Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Donepezil is a specific and potent acetylcholinesterase inhibitor according to in vitro data. It displays primarily noncompetitive inhibitory activity. In vivo, donepezil inhibited acetylcholinesterase activity in human erythrocytes and increased extracellular acetylcholine levels in the cerebral cortex and hippocampus of the rat. Donepezil demonstrated efficacy in tests of reference memory in animals, but had less consistent activity in tests of working memory. Donepezil 5 or 10 mg/day was associated with significant improvements in cognitive function [assessed by the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog)] after 14 and 30 weeks and patient global function (Clinician's Interview-based Impression of Change incorporating caregiver input score) after 30 weeks, compared with placebo, in patients with mild to moderate Alzheimer's disease. After 2 years, donepezil 5 or 10 mg/day was associated with an ADAS-cog score approximately 4 points better than would be expected in untreated patients with mild to moderate Alzheimer's disease. The most common adverse events reported in association with donepezil 5 mg/day were gastrointestinal events (nausea/vomiting, diarrhoea, gastric upset and constipation) and dizziness. No hepatotoxicity was reported after 12 weeks' treatment.
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PMID:Donepezil. 910 96

Alzheimer's disease is, in part, characterised by the loss of neurones in the basal forebrain cholinergic cells that project to the cerebral cortex and hippocampus. These impairments have correlated with the memory loss noted in dementia of the Alzheimer's type. This 'cholinergic hypothesis' has led to the rational design of drugs to enhance or stimulate acetylcholine-mediated neurotransmission. Early acetylcholinesterase inhibitors, such as tacrine and physostigmine, are poorly tolerated and have a short duration of action. Rivastigmine is a centrally-selective acetylcholinesterase inhibitor with a relatively long duration of action and is a 'pseudo-irreversible' cholinesterase inhibitor due to slow dissociation of a carbamoyl derivative from the esteratic site of acetylcholinesterase. Preclinical studies confirmed the central selectivity of the drug and its distribution into the cerebrospinal fluid (CSF). Early studies demonstrated that rivastigmine improved cognition and was relatively well-tolerated at moderate doses. Clinical investigations of rivastigmine administered at doses of 6 - 12 mg/day significantly improved cognition, as measured by the ADAS-Cog score, and activities of daily living, as measured by the Progressive Deterioration Scale. Significant global improvements were also noted as measured by the Clinician's Interview Based Impression of Change that required the use of caregiver information. The most frequent adverse effects noted in clinical trials were consistent with peripheral cholinergic stimulation and included nausea, vomiting, abdominal pain, dizziness and diarrhoea. These effects were dose-related and minimised by slow dose-escalation upon initiation of therapy. Rivastigmine undergoes minimal metabolism by the cytochrome P450 system. As a result, it has few drug interactions. The drug is currently marketed widely in over 60 countries worldwide. In the United States, the drug received 'approvable' status subsequent to the NDA filing, and should be available later this year.
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PMID:Rivastigmine, a brain-region selective acetylcholinesterase inhibitor for treating Alzheimer's disease: review and current status. 1113 19

Donepezil (donepezil hydrochloride, E-2020, Aricept, Eisai), launched in March 1997, was the first drug to be marketed for the symptomatic treatment of Alzheimer's disease (AD) in the UK. It had been launched a year earlier in the US where clinicians had already had experience of tacrine (THA). Donepezil is a piperidine based, potent, specific, non-competitive and reversible inhibitor of acetylcholinesterase (AChE). It is structurally dissimilar from other established cholinesterase inhibitors, namely THA (an acridine compound) and the carbamates, physostigmine and rivastigmine and has a pharmacokinetic and tolerability profile distinct from these agents. Experimentally, donepezil inhibits AChE activity in human erythrocytes and increases extracellular acetylcholine levels in the cerebral cortex and the hippocampus of the rat. Pharmacologically, donepezil has a half-life of approximately 70 h lending itself to once daily administration. The most common adverse events reported in clinical trials have been gastrointestinal, typically nausea, vomiting, diarrhoea and constipation. Headache, dizziness and sleep disturbance have also been reported; there has been no evidence of hepatotoxicity. Clinically a number of placebo-controlled trials have shown that donepezil 5 or 10 mg daily was associated with significant improvements in cognitive function, as assessed by the Alzheimer's disease Assessment Scale-cognitive subscale (ADAS cog) after 12 or 24 weeks treatment. Significant improvements in global function and activities of daily living have also been demonstrated after 24 weeks treatment compared with placebo in patients with mild to moderate AD. Donepezil was the first rational treatment available in the UK for this disabling condition and as such received considerable attention. Much of the original attention was negative, ostensibly based on the scientific view that there was not enough published evidence to justify widespread use, but this was driven by concerns about the potentially high drug costs if all patients with AD were eligible to receive it. Considerable data have now been produced from Phase II, III and post-marketing surveillance. This drug evaluation will review the basic pharmacology of donepezil and place it in context with the trial data and the author's clinical experience with the drug.
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PMID:The pharmacology of donepezil: a new treatment of Alzheimer's disease. 1124 55

