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)

There have been many efforts to develop novel antipsychotic drugs with improved clinical efficacy and reduced side effects such as extrapyramidal side effects and hyperprolactinemia. Recent evidences from studies on the effects of novel antipsychotic drugs such as clozapine on neurotransmitter receptors are prompting reconsideration of the dopaminergic hypothesis of schizophrenia. This paper gives an overview of the current understanding, including our data, of the effects of several antipsychotics on dopamine receptor subtypes. The recent cloning of dopamine receptors has revealed that multiple dopamine receptor subtypes are generated from at least five distinct dopamine receptor genes. Aripiprazole, a candidate for a novel antipsychotic, has an antagonistic activity against dopamine D2 receptors with a high affinity, but has a weaker potency to up-regulate D2 receptors than haloperidol in the striatum and inhibitory effects on D2-receptor binding activities and mRNA in the pituitary, when it is chronically administrated to rats. Thus the occupancy or influences in D2 receptors in the striatum are involved in the extrapyramidal side effects of typical antipsychotic drugs. These studies provide new leads to understand the pathophysiology and causes of schizophrenia and to develop more effective and safe methods of treatment.
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PMID:[How do antipsychotics exert their effects on dopamine receptor subtypes?]. 1020 60

Innovation in atypical antipsychotic agents continues with new preparations of available drugs as well as novel agents. In this article, we provide an update on these novel products by reviewing information from a computerised literature search, recent abstracts and discussions with industry representatives. A generic formulation of clozapine is now available. It may be less well absorbed and/or less effective than Clozaril, although evidence is conflicting. A fatty acid amide derivative of clozapine is in early development. A liquid formulation of risperidone is currently available, which may be a useful treatment for psychotic agitation as well as a preferable alternative to tablets for some patients. A depot formulation is in development for the long-term management of psychosis. An orally disintegrating tablet formulation of olanzepine is a useful alternative to standard tablets. A short-acting injectable formulation of the drug is in development for psychotic agitation. Sachets and slow-release formulations of quetiapine are in development. Ziprasidone, a recently launched agent, is available in tablet form for schizophrenia/schizoaffective disorder, psychotic depression and mania. A short-acting injectable formulation is in development for psychotic agitation. Aripiprazole (tablets) and iloperidone (tablets and depot injection) are two antipsychotics in development for schizophrenia/schizoaffective disorder (available information regarding iloperidone is very limited). These new formulations and agents should broaden options for the treatment of psychosis.
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PMID:Advances in atypical antipsychotics for the treatment of schizophrenia: new formulations and new agents. 1194 8

Aripiprazole, 7-[4-[4-(2,3-dichlorophenyl)-1-piperazinyl]butyloxy]-3,4-dihydro-2(1H)-quinolinone, a novel antipsychotic with partial agonist activity at dopamine D2 receptors, bound with high affinity to recombinant human 5-HT(1A) receptors (h5-HT(1A)) in Chinese hamster ovary cell membranes and displayed potent, partial agonism at 5-HT(1A) receptors in a guanosine-5'-O-(3-[(35)S]thio)-triphosphate ([(35)S]GTP gamma S)-binding assay that was blocked completely by a selective 5-HT(1A) receptor antagonist. An interaction with 5-HT(1A) receptors may contribute to the overall efficacy of aripiprazole against symptoms of schizophrenia, including anxiety, depression, cognitive and negative symptoms, and to its favorable side-effect profile. Combined with previous studies demonstrating the potent partial agonism of aripiprazole at dopamine D2 receptors, this study suggests aripiprazole is the first dopamine-serotonin system stabilizer.
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PMID:The antipsychotic aripiprazole is a potent, partial agonist at the human 5-HT1A receptor. 1206 84

Aripiprazole (OPC 14597) is an antipsychotic drug that has high affinity for dopamine D2 and D3 receptors and the dopamine autoreceptor. It is being developed for treatment of patients with schizophrenia. The purpose of this study was to determine whether a dose response following graduated doses of aripiprazole could be quantified and correlated with its occupancy of the D2 and D3 dopamine receptors in the brain of living humans. Dopamine D2 and D3 receptor occupancy in fifteen normal male human brains was measured using positron emission tomography (PET) with [11C]raclopride. PET studies were performed before and after two weeks of administration of aripiprazole. The dopamine D2 receptor occupancy was quantified with two kinetic modeling methods without using a blood input function. Administration of aripiprazole for 14 days resulted in a dose-dependent receptor occupancy between 40 - 95% after the administration of 0.5mg, 1 mg, 2 mg, 10 mg, and 30 mg per day. These results suggest that an adequate occupancy can be obtained, and this may be useful to predict an appropriate therapeutic dose for an individual patient. Interestingly, even at striatal D2 receptor occupancy values above 90%, which occurred with the higher doses, extrapyramidal side effects (EPS) were not observed. This underlines aripiprazole's unique mechanism of action as a partial dopamine receptor agonist, which might become a novel principle in the treatment of schizophrenia.
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PMID:Dopamine D2 and D3 receptor occupancy in normal humans treated with the antipsychotic drug aripiprazole (OPC 14597): a study using positron emission tomography and [11C]raclopride. 1209 98

