Clinical uses of pimozide

The inhibitory effects of pimozide, an antipsychotic drug, on voltage-gated K+ channels in rabbit coronary arterial smooth muscle cells

Pimozide is an antipsychotic drug used to treat chronic psychosis, such as Tourette's syndrome. Despite its widespread clinical use, pimozide can cause unexpected adverse effects, including arrhythmias. However, the adverse effects of pimozide on vascular K⁺ channels have not yet been determined. Therefore, we investigated the effects of pimozide on voltage-gated K⁺ (Kv) channels in rabbit coronary arterial smooth muscle cells. Pimozide concentration-dependently inhibited the Kv currents with an IC₅₀ value of 1.78 ± 0.17 μM and a Hill coefficient of 0.90 ± 0.05. The inhibitory effect on the Kv current by pimozide was highly voltage-dependent in the voltage range of Kv channel activation, and additive inhibition of the Kv current by pimozide was observed in the full activation voltage range. The decay rate of inactivation was significantly accelerated by pimozide. Pimozide shifted the inactivation curve to a more negative potential. The recovery time constant from inactivation increased in the presence of pimozide. Furthermore, pimozide-induced inhibition of the Kv current was augmented by applying train pulses. Although pretreatment with the Kv2.1 subtype inhibitor guangxitoxin and the Kv7 subtype inhibitor linopirdine did not alter the degree of pimozide-induced inhibition of the Kv currents, pretreatment with the Kv1.5 channel inhibitor DPO-1 reduced the inhibitory effects of pimozide on Kv currents. Pimozide induced membrane depolarization. We conclude that pimozide inhibits Kv currents in voltage-, time-, and use (state)-dependent manners. Furthermore, the major Kv channel target of pimozide is the Kv1.5 channel.

Inhibition of USP1 reverses the chemotherapy resistance through destabilization of MAX in the relapsed/refractory B-cell lymphoma

The patients with relapsed and refractory diffuse large B-cell lymphoma (DLBCL) have poor prognosis, and a novel and effective therapeutic strategy for these patients is urgently needed. Although ubiquitin-specific protease 1 (USP1) plays a key role in cancer, the carcinogenic effect of USP1 in B-cell lymphoma remains elusive. Here we found that USP1 is highly expressed in DLBCL patients, and high expression of USP1 predicts poor prognosis. Knocking down USP1 or a specific inhibitor of USP1, pimozide, induced cell growth inhibition, cell cycle arrest and autophagy in DLBCL cells. Targeting USP1 by shRNA or pimozide significantly reduced tumor burden of a mouse model established with engraftment of rituximab/chemotherapy resistant DLBCL cells. Pimozide significantly retarded the growth of lymphoma in a DLBCL patient-derived xenograft (PDX) model. USP1 directly interacted with MAX, a MYC binding protein, and maintained the stability of MAX through deubiquitination, which promoted the transcription of MYC target genes. Moreover, pimozide showed a synergetic effect with etoposide, a chemotherapy drug, in cell and mouse models of rituximab/chemotherapy resistant DLBCL. Our study highlights the critical role of USP1 in the rituximab/chemotherapy resistance of DLBCL through deubiquitylating MAX, and provides a novel therapeutic strategy for rituximab/chemotherapy resistant DLBCL.

Antipsychotic drug-aripiprazole against schizophrenia, its therapeutic and metabolic effects associated with gene polymorphisms

Second-generation antipsychotics are widely used for the treatment of schizophrenia. Aripiprazole (ARI) is classified as a third-generation antipsychotic drug with a high affinity for dopamine and serotonin receptors. It is considered a dopamine-system stabilizer without severe side effects. In some patients the response to ARI treatment is inadequate and they require an effective augmentation strategy. It has been found that the response to the drug and the risk of adverse metabolic effects can be related to gene polymorphisms. A reduced dose is recommended for CYP2D6 poor metabolizers; moreover, it is postulated that other polymorphisms including CYP3A4, CYP3A5, ABCB1, DRD2, and 5-HTRs genes influence the therapeutic effect of ARI. ARI can increase the levels of prolactin, C-peptide, insulin, and/or cholesterol possibly due to specific genetic variants. It seems that a pharmacogenetic approach can help predict drug response and improve the clinical management of patients with schizophrenia.

