mdl-100907 and Psychotic-Disorders

Our aim was to describe the efficacy and tolerability of pimavanserin, a highly selective serotonin 5-HT2A receptor inverse agonist/antagonist indicated for the treatment of hallucinations and delusions associated with Parkinson's disease psychosis (PDP), using the metrics of number needed to treat (NNT) and number needed to harm (NNH).. Categorical efficacy and tolerability data were extracted from the clinical trial databases of the double-blind placebo-controlled studies of pimavanserin in persons with PDP. NNT and NNH values were calculated with their respective 95% confidence intervals. The likelihood to be helped or harmed (LHH) was then calculated contrasting therapeutic response versus discontinuation because of an adverse event.. NNT values for pimavanserin 34 mg/d versus placebo for several definitions of clinical response are 10, and/or are not statistically significant, and/or show an advantage for pimavanserin over placebo (such as for postural hypotension). In terms of LHH, pimavanserin 34 mg/d is about five times more likely to result in clinical response (as measured by a ≥3 point decrease from baseline on the Scale for the Assessment of Positive Symptoms adapted for Parkinson's disease) versus discontinuation due to an adverse event.. Using the metrics of NNT, NNH, and LHH, pimavanserin 34 mg/d for the treatment of PDP appears to have a compelling benefit/risk profile.

Topics: Clinical Trials as Topic; Humans; Numbers Needed To Treat; Parkinson Disease; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Urea

We discuss features of Parkinson's disease psychosis (PDP) including symptomology and pathophysiology. Treatment options, including non-pharmacologic strategies, dose reduction of offending agents, and the addition of non-dopaminergic antipsychotics, are addressed. The efficacy of second-generation antipsychotics and novel agents is examined.. Pimavanserin, a 5-HT

Topics: Antipsychotic Agents; Delusions; Hallucinations; Humans; Parkinson Disease; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Urea

Psychosis is common across dementia types with a prevalence of 20% to 70%. Currently, no pharmacologic treatment is approved for dementia-related psychosis. Atypical antipsychotics are frequently used to treat these disorders, despite significant safety concerns. Pimavanserin, a selective 5-HT2A inverse agonist/antagonist, was approved in the U.S. for treating hallucinations and delusions associated with Parkinson's disease psychosis (PDP). Patients in the pimavanserin group experienced a significant (p=0.001) improvement in Scale for the Assessment of Positive Symptoms - Parkinson's disease (SAPS-PD) scores vs. placebo. In a subgroup analysis of patients with cognitive impairment (MMSE score ≥21 but ≤24), the observed improvement on the SAPS-PD with pimavanserin (N=50) was also significant (p=0.002) and larger than in the overall study population without an adverse effect on cognition. In a Phase 2 study with pimavanserin in Alzheimer's disease psychosis, pimavanserin significantly (p=0.045) improved psychosis at Week 6 vs. placebo on the NPI-NH Psychosis Score (PS). In a prespecified subgroup of patients with a baseline NPI-NH PS ≥12, a substantively larger treatment effect (p=0.011) was observed vs. participants with NPI-NH PS <12. The results of these studies in cognitively impaired patients with PDP provided the scientific foundation for an ongoing study of pimavanserin for treating patients with dementia-related psychosis associated with the most common neurodegenerative disorders. The study uses a relapse-prevention design with the endpoint of time-to-relapse of psychosis to evaluate the long-term efficacy and safety of pimavanserin as a potential treatment for hallucinations and delusions of dementia-related psychosis.

Topics: Alzheimer Disease; Clinical Trials as Topic; Dementia; Humans; Mental Status and Dementia Tests; Parkinson Disease; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Severity of Illness Index; Treatment Outcome; Urea

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Although its major manifestation is motor symptoms, resulting from the loss of dopaminergic neurons in the substantia nigra, psychiatric symptoms, such as depression, anxiety, hallucination, delusion, apathy and anhedonia, impulsive and compulsive behaviors, and cognitive dysfunction, may also manifest in most patients with PD. Given that the quality of life - and the need for institutionalization - is so highly dependent on the psychiatric well-being of patients with PD, psychiatric symptoms are of high clinical significance. We reviewed the prevalence, risk factors, pathophysiology, and treatment of psychiatric symptoms to get a better understanding of PD for improved management.

