Donepezil: A Review of Pharmacological Characteristics and Role in the Management of Alzheimer Disease

Translation from Preclinical Research to Clinical Trials: Transdermal Drug Delivery for Neurodegenerative and Mental Disorders

Neurodegenerative diseases (NDs), particularly dementia, provide significant problems to worldwide healthcare systems. The development of therapeutic materials for various diseases has a severe challenge in the form of the blood-brain barrier (BBB). Transdermal treatment has recently garnered widespread favor as an alternative method of delivering active chemicals to the brain. This approach has several advantages, including low invasiveness, self-administration, avoidance of first-pass metabolism, preservation of steady plasma concentrations, regulated release, safety, efficacy, and better patient compliance. Topics include the transdermal method for therapeutic NDs, their classification, and the mechanisms that allow the medicine to enter the bloodstream through the skin. The paper also discusses the obstacles and potential outcomes of transdermal therapy, emphasizing the benefits and drawbacks of different approaches.

Testing of putative antiseizure medications in a preclinical Dravet syndrome zebrafish model

Dravet syndrome is a severe genetic epilepsy primarily caused by de novo mutations in a voltage-activated sodium channel gene (SCN1A). Patients face life-threatening seizures that are largely resistant to available anti-seizure medications. Preclinical Dravet syndrome animal models are a valuable tool to identify candidate anti-seizure medications for these patients. Among these, scn1lab mutant zebrafish, exhibiting spontaneous seizure-like activity, are particularly amenable to large-scale drug screening. Thus far, we have screened more than 3000 drug candidates in scn1lab zebrafish mutants, identifying valproate, stiripentol, and fenfluramine e.g. Food and Drug Administration-approved drugs, with clinical application in the Dravet syndrome population. Successful phenotypic screening in scn1lab mutant zebrafish is rigorous and consists of two stages: (i) a locomotion-based assay measuring high-velocity convulsive swim behaviour and (ii) an electrophysiology-based assay, using in vivo local field potential recordings, to quantify electrographic seizure-like events. Historically, nearly 90% of drug candidates fail during translation from preclinical models to the clinic. With such a high failure rate, it becomes necessary to address issues of replication and false positive identification. Leveraging our scn1lab zebrafish assays is one approach to address these problems. Here, we curated a list of nine anti-seizure drug candidates recently identified by other groups using preclinical Dravet syndrome models: 1-Ethyl-2-benzimidazolinone, AA43279, chlorzoxazone, donepezil, lisuride, mifepristone, pargyline, soticlestat and vorinostat. First-stage locomotion-based assays in scn1lab mutant zebrafish identified only 1-Ethyl-2-benzimidazolinone, chlorzoxazone and lisuride. However, second-stage local field potential recording assays did not show significant suppression of spontaneous electrographic seizure activity for any of the nine anti-seizure drug candidates. Surprisingly, soticlestat induced frank electrographic seizure-like discharges in wild-type control zebrafish. Taken together, our results failed to replicate clear anti-seizure efficacy for these drug candidates highlighting a necessity for strict scientific standards in preclinical identification of anti-seizure medications.

Inhibitory effect of galantamine and donepezil combination against cholinesterase: An in silico and in vitro study

This study aimed to evaluate the in silico and in vitro inhibitory effect of the combined use of galantamine (GAL) and donepezil (DON) against acetylcholinesterase and butyrylcholinesterase (BuChE) enzymes. In silico and in vitro cholinesterase analysis were carried out for GAL and DON alone and combined. Molecular modeling studies were carried out (docking analysis, molecular dynamics simulation, and quantum theory of atoms in molecules). Cholinesterase's inhibitory activities by modified Ellman's method and the drug combination effect using the Chou-Talalay method were assayed. GAL/DON combination showed the co-occupancy of the ligands in both enzymes through in silico studies. Regarding in vitro BuChE inhibition analyses, three of five combinations showed an interaction between GAL and DON at the threshold of additive affect (0.9 < CI < 1.1), with a tendency toward a synergistic effect for higher concentrations. This is the first report showing the efficacy of the GAL/DON combinations inhibiting BuChE, showing the importance of analyzing the behavior of different ligands when co-occupancy into the active site is possible. These combinations might be a possible therapy to improved efficacy, reduced doses, minor side effects, and high levels of the neurotransmitter in the synaptic space for Alzheimer's disease.

