donepezil (hereafter memantine/donepezil) may improve medication adherence but has a 60-fold higher cost compared with combined generic components. Little is known about factors associated with prescribing memantine/donepezil. We examined the association between pharmaceutical industry payments to physicians and prescribing memantine/donepezil in Medicare.

Methods

A cross-sectional study was conducted. Using 2015-2016 Centers for Medicare and Medicaid Services Open Payments and Part D prescription databases, we identified unique physicians who prescribed ≥11 memantine/donepezil prescriptions from 2015 to 2016. Outcome variable was the number of memantine/donepezil prescriptions written per physician per year. The key independent variable was physician receipt of industry payments defined in 2 models: (1) number of payments and (2) amount of payment ($100 units) for memantine/donepezil received per physician per year. Multivariable Poisson regression was used, adjusting for potential confounders.

Results

Among 4,895 unique eligible physicians in 2015-2016, the median number of memantine/donepezil prescriptions per physician per year was 19.5 (25th percentile 13, 75th percentile 32). Physicians received between 0 and 75 payments per year (median 1, 25th percentile 0, 75th percentile 2.5) for memantine/donepezil, totaling an average of $92 per year (median $10.5, 25th percentile $0, 75th percentile $33.20). Every 1 additional payment received was associated with a 2% increase in new memantine/donepezil prescriptions prescribed per physician per year (rate ratio [RR] 1.02, 95% confidence interval [CI] 1.02-1.02). Every $100 increase in payment for memantine/donepezil was associated with a 0.3% increase in new memantine/donepezil prescriptions prescribed per physician per pear (RR 1.003, 95% CI 1.002-1.004).

Conclusions

Receipt of industry payments for memantine/donepezil was independently associated with increased likelihood of physician prescribing memantine/donepezil in Medicare.

New approaches for developing multi-targeted drug combinations for disease modification of complex brain disorders. Does epilepsy prevention become a realistic goal?

Over decades, the prevailing standard in drug discovery was the concept of designing highly selective compounds that act on individual drug targets. However, more recently, multi-target and combinatorial drug therapies have become an important treatment modality in complex diseases, including neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The development of such network-based approaches is facilitated by the significant advance in our understanding of the pathophysiological processes in these and other complex brain diseases and the adoption of modern computational approaches in drug discovery and repurposing. However, although drug combination therapy has become an effective means for the symptomatic treatment of many complex diseases, the holy grail of identifying clinically effective disease-modifying treatments for neurodegenerative and other brain diseases remains elusive. Thus, despite extensive research, there remains an urgent need for novel treatments that will modify the progression of the disease or prevent its development in patients at risk. Here we discuss recent approaches with a focus on multi-targeted drug combinations for prevention or modification of epilepsy. Over the last ~10 years, several novel promising multi-targeted therapeutic approaches have been identified in animal models. We envision that synergistic combinations of repurposed drugs as presented in this review will be demonstrated to prevent epilepsy in patients at risk within the next 5-10 years.

Structure-activity relationships of dually-acting acetylcholinesterase inhibitors derived from tacrine on N-methyl-d-Aspartate receptors

Tacrine is a classic drug whose efficacy against neurodegenerative diseases is still shrouded in mystery. It seems that besides its inhibitory effect on cholinesterases, the clinical benefit is co-determined by NMDAR-antagonizing activity. Our previous data showed that the direct inhibitory effect of tacrine, as well as its 7-methoxy derivative (7-MEOTA), is ensured via a "foot-in-the-door" open-channel blockage, and that interestingly both tacrine and 7-MEOTA are slightly more potent at the GluN1/GluN2A receptors when compared with the GluN1/GluN2B receptors. Here, we report that in a series of 30 novel tacrine derivatives, designed for assessment of structure-activity relationship, blocking efficacy differs among different compounds and receptors using electrophysiology with HEK293 cells expressing the defined types of NMDARs. Selected compounds (4 and 5) potently inhibited both GluN1/GluN2A and GluN1/GluN2B receptors; other compounds (7 and 23) more effectively inhibited the GluN1/GluN2B receptors; or the GluN1/GluN2A receptors (21 and 28). QSAR study revealed statistically significant model for the data obtained for inhibition of GluN1/Glu2B at -60 mV expressed as IC₅₀ values, and for relative inhibition of GluN1/Glu2A at +40 mV caused by a concentration of 100 μM. The models can be utilized for a ligand-based virtual screening to detect potential candidates for inhibition of GluN1/Glu2A and/or GluN1/Glu2B subtypes. Using in vivo experiments in rats we observed that unlike MK-801, the tested novel compounds did not induce hyperlocomotion in open field, and also did not impair prepulse inhibition of startle response, suggesting minimal induction of psychotomimetic side effects. We conclude that tacrine derivatives are promising compounds since they are centrally available subtype-specific inhibitors of the NMDARs without detrimental behavioral side-effects.

