Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We tested the effects of clozapine, and "atypical" neuroleptic with high affinity for the D4 (dopaminergic), and the 5-HT1c and 5-HT2 (serotonergic) receptor subtypes on locomotor activity in an animal model of Parkinson's disease showing a bimodal response curve to increasing doses of a D2 agonist. Sulpiride (D2 antagonist) and ritanserin (5-HT1c and 5-HT2 antagonist) were used for comparison. The D1 agonist SKF 38393 at a dose of 8 mg/kg significantly reversed the akinesia induced by chronic reserpine treatment (1 mg/kg for 5 days) and alpha-methyl-p-tyrosine pretreatment (300 mg/kg). In this model, the addition of a low dose of a D2 agonist, LY 171555 (quinpirole, 1 microgram/kg), inhibited the effects of SKF 38393, whereas the same drug at higher doses (5-50 microgram/kg) restored and potentiated the stimulatory response to D1 stimulation. Clozapine inhibited the inhibitory phase and potentiated the stimulatory phase of the curve. Sulpiride inhibited both phases of the dose-response curve (inhibitory/stimulatory), whereas ritanserin had no effect. We believe these results may reflect a disinhibition phenomenon possible mediated by the blockade by clozapine of a subpopulation of inhibitory, dopamine (DA) receptors belonging to the D2 "family."
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PMID:Mechanism of action of clozapine-induced modification of motor behavior in an animal model of the "super-off" phenomenon. 908 73

Clinical and preclinical investigations suggest that stimulation of D1 dopamine receptors may be responsible for dyskinesias induced by dopamine agonist treatment of Parkinson's Disease (PD), and that these dyskinesias may be decreased by treatment with a D1 antagonist (clozapine). Therefore, the effects of dopamine agonists and antagonists have been investigated in a primary cerebellar granule cell model of cAMP formation that seems to be highly responsive to the D1 receptors. SKF 38393, lisuride, apomorphine, pergolide, dopamine, bromocriptine and 7-OH-DPAT showed concentration-dependent increases in cAMP formation, with EC50s (in microM) of 0.013, 0.053, 0.25, 1.04, 2.18, 50.9 and 54.4, respectively. SKF 38393, apomorphine, dopamine and pergolide had similar intrinsic activity (100%), while the intrinsic activities of 7-OH-DPAT, bromocriptine and lisuride were 28.0%, 20.7% and 17.2%, respectively. SCH 23390, a selective D1 dopamine receptor antagonist, blocked an increase in cAMP formation produced by EC50 concentrations of all of the dopamine agonists investigated in this study. Clozapine concentration-dependently blocked pergolide-induced increases in cAMP and was approximately 1700-fold less potent than SCH 23390 (IC50: 0.97 microM and 0.56 nM, respectively). U-95666A (1-1000 microM), selective for the D2 receptors, showed no significant effect on cAMP, while pramipexole (0.1-100 microM), a D3 preferring agonist, did not elevate cAMP. These data suggest that primary cerebellar granule cell cultures are an excellent model for measuring D1 dopamine receptor-mediated changes in cellular cAMP. The results are discussed with reference to the relationship between the D1 receptor-stimulated increase in cAMP formation and the induction of dyskinesia in humans by these anti-parkinsonian drugs.
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PMID:D1 dopamine receptor activity of anti-parkinsonian drugs. 912 82

Levodopa-induced psychosis can complicate the treatment of Parkinson's disease (PD). In this retrospective, uncontrolled report, we describe our experience treating PD-related psychosis with clozapine, emphasizing those patients treated for longer than 1 year. Twenty-seven patients were treated, 14 for longer than 1 year. Most patients showed a rapid improvement from baseline within 1 month using the Clinical Global Impression and Global Psychosis Rating Scores. Five patients discontinued the drug due to side effects, but only two patients reported side effects after 6 months of treatment. Clozapine appears to be effective in treating PD related psychotic symptoms while not interfering with motor function.
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PMID:Use of clozapine to treat levodopa-induced psychosis in Parkinson's disease: retrospective review. 918 21

Dopaminergic psychosis frequently complicates the pharmacological treatment of Parkinson's disease. Dose reduction of dopaminomimetic therapy or treatment with conventional neuroleptics improves psychosis but worsens parkinsonism. In an open-label 12-month trial, the clinical antipsychotic efficacy of the atypical neuroleptic clozapine was investigated in 36 parkinsonian patients (age range 46-85 years) with symptoms of dopaminergic psychosis including delusions, vivid dreams, hallucinations, frank paranoid delirium, and hypersexuality. Clozapine, given orally at bedtime, was started at a dose of 6.25 mg and titrated upward to the minimal effective dose. In all patients, psychosis responded to very low clozapine doses (mean 10.59 +/- 6.48 mg/day). Clozapine doses correlated with the severity of psychosis. During clozapine treatment, parkinsonian disabilities and levodopa dosage remained statistically unchanged. During the 12-month study, no patient had clozapine-induced agranulocytosis or other severe side effects. These findings indicate that even at low doses, clozapine effectively controls dopaminergic psychosis in Parkinson's disease patients without compromising motor function.
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PMID:Low dose of clozapine in the treatment of dopaminergic psychosis in Parkinson's disease. 919 42

