Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence indicates that the antipsychotic drug clozapine has a low propensity for the induction of extrapyramidal motor symptoms, and also that clozapine has therapeutic effects in patients with idiopathic Parkinson's disease. Because tacrine-induced tremulous jaw movements in rats have been suggested as a possible model of extrapyramidal motor dysfunctions, including parkinsonian tremor, the present work was undertaken to investigate the effects of clozapine on tremulous jaw movements. Clozapine decreased tacrine-induced tremulous jaw movements in a dose-related manner, with an ED50 of approximately 3.3 mg/kg. In order to determine the relative potency of this effect compared to other behavioral effects of clozapine, suppression of lever pressing was also studied. Clozapine reduced lever pressing in a dose-related manner, with an ED50 of approximately 5.4 mg/kg. This indicates that clozapine suppressed jaw movements at or below the doses required for suppression of lever pressing. In contrast, the typical antipsychotic drug haloperidol failed to suppress tacrine-induced tremulous jaw movements in doses up to 1.0 mg/kg, which is about 11-fold higher than the ED50 for suppression of lever pressing with that drug. Thioridazine and risperidone also suppressed tremulous jaw movements in roughly the same dose range at which lever pressing was reduced. It is possible that the suppression of tacrine-induced tremulous jaw movements by clozapine in rats is related to the unique behavioral and motor effects of clozapine. The ratio of potencies of these effects (i.e., suppression of tremulous jaw movements versus suppression of lever pressing) could be used as a behavioral procedure for assessing clozapine-like activity in novel compounds.
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PMID:Effects of clozapine, thioridazine, risperidone and haloperidol on behavioral tests related to extrapyramidal motor function. 927 62

The effects of the acute administration of clozapine on parkinsonian mixed tremor (i.e., resting and postural tremors) were evaluated to establish clozapine's predictive value for long-term response and to determine if there is a difference in the pharmacologic responses of the two tremors. We also investigated the correlation between reduction of tremor and induction of sedation after acute and chronic administration of clozapine. Clozapine (12.5 mg) or placebo were administered po in a double-blind manner to 17 PD patients with mixed L-dopa-resistant tremors. Two patients did not reach 50% improvement and were considered nonresponders. The remaining 15 patients reported moderate to marked reduction of tremor. Responsive patients in the acute test moved on to a long-term, open clozapine add-on study receiving an average daily dose +/- SD of 45 +/- 9.6 mg for a period of 15.5 +/- 8.3 months. A significant reduction of both resting (p < 0.05) and postural (p < 0.05) tremors was observed under clozapine from the first week of treatment through the entire period of the study. There was no statistically significantly difference between the degree of improvement for resting and postural tremors after either single or chronic clozapine administration. Sedation was the only side effect reported after clozapine; however, the time courses of sedation and tremor reduction did not coincide in the acute or in the chronic experimental paradigm, where it decreased considerably in a few weeks in all patients. During long-term clozapine treatment, neither systemic side effects nor worsening of motor disability scores were noted. Thus we wish to propose an acute test or a therapeutic attempt, or both, with clozapine before defining a case of mixed parkinsonian tremor as resistant tremor and therefore resorting to a neurosurgical approach.
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PMID:Clozapine in Parkinson's disease tremor. Effects of acute and chronic administration. 940 51

Patients with essential tremor (ET) may not respond to commonly used drugs. Clozapine, an atypical neuroleptic drug, has been reported to improve postural Parkinson's disease tremor clinically resembling ET. The effects of a single dose of 12.5 mg clozapine and placebo were evaluated in a randomized, double-blind, crossover study in 15 drug-resistant patients with ET. Patient responders with more than 50% improvement after a single dose of clozapine subsequently received the drug (39+/-9 mg up to 50 mg) unblinded for a period of 15.8+/-7.7 months. Tremor was effectively reduced by a single dose of clozapine in 13 of 15 patients (p <0.01). Sedation was the only side effect reported during the clozapine test; however, the time course of sedation and of the antitremor effect were not coincident. A significant reduction of tremor was reported with chronic clozapine treatment (p <0.01) with no tolerance to drug antitremor effect, whereas sedation markedly decreased after 6-7 weeks of therapy. No clozapine-induced hematologic side effects were observed in our cohort of patients during long-term treatment. Our results suggest that in selected drug-resistant ET cases, clozapine should be considered before resorting to neurosurgical options.
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PMID:Acute and chronic effects of clozapine in essential tremor. 1034 71

