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Shukla D, Suryavanshi A, Bharti SK, Asati V, Mahapatra DK. Recent Advances in the Treatment and Management of Alzheimer's Disease: A Precision Medicine Perspective. Curr Top Med Chem 2024; 24:1699-1737. [PMID: 38566385 DOI: 10.2174/0115680266299847240328045737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/20/2024] [Accepted: 02/29/2024] [Indexed: 04/04/2024]
Abstract
About 60% to 70% of people with dementia have Alzheimer's Disease (AD), a neurodegenerative illness. One reason for this disorder is the misfolding of naturally occurring proteins in the human brain, specifically β-amyloid (Aβ) and tau. Certain diagnostic imaging techniques, such as amyloid PET imaging, tau PET imaging, Magnetic Resonance Imaging (MRI), Computerized Tomography (CT), and others, can detect biomarkers in blood, plasma, and cerebral spinal fluids, like an increased level of β-amyloid, plaques, and tangles. In order to create new pharmacotherapeutics for Alzheimer's disease, researchers must have a thorough and detailed knowledge of amyloid beta misfolding and other related aspects. Donepezil, rivastigmine, galantamine, and other acetylcholinesterase inhibitors are among the medications now used to treat Alzheimer's disease. Another medication that can temporarily alleviate dementia symptoms is memantine, which blocks the N-methyl-D-aspartate (NMDA) receptor. However, it is not able to halt or reverse the progression of the disease. Medication now on the market can only halt its advancement, not reverse it. Interventions to alleviate behavioral and psychological symptoms, exhibit anti- neuroinflammation and anti-tau effects, induce neurotransmitter alteration and cognitive enhancement, and provide other targets have recently been developed. For some Alzheimer's patients, the FDA-approved monoclonal antibody, aducanumab, is an option; for others, phase 3 clinical studies are underway for drugs, like lecanemab and donanemab, which have demonstrated potential in eliminating amyloid protein. However, additional study is required to identify and address these limitations in order to reduce the likelihood of side effects and maximize the therapeutic efficacy.
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Affiliation(s)
- Deepali Shukla
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya (A Central University), Bilaspur, Chhattisgarh, India
| | - Anjali Suryavanshi
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya (A Central University), Bilaspur, Chhattisgarh, India
| | - Sanjay Kumar Bharti
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya (A Central University), Bilaspur, Chhattisgarh, India
| | - Vivek Asati
- Department of Pharmaceutical Chemistry, ISF College of Pharmacy, Moga, Punjab, India
| | - Debarshi Kar Mahapatra
- Department of Pharmaceutical Chemistry, Dr. D.Y. Patil Institute of Pharmaceutical Sciences and Research, Pimpri, Pune, Maharashtra, India
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Toxicity of Glycyl-l-Prolyl-l-Glutamate Pseudotripeptides: Cytotoxic, Oxidative, Genotoxic, and Embryotoxic Perspectives. J Toxicol 2022; 2022:3775194. [DOI: 10.1155/2022/3775194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 10/31/2022] [Accepted: 11/09/2022] [Indexed: 11/20/2022] Open
Abstract
The tripeptide H-Gly-Pro-Glu-OH (GPE) and its analogs began to take much interest from scientists for developing effective novel molecules in the treatment of several disorders including Alzheimer’s disease, Parkinson’s disease, and stroke. The peptidomimetics of GPEs exerted significant biological properties involving anti-inflammatory, antiapoptotic, and anticancer properties. The assessments of their hematological toxicity potentials are critically required for their possible usage in further preclinical and clinical trials against a wide range of pathological conditions. However, there is so limited information on the safety profiling of GPE and its analogs on human blood tissue from cytotoxic, oxidative, and genotoxic perspectives. And, their embryotoxicity potentials were not investigated yet. Therefore, in this study, measurements of mitochondrial viability (using MTT assay) and lactate dehydrogenase (LDH) release as well as total antioxidant capacity (TAC) assays were performed on cultured human whole blood cells after treatment with GPE and its three novel peptidomimetics for 72 h. Sister chromatid exchange (SCE), micronucleus (MN), and 8-oxo-2-deoxyguanosine (8-OH-dG) assays were performed for determining the genotoxic damage potentials. In addition, the nuclear division index (NDI) was figured out for revealing their cytostatic potentials. Embryotoxicity assessments were performed on cultured human pluripotent NT2 embryonal carcinoma cells by MTT and LDH assays. The present results from cytotoxicity, oxidative, genotoxicity, and embryotoxicity testing clearly propounded that GPEs had good biosafety profiles and were trouble-free from the toxicological point of view. Noncytotoxic, antioxidative, nongenotoxic, noncytostatic, and nonembryotoxic features of GPE analogs are worthwhile exploring further and may exert high potentials for improving the development of novel disease-modifying agents.
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Marinelli L, Fornasari E, Di Stefano A, Turkez H, Arslan ME, Eusepi P, Ciulla M, Cacciatore I. (R)-α-Lipoyl-Gly-l-Pro-l-Glu dimethyl ester as dual acting agent for the treatment of Alzheimer's disease. Neuropeptides 2017; 66:52-58. [PMID: 28993014 DOI: 10.1016/j.npep.2017.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 09/05/2017] [Accepted: 09/25/2017] [Indexed: 12/17/2022]
Abstract
In this study, effects of LA-GPE (R-α-Lipoyl-Gly-l-Pro-l-Glu dimethyl ester) and GPE (Gly-L-Pro-L-Glu) on the cytotoxic action of Aβ1-42 were tested with differentiated human neuroblastoma SH-SY5Y cells as cellular Alzheimer model via measurements of mitochondrial viability (MTT assay) and lactate dehydrogenase release (LDH assay). Effects of LA-GPE and GPE on acetylcholinesterase (AChE) activity, total antioxidant capacity (TAC) and total oxidative status (TOS) levels, and neural cell apoptosis and necrosis were also determined. In addition, biological safety of these novel formulations was evaluated in human blood cells using different cytotoxicity and genotoxicity assays. Our results indicated that both compounds could block Aβ1-42 induced cell death. LA-GPE reduced Aβ-induced AChE activity and oxidative stress, suggesting it as a multifunctional compound potentially valuable for the treatment of Alzheimer's disease (AD).