Antidepressants and Antipsychotic Agents as Repurposable Oncological Drug Candidates

Drug repurposing, also known as drug repositioning/reprofiling, is a relatively new strategy for the identification of alternative uses of well-known therapeutics that are outside the scope of their original medical indications. Such an approach might entail a number of advantages compared to standard de novo drug development, including less time needed to introduce the drug to the market, and lower costs. The group of compounds that could be considered as promising candidates for repurposing in oncology include the central nervous system drugs, especially selected antidepressant and antipsychotic agents. In this article, we provide an overview of some antidepressants (citalopram, fluoxetine, paroxetine, sertraline) and antipsychotics (chlorpromazine, pimozide, thioridazine, trifluoperazine) that have the potential to be repurposed as novel chemotherapeutics in cancer treatment, as they have been found to exhibit preventive and/or therapeutic action in cancer patients. Nevertheless, although drug repurposing seems to be an attractive strategy to search for oncological drugs, we would like to clearly indicate that it should not replace the search for new lead structures, but only complement de novo drug development.

Emerging Drugs for the Treatment of Amyotrophic Lateral Sclerosis: A Focus on Recent Phase 2 Trials

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease involving both upper and lower motor neurons and resulting in increasing disability and death 3-5 years after onset of symptoms. Over 40 large clinical trials for ALS have been negative, except for Riluzole that offers a modest survival benefit, and Edaravone that modestly reduces disease progression in patients with specific characteristics. Thus, the discovery of efficient disease modifying therapy is an urgent need.

AREAS COVERED

Although the cause of ALS remains unclear, many studies have demonstrated that neuroinflammation, proteinopathies, glutamate-induced excitotoxicity, microglial activation, oxidative stress, and mitochondrial dysfunction may play a key role in the pathogenesis. This review highlights recent discoveries relating to these diverse mechanisms and their implications for the development of therapy. Ongoing phase 2 clinical trials aimed to interfere with these pathophysiological mechanisms are discussed.

EXPERT OPINION

This review describes the challenges that the discovery of an efficient drug therapy faces and how these issues may be addressed. With the continuous advances coming from basic research, we provided possible suggestions that may be considered to improve performance of clinical trials and turn ALS research into a 'fertile ground' for drug development for this devastating disease.

In silico Selection and Experimental Validation of FDA-Approved Drugs as Anti-quorum Sensing Agents

The emergence of antibiotic resistant bacterial pathogens is increasing at an unprecedented pace, calling for the development of new therapeutic options. Small molecules interfering with virulence processes rather than growth hold promise as an alternative to conventional antibiotics. Anti-virulence agents are expected to decrease bacterial virulence and to pose reduced selective pressure for the emergence of resistance. In the opportunistic pathogen Pseudomonas aeruginosa the expression of key virulence traits is controlled by quorum sensing (QS), an intercellular communication process that coordinates gene expression at the population level. Hence, QS inhibitors represent promising anti-virulence agents against P. aeruginosa. Virtual screenings allow fast and cost-effective selection of target ligands among vast libraries of molecules, thus accelerating the time and limiting the cost of conventional drug-discovery processes, while the drug-repurposing approach is based on the identification of off-target activity of FDA-approved drugs, likely endowed with low cytotoxicity and favorable pharmacological properties. This study aims at combining the advantages of virtual screening and drug-repurposing approaches to identify new QS inhibitors targeting the pqs QS system of P. aeruginosa. An in silico library of 1,467 FDA-approved drugs has been screened by molecular docking, and 5 hits showing the highest predicted binding affinity for the pqs QS receptor PqsR (also known as MvfR) have been selected. In vitro experiments have been performed by engineering ad hoc biosensor strains, which were used to verify the ability of hit compounds to decrease PqsR activity in P. aeruginosa. Phenotypic analyses confirmed the impact of the most promising hit, the antipsychotic drug pimozide, on the expression of P. aeruginosa PqsR-controlled virulence traits. Overall, this study highlights the potential of virtual screening campaigns of FDA-approved drugs to rapidly select new inhibitors of important bacterial functions.