Topics: Anxiety; Dementia; Depression; Disruptive, Impulse Control, and Conduct Disorders; Dopamine; Humans; Parkinson Disease; Psychotic Disorders; Selective Serotonin Reuptake Inhibitors; Serotonin 5-HT2 Receptor Antagonists

Patients with Parkinson's disease psychosis (PDP) are often treated with an atypical antipsychotic, especially quetiapine or clozapine, but side effects, lack of sufficient efficacy, or both may motivate a switch to pimavanserin, the first medication approved for management of PDP. How best to implement a switch to pimavanserin has not been clear, as there are no controlled trials or case series in the literature to provide guidance. An abrupt switch may interrupt partially effective treatment or potentially trigger rebound effects from antipsychotic withdrawal, whereas cross-taper involves potential drug interactions. A panel of experts drew from published data, their experience treating PDP, lessons from switching antipsychotic drugs in other populations, and the pharmacology of the relevant drugs, to establish consensus recommendations. The panel concluded that patients with PDP can be safely and effectively switched from atypical antipsychotics used off label in PDP to the recently approved pimavanserin by considering each agent's pharmacokinetics and pharmacodynamics, receptor interactions, and the clinical reason for switching (efficacy or adverse events). Final recommendations are that such a switch should aim to maintain adequate 5-HT2A antagonism during the switch, thus providing a stable transition so that efficacy is maintained. Specifically, the consensus recommendation is to add pimavanserin at the full recommended daily dose (34 mg) for 2-6 weeks in most patients before beginning to taper and discontinue quetiapine or clozapine over several days to weeks. Further details are provided for this recommendation, as well as for special clinical circumstances where switching may need to proceed more rapidly.

Topics: Antiparkinson Agents; Antipsychotic Agents; Consensus; Drug Substitution; Humans; Off-Label Use; Parkinson Disease; Piperidines; Practice Guidelines as Topic; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Urea

Psychosis is a common and difficult to treat symptom in Alzheimer's disease (AD). It is a cause of diminished quality of life and caregiver distress. Atypical antipsychotics are frequently used for the treatment of dementia-related psychosis, despite FDA warnings because of increased mortality associated with the use of these medications in dementia patients. Aripiprazole is a newer atypical antipsychotic drug with partial agonist activity at dopamine receptors and antagonist activity at 5-HT(2A) receptors, with a low side-effect profile.. This descriptive review gives a short overview of the pathology and epidemiology of AD, including psychotic symptoms, and describes the mode of action of aripiprazole and results of preclinical studies. Finally, randomized controlled trials evaluating the use of aripiprazole in AD-related psychosis and agitation are discussed. Whenever relevant, meta-analytical data from literature are referred to.. In randomized placebo-controlled clinical trials, aripiprazole shows modest efficacy in the treatment of AD-related psychosis. Neuropsychiatric symptoms alleviated were predominantly psychotic features and agitation. In individual trials, aripiprazole was generally well tolerated, serious side effects were seldom reported and included accidental injury and somnolence. Meta-analyses however demonstrated increased mortality as a class effect for atypical, but also for typical antipsychotics. No increased cardiovascular outcomes, cerebrovascular accidents, increased appetite or weight gain were demonstrated in meta-analyses for aripiprazole-treated patients with psychosis of dementia. Aripiprazole was found to induce sedation. Aripiprazole should only be used in selected patient populations resistant to non-pharmacological treatment with persisting or severe psychotic symptoms and/or agitation, and in which symptoms lead to significant morbidity, patient suffering and potential self-harm. The indication for continuing treatment should be revised regularly.

Topics: Alzheimer Disease; Antipsychotic Agents; Aripiprazole; Dopamine Agonists; Humans; Meta-Analysis as Topic; Off-Label Use; Piperazines; Psychotic Disorders; Quinolones; Randomized Controlled Trials as Topic; Receptor, Serotonin, 5-HT2A; Receptors, Dopamine; Serotonin 5-HT2 Receptor Antagonists

Explaining the underlying mechanisms of antipsychotic drug-induced movement disorders remains a substantial challenge. The association of atypical antipsychotic agents with fewer drug-induced movement disorders than conventional agents has engendered several pathophysiologic hypotheses: (1) the hypothesis that, unlike conventional antipsychotic agents, atypical antipsychotics have greater activity in blocking serotonin-2A (5-HT(2A)) receptors than dopamine-2 (D(2)) receptors, which mitigates extrapyramidal symptoms; (2) the hypothesis that atypical antipsychotics block D(2) receptors only long enough to cause an antipsychotic action, but not as long as conventional agents; (3) the hypothesis that, in tardive dyskinesia, the nigrostriatal dopamine receptor system might develop increased sensitivity to dopamine as a result of treatment with conventional antipsychotic drugs, but this may not occur with atypical antipsychotics; and (4) the hypothesis that there might be a genetic association in tardive dystonia relating to the dopamine D(3) allele. A number of factors contribute to the difficult task of gaining insight into the pathophysiologic processes of antipsychotic agents and why these agents may lead to drug-induced movement disorders.