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Affiliation(s)
- Lisa Marinelli
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy
| | - Erika Fornasari
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy
| | - Antonio Di Stefano
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy
| | - Hasan Turkez
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy; Department of Molecular Biology and Genetics, Faculty of Science, Erzurum Technical University, 25240 Erzurum, Turkey
| | - Mehmet Enes Arslan
- Department of Molecular Biology and Genetics, Faculty of Science, Erzurum Technical University, 25240 Erzurum, Turkey
| | - Piera Eusepi
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy
| | - Michele Ciulla
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy
| | - Ivana Cacciatore
- Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti Scalo (CH), Italy.
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Fischer A, Wolman M, Granato M, Parsons M, McCallion AS, Proescher J, English E. Carbamate nerve agent prophylatics exhibit distinct toxicological effects in the zebrafish embryo model. Neurotoxicol Teratol 2015; 50:1-10. [PMID: 25968237 DOI: 10.1016/j.ntt.2015.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 03/25/2015] [Accepted: 05/01/2015] [Indexed: 12/14/2022]
Abstract
Pyridostigmine bromide (PB) is an FDA-approved drug for the treatment of myasthenia gravis and a prophylactic pre-treatment for organophosphate nerve agent poisoning. Current methods for evaluating nerve agent treatments include enzymatic studies and mammalian models. Rapid whole animal screening tools for assessing the effects of nerve agent pre-treatment and post-exposure drugs represent an underdeveloped area of research. We used zebrafish as a model for acute and chronic developmental exposure to PB and two related carbamate acetylcholinesterase (AChE) inhibitors, neostigmine bromide (NB) and physostigmine (PS). Lethal doses and gross morphological phenotypes resulting from exposure to sub-lethal doses of these compounds were determined. Quantitative analyses of motility impairment and AChE enzyme inhibition were used to determine optimal dosing conditions for evaluation of the effects of carbamate exposures on neuronal development; ~50% impairment of response to startle stimuli and >50% inhibition of AChE activity were observed at 80 mMPB, 20 mM NB and 0.1 mM PS. PB induced stunted somite length, but no other phenotypic effects were observed. In contrast, NB and PS induced more severe phenotypic morphological defects than PB as well as neurite outgrowth mislocalization. Additionally, NB induced mislocalization of nicotinic acetylcholine receptors, resulting in impaired synapse formation. Taken together, these data suggest that altered patterns of neuronal connectivity contribute to the developmental neurotoxicity of carbamates and demonstrate the utility of the zebrafish model for distinguishing subtle structure-based differential effects of AChE inhibitors, which include nerve agents, pesticides and drugs.
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Affiliation(s)
- Audrey Fischer
- Asymmetric Operations Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, United States; McKusick Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Marc Wolman
- Department of Cell & Developmental Biology, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, United States
| | - Michael Granato
- Department of Cell & Developmental Biology, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, United States
| | - Michael Parsons
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Andrew S McCallion
- McKusick Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States; Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Jody Proescher
- Asymmetric Operations Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, United States
| | - Emily English
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, United States.
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Schneider LS, Mangialasche F, Andreasen N, Feldman H, Giacobini E, Jones R, Mantua V, Mecocci P, Pani L, Winblad B, Kivipelto M. Clinical trials and late-stage drug development for Alzheimer's disease: an appraisal from 1984 to 2014. J Intern Med 2014; 275:251-83. [PMID: 24605808 PMCID: PMC3956752 DOI: 10.1111/joim.12191] [Citation(s) in RCA: 481] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The modern era of drug development for Alzheimer's disease began with the proposal of the cholinergic hypothesis of memory impairment and the 1984 research criteria for Alzheimer's disease. Since then, despite the evaluation of numerous potential treatments in clinical trials, only four cholinesterase inhibitors and memantine have shown sufficient safety and efficacy to allow marketing approval at an international level. Although this is probably because the other drugs tested were ineffective, inadequate clinical development methods have also been blamed for the failures. Here, we review the development of treatments for Alzheimer's disease during the past 30 years, considering the drugs, potential targets, late-stage clinical trials, development methods, emerging use of biomarkers and evolution of regulatory considerations in order to summarize advances and anticipate future developments. We have considered late-stage Alzheimer's disease drug development from 1984 to 2013, including individual clinical trials, systematic and qualitative reviews, meta-analyses, methods, commentaries, position papers and guidelines. We then review the evolution of drugs in late clinical development, methods, biomarkers and regulatory issues. Although a range of small molecules and biological products against many targets have been investigated in clinical trials, the predominant drug targets have been the cholinergic system and the amyloid cascade. Trial methods have evolved incrementally: inclusion criteria have largely remained focused on mild-to-moderate Alzheimer's disease criteria, recently extending to early or prodromal Alzheimer disease or 'mild cognitive impairment due to Alzheimer's disease', for drugs considered to be disease modifying. The duration of trials has remained at 6-12 months for drugs intended to improve symptoms; 18- to 24-month trials have been established for drugs expected to attenuate clinical course. Cognitive performance, activities of daily living, global change and severity ratings have persisted as the primary clinically relevant outcomes. Regulatory guidance and oversight have evolved to allow for enrichment of early-stage Alzheimer's disease trial samples using biomarkers and phase-specific outcomes. In conclusion, validated drug targets for Alzheimer's disease remain to be developed. Only drugs that affect an aspect of cholinergic function have shown consistent, but modest, clinical effects in late-phase trials. There is opportunity for substantial improvements in drug discovery and clinical development methods.