Chronic Administration of Pimozide Fails to Attenuate Motor and Pathological Deficits in Two Mouse Models of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease which presently does not have any efficient therapeutic approach. Pimozide, a Food and Drug Administration (FDA)-approved neuroepileptic drug, has been recently proposed as a promising treatment for ALS patients based on apparent stabilization of right hand muscles after a short-time administration. A new clinical trial started at the end of 2017 to recruit patients with a prolonged drug delivery schedule. Here, our aim was to investigate the effects of chronic administration of pimozide on disease progression and pathological events in two mouse models of ALS. Pimozide was administered every 2 days to transgenic mice bearing the ALS-linked A315T mutation on the human TAR DNA-binding protein 43 (TDP-43) gene and to mice carrying the human superoxide dismutase 1 (SOD1) gene with the ALS-linked G93A mutation. Chronic administration of pimozide exacerbated motor performances in both animal models and reduced survival in SOD1G93A mice. In TDP-43A315T, it decreased the percentage of innervated neuromuscular junctions (NMJs) and increased the accumulation of insoluble TDP-43. In SOD1G93A mice, pimozide had no effects on NMJ innervation or motoneuron loss, but it increased the levels of misfolded SOD1. We conclude that a chronic administration of pimozide did not confer beneficial effects on disease progression in two mouse models of ALS. In light of a new clinical trial on ALS patients with a chronic regime of pimozide, these results with mouse models suggest prudence and careful monitoring of ALS patients subjected to pimozide treatment.

Chemical biology applied to the study of bacterial pathogens

In recent years, chemical biology and chemical genomics have been increasingly applied to the field of microbiology to uncover new potential therapeutics as well as to probe virulence mechanisms in pathogens. The approach offers some clear advantages, as identified compounds (i) can serve as a proof of principle for the applicability of drugs to specific targets; (ii) can serve as conditional effectors to explore the function of their targets in vitro and in vivo; (iii) can be used to modulate gene expression in otherwise genetically intractable organisms; and (iv) can be tailored to a narrow or broad range of bacteria. This review highlights recent examples from the literature to illustrate how the use of small molecules has advanced discovery of novel potential treatments and has been applied to explore biological mechanisms underlying pathogenicity. We also use these examples to discuss practical considerations that are key to establishing a screening or discovery program. Finally, we discuss the advantages and challenges of different approaches and the methods that are emerging to address these challenges.

Pimozide for schizophrenia or related psychoses

BACKGROUND

Pimozide, formulated in the 1960s, continues to be marketed for the care of people with schizophrenia or related psychoses such as delusional disorder. It has been associated with cardiotoxicity and sudden unexplained death. Electrocardiogram monitoring is now required before and during use.

OBJECTIVES

To review the effects of pimozide for people with schizophrenia or related psychoses in comparison with placebo, no treatment or other antipsychotic medication.A secondary objective was to examine the effects of pimozide for people with delusional disorder.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Register (28 January 2013).

SELECTION CRITERIA

We sought all relevant randomised clinical trials (RCTs) comparing pimozide with other treatments.

DATA COLLECTION AND ANALYSIS

Working independently, we inspected citations, ordered papers and then re-inspected and assessed the quality of the studies and of extracted data. For homogeneous dichotomous data, we calculated the relative risk (RR), the 95% confidence interval (CI) and mean differences (MDs) for continuous data. We excluded data if loss to follow-up was greater than 50%. We assessed risk of bias for included studies and used GRADE to rate the quality of the evidence.

