Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new and accurate chiral liquid chromatographic method was developed for the enantiomeric resolution of Rivastigmine hydrogen tartarate, (-)S-N-ethyl-3-[(1-dimethyl-amino)ethyl]-N-methylphenyl-carbamate hydrogen tartarate, a cholinesterase inhibitor in bulk drugs. The enantiomers of Rivastigmine hydrogen tartarate were baseline resolved on a Chiralcel OD-H (250 mm x 4.6 mm, 5 microm) column using a mobile phase system containing hexane: isopropanol: trifluoroacetic acid (80:20:0.2, v/v/v). The resolution between the enantiomers was not less than four and interestingly distomer was eluted prior to eutomer in the developed method. The presence of trifluoroacetic acid in the mobile phase has played an important role in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was extensively validated and proved to be robust. The limit of detection and limit of quantification of (R)-enantiomer were found to be 500 and 1500 ng/ml, respectively for 10 microl injection volume. The percentage recovery of (R)-enantiomer was ranged from 95.2 to 104.3 in bulk drug samples of Rivastigmine hydrogen tartarate. Rivastigmine hydrogen tartarate sample solution and mobile phase were found to be stable for at least 48 h. The proposed method was found to be suitable and accurate for the quantitative determination of (R)-enantiomer in bulk drugs. Chiralcel OJ-H column can also be used as an alternative for the above purpose.
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PMID:A validated chiral liquid chromatographic method for the enantiomeric separation of Rivastigmine hydrogen tartarate, a cholinesterase inhibitor. 1592 25

Rivastigmine is a second-generation cholinesterase inhibitor with selectivity for the CNS, with capacity to inhibit both acetylcholinesterase and butyrylcholinesterase. Rivastigmine is currently approved for the treatment of mild-to-moderate Alzheimer's disease. In addition to its effects on cognition and activities of daily living, rivastigmine appears to be useful in preventing and controlling behavioral and neuropsychiatric manifestations in Alzheimer's disease and dementia with Lewy bodies. This drug profile could be potentially useful in patients with subcortical vascular dementia who often present these symptoms. Small open-label studies of patients with subcortical vascular dementia showed that rivastigmine improved attention, executive function, apathy and other behavioral deficits. Rivastigmine appears to be a promising agent in vascular dementia but its effects remain to be established in double-blind, placebo-controlled clinical trials.
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PMID:Rivastigmine for subcortical vascular dementia. 1593 63

Pharmacological therapy in Alzheimer's disease. Current clinical practice in The Netherlands. Dementia affects 195,000 patients of 65 years and older in The Netherlands currently. Rivastigmine and galantamine, both cholinesterase inhibitors, and memantine, an NMDA (N-methyl-D-aspartate) antagonist, are licensed for the treatment of AD. In clinical practice, these drugs have limited effects on cognitive and other symptoms of dementia. We describe the practical care of some patients treated with these drugs and discuss the pros and cons of pharmacotherapy in AD. Extensive knowledge of the drugs, other treatment options and of dementia are necessary for good clinical practice in the treatment of these patients and the counselling of their caregivers.
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PMID:[Pharmacological therapy in Alzheimer's disease. Current clinical practice in The Netherlands]. 1607 59

Donepezil, rivastigmine, and galantamine are three drugs with acetylcholinesterase (AChE)-inhibiting activity that are currently being used to treat patients suffering from Alzheimer's disease. We have studied the neuroprotective effects of these drugs, in comparison with nicotine, on cell death caused by beta-amyloid (Abeta) and okadaic acid, two models that are relevant to Alzheimer's pathology, in the human neuroblastoma cell line SH-SY5Y. Galantamine and donepezil showed a U-shaped neuroprotective curve against okadaic acid toxicity; maximum protection was achieved at 0.3 microM galantamine and at 1 microM donepezil; at higher concentrations, protection was diminished. Rivastigmine showed a concentration-dependent effect; maximum protection was achieved at 3 microM. When apoptosis was induced by Abeta25-35, galantamine, donepezil, and rivastigmine showed maximum protection at the same concentrations: 0.3, 1, and 3 microM, respectively. Nicotine also afforded protection against Abeta- and okadaic acid-induced toxicity. The neuroprotective effects of galantamine, donepezil, and nicotine were reversed by the alpha7 nicotinic antagonist methyllycaconitine but not by the alpha4beta2 nicotinic antagonist dihydro-beta-erythroidine. The phosphoinositide 3-kinase (PI3K)-Akt blocker 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002) reversed the protective effects of galantamine, donepezil, and nicotine but not that of rivastigmine. In contrast, the bcl-2 antagonist ethyl[2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)]-4H-chromene-3-carboxylate (HA 14-1) reversed the protective effects of the three AChE inhibitors and that of nicotine. Our results show that galantamine, donepezil, and rivastigmine afford neuroprotection through a mechanism that is likely unrelated to AChE inhibition. Such neuroprotection seemed to be linked to alpha7 nicotinic receptors and the PI3K-Akt pathway in the case of galantamine and donepezil but not for rivastigmine.
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PMID:Unequal neuroprotection afforded by the acetylcholinesterase inhibitors galantamine, donepezil, and rivastigmine in SH-SY5Y neuroblastoma cells: role of nicotinic receptors. 1614 75