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Affiliation(s)
- Lon S. Schneider
- Departments of Psychiatry and the Behavioral Sciences, and Neurology, Keck School of Medicine, and the Leonard Davis School of Gerontology of the University of Southern California, Los Angeles, CA, USA
| | - Francesca Mangialasche
- Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden
- Section of Gerontology and Geriatrics, University of Perugia, Perugia, Italy
| | - Niels Andreasen
- Department of Geriatric Medicine, Karolinska University Hospital, Huddinge, Sweden
- Alzheimer Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Howard Feldman
- Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Ezio Giacobini
- Departments of Internal Medicine, Rehabilitation and Geriatrics, University of Geneva Hospitals, Geneva, Switzerland
| | - Roy Jones
- The Research Institute for the Care of Older People (RICE) and University of Bath, Bath, UK
| | - Valentina Mantua
- European Assessment Office, Italian Medicines Agency (AIFA), Rome, Italy
| | - Patrizia Mecocci
- Section of Gerontology and Geriatrics, University of Perugia, Perugia, Italy
| | - Luca Pani
- European Assessment Office, Italian Medicines Agency (AIFA), Rome, Italy
| | - Bengt Winblad
- Alzheimer Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Miia Kivipelto
- Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden
- Alzheimer Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
- Department of Neurology, University of Eastern Finland, Kuopio, Finland
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Tasso B, Catto M, Nicolotti O, Novelli F, Tonelli M, Giangreco I, Pisani L, Sparatore A, Boido V, Carotti A, Sparatore F. Quinolizidinyl derivatives of bi- and tricyclic systems as potent inhibitors of acetyl- and butyrylcholinesterase with potential in Alzheimer’s disease. Eur J Med Chem 2011; 46:2170-84. [DOI: 10.1016/j.ejmech.2011.02.071] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/23/2011] [Accepted: 02/26/2011] [Indexed: 10/18/2022]
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Chaudhaery SS, Roy KK, Shakya N, Saxena G, Sammi SR, Nazir A, Nath C, Saxena AK. Novel Carbamates as Orally Active Acetylcholinesterase Inhibitors Found to Improve Scopolamine-Induced Cognition Impairment: Pharmacophore-Based Virtual Screening, Synthesis, and Pharmacology. J Med Chem 2010; 53:6490-505. [DOI: 10.1021/jm100573q] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Manders M, De Groot LCPGM, Hoefnagels WHL, Dhonukshe-Rutten RAM, Wouters-Wesseling W, Mulders AJMJ, Van Staveren WA. The effect of a nutrient dense drink on mental and physical function in institutionalized elderly people. J Nutr Health Aging 2009; 13:760-7. [PMID: 19812865 DOI: 10.1007/s12603-009-0211-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To determine whether in the current study the supply of a nutrient dense drink has a positive effect on mental and physical function of institutionalized elderly people. DESIGN A 24-week, randomized, double-blind, placebo-controlled, parallel-group, intervention trial. SETTING Homes for the elderly and nursing homes in the Netherlands. PARTICIPANTS Institutionalized elderly people older than 60 years, with a BMI < or = 30 kg/m2, and a Mini-Mental State Examination score of at least 10 points. INTERVENTION In addition to their usual diet the participants (n=176) received either a nutrient dense drink or a placebo drink twice a day during 24 weeks. MEASUREMENTS The functionality measures included cognitive function, mood, physical performance and the ability to perform activities of daily living. RESULTS In the supplement group a favorable effect of the intervention drink on body weight (1.6 kg difference in change; P = .035), calf circumference (0.9 cm difference in change; P = .048), and blood values (e.g. Hcy decreased from 16.8 to 11.2 mumol/L in the supplement group) was found. In the total group no significant effect was found on functionality outcomes. However, a subgroup of participants with BMI at baseline below 24.4 kg/m2 performed better on the cognitive subscale of Alzheimer's Disease Assessment Scale (P = .09), and its language sub score (P = .01) after 24 weeks of intervention. CONCLUSION The results in the total group of this trial suggest that the nutritional supplement used in this study improves nutritional status. Furthermore, the results of this trial suggest that it is effective as treatment for decreasing function in a subgroup of institutionalized elderly people with low BMI.
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Affiliation(s)
- M Manders
- Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, the Netherlands
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Ahmad B, Shah SMH, Bashir S, Shah J. Enzyme inhibition activities of Andrachne cardifolia Muell. J Enzyme Inhib Med Chem 2008; 22:235-8. [PMID: 17518351 DOI: 10.1080/14756360601051258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The crude methanolic extract and various fractions of Andrachne cardifolia Muell, including chloroform, ethyl acetate and n-butanol fractions were subjected to in vitro enzyme inhibition activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase and urease enzymes. A significant enzyme inhibition activity (40-89%) was shown by the crude methanolic extract and its fractions against lipoxygenase, while low to significant activity (40-71%) against butyrylcholinesterase. The crude methanolic extract and its various fractions demonstrated poor to significant activity (25-73%) against acetylcholinesterase and no activity against urease.