MAIN RESULTS

We included 32 studies in total: Among the five studies that compared pimozide versus placebo, only one study provided data for global state relapse, for which no difference between groups was noted at medium term (1 RCT n = 20, RR 0.22 CI 0.03 to 1.78, very low quality of evidence). None of the five studies provided data for no improvement or first-rank symptoms in mental state. Data for extrapyramidal symptoms demonstrate no difference between groups for Parkinsonism (rigidity) at short term (1 RCT, n = 19, RR 5.50 CI 0.30 to 101.28, very low quality of evidence) or at medium term (1 RCT n = 25, RR 1.33 CI 0.14 to 12.82, very low quality of evidence), or for Parkinsonism (tremor) at medium term (1 RCT n = 25, RR 1 CI 0.2 to 4.95, very low quality of evidence). No data were reported for quality of life at medium term.Of the 26 studies comparing pimozide versus any antipsychotic, seven studies provided data for global state relapse at medium term, for which no difference was noted (7 RCTs n = 227, RR 0.82 CI 0.57 to 1.17, moderate quality of evidence). Data from one study demonstrated no difference in mental state (no improvement) at medium term (1 RCT n = 23, RR 1.09 CI 0.08 to 15.41, very low quality evidence); another study demonstrated no difference in the presence of first-rank symptoms at medium term (1 RCT n = 44, RR 0.53 CI 0.25 to 1.11, low quality of evidence). Data for extrapyramidal symptoms demonstrate no difference between groups for Parkinsonism (rigidity) at short term (6 RCTs n = 186, RR 1.21 CI 0.71 to 2.05,low quality of evidence) or medium term (5 RCTs n = 219, RR 1.12 CI 0.24 to 5.25,low quality of evidence), or for Parkinsonism (tremor) at medium term (4 RCTs n = 174, RR 1.46 CI 0.68 to 3.11, very low quality of evidence). No data were reported for quality of life at medium term.In the one study that compared pimozide plus any antipsychotic versus the same antipsychotic, significantly fewer relapses were noted in the augmented pimozide group at medium term (1 RCT n = 69, RR 0.28 CI 0.15 to 0.50, low quality evidence). No data were reported for mental state outcomes or for extrapyramidal symptoms (EPS). Data were skewed for quality of life scores, which were not included in the meta-analysis but were presented separately.Two studies compared pimozide plus any antipsychotics versus antipsychotic plus placebo; neither study reported data for outcomes of interest, apart from Parkinsonism at medium term and quality of life using the Specific Level of Functioning scale (SLOF); however, data were skewed.Only one study compared pimozide plus any antipsychotic versus antipsychotics plus antipsychotic; no data were reported for global state and mental state outcomes of interest. Data were provided for Parkinsonism (rigidity and tremor) using the Extrapyramidal Symptom Rating Scale (ESRS); however, these data were skewed.

AUTHORS' CONCLUSIONS

Although shortcomings in the data are evident, enough overall consistency over different outcomes and time scales is present to confirm that pimozide is a drug with efficacy similar to that of other, more commonly used antipsychotic drugs such as chlorpromazine for people with schizophrenia. No data support or refute its use for those with delusional disorder.

Glioblastoma chemotherapy adjunct via potent serotonin receptor-7 inhibition using currently marketed high-affinity antipsychotic medicines

Glioblastoma treatment as now constituted offers increased survival measured in months over untreated patients. Because glioblastomas are active in synthesizing a bewildering variety of growth factors, a systematic approach to inhibiting these is being undertaken as treatment adjunct. The serotonin 7 receptor is commonly overexpressed in glioblastoma. Research documentation showing agonists at serotonin receptor 7 cause increased extracellular regulated kinase 1/2 activation, increased interleukin-6 synthesis, increased signal transducer and activator of transcription-3 activation, increased resistance to apoptosis and other growth enhancing changes in glioblastoma is reviewed in this paper. Because three drugs in wide use to treat thought disorders - paliperidone, pimozide and risperidone - are also potent and well-tolerated inhibitors at serotonin receptor 7, these drugs should be studied for growth factor deprivation in an adjunctive role in glioblastoma treatment.