Alzheimer's disease is the most common form of neurodegenerative dementia and poses considerable health challenges to both patients and their families. Rivastigmine is a powerful slow-reversible, noncompetitive carbamate cholinesterase inhibitor that is approved for the treatment of mild-to-moderate Alzheimer's disease. Randomized, double-blind, placebo-controlled trials of up to 6 months duration have shown beneficial effects of rivastigmine compared with placebo in measures of cognition and global functioning. Less rigorous but growing data suggest that the beneficial effects may endure for up to 5 years, extend to more advanced stages of Alzheimer's disease and may occur in noncognitive domains, such as activities of daily living and the behavioral symptoms of Alzheimer's disease. Evidence from controlled studies also supports the use of rivastigmine for cognitive and behavioral symptoms in Alzheimer's disease associated with vascular risk factors, dementia with Lewy bodies and Parkinson's disease dementia. Early and continued treatment of Alzheimer's disease with rivastigmine maximizes the observed beneficial effects. The most prominent adverse effect of rivastigmine is centrally mediated cholinergic gastrointestinal events, which can be minimized by slower dose-escalation intervals and administration with a full meal. Therapeutic dosing is 6-12 mg/day given twice daily, with higher doses having the potential for greater benefits.
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PMID:Rivastigmine for Alzheimer's disease. 1616 80

Vascular dementia (VaD), like Alzheimer's disease (AD), is associated with cholinergic deficits. Rivastigmine provides sustained, brain-selective inhibition of acetylcholinesterase and butyrylcholinesterase. Preliminary data suggest that rivastigmine may provide significant benefits in patients with AD and cerebrovascular disease (mixed dementia), and in patients with VaD. Open-label rivastigmine treatment has been associated with improved cognitive and functional abilities, behavioral symptoms, and reduced caregiver stress in a small pilot study in these patients. Larger, prospective, double-blind studies of rivastigmine in patients with VaD are under way. These studies will confirm whether rivastigmine is an efficacious treatment option for a range of patients for whom, until now, there have been few symptomatic therapies.
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PMID:Rivastigmine in vascular dementia. 1619 Dec 41

Acetylcholinesterase and butyrylcholinesterase activities emerge in association with plaques and tangles in Alzheimer's disease. These pathological cholinesterases, with altered properties, are suggested to participate in formation of plaques. The present experiment assessed the ability of rivastigmine, a clinically utilized agent that inhibits acetylcholinesterase and butyrylcholinesterase activities, to inhibit cholinesterases in plaques and tangles. Cortical sections from cases of Alzheimer's disease were processed using cholinesterase histochemistry in the presence or absence of rivastigmine. Optical densities of stained sections were utilized as a measure of inhibition. The potency of rivastigmine was compared with those of other specific inhibitors. Optimum staining for cholinesterases in neurons and axons was obtained at pH 8.0. Cholinesterases in plaques, tangles and glia were stained best at pH 6.8. Butyrylcholinesterase-positive plaques were more numerous than acetylcholinesterase-positive plaques. Rivastigmine inhibited acetylcholinesterase in all positive structures in a dose-dependent manner (10(-6)-10(-4) M). However, even at the highest concentration, faint activity remained. In contrast, rivastigmine resulted in complete inhibition of butyrylcholinesterase in all structures at 10(-5) M. Rivastigmine was equipotent to the specific acetylcholinesterase inhibitor BW284C51 and more potent than the butyrylcholinesterase inhibitors iso-OMPA and ethopropazine. In conclusion, rivastigmine is a potent inhibitor of acetylcholinesterase and a more potent inhibitor of butyrylcholinesterase in plaques and tangles. Unlike other cholinesterase inhibitors tested, rivastigmine inhibited cholinesterases in normal and pathological structures with the same potency. Thus, at the therapeutic concentrations used, rivastigmine is likely to result in inhibition of pathological cholinesterases, with the potential of interfering with the disease process.
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PMID:Rivastigmine is a potent inhibitor of acetyl- and butyrylcholinesterase in Alzheimer's plaques and tangles. 1621 45

