A clinical trial of nifedipine in schizophrenia and tardive dyskinesia

L-type calcium channel regulation of dopamine activity in the ventral tegmental area to nucleus accumbens pathway: Implications for substance use, mood disorders and co-morbidities

L-type calcium channels (LTCCs), including the Cav1.2 and Cav1.3 LTCC subtypes, are important regulators of calcium entry into neurons, which mediates neurotransmitter release and synaptic plasticity. Cav1.2 and Cav1.3 are encoded by the CACNA1C and CACNA1D genes, respectively. These genes are implicated in substance use disorders and depression in humans, as demonstrated by genetic-wide association studies (GWAS). Pre-clinical models have also revealed a critical role of LTCCs on drug and mood related behavior, including the co-morbidity of substance use and mood disorders. Moreover, LTCCs have been shown to regulate the neuronal firing of dopamine (DA) neurons as well as drug and stress-induced plasticity within the ventral tegmental area (VTA) to nucleus accumbens (NAc) pathway. Thus, LTCCs are interesting targets for the treatment of neuropsychiatric diseases. In this review, we provide a brief introduction to voltage-gated calcium channels, specifically focusing on the LTCCs. We place particular emphasis on the ability of LTCCs to regulate DA neuronal activity and downstream signaling in the VTA to NAc pathway, and how such processes mediate substance use and mood disorder-related behavioral responses. We also discuss the bi-directional control of VTA LTCCs on drug and mood-related behaviors in pre-clinical models, with implications for co-morbid psychiatric diagnosis. We conclude with a section on the clinical implications of LTCC blockers, many which are already FDA approved as cardiac medications. Thus, pre-clinical and clinical work should examine the potential of LTCC blockers to be repurposed for neuropsychiatric illness. This article is part of the Special Issue on 'L-type calcium channel mechanisms in neuropsychiatric disorders'.

Variation within voltage-gated calcium channel genes and antipsychotic treatment response in a South African first episode schizophrenia cohort

Voltage-gated calcium channels have been implicated in schizophrenia aetiology; however, little is known about their involvement in antipsychotic treatment response. This study investigated variants within the calcium channel subunit genes for association with antipsychotic treatment response in a first episode schizophrenia cohort. Twelve regulatory variants within seven genes were shown to be significantly associated with treatment outcome. Most notably, the CACNA1B rs2229949 CC genotype was associated with improved negative symptomology, where the C allele was predicted to abolish a miRNA-binding site (has-mir-5002-3p), suggesting a possible mechanism of action through which this variant may have an effect. These results implicate the calcium channel subunits in antipsychotic treatment response and suggest that increased activation of these channels may be explored to enhance or predict antipsychotic treatment outcome.

Calcium channel blockers for antipsychotic-induced tardive dyskinesia

BACKGROUND

Schizophrenia and related disorders affect a sizable proportion of any population. Antipsychotic medications are the primary treatment for these disorders. Antipsychotic medications are associated with a variety of adverse effects including tardive dyskinesia. Dyskinesia is a disfiguring movement disorder of the orofacial region that can be tardive (having a slow or belated onset). Tardive dyskinesia is difficult to treat, despite experimentation with several treatments. Calcium channel blockers (diltiazem, nifedipine, nimodipine, verapamil, flunarizine) have been among these experimental treatments.

OBJECTIVES

To determine the effects of calcium channel blocker drugs (diltiazem, nifedipine, nimodipine, verapamil) for treatment of neuroleptic-induced tardive dyskinesia in people with schizophrenia, schizoaffective disorder or other chronic mental illnesses.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group Trials Register (July 2015 and April 2017), inspected references of all identified studies for further trials and contacted authors of trials for additional information.

SELECTION CRITERIA

We selected randomised controlled trials comparing calcium channel blockers with placebo, no intervention or any other intervention for people with both tardive dyskinesia and schizophrenia or serious mental illness who remained on their antipsychotic medication.