Testing of putative antiseizure drugs in a preclinical Dravet syndrome zebrafish model

Dravet syndrome (DS) is a severe genetic epilepsy primarily caused by de novo mutations in a voltage-activated sodium channel gene (SCN1A). Patients face life-threatening seizures that are largely resistant to available anti-seizure medications (ASM). Preclinical DS animal models are a valuable tool to identify candidate ASMs for these patients. Among these, scn1lab mutant zebrafish exhibiting spontaneous seizure-like activity are particularly amenable to large-scale drug screening. Prior screening in a scn1lab mutant zebrafish line generated using N-ethyl-Nnitrosourea (ENU) identified valproate, stiripentol, and fenfluramine e.g., Federal Drug Administration (FDA) approved drugs with clinical application in the DS population. Successful phenotypic screening in scn1lab mutant zebrafish consists of two stages: (i) a locomotion-based assay measuring high-velocity convulsive swim behavior and (ii) an electrophysiology-based assay, using in vivo local field potential (LFP) recordings, to quantify electrographic seizure-like events. Using this strategy more than 3000 drug candidates have been screened in scn1lab zebrafish mutants. Here, we curated a list of nine additional anti-seizure drug candidates recently identified in preclinical models: 1-EBIO, AA43279, chlorzoxazone, donepezil, lisuride, mifepristone, pargyline, soticlestat and vorinostat. First-stage locomotion-based assays in scn1lab mutant zebrafish identified only 1-EBIO, chlorzoxazone and lisuride. However, second-stage LFP recording assays did not show significant suppression of spontaneous electrographic seizure activity for any of the nine anti-seizure drug candidates. Surprisingly, soticlestat induced frank electrographic seizure-like discharges in wild-type control zebrafish. Taken together, our results failed to replicate clear anti-seizure efficacy for these drug candidates highlighting a necessity for strict scientific standards in preclinical identification of ASMs.

Guidelines for pharmacotherapy in Alzheimer's disease - A primer on FDA-approved drugs

The growing prevalence of dementia makes it important for us to better understand its pathophysiology and treatment modalities, to improve the quality of life of patients and caregivers. Alzheimer's disease (AD), a neurodegenerative disease, is the most common form of amnestic dementia in the geriatric population. Pathophysiology of AD is widely attributed to aggregation of amyloid-beta (Aβ) plaques and hyperphosphorylation of tau proteins. Initial treatment modalities aimed to increase brain perfusion in a non-specific manner. Subsequent therapy focused on rectifying neurotransmitter imbalance in the brain. Newer drugs modify the progression of the disease by acting against aggregated Aβ plaques. However, not all drugs used in therapy of AD have been granted approval by the United States Food and Drug Administration (FDA). This review categorizes and summarizes the FDA-approved drugs in the treatment of AD in a manner that would make it a convenient reference for researchers and practicing physicians alike. Drugs that mitigate symptoms of dementia may be categorized into mitigators of Behavioral and Psychological Symptoms of Dementia (BPSD), and mitigators of cognitive decline. BPSD mitigators include brexpiprazole, an atypical antipsychotic with a once-daily dosage suited to treat agitation in dementia patients, and suvorexant, an orexin receptor antagonist used to treat sleep disturbances. Cognitive decline mitigators include cholinesterase inhibitors such as donepezil, rivastigmine, and galantamine and glutamate inhibitors such as memantine. Donepezil is the most commonly prescribed drug. It is cheap, well-tolerated, and may be prescribed orally once daily, or as a transdermal patch once weekly. It increases ACh levels, enhances oligodendrocyte differentiation and also protects against Aβ toxicity. However, regular cardiac monitoring is required due to reports of cardiac conduction side effects. Rivastigmine requires a twice-daily oral dosage or once-daily replacement of transdermal patch. It has fewer cardiac side effects than donepezil, but local application-site reactions have been noted. Galantamine, in addition to improving cognitive symptoms in a short span of time, also delays the development of BPSDs and has minimal drug-drug interactions by virtue of having multiple metabolic pathways. However, cardiac conduction disturbances must be closely monitored for. Memantine, a glutamate regulator, acts as an anti-Parkinsonian agent and an antidepressant, in addition to improving cognition and neuroprotection, and requires a once-daily dosage in the form of immediate-release or sustained-release oral tablets. Disease-modifying drugs such as aducanumab and lecanemab reduce the Aβ burden. Both act by binding with fibrillary conformations of Aβ plaques in the brain. These drugs have a risk of causing amyloid-related imaging abnormalities, especially in persons with ApoE4 gene. Aducanumab is administered once every 4 weeks and lecanemab once every 2 weeks. The decision on the choice of the drug must be made after considering the availability of drug, compliance of patient (once-daily vs. multiple doses daily), cost, specific comorbidities, and the risk-benefit ratio for the particular patient. Other non-pharmacological treatment modalities must also be adopted to have a holistic approach toward the treatment of AD.