Aripiprazole is a quinolinone derivative and the first of a new class of atypical antipsychotics. The drug has partial agonist activity at dopamine D(2) and serotonin 5-HT(1A) receptors, and is also an antagonist at 5-HT(2A) receptors. In patients with acute relapse of schizophrenia or schizoaffective disorder, aripiprazole 15 to 30 mg/day was at least as effective as haloperidol 10 mg/day and had similar efficacy to risperidone 6 mg/day in well designed, 4-week, placebo-controlled trials. Negative symptoms improved earlier in the aripiprazole than the risperidone group. Efficacy of aripiprazole was observed at week 1 in several trials and was sustained throughout the study periods. Aripiprazole was superior to placebo in a 26-week trial in patients with stable, chronic schizophrenia. In a 52-week trial involving patients with acute relapsing disease, aripiprazole was similar to haloperidol as assessed by time to failure to maintain response and was superior in ameliorating negative and depressive symptoms. The incidence of extrapyramidal symptoms during aripiprazole therapy was similar to that with risperidone and placebo but lower than with haloperidol. Compared with placebo, the proportion of patients with increased plasma prolactin levels and QTc prolongation was similar in patients treated with aripiprazole 15 to 30 mg/day but was significantly increased with haloperidol and risperidone.
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PMID:Aripiprazole. 1238 35

Aripiprazole (Abilitat, Bristol-Myers Squibb) is the most recent addition to the new class of atypical antipsychotic medications, following the release of clozapine, risperidone, olanzapine, quetiapine and ziprasidone. Aripiprazole exhibits typical antagonism at dopamine (D2) receptors in the mesolimbic pathway, as well as having unique partial agonist activity at D2 receptors in the mesocortical pathway. As exemplified by other atypical antipsychotics, it displays strong 5-HT(2a) receptor antagonism and is similar to ziprasidone in also having agonistic activity at the 5-HT(1a) receptor. Among the atypical antipsychotics, aripiprazole displays the lowest affinity for alpha(1)adrenergic (alpha(1)), histamine (H1) and muscarinic (M1) receptors. This combination of effects may be responsible for its efficacy in positive and negative symptoms of schizophrenia and in bipolar disorder. Similarly, this profile may be the reason for the low rates of reported side effects observed. This includes general adverse events, a low incidence of reported weight gain and a low liability for inducing movement disorders. Other early data suggest that aripiprazole may induce reductions in plasma prolactin, as well as in plasma glucose and lipid profiles. Finally, results also support the proposition that aripiprazole may lead to reductions in corrected QT interval and have minimal drug interactions.
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PMID:Aripiprazole: profile on efficacy and safety. 1247 74

Atypical antipsychotics generally have a lower propensity for extrapyramidal side-effects (EPSE), hyperprolactinaemia and tardive dyskinesia than that associated with typical antipsychotics but may still produce troublesome side-effects, such as weight gain, cardiac rhythm changes and impaired glucose tolerance. Aripiprazole is a new atypical antipsychotic with a unique receptor binding profile that combines partial agonist activity at D2 and 5HT1A receptors with potent antagonism at 5HT2A receptors. Clinical studies in acute schizophrenic relapse, chronic schizophrenia and acute mania show it is robustly more effective than placebo. Once-daily aripiprazole 15-30 mg is as effective as haloperidol 10 mg/day and risperidone 6 mg/day in short-term treatment of schizophrenia and more effective than haloperidol 7-10 mg/day in maintenance of response in chronic schizophrenia. Aripiprazole appears to be well tolerated, with most studies suggesting a frequency of adverse effects similar to placebo. Aripiprazole seems not to cause significant EPSE, hyperprolactinaemia, excessive weight gain or cardiac rhythm disturbance. Limited data suggest that aripiprazole is not associated with impaired glucose tolerance.
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PMID:Aripiprazole: a review of its pharmacology and clinical use. 1258 43