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Affiliation(s)
- Bashir Ahmad
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
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Sonkusare SK, Kaul CL, Ramarao P. Dementia of Alzheimer's disease and other neurodegenerative disorders--memantine, a new hope. Pharmacol Res 2005; 51:1-17. [PMID: 15519530 DOI: 10.1016/j.phrs.2004.05.005] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/19/2004] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease is the fourth largest cause of death for people over 65 years of age. Dementia of Alzheimer's type is the commonest form of dementia, the other two forms being vascular dementia and mixed dementia. At present, the therapy of Alzheimer's disease is aimed at improving both, cognitive and behavioural symptoms and thereby, quality of life for the patients. Since the discovery of Alzheimer's disease by Alois Alzheimer, many pathological mechanisms have been proposed which led to the testing of various new treatments. Until recently the available drugs for the treatment of Alzheimer's disease are cholinesterase inhibitors, which have limited success because these drugs improve cognitive functions only in mild dementia and cannot stop the process of neurodegeneration. Moreover, drugs of this category show gastrointestinal side effects. As the cells of central and peripheral nervous system cannot regenerate, newer strategies are aimed at preserving the surviving neurons by preventing their degeneration. NMDA-receptor-mediated glutamate excitotoxicity plays a major role in Abeta-induced neuronal death. Hence, it was thought that NMDA receptors could be a promising target for preventing the progression of Alzheimer's disease. All the compounds synthesized initially in this category showed toxicity mainly because of their high affinity for NMDA receptors. Memantine (1-amino adamantane derivative), NMDA-receptor antagonist was reported to be effective therapeutically in Alzheimer's disease. It was available in Germany as well as European Union and has been approved for moderate to severe dementia in United States of America recently. It is an uncompetitive, moderate affinity antagonist of NMDA receptors that inhibits the pathological functions of NMDA receptors while physiological processes in learning and memory are unaffected. Memantine is also reported to have beneficial effects in other CNS disorders viz., Parkinson's disease (PD), stroke, epilepsy, CNS trauma, amyotrophic lateral sclerosis (ALS), drug dependence and chronic pain. Mechanisms of neuroprotection, preclinical and clinical evidence for effectiveness of memantine have been provided. Pharmacology and pharmacokinetics of memantine and other NMDA-receptor antagonists in comparison with currently approved drugs for dementia treatment have been discussed. The focus is on 'glutamate excitotoxicity' and glutamate receptors as drug target. Various other novel strategies for the treatment of dementia of neurodegenerative disorders have also been discussed.
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Affiliation(s)
- S K Sonkusare
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, S.A.S. Nagar, Mohali 160 062, India
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Alavi A, Lakhani P, Mavi A, Kung JW, Zhuang H. PET: a revolution in medical imaging. Radiol Clin North Am 2004; 42:983-1001, vii. [PMID: 15488553 DOI: 10.1016/j.rcl.2004.08.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
FDG-PET has had remarkable influence on the assessment of physiologic and pathologic states. The authors predict that FDG-PET imaging could soon become the most common procedure used by nuclear medicine laboratories and could remain so for an extended period of time. The power of molecular imaging lies in the vast potential for using biochemical and pharmacologic probes to extend applications arising from an understanding of cell biology to a large number of well-characterized pathologic states. Molecular imaging based upon tracer kinetics with positron-emitting radiopharmaceuticals could become the main source of information for the management of cancer patients. In that case, nuclear medicine procedures might become the most common imaging studies performed in the practice of medicine. This speculation is not farfetched when one realizes the enormous change that a single biologically important compound, FDG, has brought to the medical arena. The major challenge today is to attract the highly qualified individuals and to secure the resources needed to harness the opportunities in the specialty of molecular imaging.
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Affiliation(s)
- Abass Alavi
- Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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Schoenmaker N, Van Gool WA. The age gap between patients in clinical studies and in the general population: a pitfall for dementia research. Lancet Neurol 2004; 3:627-30. [PMID: 15380160 DOI: 10.1016/s1474-4422(04)00884-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The growing global disease burden attributable to dementia has strongly stimulated research activities. However, patients with dementia that are included in clinical research are systematically younger than patients from the general population. This large age gap perhaps indicates a lack of methodological rigour, but, more importantly, has the potential to affect the interpretation of research finding-eg, those relating to neuropathology, apolipoprotein E polymorphisms, the effects of cholinesterase inhibitors, and many other issues relevant to patients with dementia. Research on dementia has a lot to gain from the study of patients that more appropriately reflect the population at risk.
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Affiliation(s)
- Niels Schoenmaker
- Department of Neurology, Academic Medical Centre, Amsterdam, Netherlands
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Galasko D, Kershaw PR, Schneider L, Zhu Y, Tariot PN. Galantamine Maintains Ability to Perform Activities of Daily Living in Patients with Alzheimer's Disease. J Am Geriatr Soc 2004; 52:1070-6. [PMID: 15209643 DOI: 10.1111/j.1532-5415.2004.52303.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To examine the effect of galantamine on activities of daily living (ADLs) with respect to baseline dementia severity, correlation with cognitive and global function, specific ADLs affected, and maintenance of ADL independence. DESIGN Secondary analysis of a 5-month randomized, placebo-controlled trial. SETTING Multiple U.S. clinical centers. PARTICIPANTS Six hundred fifty-nine patients with mild to moderate Alzheimer's disease (AD) who completed 5 months of treatment. INTERVENTION Galantamine at a maintenance dose of 16 or 24 mg/d. MEASUREMENTS The AD Cooperative Study ADL Inventory (ADCS/ADL). RESULTS Galantamine resulted in more improvement in ADCS/ADL scores than placebo regardless of baseline dementia severity, with the greatest differences occurring in patients with more severe disease. Changes in ADCS/ADL scores correlated significantly with change scores on the cognitive subscale of the AD Assessment Scale (r=-0.24). Galantamine treatment resulted in maintenance or improvement of basic and instrumental ADLs, and change from baseline to Month 5 in scores for each individual ADL item favored galantamine over placebo in three of six basic ADLs and six of 17 instrumental ADLs. CONCLUSION Galantamine has a favorable effect on ADL performance in patients with AD, detectable after 5 months of treatment, regardless of dementia severity. The ADCS/ADL appears to better measure distinct abilities that may be relevant not only in clinical trials but also in individual patients than do cognitive assessments.
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Affiliation(s)
- Douglas Galasko
- Department of Neurosciences, University of California at San Diego, San Diego, California, USA.