DATA COLLECTION AND ANALYSIS

We independently extracted data and estimated risk ratios of dichotomous data or mean differences (MD) of continuous data, with 95% confidence intervals (CI). We assumed that people who left the trials early had no improvement. We also created a 'Summary of findings' table using GRADE.

MAIN RESULTS

Previous versions of this review included no trials. From the 2015 search, we identified three cross-over trials that could be included. The 2017 search found no new studies relevant to this review. The included trials randomised 47 inpatients with chronic mental illnesses in the USA and China. Trials were published in the 1990s and were of short duration (six to 10 weeks). Overall, the risk of bias was unclear, mainly due to poor reporting; allocation concealment was not described, generation of the sequence was not explicit, studies were not clearly blinded, and attrition and outcome data were not fully reported. Findings were sparse, no study reported on the primary outcome 'no clinically important improvement in tardive dyskinesia symptoms,' but two small studies (37 participants) found no difference on the tardive dyskinesia symptoms scale Abnormal Involuntary Movement Scale (AIMS) scores between diltiazem or flunarizine and placebo after three to four weeks' treatment (MD -0.71, 95% CI -2.68 to 1.26, very low quality evidence). Only one study randomising 20 participants reported on adverse events, and reported that there were no adverse events with flunarizine or with placebo (very low quality evidence). One study with 18 participants reported no events of deterioration in mental state with diltiazem or with placebo (very low quality evidence). No studies reported on acceptability of treatment or on social confidence, social inclusion, social networks or personalised quality of life outcomes designated important to patients.

AUTHORS' CONCLUSIONS

Available evidence from randomised controlled trials is extremely limited and very low quality, conclusions cannot be drawn. The effects of calcium channel blockers for antipsychotic-induced tardive dyskinesia are unknown. Their use is experimental and should only be given in the context of well-designed randomised trials.

From Gene to Behavior: L-Type Calcium Channel Mechanisms Underlying Neuropsychiatric Symptoms

The L-type calcium channels (LTCCs) Cav1.2 and Cav1.3, encoded by the CACNA1C and CACNA1D genes, respectively, are important regulators of calcium influx into cells and are critical for normal brain development and plasticity. In humans, CACNA1C has emerged as one of the most widely reproduced and prominent candidate risk genes for a range of neuropsychiatric disorders, including bipolar disorder (BD), schizophrenia (SCZ), major depressive disorder, autism spectrum disorder, and attention deficit hyperactivity disorder. Separately, CACNA1D has been found to be associated with BD and autism spectrum disorder, as well as cocaine dependence, a comorbid feature associated with psychiatric disorders. Despite growing evidence of a significant link between CACNA1C and CACNA1D and psychiatric disorders, our understanding of the biological mechanisms by which these LTCCs mediate neuropsychiatric-associated endophenotypes, many of which are shared across the different disorders, remains rudimentary. Clinical studies with LTCC blockers testing their efficacy to alleviate symptoms associated with BD, SCZ, and drug dependence have provided mixed results, underscoring the importance of further exploring the neurobiological consequences of dysregulated Cav1.2 and Cav1.3. Here, we provide a review of clinical studies that have evaluated LTCC blockers for BD, SCZ, and drug dependence-associated symptoms, as well as rodent studies that have identified Cav1.2- and Cav1.3-specific molecular and cellular cascades that underlie mood (anxiety, depression), social behavior, cognition, and addiction.

Pharmacotherapy for the treatment of tardive dyskinesia in schizophrenia patients

INTRODUCTION

Tardive dyskinesia (TD) is an iatrogenic movement disorder most commonly observed in patients with psychotic disorders who are treated with dopamine blocking antipsychotic medications. Treatment options are limited, and recommendations for treatment are based on a relative scarcity of evidence. Areas covered: After briefly highlighting current mechanistic theories of TD, this review will discuss the evidence for a number of medications of several different classes that have been studied for the treatment of TD since the 1970s with an emphasis on placebo controlled trials when possible. We used a Pubmed search of primary studies, reviews, and metaanalyses on the topic of TD treatment in order to cover this topic. Expert opinion: Treatment of TD is difficult given limited data and incomplete understanding of the mechanism. Treatment of TD must be evaluated on an individual basis with careful weight given to severity of symptoms. We suggest the use of atypical versus conventional antipsychotics whenever possible and would recommend trials with one or more of a number of additional agents starting with valbenazine.