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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PMID:Pharmacodynamic-tolerability relationships of cholinesterase inhibitors for Alzheimer's disease. 1147 43

The aim of the reported trial was to investigate the safety and efficacy of memantine in mild to moderate vascular dementia (VaD). This was a 28-week, double-blind, parallel, randomized controlled trial of memantine 20 mg daily versus placebo which was conducted in 54 centres in the UK. Memantine is a uncompetitive, moderate affinity N-methyl-D-aspartate receptor antagonist. Patients with a diagnosis of probable VaD and Mini Mental State Examination total scores between 10 and 22 were eligible for inclusion. Primary efficacy parameters were the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) and the Clinical Global Impression of Change (CGI-C). A total of 579 patients were randomized and 548 patients with at least one post-baseline efficacy assessment qualified for the intent-to-treat analysis. At endpoint, memantine was shown to improve cognition relative to placebo in VaD: the change of ADAS-cog from baseline differed by a mean of -1.75 points (95% confidence intervals -3.023 to -0.49) and a median of 2 points between the two groups, while CGI-C ratings showed no significant differences between treatment groups. A total of 77% of all memantine-treated patients experienced adverse event, versus 75% of the placebo-treated patients, dizziness being the most frequent adverse event (11% versus 8%, respectively). Memantine was well tolerated and safe.
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PMID:A double-blind, placebo-controlled multicentre study of memantine in mild to moderate vascular dementia (MMM500). 1240 83

The objective is to evaluate the efficacy of galantamine when a slow titration regimen is employed in Thai Alzheimer's disease (AD) patients with or without cerebrovascular disease and vascular dementia (VaD). A 6-month, multicentre, open-label, uncontrolled trial was undertaken in 75 AD patients. Eligible patients received an initial galantamine dose of 8 mg/day and escalated over 5-8 weeks to maintenance doses of 16 or 24 mg/day. Primary efficacy measures were AD Assessment Scale-cognitive subscale (ADAS-cog) and the Clinician's Interview-Based Impression of Change-Plus version (CIBIC-plus). The Behavioural Pathology in AD Rating Scale (BEHAVE AD), the AD Cooperative Study Activities of Daily Living Inventory and Pittsburgh Sleep Quality Index were the secondary efficacy variables. Analyses were based on the intent-to-treat population. Treatment with galantamine showed significant improvement in cognition on the ADAS-cog and CIBIC-plus at month 6. Galantamine showed favourable effects on activities of daily living. Behavioural symptoms and sleep quality were also significantly improved (p < 0.05). Galantamine was well tolerated. The adverse events were mild-to-moderate intensity. The most frequent adverse events commonly reported were nausea (16.4%), dizziness (9.6%) and vomiting (6.8%). The results of this study may be consistent with galantamine being an effective and safe treatment for mild-to-moderate AD patients with or without cerebrovascular disease and VaD. Flexible dose escalation of galantamine was well tolerated. The daily maintenance dose of galantamine was 16 mg/day, followed by a back up dose of 24 mg/day.
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PMID:Efficacy study of galantamine in possible Alzheimer's disease with or without cerebrovascular disease and vascular dementia in Thai patients: a slow-titration regimen. 1670 Aug 49

The purpose of this study was to explore factors that influence the clinical safety and tolerability associated with galantamine administration in Thai Alzheimer's disease patients with or without cerebrovascular disease and vascular dementia. This was an analysis of previous study. Tolerability and safety profile were analyzed according to sex, age, body weight, Thai mental state examination (TMSE) score, Alzheimer's disease assessment scale-cognitive subscale (ADAS-cog) score, and Alzheimer's disease cooperative study/activities of daily living (ADCS/ADL) score. The most common adverse events were nausea, dizziness, and weight loss which more often occurred during the dose-escalation phase. Mean body weight lost at week 24 was 0.9 kg. Sex, age, body weight, and ADAS-cog score did not influence the incidence of any adverse events. Dizziness was more likely to occur in patients with low TMSE and high ADCS/ADL score (p = 0.02 and p = 0.050, respectively). Patients with TMSE score equal or higher than 23 more often experienced muscle cramps and fatigue than who had TMSE lower 23 (p < 0.05). However, flexible dose escalation of galantamine with a 4-week schedule was safe and well tolerated in Thai AD patients.
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PMID:Safety and tolerability of galantamine in possible Alzheimer's disease with or without cerebrovascular disease and vascular dementia in Thai patients. 1956 80