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14
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Alavi A, Kung JW, Zhuang H. Implications of PET based molecular imaging on the current and future practice of medicine. Semin Nucl Med 2004; 34:56-69. [PMID: 14735459 DOI: 10.1053/j.semnuclmed.2003.09.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The last quarter century has witnessed the introduction of a variety of powerful techniques that have allowed visualization of organ structure and function with exquisite detail. This in turn has brought about a true revolution in the day-to-day practice of medicine. Structural imaging with x-ray computerized tomography and magnetic resonance imaging has added tremendously to many areas of medicine, including preoperative evaluation of patients. Many surgical procedures have been replaced by minimally invasive techniques, which have become a reality only because of the availability of modern imaging modalities. However, despite such accomplishments, structural imaging is quite insensitive for detecting early disease in which there often are no gross structural alterations in organ anatomy. Therefore, these modalities should be complemented by methodologies that can detect abnormalities at the molecular and cellular levels. The introduction of [(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET) in 1976 as a molecular imaging technique clearly has shown the power of this approach for treating a multitude of serious disorders. The impact of FDG-PET has been particularly impressive in patients with cancer diagnosis, for whom it has become important in staging, monitoring response to treatment, and detecting recurrence. In this review, we emphasize the role of FDG-PET in the assessment of central nervous system maladies, malignant neoplastic processes, infectious and inflammatory diseases, and cardiovascular disorders. New radiotracers are being developed and promise to expand further the list of indications for PET. These include novel tracers for cancer diagnosis and treatment capable of detecting hypoxia and angiogenesis. Prospects for developing new tracers for imaging other organ diseases also appear very promising.
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Affiliation(s)
- Abass Alavi
- Division of Nuclear Medicine, Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104, USA
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Trinh NH, Hoblyn J, Mohanty S, Yaffe K. Efficacy of cholinesterase inhibitors in the treatment of neuropsychiatric symptoms and functional impairment in Alzheimer disease: a meta-analysis. JAMA 2003; 289:210-6. [PMID: 12517232 DOI: 10.1001/jama.289.2.210] [Citation(s) in RCA: 318] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Cholinesterase inhibitors are the primary treatment for the cognitive symptoms of Alzheimer disease (AD). Cholinergic dysfunction is also associated with neuropsychiatric and functional deficits, but results from randomized controlled trials of cholinesterase inhibitors are conflicting. OBJECTIVE To conduct a systematic review and meta-analysis to quantify the efficacy of cholinesterase inhibitors for neuropsychiatric and functional outcomes in patients with mild to moderate AD. DATA SOURCES We performed a literature search of trials using MEDLINE (January 1966-December 2001), Dissertations Abstracts On-line, PSYCHINFO, BIOSIS, PubMed, and the Cochrane Controlled Trials Register. We retrieved English- and non-English-language articles for review and collected references from bibliographies of reviews, original research articles, and other articles of interest. We searched for both published and unpublished trials, contacting researchers and pharmaceutical companies. STUDY SELECTION We included 29 parallel-group or crossover randomized, double-blind, placebo-controlled trials of outpatients who were diagnosed as having mild to moderate probable AD and were treated for at least 1 month with a cholinesterase inhibitor. Sixteen trials included neuropsychiatric and 18 included functional measures. DATA EXTRACTION Two investigators (N.H.T. and J.H.) independently extracted study methods, sources of bias, and outcomes. Neuropsychiatric outcomes were measured with the Neuropsychiatric Inventory (NPI, 0-120 points) and the Alzheimer Disease Assessment Scale, noncognitive (ADAS-noncog, 0-50 points) and were analyzed with the weighted mean difference method. Functional outcomes were measured with several activities of daily living (ADL) and instrumental activities of daily living (IADL) scales and analyzed with the standardized mean difference method. DATA SYNTHESIS For neuropsychiatric outcomes, 10 trials included the ADAS-noncog and 6 included the NPI. Compared with placebo, patients randomized to cholinesterase inhibitors improved 1.72 points on the NPI (95% confidence interval [CI], 0.87-2.57 points), and 0.03 points on the ADAS-noncog (95% CI, 0.00-0.05 points). For functional outcomes, 14 trials used ADL and 13 trials used IADL scales. Compared with placebo, patients randomized to cholinesterase inhibitors improved 0.1 SDs on ADL scales (95% CI, 0.00-0.19 SDs), and 0.09 SDs on IADL scales (95% CI, 0.01 to 0.17 SDs). There was no difference in efficacy among various cholinesterase inhibitors. CONCLUSIONS These results indicate that cholinesterase inhibitors have a modest beneficial impact on neuropsychiatric and functional outcomes for patients with AD. Future research should focus on how such improvements translate into long-term outcomes such as patient quality of life, institutionalization, and caregiver burden.
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Affiliation(s)
- Nhi-Ha Trinh
- Department of Psychiatry, Massachusetts General Hospital, Boston, USA
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16
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Bachurin SO. Medicinal chemistry approaches for the treatment and prevention of Alzheimer's disease. Med Res Rev 2003; 23:48-88. [PMID: 12424753 DOI: 10.1002/med.10026] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia, which is characterised by progressive deterioration of memory and higher cortical functions that ultimately result in total degradation of intellectual and mental activities. Modern strategies in the search of new therapeutic approaches are based on the morphological and biochemical characteristics of AD, and focused on following directions: agents that compensate the hypofunction of cholinergic system, agents that interfere with the metabolism of beta-amyloid peptide, agents that protect nerve cells from toxic metabolites formed in neurodegenerative processes, agents that activate other neurotransmitter systems that indirectly compensate for the deficit of cholinergic functions, agents that affect the process of the formation of neurofibrillary tangles, anti-inflammatory agents that prevent the negative response of nerve cells to the pathological process. The goal of the present review is the validation and an analysis from the point of view of medicinal chemistry of the principles of the directed search of drugs for the treatment and prevention of AD and related neurodegenerative disorders. It is based on systematization of the data on biochemical and structural similarities in the interaction between physiologically active compounds and their biological targets related to the development of such pathologies. The main emphasis is on cholinomimetic, anti-amyloid and anti-metabolic agents, using the data that were published during the last 3 to 4 years, as well as the results of clinical trials presented on corresponding websites.
