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: UMLS:C0036341 (schizophrenia)
60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Both haloperidol and risperidone have been widely used in the treatment of schizophrenia. Because of wider therapeutic spectrum of risperidone, switching from haloperidol to risperidone is recommended in patients who do not sufficiently respond to haloperidol. The present study investigated the correlation between the steady-state plasma concentrations of haloperidol and risperidone together with the effects of CYP2D6 status on the steady-state kinetics of both drugs. Subjects were 22 schizophrenic inpatients. Eleven patients first received risperidone 6 mg/day and then haloperidol 12 mg/day, while the remaining 11 patients received these two treatments in the opposite sequence. The steady-state plasma concentrations of risperidone, 9-hydroxyrisperidone, haloperidol, and reduced haloperidol were measured after the subjects had been on the treatment for at least 2 weeks, and CYP2D6 genotypes were identified in all subjects. Neither the correlation between the steady-state plasma concentrations of haloperidol and those of risperidone (r = 0.061, ns) nor the active moiety (sum of concentration of risperidone and 9-hydroxyrisperidone) of risperidone (r = 0.141, ns) was significant. The mean (+/- SD) plasma concentration of risperidone in patients with mutated allele(s)for CYP2D6 was significantly higher than those without mutated allele (1.5 +/- 0.7 vs. 8.5 +/- 11.0, p < 0.05), while such a tendency for haloperidol was not observed. The present study suggests that the steady-state plasma concentration of risperidone is not predicted from that of haloperidol in the same individual, probably because of the much greater involvement of CYP2D6 in the metabolism of risperidone than in that of haloperidol.
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PMID:Lack of correlation between the steady-state plasma concentrations of haloperidol and risperidone. 1236 21

N,N-Dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine monohydrochloride (NE-100) has been developed to treat subjects with schizophrenia. This drug is mainly excreted in the form of oxidative metabolites. In the present study, identification of p450 forms involved in the metabolism was carried out using human livers and intestinal microsomes (HLM and HIM). Eadie-Hofstee plots for NE-100 disappearance in HLM were biphasic, thus indicating the involvement of at least two p450 forms. The metabolism of NE-100 was mediated with recombinant CYP1A1, CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. A significant correlation was observed between activities of NE-100 metabolism and dextromethorphan O-demethylation (a specific activity for CYP2D6) or testosterone 6beta-hydroxylation (a specific activity for CYP3A4) in HLM. The activity of NE-100 metabolism was inhibited by approximately 80% by an anti-CYP2D6 antibody and only by quinidine among the p450-selective inhibitors at a low substrate concentration (0.1 microM). In contrast, with a high substrate concentration (10 microM), the activity was inhibited by an anti-CYP3A4 antibody and by ketoconazole. On the other hand, in HIM, the Eadie-Hofstee plots for NE-100 disappearance were monophasic, and the metabolism was strongly inhibited by an anti-CYP3A4 antibody and by ketoconazole but not by other inhibitors used. These results strongly suggest that NE-100 has different profiles regarding metabolism between liver and intestine. During absorption, NE-100 is mainly metabolized by CYP3A4 in the intestine and thereafter by CYP2D6 in the liver in the presence of therapeutic doses.
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PMID:Differences in cytochrome P450 forms involved in the metabolism of N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine monohydrochloride (NE-100), a novel sigma ligand, in human liver and intestine. 1248 54

Since 1989, several novel antipsychotic drugs have become available for use including clozapine, risperidone, olanzapine, quetiapine and ziprasidone. These agents represent a substantial improvement in the treatment of schizophrenia and related disorders and are considered to have a favourable adverse effect profile relative to traditional antipsychotics. Nonetheless, in rare cases, people have died as a result of taking atypical antipsychotic drugs at therapeutic and supratherapeutic doses. Toxic doses of atypical antipsychotics are highly variable: some patients have died while taking therapeutic doses and others have survived massive overdoses. Toxicity may be increased by coingestion of other agents, particularly drugs with similar metabolic pathways. Atypical antipsychotics are metabolised predominantly by cytochrome p450 (CYP) isoenzymes, particularly CYP1A2 (clozapine and olanzapine), CYP3A4 (clozapine, quetiapine and ziprasidone) and CYP2D6 (olanzapine and risperidone). Concurrent prescription of other drugs that inhibit these isoenzymes may increase the probability of adverse events in patients taking atypical antipsychotics. Deaths due to atypical antipsychotic toxicity are often related to cardiovascular complications, but pulmonary, neurological, endocrine and gastrointestinal complications have also caused fatalities. Prevention and management of atypical antipsychotic overdose are of increased clinical relevance as prescription of these drugs increases.
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PMID:Fatalities associated with therapeutic use and overdose of atypical antipsychotics. 1266 90