Donepezil Beyond Alzheimer's Disease? A Narrative Review of Therapeutic Potentials of Donepezil in Different Diseases

Donepezil hydrochloride is an acetylcholine esterase inhibitor studied and approved to treat Alzheimer's disease (AD). However, this drug can have positive therapeutic potential in treating different conditions, including various neurodegenerative disorders such as other types of dementia, multiple sclerosis, Parkinson's disease, psychiatric and mood disorders, and even infectious diseases. Hence, this study reviewed the therapeutic potential of this drug in treating Alzheimer's and other diseases by reviewing the articles from databases including Web of Science, Scopus, PubMed, Cochrane, and Science Direct. It was shown that donepezil could affect the pathophysiology of these diseases via mechanisms such as increasing the concentration of acetylcholine, modulating local and systemic inflammatory processes, affecting acetylcholine receptors like nicotinic and muscarinic receptors, and activating various cellular signaling via receptors like sigma-1 receptors. Despite many therapeutic potentials, this drug has not yet been approved for treating non-Alzheimer's diseases, and more comprehensive studies are needed.

A Systematic Review on Donepezil-based Derivatives as Potential Cholinesterase Inhibitors for Alzheimer’s Disease

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Alzheimer’s Disease (AD) is a multifactorial progressive neurodegenerative disorder characterized by memory loss, disorientation, and gradual deterioration of intellectual capacity. Its etiology has not been elucidated yet. To date, only one therapeutic approach has been approved for the treatment of AD. The pharmacotherapy of AD has relied on noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist - memantine, and acetylcholinesterase (AChE) inhibitors (AChEIs) - tacrine, donepezil, rivastigmine and galantamine. Donepezil was able to ameliorate the symptoms related to AD mainly via AChE, but also through reduction of β-amyloid burden. This review presents the overview of donepezilrelated compounds as potential anti-AD drugs developed on the basis of cholinergic hypothesis to act as solely AChE and butyrylcholinesterase (BChE) inhibitors.

Design, Synthesis and Pharmacological Evaluation of Novel Antiinflammatory and Analgesic O-Benzyloxime Compounds Derived From Natural Eugenol

Background: :

A new series of O-benzyloximes derived from eugenol was synthesized and was evaluated for its antinociceptive and anti-inflammatory properties.

Methods: :

The target compounds were obtained in good global 25-28% yields over 6 steps, which led us to identify compounds (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-(4- (methylthio)benzyloxime (8b), (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-4- bromobenzyloxime (8d) and (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-4- (methylsulfonyl)benzyloxime (8f) as promising bioactive prototypes.