Pursuing the Complexity of Alzheimer's Disease: Discovery of Fluoren-9-Amines as Selective Butyrylcholinesterase Inhibitors and N-Methyl-d-Aspartate Receptor Antagonists

Alzheimer’s disease (AD) is a complex disorder with unknown etiology. Currently, only symptomatic therapy of AD is available, comprising cholinesterase inhibitors and N-methyl-d-aspartate (NMDA) receptor antagonists. Drugs targeting only one pathological condition have generated only limited efficacy. Thus, combining two or more therapeutic interventions into one molecule is believed to provide higher benefit for the treatment of AD. In the presented study, we designed, synthesized, and biologically evaluated 15 novel fluoren-9-amine derivatives. The in silico prediction suggested both the oral availability and permeation through the blood–brain barrier (BBB). An initial assessment of the biological profile included determination of the cholinesterase inhibition and NMDA receptor antagonism at the GluN1/GluN2A and GluN1/GluN2B subunits, along with a low cytotoxicity profile in the CHO-K1 cell line. Interestingly, compounds revealed a selective butyrylcholinesterase (BChE) inhibition pattern with antagonistic activity on the NMDARs. Their interaction with butyrylcholinesterase was elucidated by studying enzyme kinetics for compound 3c in tandem with the in silico docking simulation. The docking study showed the interaction of the tricyclic core of new derivatives with Trp82 within the anionic site of the enzyme in a similar way as the template drug tacrine. From the kinetic analysis, it is apparent that 3c is a competitive inhibitor of BChE.

Danger-Sensing/Patten Recognition Receptors and Neuroinflammation in Alzheimer's Disease

Fibrillar aggregates and soluble oligomers of both Amyloid-β peptides (Aβs) and hyperphosphorylated Tau proteins (p-Tau-es), as well as a chronic neuroinflammation are the main drivers causing progressive neuronal losses and dementia in Alzheimer’s disease (AD). However, the underlying pathogenetic mechanisms are still much disputed. Several endogenous neurotoxic ligands, including Aβs, and/or p-Tau-es activate innate immunity-related danger-sensing/pattern recognition receptors (PPRs) thereby advancing AD’s neuroinflammation and progression. The major PRR families involved include scavenger, Toll-like, NOD-like, AIM2-like, RIG-like, and CLEC-2 receptors, plus the calcium-sensing receptor (CaSR). This quite intricate picture stresses the need to identify the pathogenetically topmost Aβ-activated PRR, whose signaling would trigger AD’s three main drivers and their intra-brain spread. In theory, the candidate might belong to any PRR family. However, results of preclinical studies using in vitro nontumorigenic human cortical neurons and astrocytes and in vivo AD-model animals have started converging on the CaSR as the pathogenetically upmost PRR candidate. In fact, the CaSR binds both Ca²⁺ and Aβs and promotes the spread of both Ca²⁺ dyshomeostasis and AD’s three main drivers, causing a progressive neurons’ death. Since CaSR’s negative allosteric modulators block all these effects, CaSR’s candidacy for topmost pathogenetic PRR has assumed a growing therapeutic potential worth clinical testing.

Evaluation of rivastigmine in Alzheimer's disease

Dementia is the major cause of mortality and morbidity in older adults, with Alzheimer's disease (AD) being the most common cause. AD has a significant impact on economic and psychosocial status. Cholinesterase inhibitors (ChEIs) are currently the mainstay in the management of AD. Rivastigmine is the only ChEI that inhibits both acetylcholinesterase and butyrylcholinesterase enzymes in the brain. This dual inhibition makes it potentially more effective for AD patients. Its availability as both a transdermal formulation and oral capsule, may improve adherence rates and care giver satisfaction compared with other ChEIs. To date, the data from randomized clinical trials and post marketing observational studies have shown evidence for an impact on cognitive functions in AD with good safety and tolerability.

Memantine, Donepezil, or Combination Therapy-What is the best therapy for Alzheimer's Disease? A Network Meta-Analysis

INTRODUCTION

Alzheimer's disease (AD) is a degenerative brain disease that progresses over time, heavily burdening patients, families, and aging societies worldwide. Memantine and donepezil are frequently used in its treatment, both as monotherapy and in combination. This multiple treatment comparison meta-analysis assessed the efficacy of these regimens and placebo in the management of AD.

METHODS

We searched PubMed, Embase, the Cochrane Library, and Wanfang Med Online and China National Knowledge Infrastructure for English and Chinese publications from the first records to 17 April 2020. Two investigators scanned articles for placebo-controlled trials of memantine and donepezil alone and in combination. We extracted data on the following outcomes: cognition, global assessment, daily activities, neuropsychiatric symptoms, adverse events, and the acceptability and cost of these treatment regimens.

