Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Diarrhoea is a relatively frequent adverse event, accounting for about 7% of all drug adverse effects. More than 700 drugs have been implicated in causing diarrhoea; those most frequently involved are antimicrobials, laxatives, magnesium-containing antacids, lactose- or sorbitol-containing products, nonsteroidal anti-inflammatory drugs, prostaglandins, colchicine, antineoplastics, antiarrhythmic drugs and cholinergic agents. Certain new drugs are likely to induce diarrhoea because of their pharmacodynamic properties; examples include anthraquinone-related agents, alpha-glucosidase inhibitors, lipase inhibitors and cholinesterase inhibitors. Antimicrobials are responsible for 25% of drug-induced diarrhoea. The disease spectrum of antimicrobial-associated diarrhoea ranges from benign diarrhoea to pseudomembranous colitis. Several pathophysiological mechanisms are involved in drug-induced diarrhoea: osmotic diarrhoea, secretory diarrhoea, shortened transit time, exudative diarrhoea and protein-losing enteropathy, and malabsorption or maldigestion of fat and carbohydrates. Often 2 or more mechanisms are present simultaneously. In clinical practice, 2 major types of diarrhoea are seen: acute diarrhoea, which usually appears during the first few days of treatment, and chronic diarrhoea, lasting more than 3 or 4 weeks and which can appear a long time after the start of drug therapy. Both can be severe and poorly tolerated. In a patient presenting with diarrhoea, the medical history is very important, especially the drug history, as it can suggest a diagnosis of drug-induced diarrhoea and thereby avoid multiple diagnostic tests. The clinical examination should cover severity criteria such as fever, rectal emission of blood and mucus, dehydration and bodyweight loss. Establishing a relationship between drug consumption and diarrhoea or colitis can be difficult when the time elapsed between the start of the drug and the onset of symptoms is long, sometimes up to several months or years.
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PMID:Drug-induced diarrhoea. 1064 76

A randomized, double-blind, placebo-controlled, parallel-group study was undertaken to evaluate the safety and tolerability of a once-daily oral administration of metrifonate in patients with probable mild to moderate Alzheimer disease. Metrifonate was given as a loading dose of 125-225 mg based on weight (2.5 mg/kg) for 2 weeks, followed by a maintenance dose of 50-90 mg based on weight (1.0 mg/kg) for 4 weeks. Twenty-nine patients received metrifonate, and 10 patients received placebo. Metrifonate produced a mean erythrocyte acetylcholinesterase inhibition at the end of treatment of 86.3%. The proportion of patients who experienced at least one adverse event was comparable between the metrifonate (76%) and placebo (80%) groups. Selected adverse events in disfavor of metrifonate (defined as those for which the incidence in the metrifonate and placebo groups differed by at least 10%) were diarrhea, nausea, leg cramps, and accidental injury. Adverse events were predominantly mild in intensity and transient. No severe adverse events were experienced by any patient. The most notable hemodynamic change observed during metrifonate treatment was a clinically insignificant mean decrease in the heart rate (by electrocardiogram) of approximately 9 beats/min, compared with an approximate 3-beats/min decrease for the placebo group. No muscle weakness was observed in this study. No clinically relevant laboratory abnormalities, such as liver toxicity, or changes in exercise tolerance or pulmonary function tests were found with metrifonate treatment. This metrifonate dose provided a high level of acetylcholinesterase inhibition, which was associated in these patients with a favorable safety and tolerability profile. Indeed, the magnitude of the peripheral acetylcholinesterase inhibition is the highest tolerable inhibition level yet observed.
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PMID:Randomized, double-blind, placebo-controlled, multicenter study to evaluate the safety and tolerability of metrifonate in patients with probable Alzheimer disease. The Metrifonate Study Group. 1071 3

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 is an acetylcholinesterase inhibitor indicated for the symptomatic treatment of mild to moderate Alzheimer's disease. It is reported to have a relatively favourable side-effect profile. We report here on a pharmacovigilance study carried out post-marketing in England. An observational cohort study using the technique of Prescription-Event Monitoring was carried out. Some 1762 patients (mean age 72.9 years; 42% male) were followed up for 6 months minimum. The commonest adverse events were nausea, diarrhoea, malaise, dizziness and insomnia. Aggression, agitation and abnormal dreams were uncommonly associated with the drug. There were no cardiac rhythm disturbances or liver disorders causally associated. The commonest adverse drug reactions are already reported in the product information. Given the relatively small size of this cohort, the signals of abnormal dreams and psychiatric disturbance as possible adverse drug reactions need further investigation in carefully planned studies.
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PMID:Adverse effects associated with the use of donepezil in general practice in England. 1119 60