Topics: Age Factors; Antipsychotic Agents; Basal Ganglia Diseases; Dopamine D2 Receptor Antagonists; Dyskinesia, Drug-Induced; Humans; Models, Biological; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Receptors, Dopamine D2; Schizophrenia; Serotonin 5-HT2 Receptor Antagonists; Sex Factors

Parkinson's disease psychosis (PDP) is a common nonmotor symptom that affects up to 60% of patients. Pimavanserin, a selective 5-HT2A inverse agonist/antagonist, is approved for treating hallucinations and delusions associated with PDP.. Evaluate the efficacy and tolerability of pimavanserin in an open-label extension (OLE) study.. Patients completing a pivotal 6-week placebo-controlled trial (Core Study) could enroll in the OLE. All patients pimavanserin 34 mg once daily, blinded to previous treatment allocation. Prespecified blinded assessments at Week 4 were the Scale for the Assessment of Positive Symptoms (SAPS) PD version and SAPS H + D scales, Caregiver Burden Scale (CBS), and Clinical Global Impression (CGI) Improvement and Severity scales.. Of 171 who entered the OLE, 148 (87%) completed Week 4. Among patients who received placebo in the Core Study, mean (SD) change from OLE baseline to OLE Week 4 for the SAPS-PD was - 3.4 (6.3); p < 0.0001. Mean change from Core Study baseline to OLE Week 4 for SAPS-PD was similar among prior pimavanserin- and placebo-treated patients (-6.9 vs. -6.3). Improvement was similar with CGI-I, CGI-S, CBS, and SAPS-H + D in patients previously treated with placebo. Adverse events occurred in 92 (53.8%) patients during the 4-week OLE.. Improvements at OLE Week 4 from pretreatment baseline were similar with placebo and pimavanserin in the Core Study. The beneficial effects observed with pimavanserin in the 6-week Core Study were maintained for 4 weeks in the blinded OLE, supporting the durability of response with pimavanserin 34 mg for PDP over 10 weeks.

Topics: Aged; Aged, 80 and over; Double-Blind Method; Female; Humans; Male; Middle Aged; Outcome Assessment, Health Care; Parkinson Disease; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Agonists; Serotonin 5-HT2 Receptor Antagonists; Urea

Pimavanserin is a 5-HT2A receptor inverse agonist/antagonist and is approved in the United States for the treatment of hallucinations and delusions associated with Parkinson's disease psychosis.. Evaluate the efficacy of pimavanserin on symptoms of psychosis in patients with Alzheimer's disease (AD).. Randomized, double-blind, placebo-controlled trial.. Nursing home residents.. Patients with AD psychosis.. Pimavanserin 34 mg or placebo daily for 12 weeks.. The primary endpoint was mean change from baseline at Week 6 on the Neuropsychiatric Inventory-Nursing Home Version psychosis score (NPI-NH-PS). In the prespecified subgroup analysis, the mean change in NPI-NH-PS and the responder rates among those with baseline NPI-NH-PS ≥12 were evaluated.. Of 181 patients randomized (n=90 pimavanserin; n=91 placebo), 57 had baseline NPI-NH-PS ≥12 (n=27 pimavanserin; n=30 placebo). In this severe subgroup, large treatment effects were observed (delta=-4.43, Cohen's d=-0.73, p=0.011), and ≥30% improvement was 88.9% vs. 43.3% (p<0.001) and ≥50% improvement was 77.8% vs. 43.3% (p=0.008) for pimavanserin and placebo, respectively. The rate of adverse events (AEs) in the severe subgroup was similar between treatment groups, and urinary tract infection, fall, and agitation were most frequent. Serious AEs was similar with pimavanserin (17.9%) and placebo (16.7%) with fewer discontinuations due to AEs with pimavanserin (7.1%) compared to placebo (10.0%). Minimal change from baseline occurred for the mean MMSE score over 12 weeks.. Pimavanserin demonstrated significant efficacy in AD psychosis in patients with higher baseline severity of psychotic symptoms (NPI-NH-PS ≥12). Treatment with pimavanserin showed an acceptable tolerability profile.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Double-Blind Method; Female; Humans; Male; Middle Aged; Nursing Homes; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Treatment Outcome; Urea

Four studies using identical protocols evaluated the safety and efficacy of four novel, evidence-based targets for antipsychotic agents: a neurokinin (NK(3)) antagonist (SR142801), a serotonin 2A/2C (5-HT(2A/2C)) antagonist (SR46349B), a central cannabinoid (CB(1)) antagonist (SR141716), and a neurotensin (NTS(1)) antagonist (SR48692).. Adults with schizophrenia or schizoaffective disorder (N=481) were randomly assigned in a 3:1:1 ratio to receive fixed doses of investigational drug, placebo, or haloperidol for 6 weeks. Primary efficacy variables included changes from baseline in total score on the Positive and Negative Syndrome Scale, severity of illness score on the Clinical Global Impression (CGI), and total score and psychosis cluster score on the Brief Psychiatric Rating Scale (BPRS).. Significantly greater improvement in all primary efficacy variables was seen in the group receiving haloperidol than in the group receiving placebo at 6 weeks (endpoint analyses), indicating the validity of the study. The group receiving the NK(3) antagonist showed significantly greater improvement over baseline than the group receiving placebo as measured by Positive and Negative Syndrome Scale total score, CGI severity of illness score, and BPRS psychosis cluster score. Reductions in the Positive and Negative Syndrome Scale total and negative scores in the group receiving the 5-HT(2A/2C) antagonist were significantly larger than those in the group receiving placebo. The improvements in psychopathology produced by the NK(3) and 5-HT(2A/2C) antagonists were smaller than those produced by haloperidol, although the response to the NK(3) antagonist was positively correlated with plasma levels. The groups receiving the CB(1) and NTS(1) antagonists did not differ from the group receiving placebo on any outcome measure. All investigational drugs were well tolerated.. The novel design used in this study permitted the use of a smaller number of patients receiving placebo to test the efficacy of the four novel compounds. The NK(3) and 5-HT(2A/2C) antagonists showed evidence of efficacy in the treatment of schizophrenia and schizoaffective disorder. Study limitations preclude a definitive conclusion on the efficacy of CB(1) and NTS(1) antagonists in the treatment of schizophrenia. Further study of these two promising nondopaminergic mechanisms to treat schizophrenia and schizoaffective disorder appears indicated.