RESULTS

Of 936 records screened, we included 54 trials in this analysis. The combination therapy was more effective in improving cognition (mean difference (MD)-5.01, 95% credible interval (95% Crl) -10.73 to 0.86 in the Alzheimer's Disease Assessment Scale-Cognitive Subscale; MD 9.61, 95% Crl 2.29 to 16.97 in the Severe Impairment Battery), global assessment (MD -2.88, 95% Crl -6.04 to 0.40), daily activities (MD 13.06, 95% Crl -34.04 to 58.92), and neuropsychiatric symptoms (MD -6.84, 95% Crl -10.62 to -2.82) compared with placebo. Memantine was more acceptable than placebo (MD 0.93, 95% Crl 0.69 to 1.22).

CONCLUSIONS

Memantine plus donepezil showed superior outcomes for cognition, global assessment, daily activities, and neuropsychiatric symptoms, but lower acceptability than monotherapy and placebo. Combination therapy may be more cost-effective, because memantine slows the progression of AD.

Alzheimer's disease; a review of the pathophysiological basis and therapeutic interventions

Alzheimer's disease (AD) is a neurodegenerative disorder and is identified as the most common cause for dementia. Despite huge global economic burden and the impact on the close family of the patients, there is no definitive cure and thus, improved treatment methods are of need. While memory and cognition are severely affected in AD, exact etiology is yet unknown. The β-Amyloid plaque formation and aggregation hypothesis is among the well-known hypotheses used to explain disease pathogenesis. Currently there are five Food and Drug Administration (FDA) approved drugs as treatment options. All these drugs are used for symptomatic treatment of AD. Thus, disease modifying therapies which can directly address the pathological changes in AD, are needed. Such therapies could be designed based on inhibiting key steps of pathogenesis. Currently there are novel AD drug candidates with various therapeutic mechanisms, undergoing different stages of drug development. Extensive research is being done globally to broaden understanding of the exact mechanisms involved in AD and to develop therapeutic agents that can successfully hinder the occurrence and progression of the disease. In this review, a comprehensive approach to understanding AD and suggestions to be considered in the development of therapeutics for it are presented.

A Perspective on Multi-target Drugs for Alzheimer's Disease

Alzheimer's disease (AD) has a complex pathophysiology that includes aggregation of pathological proteins, impaired neurotransmission, increased oxidative stress, or microglia-mediated neuroinflammation. Therapeutics targeting only one of these AD-related subpathologies have not yet been successful in the search for a disease-modifying treatment. Therefore, multi-target drugs (MTDs) aiming simultaneously at several subpathologies are expected to be a better approach. However, the concept of MTD is inherently connected with several limitations, which are often ignored during MTD design and development. Here, we provide an overview of the MTD approach and discuss its potential pitfalls in the context of AD treatment. We also put forward ideas to be used in the rational design of MTDs to obtain drugs that are effective against AD.

Natural and synthetic drugs used for the treatment of the dementia

This review is devoted to comparative pharmacological analysis of synthetic drugs such as memantine and its isomers, as well as tacrine, velnacrine, rivastigmine, and donepezil, with natural alkaloids, terpenoids, and triterpenoid peroxides, which are used to treat dementia, Alzheimer's and Parkinson's diseases, myasthenia gravis and other neurodegenerative diseases. Recently discovered by French scientists from Marseille triterpenoid hydroperoxides demonstrate high activity as potential therapeutic agents for the treatment of dementia. The information presented in this review is of great interest to pharmacologists, medical chemists, physiologists, neurologists and doctors, as well as for the pharmaceutical industry.

Targeting Inflammatory Pathways in Alzheimer's Disease: A Focus on Natural Products and Phytomedicines

Studies of the brains of Alzheimer's disease (AD) patients have revealed key neuropathological features, such as the deposition of aggregates of insoluble amyloid-β (Aβ) peptides and neurofibrillary tangles (NFTs). These pathological protein deposits, including Aβ peptides (which form senile plaques) and hyperphosphorylated tau (which aggregates into NFTs), have been assumed to be 'the cause of AD'. Aβ has been extensively targeted to develop an effective disease-modifying therapy, but with limited clinical success. Emerging therapies are also now targeting further pathological processes in AD, including neuroinflammation. This review focuses on the inflammatory and oxidative stress-related changes that occur in AD, and discusses some emerging anti-inflammatory natural products and phytomedicines. Many of the promising compounds are cytokine-suppressive anti-inflammatory drugs (CSAIDs), which target the proinflammatory AP1 and nuclear factor-κB signalling pathways and inhibit the expression of many proinflammatory cytokines, such as interleukin (IL)-1, IL-6, tumour necrosis factor-α, or nitric oxide produced by inducible nitric oxide synthase. However, many of these phytomedicines have not been tested in rigorous clinical trials in AD patients. It is not yet clear if the active compounds reach an effective concentration in the brain (due to limited bioavailability) or if they can slow down AD progression in long-term trials. The authors suggest that it is crucial for both the pharmacological and complementary medicine industries to conduct and fund those studies to significantly advance the field.