A small-molecule screen identifies the antipsychotic drug pimozide as an inhibitor of Listeria monocytogenes infection

We developed a screening procedure to identify small-molecule compounds that altered infection by Listeria monocytogenes to gain insights into bacterial/host cellular processes required for intracellular pathogenesis. A small-molecule library of 480 compounds with known biological functions was screened, and 21 compounds that altered the L. monocytogenes infection of murine bone marrow-derived macrophages (BMM) were identified. The identified compounds affected various cellular functions, such as actin polymerization, kinase/phosphatase activity, calcium signaling, and apoptosis. Pimozide, an FDA-approved drug used to treat severe Tourette's syndrome and schizophrenia, was further examined and shown to decrease the bacterial uptake and vacuole escape of L. monocytogenes in BMM. The inhibitory effect of pimozide on internalization was not specific for L. monocytogenes, as the phagocytosis of other bacterial species (Bacillus subtilis, Salmonella enterica serovar Typhimurium, and Escherichia coli K12) was significantly inhibited in the presence of pimozide. The invasion and cell-to-cell spread of L. monocytogenes during the infection of nonprofessional phagocytic cells also was decreased by pimozide treatment. Although pimozide has been reported to be an antagonist of mammalian cell calcium channels, the infection of BMM in a calcium-free medium did not relieve the inhibitory effects of pimozide on L. monocytogenes infection. Our results provide a generalizable screening approach for identifying small-molecule compounds that affect cellular pathways that are required for intracellular bacterial pathogenesis. We also have identified pimozide, a clinically approved antipsychotic drug, as a compound that may be suitable for further development as a therapeutic for intracellular bacterial infections.

Pimozide for schizophrenia or related psychoses

BACKGROUND

Pimozide, formulated in the 1960s, continues to be marketed for the care of people with schizophrenia or related psychoses such as delusional disorder. It has been associated with cardiotoxicity and sudden unexplained deaths. Electrocardiogram monitoring is now required before and during use.

OBJECTIVES

To assess the clinical effects of pimozide for people with schizophrenia, non-affective psychotic mental illness and delusional disorder.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group's Register (July 2005).

SELECTION CRITERIA

We sought all relevant randomised clinical trials comparing pimozide with other treatments.

DATA COLLECTION AND ANALYSIS

Working independently, we inspected citations, ordered papers, and then re-inspected and quality assessed the studies and extracted data. For homogeneous dichotomous data, we calculated the relative risk (RR), 95% confidence interval (CI), and, where appropriate, the number needed to treat (NNT) and the number needed to harm (NNH), on an intention-to-treat basis. We calculated weighted mean differences (WMD) for continuous data. We excluded data if loss to follow-up was greater than 50%.

MAIN RESULTS

We found 35 relevant studies (total n=1348), all including people with schizophrenia but none with delusional disorder. 123 people were randomised to pimozide versus placebo. Data suggest that pimozide prevents relapse (2 RCTs, n=66, RR 0.45 CI 0.2 to 0.9, NNT 4 CI 3 to 22). Compared with typical antipsychotic drugs, pimozide has similar efficacy for outcomes of change in global functioning, mental state, relapse and leaving the study early. People allocated to pimozide did not have a higher mortality than those taking other antipsychotic drugs. Pimozide was more likely than typical antipsychotic drugs to cause tremor in the short-term (6 RCTs, n=192, RR 1.6 CI 1.1 to 2.3, NNH 6 CI 3 to 44) and lead to need for antiparkinsonian medication (4 RCTs, n=124, RR 1.8 CI 1.2 to 2.6, NNH 3 CI 2 to 5) than other drugs. In the medium-term, however, pimozide was less likely to cause sedation (5 RCTs, n=231, RR 0.6 CI 0.5 to 0.9, NNH 6 CI 4 to 16).