Topics: Adolescent; Adult; Aged; Antipsychotic Agents; Cannabinoids; Double-Blind Method; Drugs, Investigational; Female; Haloperidol; Humans; Male; Middle Aged; Neurotensin; Peptide Fragments; Piperidines; Placebos; Psychotic Disorders; Pyrazoles; Pyrrolidonecarboxylic Acid; Receptors, Neurokinin-3; Research Design; Rimonabant; Schizophrenia; Serotonin 5-HT2 Receptor Antagonists; Treatment Outcome

Antagonising serotonin (5-HT) type 2A receptors (5-HT. Five 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmosets exhibiting dyskinesia and psychosis-like behaviours (PLBs) were administered L-3,4-dihydroxyphenylalanine (L-DOPA) in combination with vehicle or the 5-HT. EMD-281,014 reduced dyskinesia and PLBs by up to 47% and 40%, respectively (both P < 0.001). The addition of LY-354,740, LY-487,379 and LY-354,740/LY-487,379 decreased dyskinesia by 56%, 65% and 77%, while PLBs were diminished by 55%, 63% and 71% (all P < 0.001). All treatment combinations provided anti-dyskinetic and anti-psychotic benefits significantly greater than those conferred by EMD-281,014 alone (all P < 0.05). The combination of EMD-281,014/LY-354,740/LY-487,379 resulted in anti-dyskinetic and anti-psychotic effects significantly greater than those conferred by EMD-281,014 with either LY-354,740 or LY-487,379 (both P < 0.05). No deleterious effects on L-DOPA anti-parkinsonian action were observed.. Our results suggest that combining 5-HT

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Antiparkinson Agents; Behavior, Animal; Bridged Bicyclo Compounds; Callithrix; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Female; Indoles; Levodopa; Male; Parkinsonian Disorders; Piperazines; Psychotic Disorders; Pyridines; Receptors, Metabotropic Glutamate; Serotonin 5-HT2 Receptor Antagonists; Sulfonamides

Pimavanserin is a first-in-class selective serotonin 5-HT2A receptor inverse agonist approved for the treatment of Parkinson disease psychosis. This article discusses pimavanserin's mechanism of action, which patients are appropriate candidates for therapy, adverse reactions, and appropriate dosing.

Topics: Antipsychotic Agents; Humans; Parkinson Disease; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Urea

Clozapine was the widely accepted gold standard treatment for treatment resistant psychotic symptoms. Clozapine has efficacy of about 50% and some responding patients have to discontinue it due to serious adverse effects. The search for novel agents to use for clozapine-non-responders continues. One such possible agent is the non-dopaminergic antipsychotic pimavanserin, an inverse agonist of serotonin 5-HT2A receptors which was recently approved for the hallucinations and delusions of Parkinson's Disease Psychosis. We report here the successful results of using pimavanserin in patients with refractory hallucinations and delusions who failed to respond to clozapine. We also report similar results in refractory psychosis patients who did not receive clozapine.. We present ten cases of patients with schizophrenia and schizoaffective disorder with refractory hallucinations and delusions who received a trial of pimavanserin when clozapine or multiple antipsychotics failed. Six of ten patients had not responded to a clozapine trial. The subjects' ages ranged between 21 and 77 years and were followed up for several months.. All 10 patients with refractory hallucinations and delusions showed marked response to pimavanserin 34 mg/day within 4-8 weeks, with continuation of the response for several months of follow-up. Improvements in negative symptoms and social functioning were also observed in several patients.. This series of 10 cases of patients with refractory psychosis who responded to pimavanserin is an important new finding that has never been reported before. Controlled studies comparing clozapine and pimavanserin in refractory schizophrenia are warranted to confirm these clinical observations.