Schizophrenia places an incredible burden on patients, families, communities, and governments, therefore intense efforts to find therapeutic responses to this illness continue. The traditional antipsychotics were discovered by chance, the atypical antipsychotics were configured to preserve "what worked" while adding and eliminating important effects, and the next generation continues to evolve in an attempt to improve on previous generations. Aripiprazole is extoled as a new generation of antipsychotic drugs. Information to date suggests it is an effective antipsychotic with a remarkable side effect profile. We are hopeful this drug will provide a relief for the suffering associated with schizophrenia.
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PMID:Biological perspectives. Aripiprazole: a third generation of antipsychotics begins? 1262 54

Aripiprazole is a novel antipsychotic with a unique mechanism of action. Presented here is a pooled analysis of safety and tolerability data from all completed short-term, placebo-controlled trials in schizophrenia from the aripiprazole clinical development program. Data were analyzed from five 4- to 6-week double-blind multicenter studies of patients hospitalized with acute relapse of schizophrenia or schizoaffective disorder randomized to aripiprazole (n=932), placebo (n=416), or haloperidol (n=201). Daily aripiprazole doses ranged from 2 to 30 mg. Safety assessments included adverse event (AE) reports, EPS scales, ECGs, weight, and prolactin, glucose and cholesterol levels. Aripiprazole was well tolerated, with similar AE incidence rates to placebo, and lower rates than haloperidol for akathisia, extrapyramidal syndrome and somnolence. Objective EPS assessments demonstrated no significant differences between aripiprazole and placebo on Simpson-Angus Scale (SAS) scores, no dose-dependent effects on Barnes Akathisia scores, and significant reductions in Abnormal Involuntary Movement Scale (AIMS) scores from baseline vs. placebo (p</=0.01). Haloperidol showed increased SAS and Barnes Akathisia scores over placebo (p</=0.01). There was minimal mean weight change with aripiprazole (+0.71 kg) and haloperidol (+0.56 kg), and a lack of QT(c) prolongation. Serum prolactin increased with haloperidol, but not aripiprazole. In conclusion, aripiprazole shows a favorable safety and tolerability profile with low potential for EPS, weight gain, prolactin elevation, QT(c) prolongation, and sedation. Aripiprazole's safety profile may offer benefits in schizophrenia treatment.
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PMID:Aripiprazole in the treatment of schizophrenia: safety and tolerability in short-term, placebo-controlled trials. 1272 64

Atypical antipsychotic drugs have revolutionized the treatment of schizophrenia and related disorders. The current clinically approved atypical antipsychotic drugs are characterized by having relatively low affinities for D(2)-dopamine receptors and relatively high affinities for 5-HT(2A) serotonin receptors (5-HT, 5-hydroxytryptamine (serotonin)). Aripiprazole (OPC-14597) is a novel atypical antipsychotic drug that is reported to be a high-affinity D(2)-dopamine receptor partial agonist. We now provide a comprehensive pharmacological profile of aripiprazole at a large number of cloned G protein-coupled receptors, transporters, and ion channels. These data reveal a number of interesting and potentially important molecular targets for which aripiprazole has affinity. Aripiprazole has highest affinity for h5-HT(2B)-, hD(2L)-, and hD(3)-dopamine receptors, but also has significant affinity (5-30 nM) for several other 5-HT receptors (5-HT(1A), 5-HT(2A), 5-HT(7)), as well as alpha(1A)-adrenergic and hH(1)-histamine receptors. Aripiprazole has less affinity (30-200 nM) for other G protein-coupled receptors, including the 5-HT(1D), 5-HT(2C), alpha(1B)-, alpha(2A)-, alpha(2B)-, alpha(2C)-, beta(1)-, and beta(2)-adrenergic, and H(3)-histamine receptors. Functionally, aripiprazole is an inverse agonist at 5-HT(2B) receptors and displays partial agonist actions at 5-HT(2A), 5-HT(2C), D(3), and D(4) receptors. Interestingly, we also discovered that the functional actions of aripiprazole at cloned human D(2)-dopamine receptors are cell-type selective, and that a range of actions (eg agonism, partial agonism, antagonism) at cloned D(2)-dopamine receptors are possible depending upon the cell type and function examined. This mixture of functional actions at D(2)-dopamine receptors is consistent with the hypothesis proposed by Lawler et al (1999) that aripiprazole has "functionally selective" actions. Taken together, our results support the hypothesis that the unique actions of aripiprazole in humans are likely a combination of "functionally selective" activation of D(2) (and possibly D(3))-dopamine receptors, coupled with important interactions with selected other biogenic amine receptors--particularly 5-HT receptor subtypes (5-HT(1A), 5-HT(2A)).
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PMID:Aripiprazole, a novel atypical antipsychotic drug with a unique and robust pharmacology. 1278 5


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