Results::

These compounds have significant analgesic and anti-inflammatory effects, as evidenced by formalin-induced mice paw edema and carrageenan-induced mice paw edema tests. In the formalin test, compounds 8b and 8f evidenced both anti-inflammatory and direct analgesic activities and in the carrageenan-induced paw edema, with compounds 8c, 8d, and 8f showing the best inhibitory effects, exceeding the standard drugs indomethacin and celecoxib.

Conclusion: :

Molecular docking studies have provided additional evidence that the pharmacological profile of these compounds may be related to inhibition of COX enzymes, with slight preference for COX-1. These results led us to identify the new O-benzyloxime ethers 8b, 8d and 8f as orally bioactive prototypes, with a novel structural pattern capable of being explored in further studies aiming at their optimization and development as drug candidates.

Concentration of Donepezil in the Cerebrospinal Fluid of AD Patients: Evaluation of Dosage Sufficiency in Standard Treatment Strategy

Although some studies have described the pharmacokinetics and pharmacodynamics of donepezil in the peripheral compartment, studies focused on drug transport across the blood-brain barrier are still very rare. To our knowledge, the fluctuation in the cerebrospinal fluid concentration of donepezil after administration of the drug has not been described in the literature so far. We recruited 16 patients regularly taking a standard therapeutic dose of donepezil (10 mg per day). All patients (Caucasian race) were treated for at least three months with a stable dose of 10 mg per day prior to sample collection. Patients were divided into two groups depending on the time of plasma and cerebrospinal fluid sampling: 12 h (n = 9; 4 M/5F aged 78.68 ± 7.35 years) and 24 h (n = 7; 3 M/4F aged 77.14 ± 5.87 years) after donepezil administration. The cerebrospinal fluid sample was collected by standard lumbar puncture technique using a single-use traumatic needle. The samples were analysed on an Agilent 1260 Series liquid chromatograph comprising a degasser, a quaternary pump, a light-tight autosampler unit set, a thermostated column compartment, and a UV/VIS detector. Agilent ChemStation software, the statistical software Prism4, version 5.0 (GraphPad Software, USA), and IBM^® SPSS^® Statistics were used for the analysis of the results. The difference in plasma concentration of donepezil after 12 h (mean ± SEM; 39.99 ± 5.90 ng/ml) and after 24 h (29.38 ± 1.71 ng/ml) was nonsignificant. In contrast, the donepezil concentration in the cerebrospinal fluid was significantly higher in the 24-h interval (7.54 ± 0.55 ng/ml) compared with the 12-h interval (5.19 ± 0.83 ng/ml, which is ~70 % based on mean cerebrospinal fluid values). Based on these data, it is plausible to predict that donepezil might produce a stronger AChE inhibition in the brain at 24 h compared with 12 h following the administration. This information may help physicians individually adjust the time of drug administration in the patients according to time course of the disease symptoms.

Memantine ER/Donepezil: A Review in Alzheimer's Disease

A once-daily, fixed-dose combination of memantine extended-release (ER)/donepezil 28/10 mg (Namzaric™) is available in the USA for patients with moderate to severe Alzheimer's disease (AD) on stable memantine and donepezil therapy. The fixed-dose formulation is bioequivalent to coadministration of the individual drugs. In a 24-week, phase III trial in patients with moderate to severe AD, addition of memantine ER 28 mg once daily to stable cholinesterase inhibitor (ChEI) therapy was more effective than add-on placebo on measures of cognition, global clinical status, dementia behaviour and semantic processing ability, although between-group differences on a measure of daily function did not significantly differ. In subgroup analyses in donepezil-treated patients, add-on memantine ER was more effective than add-on placebo on measures of cognition, dementia behaviour and semantic processing, although there were no significant between-group differences on measures of global clinical status and daily function. Memantine ER plus ChEI combination therapy was generally well tolerated in the phase III trial, with diarrhoea, dizziness and influenza occurring at least twice as often with add-on memantine ER as add-on placebo in donepezil-treated patients. Thus, memantine ER plus donepezil combination therapy is an effective and well tolerated treatment option for patients with moderate to severe AD. The fixed-dose combination is potentially more convenient than coadministration of the individual agents.