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Affiliation(s)
- S O Bachurin
- Institute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka, Moscow region, Russia.
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17
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Auld DS, Kornecook TJ, Bastianetto S, Quirion R. Alzheimer's disease and the basal forebrain cholinergic system: relations to beta-amyloid peptides, cognition, and treatment strategies. Prog Neurobiol 2002; 68:209-45. [PMID: 12450488 DOI: 10.1016/s0301-0082(02)00079-5] [Citation(s) in RCA: 472] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD) is the most common form of degenerative dementia and is characterized by progressive impairment in cognitive function during mid- to late-adult life. Brains from AD patients show several distinct neuropathological features, including extracellular beta-amyloid-containing plaques, intracellular neurofibrillary tangles composed of abnormally phosphorylated tau, and degeneration of cholinergic neurons of the basal forebrain. In this review, we will present evidence implicating involvement of the basal forebrain cholinergic system in AD pathogenesis and its accompanying cognitive deficits. We will initially discuss recent results indicating a link between cholinergic mechanisms and the pathogenic events that characterize AD, notably amyloid-beta peptides. Following this, animal models of dementia will be discussed in light of the relationship between basal forebrain cholinergic hypofunction and cognitive impairments in AD. Finally, past, present, and future treatment strategies aimed at alleviating the cognitive symptomatology of AD by improving basal forebrain cholinergic function will be addressed.
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Affiliation(s)
- Daniel S Auld
- Douglas Hospital Research Centre, 6875 Blvd Lasalle, Verdun, Que, Canada H4H 1R3
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18
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Cassano T, Carratù MR, Coluccia A, Di Giovanni V, Steardo L, Cuomo V, Trabace L. Preclinical progress with CHF2819, a novel orally active acetylcholinesterase inhibitor. Drug Dev Res 2002. [DOI: 10.1002/ddr.10088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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19
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Hossain M, Jhee SS, Shiovitz T, McDonald C, Sedek G, Pommier F, Cutler NR. Estimation of the absolute bioavailability of rivastigmine in patients with mild to moderate dementia of the Alzheimer's type. Clin Pharmacokinet 2002; 41:225-34. [PMID: 11929322 DOI: 10.2165/00003088-200241030-00006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
OBJECTIVE To investigate the bioavailability of rivastigmine, an approved therapy for patients with mild to moderate dementia of the Alzheimer's type, at the highest approved single dose of 6 mg. DESIGN AND SETTING Randomised, two-period crossover, single-centre, non-blinded, inpatient study. PATIENTS AND PARTICIPANTS Eleven patients (five females and six males) with mean age 69.5 years. METHODS The 6 mg oral dose was compared with a 2 mg intravenous dose of rivastigmine infused over a 1-hour period. Plasma concentrations of rivastigmine and its metabolite NAP 226-90 were measured with a gas chromatographic/mass spectrometric method. RESULTS Following oral administration of a single 6 mg capsule, rivastigmine is rapidly absorbed with an average time to peak plasma concentration of about 1 hour and an average peak concentration of about 25.6 g/L. By a noncompartmental approach, the absolute bioavailability of the 6 mg oral dose of rivastigmine was 71.7% when compared with a 2mg intravenous infusion normalised for dose. By using a population pharmacokinetic model with Michaelis-Menten elimination, absolute bioavailability was estimated at 60.2%. The average terminal elimination half-life of rivastigmine ranged from 1.4 to 1.7 hours for both treatments. Plasma concentrations of the major metabolite, NAP 226-90, formed by the hydrolysis of rivastigmine by cholinesterase are lower than those of the parent compound following oral and intravenous administration. CONCLUSION A noncompartmental approach and a compartmental approach based on a population pharmacokinetic model with Michaelis-Menten elimination yielded comparable values, 71.7% and 60.2% respectively, for the absolute bioavailability of a single 6 mg oral dose of rivastigmine. Comparison with previous studies confirmed that the oral form of the drug exhibits increased bioavailability with increasing dose, consistent with its nonlinear pharmacokinetics..
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Affiliation(s)
- Mohammad Hossain
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA
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20
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Abstract
According to the cholinergic hypothesis, the impairment of cognitive function and the behavioural disturbances that affect patients with Alzheimer's disease are mainly due to cortical deficiencies in cholinergic transmission. Numerous cholinesterase inhibitors have been investigated for treatment of this disease, the rationale being to support the cholinergic system by blocking the degradation of acetylcholine released from presynaptic neurons. These drugs can be classified as reversible (tacrine, donepezil and galantamine), pseudo-reversible (physostigmine, eptastigmine and rivastigmine) or irreversible (metrifonate) enzyme inhibitors. This article reviews efficacy and tolerability results from 6-month placebo-controlled studies of 7 cholinesterase inhibitors: tacrine (80 to 160 mg/day), donepezil (5 to 10 mg/day), rivastigmine (1 to 12 mg/day), metrifonate (30 to 80 mg/day), eptastigmine (30 to 60 mg/day), physostigmine (30 to 36 mg/day) and galantamine (8 to 32 mg/day). All these agents have demonstrated a statistically significant, although modest, effect versus placebo on the cognitive and global performance of patients with Alzheimer's disease. Dramatic clinical response has been seen in only 3 to 5% of patients. There are no major differences in terms of efficacy between the different drugs. The mean difference between drug and placebo effects on standardised psychometric scales is about 2 to 4 points on the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog; a 70-point cognitive scale) and 0.2 to 0.5 points on the Clinician's Interview-Based Impression of Change with Caregiver Input (CIBIC-Plus; a 7-point global scale), or 5 to 14% of the average value of the scales. The most common adverse effects observed after administration of cholinesterase inhibitors are nausea, vomiting, diarrhoea, dizziness, asthenia and anorexia, all symptoms linked to cholinergic overstimulation. These effects are dose related and largely depend on the degree of cholinesterase inhibition. Also important is the rate of onset of cholinesterase inhibition, which depends on the kinetics of enzyme inhibition, the presence and rate of titration, and the pharmacodynamic peak-to-trough fluctuations. A model predicting the incidence of nausea based on acetylcholinesterase inhibition and the half-life of acetylcholinesterase recovery is proposed. In conclusion, cholinesterase inhibitors are the only pharmacological agents proved to be effective for the treatment of Alzheimer's disease in large, long term, double-blind, placebo-controlled trials. While the efficacy of different cholinesterase inhibitors is similar, their tolerability profiles differ. For example, the incidence of nausea (in excess of that seen with placebo) at cognitively effective dosages ranges from 1% with eptastigmine 60 mg/day to 53% with physostigmine 30 mg/day. Differences in tolerability profile may be due to the extent of peripheral acetylcholinesterase inhibition needed to reach clinical efficacy. Other contributing pharmacodynamic factors are the rate of onset of and fluctuations in acetylcholinesterase inhibition at steady state.