AUTHORS' CONCLUSIONS

Although there are shortcomings in the data, there is enough overall consistency over different outcomes and time scales to confirm that pimozide is a drug with similar efficacy to other more commonly used antipsychotic drugs such as chlorpromazine for people with schizophrenia. There are no data to support or refute its use for those with delusional disorder.

Validation of the tremulous jaw movement model for assessment of the motor effects of typical and atypical antipychotics: effects of pimozide (Orap) in rats

Drug-induced tremulous jaw movements (TJMs) in rats have been used as a model of parkinsonian tremor. Previous studies demonstrated that the typical antipsychotic haloperidol induced TJMs after acute or subchronic administration, while atypical antipsychotics did not. Moreover, it has been suggested that the relative potency for suppression of tacrine-induced TJMs relative to the suppression of lever pressing can be used to discriminate between typical and atypical antipsychotics. In order to validate this model with additional drugs, the present studies assessed the effects of the typical antipsychotic pimozide. In the first series of experiments, the effects of acute pimozide on tacrine-induced TJMs and lever pressing were examined. As with haloperidol, pimozide failed to suppress tacrine-induced TJMs, even at doses considerably higher than those that suppressed lever pressing. In the second group of experiments, rats were given single daily injections of pimozide (0.125-1.0 mg/kg) or tartaric acid vehicle for 13 days, and were observed for TJMs on days 1, 7, and 13. Pimozide induced TJMs in a dose-related manner on all days. The jaw movements occurred largely in the 3-7 Hz frequency range characteristic of parkinsonian tremor. These data support the hypothesis that typical antipsychotics can induce TJMs in rats, and demonstrate that chronic administration of typical antipsychotics is not necessary for induction of TJMs. TJMs induced by acute or subchronic pimozide may be related to early-onset motor syndromes such as drug-induced parkinsonism.

Pimozide in dermatologic practice: a comprehensive review

Pimozide is an antipsychotic drug of the diphenylbutylpiperidine class. In the US, it is FDA-approved only as a backup treatment for Gilles de la Tourette syndrome, although it has been used in other countries for many years as a treatment for schizophrenia. In the past 20 years, pimozide has been found to be especially efficacious in the treatment of monosymptomatic hypochondriacal psychoses and is used by psychiatrists and dermatologists for this off-label purpose. In particular, pimozide is considered the treatment of choice for delusions of parasitosis. In addition, pimozide has been found to be efficacious in the treatment of body dysmorphic disorder, metastatic melanoma, trichotillomania, and trigeminal and postherpetic neuralgia. This review aims to familiarize physicians, especially dermatologists, on the uses of pimozide in dermatologic practice. A review of the literature was performed and the relevant information synthesized to give a complete overview of the drug and its therapeutic uses in dermatology.

In vitro inhibition of pimozide N-dealkylation by selective serotonin reuptake inhibitors and azithromycin

Pimozide is often coprescribed with serotonin reuptake inhibitor (SSRI) antidepressants to treat depression in patients with Tourette's syndrome. In human liver microsomes (HLMs), the inhibition of the primary route of pimozide metabolism, N-dealkylation to 1,3-dihydro-1-(4-piperidinyl)-2H-benzimidazol-2-one (DHPBI), by four SSRIs (fluoxetine, sertraline, paroxetine, and fluvoxamine) and azithromycin was tested. Inhibition constants (K(i) values) were estimated from Dixon plots (three HLMs for each inhibitor) using the appropriate enzyme inhibition model by nonlinear regression. At 10 microM paroxetine, sertraline, fluoxetine, or fluvoxamine, the formation of DHPBI from pimozide (10 microM) in HLMs was inhibited by an average (three HLMs) of 7%, 7.7%, 8%, and 16%, respectively, whereas this inhibition did not exceed 55% at the maximum concentrations (100 microM) of the SSRIs tested. Azithromycin had negligible effect on pimozide (10 microM) N-dealkylation (19% at 100 microM azithromycin). These inhibition data were compared with ketoconazole, which was included as a positive control of CYP3A inhibition. At 0.1 microM and 0.5 microM ketoconazole, the formation of DHPBI from 10 microM pimozide was inhibited by 32% and 62%, respectively. The K(i) values (+/- SD) of ketoconazole, sertraline, fluvoxamine, azithromycin, fluoxetine, and paroxetine were 0.07 microM, 89 +/- 44 microM, 89 +/- 24 microM, 103 +/- 52 microM, 117 +/- 27 microM, and 129 +/- 33 microM, respectively. These values are least 100-fold higher than the expected plasma concentrations after the usual daily doses of the SSRIs and azithromycin, suggesting that coadministration of SSRIs and azithromycin are unlikely to markedly diminish the elimination of pimozide in patients. However, in vivo predictions from in vitro data are not always perfect. In vivo, the SSRIs or azithromycin may concentrate in the liver relative to plasma. In addition, the possibility that these drugs could alter pimozide disposition through effects on transport proteins or via promoter repression cannot be ruled out.