Topics: Adult; Aged; Antipsychotic Agents; Clozapine; Delusions; Drug Resistance; Female; Hallucinations; Humans; Male; Middle Aged; Piperidines; Psychotic Disorders; Retrospective Studies; Schizophrenia; Serotonin 5-HT2 Receptor Antagonists; Urea; Young Adult

Development of 5-HT2C agonists for treatment of neuropsychiatric disorders, including psychoses, substance abuse, and obesity, has been fraught with difficulties, because the vast majority of reported 5-HT2C selective agonists also activate 5-HT2A and/or 5-HT2B receptors, potentially causing hallucinations and/or cardiac valvulopathy. Herein is described a novel, potent, and efficacious human 5-HT2C receptor agonist, (-)-trans-(2S,4R)-4-(3'[meta]-bromophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (-)-MBP), that is a competitive antagonist and inverse agonist at human 5-HT2A and 5-HT2B receptors, respectively. (-)-MBP has efficacy comparable to the prototypical second-generation antipsychotic drug clozapine in three C57Bl/6 mouse models of drug-induced psychoses: the head-twitch response elicited by [2,5]-dimethoxy-4-iodoamphetamine; hyperlocomotion induced by MK-801 [(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (dizocilpine maleate)]; and hyperlocomotion induced by amphetamine. (-)-MBP, however, does not alter locomotion when administered alone, distinguishing it from clozapine, which suppresses locomotion. Finally, consumption of highly palatable food by mice was not increased by (-)-MBP at a dose that produced at least 50% maximal efficacy in the psychoses models. Compared with (-)-MBP, the enantiomer (+)-MBP was much less active across in vitro affinity and functional assays using mouse and human receptors and also translated in vivo with comparably lower potency and efficacy. Results indicate a 5-HT2C receptor-specific agonist, such as (-)-MBP, may be pharmacotherapeutic for psychoses, without liability for obesity, hallucinations, heart disease, sedation, or motoric disorders.

Topics: 2-Naphthylamine; Amphetamine; Animals; Antipsychotic Agents; Central Nervous System Stimulants; Feeding Behavior; HEK293 Cells; Humans; Hyperkinesis; Male; Mice, Inbred C57BL; Motor Activity; Psychotic Disorders; Radioligand Assay; Receptor, Serotonin, 5-HT2A; Receptor, Serotonin, 5-HT2B; Receptor, Serotonin, 5-HT2C; Serotonin 5-HT2 Receptor Agonists; Serotonin 5-HT2 Receptor Antagonists; Stereoisomerism; Time Factors

The 5-hydroxytryptamine7 (5-HT7) receptor is a G-protein coupled receptor for serotonin that has been implicated in the pathophysiology of psychiatric and neurological disorders including anxiety, depression and schizophrenia. A number of studies have attempted to evaluate the potential role of the 5-HT7 receptor in schizophrenia by utilising genetic or pharmacological tools but to date these have provided conflicting results. Here we investigate the effect of a selective 5-HT7 receptor antagonist, SB-269970, in in vivo psychosis and cognition models and relate efficacy to brain exposures of the compound. SB-269970 significantly attenuated amphetamine-induced rearing and circling in rats. A similar effect was observed in an N-methyl d-aspartic acid (NMDA) receptor antagonist driven psychosis model, where SB-269970 significantly reversed phencyclidine-induced hyperlocomotion, rearing and circling; although the effect was not as robust as with the 5-HT2a receptor antagonist positive control, MDL100,907. SB-269970 also attenuated a temporal deficit in novel object recognition (NOR), indicative of an improvement in recognition memory. Pharmacokinetic analysis of plasma and brain samples taken after behavioural testing confirmed that efficacy was achieved at doses and pre-treatment times where receptor occupancy was substantial. These findings highlight the anti-psychotic and pro-cognitive potential of 5-HT7 receptor antagonists and warrant further studies to explore their therapeutic potential in schizophrenia.

Topics: Amphetamine; Animals; Animals, Outbred Strains; Cognition; Disease Models, Animal; Fluorobenzenes; Locomotion; Male; Phencyclidine; Phenols; Piperidines; Psychotic Disorders; Rats; Rats, Sprague-Dawley; Receptors, Serotonin; Recognition, Psychology; Serotonin Antagonists; Sulfonamides

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration in cognitive functioning. Overall, 25-50% of patients with AD also show symptoms of psychosis including hallucinations and delusions. As all available antipsychotic drugs have a 'black-box' warning for use in these patients because of increased mortality, no appropriate treatment for psychotic symptoms in AD currently exists. In the present study, we examined whether selective antagonism of 5-HT(2A) serotonin receptors has antipsychotic-like activity in an animal model of AD. Mice receiving an intracerebroventricular infusion of the amyloid β(25-35) peptide fragment showed AD-like histopathology and a psychosis-related behavioral phenotype with enhanced responses to the psychostimulants 2,5-dimethoxy-4-iodoamphetamine hydrochloride and amphetamine as well as disrupted prepulse inhibition. Treatment with pimavanserin, a selective serotonin 5-HT(2A) receptor inverse agonist, prevented 2,5-dimethoxy-4-iodoamphetamine hydrochloride-induced head twitches, reversed the augmented locomotor response to amphetamine, and normalized prepulse inhibition in mice with amyloid pathology. These data suggest that an infusion of amyloid β might induce alterations in serotonergic function that underlie a psychosis-like phenotype that can be normalized by treatment with a 5-HT(2A) inverse agonist. This in turn suggests that 5-HT(2A) inverse agonists, such as pimavanserin, might have therapeutic benefits in the treatment of psychosis in AD patients.