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Affiliation(s)
- B P Imbimbo
- Research & Development Department, Chiesi Farmaceutici, Parma, Italy.
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21
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Braida D, Sala M. Eptastigmine: ten years of pharmacology, toxicology, pharmacokinetic, and clinical studies. CNS DRUG REVIEWS 2001; 7:369-86. [PMID: 11830755 PMCID: PMC6741646 DOI: 10.1111/j.1527-3458.2001.tb00205.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Eptastigmine (heptyl-physostigmine tartrate) is a carbamate derivative of physostigmine in which the carbamoylmethyl group in position 5 of the side chain has been substituted with a carbamoylheptyl group. In vitro and ex vivo results suggest that eptastigmine has a long-lasting reversible brain cholinesterase (i.e., acetylcholinesterase and butyryl-cholinesterase) inhibitory effect. When administered in vivo to rodents by various routes, eptastigmine inhibits cerebral acetylcholinesterases (AChE) and increases acetylcholine (Ach) brain levels by 2500-3000%, depending on the dose. This effect leads to an improvement in the cerebral blood flow in the ischemic brain, excitatory and inhibitory effects on the gastrointestinal tract and to a protection from acute soman and diisopropylfluorophosphate intoxication. Eptastigmine, by either acute or chronic administration, has been found to have memory enhancing effects in different species of normal, aged and lesioned animals. It also restored to normal the age-related increase of EEG power without affecting spontaneous motor activity. Clinical investigations on more than 1500 patients with Alzheimer's disease demonstrated that eptastigmine significantly improved cognitive performance (as assessed by the cognitive subscale of the Alzheimer's Disease Assessment Scale) as compared with placebo. This improvement was most evident in patients with more severe cognitive impairment at the baseline. The relationship between patient performance and average steady-state AChE inhibition was described by an inverted U-shaped dose-response curve. Pharmacokinetic studies have revealed that after oral administration eptastigmine is rapidly distributed to the tissues and readily enters the CNS, where it can be expected to inhibit AChE for a prolonged period. Eptastigmine is generally well tolerated and the majority of adverse events (cholinergic) were mild to moderate in intensity. However, the adverse hematologic (granulocytopenia) effects reported in two studies have resulted in the suspension of further clinical trials.
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Affiliation(s)
- Daniela Braida
- Department of Pharmacology, Chemotherapy and Medical Toxicology, University of Milan, Italy
| | - Mariaelvina Sala
- Department of Pharmacology, Chemotherapy and Medical Toxicology, University of Milan, Italy
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22
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Abstract
The authors review the literature from the last year examining the benefits of cholinesterase inhibitors in the treatment of behavioral disturbance in Alzheimer's disease (AD) and other dementias. Previous review has indicated that cholinesterase inhibitors have psychotropic properties. We found more evidence to support both the benefits of cholinesterase inhibitors in behavioral disturbance, and that specific behaviors may be selectively responsive to treatment.
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Affiliation(s)
- E J Daly
- Department of Psychiatry, Massachusetts General Hospital, MGH East (149-9124), 149 13th Street, Charlestown, MA 02129, USA.
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23
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Abstract
During the last decade, a systematic effort to develop a pharmacological treatment for Alzheimer disease (AD) has resulted into three drugs being registered for the first time in the USA and Europe for this specific indication. All three are cholinesterase inhibitors (ChEI). The major therapeutic effect of ChEI on AD patients is to maintain cognitive function at a constant level during a six-month to one-year period of treatment, as compared to placebo. Additional drug effects might slow cognitive deterioration and improve behavioral and daily living conditions. Comparison of clinical effects of six ChEI demonstrates a rather similar magnitude of improvement in cognitive measures. For some drugs, this may represent an upper limit, whereas for other it may still be possible to further increase the benefit. In order to maximize and prolong positive drug effects, it is important to start early and adjust dosage during the treatment. Recent studies show that in many patients the stabilization effect produced by ChEI can be prolonged for as long as a 24-month period. In order to explain the stabilizing effect of ChEI, a mechanism other than AChE inhibition, based on beta-amyloid metabolism, is postulated.
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Affiliation(s)
- E Giacobini
- University Hospitals of Geneva, Department of Geriatrics, University of Geneva, Medical School, CH-1226 Thonex, Geneva, Switzerland.
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24
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Abstract
This article reviews the rationale and provides a progress update regarding the major treatment strategies being developed for the prevention and treatment of Alzheimer's disease. Various therapeutic areas are discussed, including acetylcholinesterase inhibitors and other cholinergic agents, antioxidants, anti-inflammatory drugs, hormone replacement therapy, antiamyloid treatment, and neurotrophic agents.