Neurotropic and psychotropic drugs in dermatology

Several psychotropic and neurotropic agents are useful in treating patients with skin diseases such as obsessive compulsive skin manipulation, delusions of parasitosis, generalized pruritus, and post-herpetic neuralgia. The mechanism of action of these agents is based on their interaction with central and peripheral neuronal receptors. The medications discussed in this article include the tricyclic antidepressants, serotonin reuptake inhibitors, naltrexone, pimozide, and gabapentin. The pharmacology, mechanism of action, adverse effects, drug interactions, and monitoring guidelines are outlined for each of these drugs.

Therapeutic update: use of risperidone for the treatment of monosymptomatic hypochondriacal psychosis

Monosymptomatic hypochondriacal psychoses such as delusions of parasitosis are often difficult to treat. For the past two decades, pimozide has been considered the drug of choice. Although a few controlled studies have been done to support the efficacy of pimozide, the recommendation of treatment of choice is largely based on case reports. Pimozide has significant side effects, including cardiac and extrapyramidal abnormalities, which are of most concern in the treatment of the elderly. Although pimozide does appear to be effective in some cases of somatic delusional disorders, newer antipsychotics such as risperidone have also been shown to be beneficial in treating this perplexing cluster of disorders. Risperidone is generally considered safer than pimozide and should be considered as first-line therapy for monosymptomatic hypochondriacal psychoses.

Acute and subchronic effects of pimozide on isolation-induced aggression in male mice

The aim of this study was to examine the effects of pimozide (0.25-1.25 mg/kg), administered acutely or subchronically for 10 days, on agonistic behavior elicited by isolation in male mice. Individually housed mice were exposed to anosmic "standard opponents" 90 min after pimozide injections, and the encounters were videotaped and evaluated using an ethologically based analysis. 3. After acute treatment pimozide did not affect significantly aggression and immobility. However, mice treated subchronically with pimozide (0.75 and 1.25 mg/kg) showed a significant reduction in offensive behaviors (threat and attack) and an increase of immobility (1.25 mg/kg). The antiaggressive and motor actions of pimozide were more marked after subchronic treatment than after acute treatment. It might reflect an accumulation of the drug over time, an effect also described with other neuroleptics such as amisulpride.

Pimozide for schizophrenia or related psychoses

BACKGROUND

Pimozide was first formulated in the late 1960s and marketed for the care of those with schizophrenia or related psychoses such as delusional disorder.

OBJECTIVES

To assess the effects of pimozide for people with schizophrenia, non-affective psychotic mental illness and delusional disorder in terms of clinical, social and economic outcomes.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1982-1995), The Cochrane Schizophrenia Group's Register, EMBASE (1980-1995), Janssen-Cilag UK's register of studies (1999), MEDLINE (1966-1995), PsycLIT (1974-1995), hand-searching the references of all included studies and contacting the manufacturers of the compound.