Topics: Alzheimer Disease; Amphetamine; Amphetamines; Animals; Antipsychotic Agents; Behavior, Animal; Disease Models, Animal; Drug Inverse Agonism; Male; Mice; Piperidines; Psychotic Disorders; Serotonin 5-HT2 Receptor Antagonists; Urea

Parkinson's disease psychosis (PDP) is a condition for which a safe, tolerated, and effective therapy is lacking. Treatment with typical or atypical antipsychotics may be contraindicated in patients with PDP because of the potential for aggravating motor symptoms. This study used a novel animal model with features of both Parkinson's disease (PD) and psychosis to examine a potential mechanism for reversing PDP. Animals with bilateral 6-hydroxydopamine lesions of the substantia nigra displayed motoric impairments characteristic of humans with PD. In addition, they displayed augmented head twitches, augmented amphetamine-induced locomotor activity, and disrupted prepulse inhibition compared with sham controls, behavioral indices frequently used to assess antipsychotic activity in animal models. Pimavanserin, a selective 5-HT2A antagonist/inverse agonist, reversed the psychotic-like behavioral deficits, suggesting that nigrostriatal (6-hydroxydopamine) lesions induced alterations in 5-HT2A-mediated signaling. The selective 5-HT2A inverse agonist M100907, but not the selective 5-HT2C inverse agonist SB 252084 paralleled the effects of pimavanserin. Of note, the reversal of psychotic-like behaviors produced by 5-HT2A inverse agonists occurred without disrupting motor behaviors in lesioned subjects, suggesting that 5HT2A antagonism/inverse agonism may be beneficial in the treatment of PDP.

Topics: Amphetamine; Amphetamines; Animals; Antipsychotic Agents; Behavior, Animal; Central Nervous System Stimulants; Disease Models, Animal; Dyskinesias; Fenfluramine; Fluorobenzenes; Hyperkinesis; Male; Motor Activity; Oxidopamine; Parkinson Disease; Piperidines; Psychotic Disorders; Rats, Sprague-Dawley; Receptor, Serotonin, 5-HT2A; Sensory Gating; Serotonin 5-HT2 Receptor Antagonists; Serotonin Agents; Serotonin Receptor Agonists; Substantia Nigra; Tyrosine 3-Monooxygenase; Urea

Topics: Animals; Antipsychotic Agents; Clinical Trials as Topic; Clozapine; Cognition; Dopamine D2 Receptor Antagonists; Drug Evaluation, Preclinical; Drug Industry; Humans; Perphenazine; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Receptors, Dopamine D2; Schizophrenia; Serotonin 5-HT2 Receptor Antagonists

The role of fibroblast growth factor receptors (FGFR) in normal brain development has been well-documented in transgenic and knock-out mouse models. Changes in FGF and its receptors have also been observed in schizophrenia and related developmental disorders. The current study examines a transgenic th(tk-)/th(tk-) mouse model with FGF receptor signaling disruption targeted to dopamine (DA) neurons, resulting in neurodevelopmental, anatomical, and biochemical alterations similar to those observed in human schizophrenia. We show in th(tk-)/th(tk-) mice that hypoplastic development of DA systems induces serotonergic hyperinnervation of midbrain DA nuclei, demonstrating the co-developmental relationship between DA and 5-HT systems. Behaviorally, th(tk-)/th(tk-) mice displayed impaired sensory gaiting and reduced social interactions correctable by atypical antipsychotics (AAPD) and a specific 5-HT2A antagonist, M100907. The adult onset of neurochemical and behavioral deficits was consistent with the postpubertal time course of psychotic symptoms in schizophrenia and related disorders. The spectrum of abnormalities observed in th(tk-)/th(tk-) mice and the ability of AAPD to correct the behavioral deficits consistent with human psychosis suggests that midbrain 5-HT2A-controlling systems are important loci of therapeutic action. These results may provide further insight into the complex multi-neurotransmitter etiology of neurodevelopmental diseases such autism, bipolar disorder, Asperger's Syndrome and schizophrenia.