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Affiliation(s)
- M Grundman
- Department of the Neurosciences, Alzheimer's Disease Cooperative Study, University of California, San Diego and La Jolla, California 92037, USA
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25
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Sramek JJ, Cutler NR. RBC cholinesterase inhibition: a useful surrogate marker for cholinesterase inhibitor activity in Alzheimer disease therapy? Alzheimer Dis Assoc Disord 2000; 14:216-27. [PMID: 11186600 DOI: 10.1097/00002093-200010000-00006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Red blood cell (RBC) acetylcholinesterase (AChE) inhibition has been used as a peripheral surrogate marker for the activity of centrally acting AChE inhibitors (AChEIs) in the treatment of Alzheimer disease. As a valid peripheral surrogate marker, RBC AChE inhibition should reflect the central pharmacodynamic activity of the compound and should demonstrate a relation with cognitive or global improvement in patients with Alzheimer disease. As a useful clinical tool, RBC AChE inhibition should also provide an advantage in dose optimization. However, the application of surrogate markers in research and clinical use is controversial (Prentice, 1989; Gotzsche, 1996; Colburn, 1997; De Gruttola et al., 1997). For instance, surrogate markers that have been identified or applied inappropriately can lead to erroneous conclusions, slowing the drug development process (Colburn, 1997). Also, the validation of surrogate markers for the pharmacodynamic activity of central nervous system drugs is not always possible because samples of brain tissue cannot be analyzed in humans. Finally, although validation of peripheral markers for central nervous system drugs has been approached via analysis of cerebrospinal fluid (Cutler et al., 1998a), few markers have been subjected to such rigorous evaluation in clinical studies. The extent to which measures of peripheral AChE inhibition accurately model central drug activity and therapeutic effectiveness of AChEIs, both as individual agents and as a drug class, is the focus of this review. AChEIs comprise a group of structurally diverse compounds with a wide range of relative specificities for the various molecular species of cholinesterase found in plasma, RBCs, and the brain. Studies of RBC AChE inhibition after administration of AChEIs in animals are of limited utility because of the differential sensitivity of AChEIs for human versus animal forms of AChE, the poor correlation between effective doses in animals and humans, and the lack of standardized measurements of effectiveness. Although clinical studies of donepezil, metrifonate, and eptastigmine have suggested the potential use of RBC AChE inhibition as a predictor of clinical response, the degree of inhibition yielding maximum cognitive improvements was highly variable from compound to compound (30-80%). Further, investigators did not prove a relation between central and peripheral pharmacodynamics or demonstrate an advantage over dose in the ability of RBC AChE inhibition to predict clinical response. A study of rivastigmine in patients with Alzheimer disease revealed that cerebrospinal fluid AChE inhibition correlated well with cognitive performance, whereas peripheral inhibition did not. Therefore, RBC cholinesterase inhibition is not a reliable surrogate marker for the activity of AChEIs as a class of drugs, and its usefulness as a dose optimization tool for individual agents has yet to be demonstrated clearly.
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Affiliation(s)
- J J Sramek
- California Clinical Trials, Beverly Hills 90211, USA
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26
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Abstract
During the last decade, a systematic effort to develop a pharmacological treatment for Alzheimer disease (AD) has resulted into three drugs being registered for the first time in USA and Europe for this specific indication. All three are cholinesterase inhibitors (ChEI). The major therapeutic effect of ChEI on AD patients is to maintain cognitive function at a constant level during a 6 months to one year period of treatment as compared to placebo. Additional drug effects might be slowing cognitive deterioration and improving behavioral and daily living conditions. Comparison of clinical effects of 6 ChEI demonstrates a rather similar magnitude of improvement in cognitive measures. For some drugs. this may represent an upper limit while for other it may still be possible to increase further the benefit. In order to maximize and prolong positive drug effects it is important to start early and adjust dosage during the treatment. Recent studies show that in many patients the stabilization effect produced by ChEI can be prolonged for as long as a 24 month period. In order to explain the stabilizing effect of ChEI, a mechanism other than AChE inhibition, based on beta-amyloid metabolism, is postulated.
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Affiliation(s)
- E Giacobini
- University Hospitals of Geneva, Department of Geriatrics, University of Geneva, Medical School, Thonex, Switzerland.
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27
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Abstract
Researchers have sought to understand the underlying pathophysiology of Alzheimer's disease (AD) ever since Dr A Alzheimer first described the condition in 1907. Unfortunately however, until recently, they have done so with limited success. This lack of clarity has deterred advancements in therapeutic drug research beyond all but the purely symptomatic treatment relief currently available. However, through spatio-temporal analysis of the two types of cerebral lesions that characterise the disorder (senile plaques and neurofibrillary tangles) and the compilation of genetic data concerning familial AD, there now exists the foundation for a more comprehensive understanding of the disease. Although symptomatic cholinergic strategies have beneficial effects, their benefits are modest and current research has turned to the development of other promising strategies, including oestrogen replacement, anti-inflammatory agents, free radical scavengers, anti-oxidants and monoamine oxidase-B (MAO-B) inhibitors. Many of these strategies may have some merit, however further analysis and structured research are necessary before a definitive decision can be made about their efficacy and possible role in AD therapy. Strategies that are directed at halting the underlying biochemical changes in AD are nearing clinical testing and offer the promise for meaningful therapeutic outcomes.
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Affiliation(s)
- J J Sramek
- California Clinical Trials, 8500 Wilshire Boulevard, 7th Floor, Beverly Hills, CA 90211, USA. jsramek@cctrials:com
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28
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Affiliation(s)
- R Mayeux
- Taub Institute on Alzheimer's Disease and the Aging Brain, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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