Antipsychotic drug-induced tardive dyskinesia (TD) is a serious problem during psychopharmacologic treatment of schizophrenic patients. In search of genetic factors contributing to TD, there is a lack of consensus regarding the role of the polymorphic isozyme cytochrome P450 CYP2D6, which is involved in the oxidative metabolism of antipsychotic drugs. In the present case-control study, we tested the putative influence of the CYP2D6 genotype on the development of TD. Out of 157 patients, 109 were retrospectively selected meeting DSM IV criteria for schizophrenia or schizoaffective disorder, and 50 of them persistently presenting with TD. Genotyping detected the functional allele CYP2D6 *1, the known major defective alleles CYP2D6 *3, *4, *5, *6, and gene duplication. According to their number of functional CYP2D6 alleles, subjects were divided into carriers of none, one, or at least two functional CYP2D6 alleles. The proportions of these categories did not differ between patients and an ethnically homogenous control population (n = 195, p = 0.99) or between patients with and without TD (p = 0.818). Schizophrenic patients were carriers of gene duplication more often than healthy probands, without revealing statistical significance (p = 0.10). Out of seven patients with gene duplication, three developed persistent TD. Furthermore, patients with and without TD were comparable according to age, age of onset, gender, and duration of illness, but subjects with TD had taken more lifetime chlorpromazine equivalents (CPZ) than had patients without TD (chi 2-test, Student's t-test). Forward as well as backward logistic regression analyses confirmed that the presence of TD was influenced by lifetime CPZ but not by age, age of onset, gender, duration of illness, or CYP2D6 genotype. In contrast to the relevance of lifetime CPZ, the lifetime dose of antipsychotic drugs known to be metabolized by CYP2D6 did not significantly influence the presence of TD. In conclusion, our results provide no evidence for the contribution of CYP2D6 genotype to the development of TD in schizophrenic patients receiving long-term antipsychotic medication.
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PMID:CYP2D6 polymorphism and tardive dyskinesia in schizophrenic patients. 1273 65

The effect of sertraline on the steady-state plasma concentrations of risperidone and its active metabolite 9-hydroxyrisperidone (9-OH-risperidone) was studied in 11 patients with schizophrenia or schizoaffective disorder. To treat concomitant depressive symptoms, additional sertraline, at the dose of 50 mg/d, was administered for 4 weeks to patients stabilized on risperidone (4-6 mg/d). Mean plasma concentrations of risperidone, 9-OH-risperidone, and the active moiety (sum of the concentrations of risperidone and 9-OH-risperidone) did not change significantly during combined treatment with sertraline. At the end of week 4, sertraline dosage was adjusted in some patients on the basis of the individual response and then maintained until the end of week 8. At final evaluation, mean plasma levels of risperidone active moiety were not modified in the 4 patients who were still receiving the initial sertraline dose, but concentrations were slightly but not significantly increased (by a mean 15% over pretreatment) in the subgroup of 5 subjects treated with a final dose of 100 mg/d. In the 2 patients receiving the highest dose of sertraline, 150 mg/d, at week 8 total plasma risperidone concentrations were increased by 36% and 52%, respectively, as compared with baseline values. Sertraline coadministration with risperidone was well tolerated, and no patient developed extrapyramidal symptoms. These findings indicate that sertraline at dosages up to 100 mg/d is not associated with clinically significant changes in plasma risperidone concentrations. However, higher doses of sertraline may elevate plasma risperidone levels, presumably as a result of a dose-dependent inhibitory effect of sertraline on CYP2D6-mediated 9-hydroxylation of risperidone.
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PMID:Plasma risperidone concentrations during combined treatment with sertraline. 1525 68

Although a number of antipsychotics have been introduced for the treatment of schizophrenia, inter-individual differences of in antipsychotic response and the number of refractory schizophrenic patients have become two of the most challenging problems in clinical psychiatry. Thus, the pharmacogenetics of antipsychotics have been aimed at providing genetic components of this inter-individual variability in antipsychotic response in order to establish an individually-based pharmacotherapy for schizophrenia and to elucidate the mechanism of antipsychotic response so as to solve the refractoriness of schizophrenia. Pharmacogenetics, which is defined as the science of pharmacological response and its modification by hereditary influence can be divided into two categories: the genetic background of pharmacokinetics, i.e. the absorption, distribution, tissue localization, biotransformation and excretion of drugs, and pharmacodynamics, i.e. the biochemical and physiological consequences of a drug and its mechanism of action. Pharmacokinetics of antipsychotics has been focused mainly on the association between genetic polymorphisms in CYP genes, including CYP2D6, and the metabolism of these drugs. Polymorphism in CYP2D6 enables a division of individuals within a given population into at least two groups, i.e. poor metabolizers (PMs), extensive metabolizers (EMs), and ultrarapid metabolizers (UMs) of certain drugs. PMs have higher plasma concentrations of and more adverse effects from antipsychotics. UMs could be one of the important factors that induce treatment-refractoriness to antipsychotics. Genetic polymorphisms in serotonin and dopamine receptors that have a high affinity for antipsychotics have so far been extensively investigated in the pharmacodynamics of this type of drug. Not just one gene but multiple genes play a role in complex phenotypes, including the clinical response to medication. Thus, a multiple candidate genes approach has recently been adopted in the pharmacogenetics of antipsychotics. The new field of pharmacogenomics using DNA microarray analysis, which focuses on the genetic determinants of drug response at the level of the entire human genome, is important for development and prescription of safer and more effective individually-tailored antipsychotics.
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PMID:Pharmacogenetics of antipsychoatics. 1527 62