SELECTION CRITERIA

All randomised trials relating to people with schizophrenia, or similar disorders comparing pimozide to other drug treatments were sought. Studies where randomisation was implied rather than stated were included if they did not change the results. Primary outcomes were clinically significant change in global function, mental state, relapse, hospital admission, death, adverse events and acceptability of treatment.

DATA COLLECTION AND ANALYSIS

Studies were selected, rated and data extracted. For dichotomous data Relative Risks (RR) based on a random effects model with the 95% confidence intervals (CI) were estimated. The number needed to treat statistic (NNT) was calculated where indicated. Analysis was by intention-to-treat.

MAIN RESULTS

This review currently includes 34 studies focusing on those with schizophrenia, none on people with delusional disorder. Few people have been randomised to pimozide versus placebo, but data from three longer term studies does suggest that the active drug prevents relapse (RR 0.59 CI 0.4-0.8, NNT 4 CI 2-13). Pimozide has similar efficacy to that of typical antipsychotic drugs for the outcomes of change in global functioning, mental state, relapse and leaving the study early. People allocated to pimozide did not have a higher mortality than those taking other antipsychotics. Pimozide was more likely to cause parkinsonian tremor (RR 1.6 CI 1.1-2.3, NNH 6 CI 3-44) and lead to a requirement for antiparkinsonian medication more frequently (RR 1.8, CI 1.2-2.6, NNH 3 CI 2-5) than other drugs. It was, however, less likely to cause sedation (RR 0.38 CI 0.2-0.7, NNH 6 CI 4-16).

REVIEWER'S CONCLUSIONS

Although there are shortcomings in the data there is enough overall consistency, over different outcomes and time scales, to confirm that pimozide is a drug with similar efficacy to other more commonly used antipsychotics such as chlorpromazine for those with schizophrenia. There are no data to support or refute its use for those with delusional disorder.

Effect of clarithromycin on the pharmacokinetics and pharmacodynamics of pimozide in healthy poor and extensive metabolizers of cytochrome P450 2D6 (CYP2D6)

BACKGROUND

The use of pimozide is associated with prolongation of the QT interval and fatal ventricular arrhythmia. We recently reported 2 fatal cases in patients taking pimozide and clarithromycin and we have shown that clarithromycin inhibits CYP3A-mediated metabolism of pimozide in vitro. In this study, we examined the effect of clarithromycin on pimozide pharmacokinetics and QT interval changes in a total of 12 healthy subjects (7 men and 5 women), documented as extensive metabolizers or poor metabolizers of CYP2D6.

METHODS

In a randomized, double-blind placebo-controlled crossover design, subjects were given a single 6-mg oral dose of pimozide after 5 days of treatment with clarithromycin (500 mg twice a day) or a placebo pill. Blood samples were obtained before and for 96 hours after pimozide administration, and plasma pimozide and clarithromycin concentrations were measured by HPLC. Electrocardiograms for the analysis of the QTc intervals were recorded immediately before each blood sample.

RESULTS

Pimozide significantly lengthened QTc interval in the first 20 hours in both the placebo-treated groups (delta QTcmax = 13.3 +/- 5.3 ms; P = .003) and clarithromycin-treated groups (delta QTcmax = 15.7 +/- 9.5 ms; P = .005) compared with baseline values. This is consistent with an effect of the parent drug. Clarithromycin caused a significant increase in the peak plasma concentration (P = .015), terminal elimination half-life (P = .003), and area under the plasma concentration-time curve (P = .024) and a decrease in the clearance (P = .029) of pimozide. Mean QTcmax observed within 20 hours of pimozide administration was significantly greater in the clarithromycin-treated group (23.8 +/- 12.2 ms; P = .0397) than in the placebo-treated group (16.8 +/- 6 ms). There was no significant effect of CYP2D6 or gender on the pharmacokinetics or pharmacodynamics of pimozide.

CONCLUSIONS

A single 6-mg oral dose of pimozide resulted in measurable QT interval changes. Clarithromycin inhibited CYP3A-mediated pimozide metabolism and the resulting elevation in plasma concentrations may increase the risk of pimozide cardiotoxicity.