Clozapine, the only commercially available atypical neuroleptic, is approved for the treatment of schizophrenic patients who are unresponsive to or intolerant of typical neuroleptics. It has an unusual pharmacologic profile compared with standard neuroleptics, and it follows that clinical response to this drug is also different. It has shattered the notion that a drug must be capable of inducing or worsening parkinsonism to be a potent antipsychotic. Based on these findings, it is being used increasingly by neurologists for psychiatric and nonpsychiatric problems in patients with movement disorders. The most common use for clozapine among neurologists is in the management of drug-induced psychosis in Parkinson's disease (PD). This problem has been a source of increased morbidity and mortality in PD because of a lack of adequate therapeutic intervention. At this time, because of success in numerous open trials, with improvement of > 80% of patients, clozapine therapy for psychosis in PD is becoming the standard of care. It also appears to be of value in the management of some motor features of PD, including tremors and dyskinesia and possibly even sensory symptoms such as akathisia and pain. The literature also suggests that clozapine may be of potential benefit in hyperkinetic movement disorders including essential tremor, Huntington's disease, and tardive dyskinesia. We review the current data concerning the use of clozapine in patients with these movement disorders and others.
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PMID:The emerging role of clozapine in the treatment of movement disorders. 925 Oct 65

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

There is increasing evidence that a defect of the mitochondrial respiratory chain is implicated in the development of Parkinson disease. Decreased complex I activity of the mitochondrial respiratory chain has been reported in platelets, muscle, and brain of patients with Parkinson disease. Extrapyramidal symptoms (e.g. parkinsonism and dystonic reactions) are major limiting side effects of neuroleptics. Experimental evidence suggests that neuroleptics inhibit complex I in rat brain. There has not been a study of the effects of neuroleptics in human tissue, however. We therefore analyzed the activities of complexes I + III, complexes II + III, succinate dehydrogenase, complex IV (cytochrome c oxidase), and of citrate synthase in normal human brain cortex after the addition of haloperidol and chlorpromazine and the atypical neuroleptics risperidone, zotepine, and clozapine. Activity of complex I was progressively inhibited by all neuroleptics. Half-maximal inhibition (IC50) was 0.1 mM for haloperidol, 0.4 mM for chlorpromazine, and 0.5 mM for risperidone and zotepine. Clozapine had no effect on enzyme activity at concentrations up to 0.5 mM, followed by a slow decline with a maximum inhibition of 70% at 10 mM. IC50 was at about 2.5 mM. Thus, the concentration of clozapine needed to cause 50% inhibition of the activity of complexes I and III was about 5 times that of zotepine and risperidone, about 6 times that of chlorpromazine, and 25 times that of haloperidol. The inhibition thus paralleled the incidence of extrapyramidal effects caused by the different neuroleptics as they are known from numerous clinical studies. Our data support the hypothesis that neuroleptic-induced extrapyramidal side effects may be due to inhibition of the mitochondrial respiratory chain.
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PMID:Inhibition of complex I by neuroleptics in normal human brain cortex parallels the extrapyramidal toxicity of neuroleptics. 930 97

Clozapine is a novel antipsychotic agent used in the treatment of schizophrenic patients who have not responded to or have been unable to tolerate conventional neuroleptic therapy. In this paper, the literature surveying the uses of clozapine in the treatment of patients with nonschizophrenic illnesses, in particular psychotic affective disorders (bipolar disorder and schizoaffective disorder), will be reviewed. (A Medline search was done for all papers concerning clozapine; those that represented major contributions to the literature were used.) Results from a prospective study at McLean Hospital assessing the effects of diagnosis on response will be presented. Several other uses in nonschizophrenic patients will also be discussed. Because of its relative freedom from extrapyramidal side effects, it is an important agent in the treatment of patients with Parkinson's disease who also have psychotic symptoms. It may be effective in the treatment of tardive dyskinesia in nearly 50% of patients with that symptom. In addition, the drug may be useful in treating violent patients and those with certain movement disorders, atypical borderline personality disorder, or chronic psychotic symptoms. Due to the risk of agranulocytosis, clozapine cannot yet be considered a first-choice treatment for psychotic symptoms, but many studies indicate it to be helpful with a wide variety of treatment-resistant ones.
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PMID:Uses of clozapine in nonschizophrenic patients. 938 95

Clozapine, an atypical antipsychotic, is mainly approved for the treatment of resistant schizophrenia. However, a substantial body of evidence suggests that it might be useful in other psychiatric indications, such as treatment-resistant depression, Parkinson's disease, and dementia. In this report we present the cases of three patients hospitalized at the psychiatric division of the Sheba Medical Center, diagnosed with major depressive disorder with cognitive impairment, whose presenting symptom was agitation. These patients were nonresponders to various treatment modalities. However, treatment with clozapine brought about a favorable response.
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PMID:Clozapine for the treatment of agitated-depressed patients with cognitive impairment: a report of three cases. 957 2

Psychosis induced by the standard drugs for treating idiopathic Parkinson's disease (PD) occurs, in the long term, in approximately 5-8% of patients. Until the development of atypical antipsychotic drugs, treatment of this psychosis was extremely limited and unsatisfactory. Clozapine has been reported to be an effective and well-tolerated treatment for this problem. Clozapine, however, is a difficult drug to use as a result of the monitoring system mandated by the Food and Drug Administration because of the potential for agranulocytosis. Treatment with risperidone has been shown to be poorly-tolerated. This article reports on the authors' open label experience with the newest atypical antipsychotic, olanzapine, and the switching of stable patients from clozapine to olanzapine. Nine of twelve subjects were unable to make the transition because of worsened parkinsonism. Most subjects preferred taking clozapine, despite the onerous monitoring procedure.
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PMID:Substituting clozapine for olanzapine in psychiatrically stable Parkinson's disease patients: results of an open label pilot study. 978 8


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