The present study aimed to evaluate whether there is any association between CYP2D6 alleles and susceptibility to tardive dyskinesia in patients with schizophrenia under treatment. A meta-analysis considered case-control studies determining the distribution of genotypes for any CYP2D6 polymorphism in unrelated tardive dyskinesia cases and controls without tardive dyskinesia among patients with schizophrenia who were treated with antipsychotic agents. Loss of function alleles were grouped together in a single comparison, whereas other alleles (2 and 10) were examined separately. Data were available for eight (n=569 patients), three (n=325 patients) and four (n=556) studies evaluating the effect of the loss of function alleles, the 2 allele and the 10 allele, respectively. Summary odds ratios (ORs) suggested that loss of function alleles increased the risk of tardive dyskinesia significantly [OR=1.43, 95% confidence interval (CI) 1.06-1.93, P=0.021], whereas there was no effect for 2 and inconclusive evidence for 10 (OR=0.82, 95% CI 0.50-1.32, P=0.41 and OR=1.19, 95% CI, 0.89-1.60, P=0.24, respectively). Patients who were homozygotes for loss of function alleles (poor metabolizers) had 1.64-fold greater odds of suffering tardive dyskinesia compared to other patients with schizophrenia, but the effect was not formally significant (95% CI 0.79-3.43). For the risk conferred by loss of function alleles, large studies provided more conservative estimates of a genetic effect than smaller studies (P=0.003). CYP2D6 loss of function alleles may predispose to tardive dyskinesia in patients with schizophrenia under treatment, but bias cannot be excluded.
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PMID:CYP2D6 polymorphisms and the risk of tardive dyskinesia in schizophrenia: a meta-analysis. 1586 Oct 39

Neuroleptic malignant syndrome (NMS) is a potentially fatal adverse reaction to psychopharmacologic treatment. Reported herein are two NMS patients with schizophrenia who were found to possess a CYP2D6 gene deletion allele (CYP2D6*5). The deletion results in decreased CYP2D6 activity, possibly leading to drug accumulation. Both patients with NMS had been treated with neuroleptics, including CYP2D6 substrates. Polymerase chain reaction (PCR) followed by restriction fragment length polymorphism analyses and long PCR were performed to detect CYP2D6 genotype. One patient was found to possess *5/*10; the other had a *1/*5 genotype. The present preliminary report suggests that pharmacokinetic factors cannot be excluded and the CYP2D6 polymorphism is possibly associated with the etiology of NMS.
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PMID:CYP2D6 gene deletion allele in patients with neuroleptic malignant syndrome: preliminary report. 1604 58

The underlying pathophysiology of polydipsia in schizophrenia is poorly understood. Several studies, however, have suggested that there might be a genetic predisposition to polydipsia. In the present study, using a case-control sample that is independent from the previous family sample, we examined a possible association between polydipsia and functional polymorphisms in the genes of cytochrome P450 (CYP) 1A2 and 2D6, primarily important enzymes to the pharmacokinetics of antipsychotic drugs. Japanese patients with schizophrenia (63 polydipsics and 78 nonpolydipsics) were genotyped for two functional polymorphisms, the 734C/A polymorphism in the CYP1A2 gene and the 2D6*10 allele of the CYP2D6 gene. Neither of the polymorphisms was found to be associated with polydipsia nor was any evidence found that the two polymorphisms have an additive effect on the liability to polydipsia. Our results suggest that the CYP1A2 and CYP2D6 polymorphisms are not likely to play a major role in the development of polydipsia in schizophrenia, although further studies testing other alleles of CYP1A2 and CYP2D6 using different ethnic populations are warranted.
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PMID:Association study between functional polymorphisms in the cytochrome P450 1A2 and 2D6 genes and polydipsia in schizophrenia. 1677 89

We evaluated whether cytochrome P450 (CYP) poor metabolizer polymorphisms of CYP2D6 and CYP2C19 are relevant for the outcome (measured by length of hospitalization) during treatment with psychotropic medications in patients with depression or schizophrenia. 229 patients were genotyped by real-time PCR hybridization probe melting curve technique for CYP2C19*2, CYP2D6*3, *4, and *6, respectively. The gene deletion CYP2D6*5 was analyzed by a long PCR method. Detailed clinical information was obtained from 53 subjects. Patients genotyped homozygous or heterozygous for those CYP2D6 and CYP2C19 poor metabolizer alleles were treated for a longer time in hospital (median 57.5 vs. 40.0 days). Psychiatric patients might benefit from CYP genotyping, the duration of stay as inpatient might be reduced by a priori selection of the appropriate drug for the individual patient.
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PMID:Cytochrome P-450 2D6 and 2C19 polymorphisms and length of hospitalization in psychiatry. 1681 49


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