Tremor is the most common initial symptom and one of the cardinal features of Parkinson's disease. Mild tremor causes only minimal disability, but severe tremor causes more significant disability and distress for the patient than rigidity and/or bradykinesia. Anticholinergic agents, levodopa/DCI and dopamine agonists are most common and beneficial in parkinsonian tremor, but efficacies of these medications are variable among patients. Rigidity and bradykinesia are more responsive to levodopa/DCI therapy than tremor. Clozapine is an atypical neuroleptic agent, not on the market in Japan, and has been reported to decrease or ameliorate parkinsonian tremor through the studies of open label and double blind crossover as a new drug for parkinsonian tremor.
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PMID:[Pharmacological treatment of parkinsonian tremor]. 1106 52

Clozapine is known to be beneficial for the treatment of dopamine agonist-induced psychotic states in patients with Parkinson's disease (PD). Many reports have suggested that it may also be efficacious for the treatment of parkinsonian tremor. We describe a patient with schizophrenia in whom early-onset PD appeared after treatment with antipsychotic drugs. When the parkinsonian symptoms proved resistant to anticholinergic agents, we introduced a trial with up to 50 mg clozapine daily, which yielded a prompt and dramatic response. Thereafter, the parkinsonian symptoms reappeared each time the patient discontinued clozapine and rapidly disappeared on its repeat initiation. There was also a marked improvement in his psychotic and depressive symptoms. This report suggests that some patients with concomitant schizophrenia and PD-a difficult treatment challenge-may benefit from clozapine treatment alone for both disorders.
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PMID:Low-dose clozapine for the treatment of Parkinson's disease in a patient with schizophrenia. 1130 50

Following acceptance of clozapine as a superior antipsychotic agent with low risk of adverse extrapyramidal syndromes (EPS), such as dystonia, parkinsonism, akathisia or tardive dyskinesia, several novel antipsychotic drugs have been developed with properties modelled on those of clozapine. Though generally considered 'atypical' in their relatively low risk of inducing EPS, these agents vary considerably in their pharmacology and impact on neurological functioning. Although few comparative data are available, the atypical antipsychotics can be tentatively ranked by EPS risk (excluding akathisia and neuroleptic malignant syndrome) in the following order: clozapine < quetiapine < olanzapine = ziprasidone. At higher doses, risperidone is ranked with a higher EPS risk than olanzapine and ziprasidone, but its risk of EPS is lower with lower doses. In general, this ranking is inversely related to antidopaminergic (D2 receptor) potency. The high antiserotonergic (5-HT2A receptor) potency of risperidone, clozapine, ziprasidone and olanzapine, but not quetiapine, as well as the antimuscarinic activity of olanzapine and clozapine may also limit EPS. For the treatment of psychotic reactions to dopamine agonist therapy in Parkinson's disease, clozapine is both effective and relatively well tolerated; quetiapine may be tolerated, olanzapine is not well tolerated, risperidone is poorly tolerated, and amisulpride and ziprasidone have not been well evaluated. Clozapine, perhaps because of its anticholinergic activity, can reduce parkinsonian tremor. It is useful for ongoing psychosis with tardive dyskinesia, especially for dystonic features. No atypical antipsychotic is clearly effective for motor abnormalities in Huntington's disease or Tourette's syndrome, and the effect of these drugs on other neurological disorders have been well evaluated in only small numbers of patients. In summary, with the exception of clozapine, and perhaps quetiapine, atypical antipsychotics have brought only relative avoidance of EPS, strongly encouraging continued searches for novel antipsychotic agents.
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PMID:Effects of newer antipsychotics on extrapyramidal function. 1177 17