The effects of association of cholinergic precursors choline or choline alphoscerate with the cholinesterase inhibitor rivastigmine on acetylcholine levels and [(3)H]hemicholinium-3 binding were assessed in rat frontal cortex, hippocampus and striatum. Acetylcholine immunoreactivity was also evaluated in cerebrocortical cholinergic fibers by immunohistochemistry. Choline alphoscerate or rivastigmine, but not choline increased acetylcholine levels as well as [(3)H]hemicholinium-3 binding used as a marker of high affinity cholinergic transporter. The association of choline alphoscerate with rivastigmine dose-dependently increased both acetylcholine levels and [(3)H]hemicholinium-3 binding. Rivastigmine alone or in association with either choline or choline alphoscerate decreased acetylcholinesterase (AChE), whereas choline or choline alphoscerate alone did not affect AChE activity. Choline alphoscerate or rivastigmine alone or in association, but not choline increased acetylcholine immunoreactivity in nerve fibers supplying cerebral cortex. These data suggest that combination of a suitable precursor of brain acetylcholine such as choline alphoscerate and of a cholinesterase inhibitor may represent an association worthwhile of being further investigated as a cholinergic replacement therapy in pathologies characterized by altered cholinergic neurotransmission.
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PMID:Association with the cholinergic precursor choline alphoscerate and the cholinesterase inhibitor rivastigmine: an approach for enhancing cholinergic neurotransmission. 1629 35

Rivastigmine, which has been approved by the US Food and Drugs Administration for the treatment of Alzheimer's disease, is a non-competitive reversible inhibitor of acetylcholinesterase. We present a case of rivastigmine toxicity at a dose of 90 mg, with evidence of respiratory depression. To our knowledge, this case report provides evidence of the highest rivastigmine ingestion recorded (90 mg) that caused respiratory depression but requiring only supportive intervention without the need for ralidoxime. Emergency physicians should strongly consider cholinesterase inhibitor (rivastigmine, galantamine, and tacrine) ingestion in patients who present with short and temporary organophosphate-like toxidromes.
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PMID:Case of the month: rivastigmine (Exelon) toxicity with evidence of respiratory depression. 1637 16

The amyloid-beta (Abeta) peptide has been linked to the pathology of Alzheimer's disease (AD). There is now evidence to support a vasoconstrictive effect of Abeta protein that could be detected in peripheral skin microvasculature. In this study we investigated the ability of acetylcholinesterase (AChE) inhibitors, Donepezil and Rivastigmine, to modulate the vasoconstrictor activity of Abeta25-35 and Abeta1-40. The ability of these drugs to improve endothelial mediated vascular responses to acetylcholine and bradykinin subsequent to perfusion of Abeta peptides was also investigated. The vascular responses to Abeta peptides, acetylcholine, bradykinin and sodium nitroprusside and their modulation by acetylcholinesterase inhibitors were examined in the base of a vacuum induced blister raised on the rat hind footpad using laser Doppler flowmetry. Abeta25-35 (1 microM) and Abeta1-40 (0.1 microM) induced a vasoconstrictor effect and significantly reduced the vasodilator response to acetylcholine (100 microM) and bradykinin (1 microM). Donepezil (100 microM) and Rivastigmine (100 microM) both reduced the vasoconstrictor effect of Abeta peptides, and significantly restored the endothelial vascular response to acetylcholine. Similarly, Donepezil significantly restored the endothelial vascular response to bradykinin. The results also showed that the actions of acetylcholinesterase inhibitors are independent of a direct action on smooth muscle cell reactivity or on endothelial cell function in the absence of Abeta. The current study provides the first evidence in vivo to suggest that acetylcholinesterase inhibitors modulate the vasoconstrictive effects of Abeta peptides at the level of skin microvasculature. We raise the notion that Donepezil and Rivastigmine mediate these vascular modulatory effects via an action on Abeta-mediated vasoconstrictor mechanisms rather than an independent action on endothelial or smooth muscle cell mediated responses.
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PMID:Pharmacological manipulation of the vasoconstrictive effects of amyloid-beta peptides by donepezil and rivastigmine. 1661 Oct 14


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