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

Aldicarb (2-methyl-2(methylthio) propanal o-[(methylamino)-carbonyl] oxime) is a pesticide manufactured since 1965. This carbamate ester is sold under the tradename, Temik, and is used as insecticide and nematicide. The Environmental Protection Agency has classified aldicarb in the highest toxicity category and has defined a strict control for its delivery and use. In Brazil and the Caribbean island, aldicarb is illegally used as a household rodenticide with a widespread risk of poisoning. Our study presents the first review of aldicarb poisoning circumstances associated with clinical and analytical findings. Moreover, the oxime treatment is discussed. Eighteen patients with cholinergic symptoms admitted to the Emergency Unit and two deceased with a history of aldicarb poisoning were included in the study. As agricultural workers, only two of them could legally use Temik. Seventy percent of the patients was managed by the Emergency Mobil Unit. Serum cholinesterase activity was always lower than 30% of the normal range and aldicarb was identified by UV spectra and retention time after liquid chromatography separation. The most common muscarinic effect was diarrhea, the main nicotinic sign fasciculation and almost half of the poisoned patients had central nervous system (CNS) depression (Glasgow Coma Score lower than 8). Four patients had serious conduction abnormalities and two of them died. These results suggest that aldicarb intoxication is always severe. Oxime treatment did not produce side effects and should be recommended whenever the pesticide involved is unknown. Effective measures should be implemented to stamp out the illicit use of aldicarb.
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PMID:Aldicarb poisoning. 1129 36

Eleven A-ring modified hexacyclic analogues of camptothecin (CPT) containing a 1,4-oxazine ring were synthesized from 10-hydroxycamptothecin (11a) and 7-ethyl-10-hydroxycamptothecin (3) (SN-38) in four to five steps and were subjected to the biological tests such as cytotoxicity, topoisomerase I (Topo I) inhibitory activity, acetylcholinesterase (AChE) inhibition, and stability in human plasma. Four compounds 15a, 15b, 16a, and 16c were about 2-fold more potent than topotecan and as potent as CPT toward human cancer cell lines A549, H128, WiDr, MKN45, SK-OV-3, and SK-BR-3 in vitro, even though the most active compound 15b was slightly less potent than SN-38. The potency of Topo I inhibition of these compounds showed relatively good correlation with their cytotoxicity. Most of the compounds exhibited AChE inhibitory activity weaker (9 +/- 2 to 20 +/- 3%) than CPT (23 +/- 5%) or topotecan (20 +/- 4%) and similar to SN-38 (13 +/- 2%), indicating that they might have little effect on causing early diarrhea. The stability of lactone forms of these compounds in human plasma seemed to be much higher than that of CPT and similar to that of topotecan but lower than that of SN-38. Among the new hexacyclic CPT analogues, compound 15b showed higher antitumor activity against human tumor xenograft, WiDr, in nude mice compared to that of SN-38. The most promising compound 15b has been selected for further development.
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PMID:Synthesis and biological evaluation of novel A-ring modified hexacyclic camptothecin analogues. 1133 69

Ideally, treatment for Alzheimer's disease (AD) should prevent or cure the disease. Unfortunately, these goals appear unobtainable in the foreseeable future. Nevertheless, symptomatic relief is a feasible treatment option for AD patients and is available currently in the form of cholinesterase inhibitors such as tacrine, donepezil, metrifonate and rivastigmine. Donepezil is a second-generation, piperidine-class, selective and reversible acetylcholinesterase inhibitor. Four double-blind, placebo-controlled clinical trials of donepezil, involving over 1900 individuals with mild to moderate AD, have been published recently. In all trials, significant improvements in cognition were observed consistently for both therapeutic doses of donepezil (5 and 10 mg/d), relative to placebo. Similar donepezil-associated benefits were reported for global functioning. In addition, in one 24-wk, multinational clinical trial, patients receiving donepezil (10 mg/d) performed better than placebo-treated patients in their ability to perform complex daily functioning tasks. Donepezil was well tolerated in all trials, with approx. 79% of all donepezil-treated patients completing the studies compared with approx. 84% of placebo-treated patients. The most common adverse events associated with donepezil were generally cholinergic-induced and gastrointestinal in nature (e.g. nausea, diarrhoea, and vomiting) which were generally mild, transient and tended to occur after the dose was increased to 10 mg/d from 5 mg/d after 1 wk only. Sleep disturbances also occurred as the clinical trials utilized a bedtime dosing regimen. There was no evidence of organ toxicity or clinically significant treatment-emergent laboratory test abnormalities. Thus, donepezil appears to be a beneficial symptomatic treatment for patients with mild to moderate AD.
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PMID:Management of cognition and function: new results from the clinical trials programme of Aricept(R) (donepezil HCl). 1134 20

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

Acute health effects of organophosphorus (OP) pesticides on coffee farmworkers in 1991-1992 in Tanzania are reported to provide a basis for concern over farmworkers being overexposed during application. Workers exposed to OP pesticides (N=133) were drawn from a population of about 240,000 coffee farmers. They were interviewed on symptoms and personal protection, and their erythrocyte acetylcholinesterase (AChE) activity was determined during both spraying and nonspraying period. AChE activities during spraying and nonspraying period were comparable (mean 32.0, SD 7.8 vs. 33.0, SD 8.7 U/g HgB, P=0.26). The prevalence of cough, headache, abdominal pain, excessive sweating, nausea, excessive salivation, diarrhea, and vomiting did not differ significantly between spraying and nonspraying periods. There was no suggestion of decreased AChE in exposed subjects who complained of OP-related symptoms compared to symptomless exposed subjects. Use of gloves, long boots, head cover, face cover, and coverall was not significantly associated with AChE activity. No marked AChE depression was found during spraying season, which may explain the lack of association between symptoms and AChE. The fact that only moderately toxic OP pesticides were used may indicate that toxicity was not sufficiently high to cause depression. Experience, however, suggests that occupational poisoning remains a potential serious danger in coffee cultivation in Tanzania.
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PMID:Acute health effects of organophosphorus pesticides on Tanzanian small-scale coffee growers. 1157 13


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