Topics: Animals; Animals, Newborn; Antipsychotic Agents; Behavior, Animal; Disease Models, Animal; Exploratory Behavior; Female; Fluorobenzenes; Gait Disorders, Neurologic; Grooming; Hydroxyindoleacetic Acid; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neural Inhibition; Piperidines; Protein-Tyrosine Kinases; Psychotic Disorders; Rats; Receptors, Fibroblast Growth Factor; Reflex, Startle; Serotonin; Serotonin Antagonists; Social Behavior

The effect of LSD in humans has been described as occurring in two temporal phases. The behavioral effects in rats also occur in two temporal phases: an initial suppression of exploration followed by increased locomotor activity.. We decided to investigate this phenomenon from the perspective that the pharmacology might have relevance to the neurochemical mechanisms underlying psychosis.. Twenty-five male Sprague-Dawley rats were trained to discriminate LSD (186 nmol/kg, 0.08 mg/kg, i.p.) with a 30-min preinjection time (LSD-30, N=12) and LSD (372 nmol/kg, 0.16 mg/kg, i.p.) with a 90-min preinjection time (LSD-90, N=13) from saline, using a two-lever, food-reinforced operant conditioning task.. LSD (186 or 372 nmol/kg, 0.08 or 0.16 mg/kg) given 30 min prior to training produced a cue that was completely antagonized by 5-HT2A antagonists and lasted no longer than 1 h. LSD (372 nmol/kg, 0.16 mg/kg) injected 90 min before training produced a cue that was not fully blocked by 5-HT2A antagonists, but instead was significantly inhibited by haloperidol. In these rats, substitution no longer occurred with the 5-HT2 agonists DOI or LSD (30 min preinjection), but full substitution was obtained with the D2 agonists apomorphine, N-propyldihydrexidine, and quinelorane.. The discriminative stimulus effect of LSD in rats occurs in two phases, and these studies provide evidence that the later temporal phase is mediated by D2 dopamine receptor stimulation. A second temporal phase that involves dopaminergic pathways would be consistent with the widespread belief that excessive dopaminergic activity may be an underlying cause of paranoid psychosis.

Topics: Amphetamine; Amphetamines; Animals; Apomorphine; Behavior, Animal; Cues; Discrimination Learning; Dopamine Agonists; Dopamine Antagonists; Dopamine D2 Receptor Antagonists; Dopamine Uptake Inhibitors; Dose-Response Relationship, Drug; Fluorobenzenes; Hallucinogens; Haloperidol; Indans; Injections, Intraperitoneal; Lysergic Acid Diethylamide; Male; Piperidines; Psychotic Disorders; Quinolines; Rats; Rats, Sprague-Dawley; Receptors, Dopamine D2; Serotonin Antagonists; Serotonin Receptor Agonists; Time Factors

Abnormalities of serotonin (5HT) function have been implicated in mood disorders, and lithium treatment may produce its beneficial effects by modifying serotonergic mechanisms. It has also been observed that 5HT2A receptors are upregulated both in the postmortem brain and platelets of patients with depression and suicidal behavior. However, the role of 5HT2A receptors in bipolar disorders and in the mechanism of action of lithium is unclear.. The major objective of this study was to examine if abnormalities of 5HT2A receptors are associated with bipolar or schizoaffective disorders and if treatment with lithium would cause changes in the 5HT2A receptors.. 5HT2A receptors were studied in the platelets obtained from drug-free normal control subjects and patients with bipolar ( n=41) or schizoaffective ( n=20) disorders during a drug-free washout period and after treatment (4.0+/-0.44 weeks) with lithium ( n=16). The Bmax and K(D) of 5HT2A receptors were quantitated by binding techniques using [125I]lysergic acid diethylamide (LSD) as a ligand.. We observed that the 5HT2A receptor Bmax was increased in platelets obtained from drug-free bipolar or schizoaffective patients as compared with normal control subjects. The 5HT2A receptor density was even more increased in bipolar or schizoaffective suicidal patients, and the 5HT2A receptor Bmax in the non-suicidal bipolar or schizoaffective subgroup also was significantly higher than in normal control subjects. Treatment with lithium caused a significant increase in the B(max) of platelet 5HT2A receptors in bipolar or schizoaffective patients.. Our studies indicate that increased 5HT2A receptors may be associated with the pathophysiology of bipolar illness and that treatment with lithium further increases the density of 5HT2A receptors. Whether this increase in 5HT2A receptors caused by lithium is associated with its therapeutic mechanism of action is unclear. It is also not clear whether the increase in 5HT2A receptors in bipolar or schizoaffective patients, or in suicidal bipolar or schizoaffective patients, is a trait or state marker.