Abrupt clozapine withdrawal can cause rebound psychosis and severe somatic symptoms in psychiatric patients. We report on the case of an advanced Parkinson's disease patient who developed myoclonus, tremor, rigidity, hyperreflexia, and stupor after abrupt clozapine withdrawal. The patient's symptoms resolved with treatment with cyproheptadine. This clinical picture suggests serotonergic rebound as an explanation for the patient's symptoms, although other pharmacological mechanisms are possible. Clozapine should be gradually withdrawn over a period of 1 to 2 weeks when possible, and abruptly discontinued only when necessary.
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PMID:Clozapine withdrawal symptoms in a Parkinson's disease patient. 1246 85

Psychosis only rarely occurs in patients with untreated Parkinson's disease. Much more commonly, psychosis is induced by drug therapy for Parkinson's disease and is the strongest known risk factor for nursing home placement. Delusions are less frequent than hallucinations, but are more concerning as they are often paranoid in nature. Treatment begins with a search for correctable infectious, toxic, and metabolic aetiologies. If symptoms persist, anti-Parkinson's disease medications are slowly reduced. However, withdrawal of these drugs usually worsens parkinsonism and is often not tolerated. Certain atypical antipsychotics can be used to treat psychosis without compromising motor function. The choice of atypical antipsychotic is largely based on ease of use and adverse effect profile as most have comparable efficacy in improving psychosis. Currently, there are five marketed atypical drugs - clozapine, risperidone, olanzapine, quetiapine and ziprasidone. Ziprasidone is the only agent whose adverse effect profile has not been reported in Parkinson's disease. The most common adverse effects of clozapine in Parkinson's disease are sedation, orthostatic hypotension and sialorrhoea. Sedation is generally helpful since these patients are frequently awake at night and tend to have worse behavioural problems then. Clozapine does not induce deterioration of motor function, but it has the potential to cause agranulocytosis, which is idiosyncratic and not dose-related. In risperidone-treated Parkinson's disease patients, reported adverse effects include somnolence, sialorrhoea, dizziness, palpitations, constipation, delirium, fatigue, leg cramps, depression, urinary incontinence and hypotension. Although in some Parkinson's disease studies, risperidone has been well tolerated, others have shown that many patients are unable to tolerate the drug due to deterioration of motor function. While an initial study of olanzapine in Parkinson's disease psychosis showed the drug to be effective without deterioration of motor function, succeeding reports demonstrated a deleterious effect of the drug on motor functioning. The most common adverse effects of quetiapine in Parkinson's disease patients are sedation and orthostatic hypotension. There is a lack of double-blind trials; however, cumulative reports involving >200 Parkinson's disease patients strongly suggest that quetiapine is well tolerated and effective. Unlike clozapine, it does not improve tremor and may induce mild deterioration of motor function. Recently, cholinesterase inhibitors have been reported to alleviate psychosis in Parkinson's disease. Although ondansetron, an antiemetic with antiserotonergic properties, has been reported to relieve psychosis in Parkinson's disease, its prohibitive cost has prevented further study in this population. Electroconvulsive treatment is generally reserved for the patient with psychotic depression who is unable to tolerate any pharmacological therapy.
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PMID:Treatment of psychosis in Parkinson's disease: safety considerations. 1281 32

Clozapine is the gold standard treatment for Parkinson's disease (PD) psychosis based on double blinded, placebo controlled trials, and has also been shown to alleviate tremor and dyskinesia. There is accumulating data suggesting that clozapine may be associated with increased frequency of diabetes mellitus (DM) compared to conventional neuroleptic drugs in treating schizophrenia. Forty-four predominantly geriatric parkinsonian subjects on clozapine for psychosis, tremor or dyskinesia, on an average dose of 50.6 mg/d for a mean duration of 41 months were reviewed. The prevalence of DM in this cohort was 18.1% (8/44). This rate was similar to that reported in the aged-matched general population (prevalence = 19.3% for ages > or = 60 years). In this small study, parkinsonian patients on long-term, low dose clozapine were not at increased risk for developing DM. Larger controlled prospective studies are needed to confirm this.
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PMID:Diabetes mellitus among parkinsonian patients treated chronically with clozapine. 1546 3


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