Topics: Adult; Analysis of Variance; Antipsychotic Agents; Binding Sites; Bipolar Disorder; Blood Platelets; Drug Therapy, Combination; Female; Humans; Iodine Isotopes; Lithium; Lysergic Acid Diethylamide; Male; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Serotonin 5-HT2 Receptor Agonists; Serotonin 5-HT2 Receptor Antagonists; Suicide, Attempted; Tissue Distribution

Risperidone is a widely used atypical antipsychotic with certain advantages over typical antipsychotics. Although variations in the efficacy of treatment with risperidone have been observed, no specific predictable marker has been identified as of yet. In all, 73 Japanese patients with schizophrenia were given risperidone for 8 weeks, and clinical symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). Six candidate polymorphisms (HTR2A -1438G>A, 102T>C, H452Y; DRD2 -141delC, Taq I A; COMT V158M) were genotyped. The diplotype configuration for each individual was estimated by the maximum-likelihood method. Multiple linear regressions were used to analyze the effects of these haplotypes/genotype and other prognostic factors on PANSS scale performance. After adjustment for the effects of patient-related variables, HTR2A diplotype and COMT genotype, as well as other potential prognostic factors, did not significantly influence the clinical performance. A DRD2 haplotype tended to correlate with better clinical performance. Compared with patients who had Ins-A2/Ins-A2 diplotype (n=25), PANSS total scores of patients with Ins-A2/Del-A1 diplotype (n=10) showed 40% greater improvement (P=0.03). The PANSS total scores of patients with HTR2A A-T/A-T diplotype (n=22) tended to show 15% worse improvement compared with A-T/G-C diplotype (n=33) (P=0.06). These results should be treated with caution because of limitations due to small sample size, heterogeneity of patients with respect to past antipsychotic use history, and no correction for multiple corrections. However, the present findings generate important hypotheses in a sample of Japanese schizophrenia patients that may lay the foundation for future pharmacogenomics investigations in other populations.

Topics: Adult; Antipsychotic Agents; Catechol O-Methyltransferase; Chi-Square Distribution; Dopamine D2 Receptor Antagonists; Female; Humans; Male; Middle Aged; Polymorphism, Genetic; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Receptors, Dopamine D2; Risperidone; Schizophrenia; Serotonin 5-HT2 Receptor Antagonists; Statistics, Nonparametric

The goal of this study was to develop a suitable kinetic analysis method for quantification of 5-HT2A receptor parameters with [11C]MDL 100,907. Twelve control studies and four preblocking studies (400 nmol/kg unlabeled MDL 100,907) were performed in isoflurane-anesthetized rhesus monkeys. The plasma input function was determined from arterial blood samples with metabolite measurements by extraction in ethyl acetate. The preblocking studies showed that a two-tissue compartment model was necessary to fit the time activity curves of all brain regions including the cerebellum--in other words, the need for two compartments is not proof of specific binding. Therefore, a three-tissue compartment model was used to analyze the control studies, with three parameters fixed based on the preblocking data. Reliable fits of control data could be obtained only if no more than three parameters were allowed to vary. For routine use of [11C]MDL 100,907, several simplified methods were evaluated. A two-tissue (2T') compartment with one fixed parameter was the most reliable compartmental approach; a one-compartment model failed to fit the data adequately. The Logan graphical approach was also tested and produced comparable results to the 2T' model. However, a simulation study showed that Logan analysis produced a larger bias at higher noise levels. Thus, the 2T' model is the best choice for analysis of [11C]MDL 100,907 studies.

Topics: Animals; Blood Pressure; Brain; Carbon Radioisotopes; Depression; Fluorobenzenes; Heart Rate; Ligands; Macaca mulatta; Models, Biological; Piperidines; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Receptors, Serotonin; Serotonin; Serotonin Antagonists; Tomography, Emission-Computed

The present study has shown that a subthreshold dose of the uncompetitive N-methyl-D-aspartate (NMDA) antagonist MK-801, combined with a subthreshold dose of LSD, produces marked locomotor stimulation in monoamine-depleted mice. Likewise, MK-801, as well as the muscarine receptor antagonist atropine and the alpha-adrenoceptor agonist clonidine, were found to interact synergistically with the putative 5-HT2 receptor agonist UH-232 to produce locomotor activation in monoamine-depleted mice. All these responses were effectively blocked by the highly selective 5-HT2A receptor antagonist MDL 100,907. On the other hand, MDL 100,907 did not antagonize the hyperactivity response produced by clonidine given in combination with MK-801 or atropine in monoamine-depleted mice, nor the response produced by the mixed DA receptor agonist apomorphine, underlining the selectivity in the antagonistic action of MDL 100,907. Furthermore, MDL 100,907 attenuated the hyperactivity produced in intact mice by such disparate agents as MK-801, atropine or the DA uptake inhibitor GBR 12,909. A putative "permissive" role of the 5-HT2 receptor in the context of psychomotor activation is discussed, as well as its possible importance as target for antipsychotic therapy.

Topics: Animals; Biogenic Monoamines; Disease Models, Animal; Dizocilpine Maleate; Dopamine Uptake Inhibitors; Excitatory Amino Acid Antagonists; Fluorobenzenes; Glutamic Acid; Hallucinogens; Lysergic Acid Diethylamide; Male; Mice; Mice, Inbred Strains; Neurotransmitter Agents; Piperazines; Piperidines; Psychomotor Performance; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Receptors, Muscarinic; Receptors, Serotonin; Serotonin; Serotonin Antagonists