Targeting the schizophrenia genome: a fast track strategy from GWAS to clinic

The Psychiatric Genomics Consortium-Schizophrenia Workgroup (PGC-SCZ) has recently published a genomewide association study (GWAS) identifying >100 genetic loci, encompassing a total of 341 protein-coding genes, attaining genomewide significance for susceptibility to schizophrenia. Given the extremely long time (12-15 years) and expense (>$1 billion) associated with the development of novel drug targets, repurposing of drugs with known and validated targets may be the most expeditious path toward deriving clinical utility from these GWAS findings. In the present study, we examined all genes within loci implicated by the PGC-SCZ GWAS against databases of targets of both approved and registered pharmaceutical compounds. We identified 20 potential schizophrenia susceptibility genes that encode proteins that are the targets of approved drugs. Of these, we prioritized genes/targets that are of clear neuropsychiatric interest and that are also sole members of the linkage disequilibrium block surrounding a PGC-SCZ GWAS hit. In addition to DRD2, 5 genes meet these criteria: CACNA1C, CACNB2, CACNA1I, GRIN2A and HCN1. An additional 20 genes coding for proteins that are the targets of drugs in registered clinical trials, but without approved indications, were also identified. Although considerable work is still required to fully explicate the biological implications of the PGC-SCZ GWAS results, pathways related to these known, druggable targets may represent a promising starting point.

Calcium channel blockers for neuroleptic-induced tardive dyskinesia

BACKGROUND

Schizophrenia and related disorders affect a sizable proportion of any population. Neuroleptic (antipsychotic) medications are the primary treatment for these disorders. Neuroleptic medications are associated with a variety of side effects including tardive dyskinesia. Dyskinesia is a disfiguring movement disorder of the orofacial region that can be tardive (having a slow or belated onset). Tardive dyskinesia is difficult to treat, despite experimentation with several treatments. Calcium channel blockers (diltiazem, nifedipine, nimodipine, verapamil) have been among these experimental treatments.

OBJECTIVES

To determine the effects of calcium-channel blocker drugs (diltiazem, nifedipine, nimodipine, verapamil) for treatment of neuroleptic-induced tardive dyskinesia in people with schizophrenia, schizoaffective disorder or other chronic mental illnesses.

SEARCH STRATEGY

We updated previous searches in May 2010 by searching the Cochrane Schizophrenia Group Register using the Cochrane Schizophrenia Group search strategy.

SELECTION CRITERIA

Randomised clinical trials comparing calcium-channel blockers with placebo, no intervention or any other intervention for people with both tardive dyskinesia and schizophrenia or serious mental illness.

DATA COLLECTION AND ANALYSIS

We planned to extract and analyse data on an intention-to-treat (ITT) basis. We intended to calculate the relative risk (RR) and 95% confidence intervals (CI) of homogeneous dichotomous data using a random-effects model, and, where possible, calculate the number needed to treat. We planned to calculate mean differences (MD) for continuous data.

MAIN RESULTS

We did not include any trials in this review. We excluded 15 studies; eight were not randomised, one did not use calcium channel blockers, five small, randomised, studies reported no usable data and one did not include people with both tardive dyskinesia and schizophrenia.

AUTHORS' CONCLUSIONS

The effects of calcium-channel blockers for antipsychotic induced tardive dyskinesia are unknown. Their use is experimental and should only be given in the context of well designed randomised clinical trials.

The potential role of lamotrigine in schizophrenia

RATIONALE

Atypical antipsychotic drugs are the drugs of choice for the treatment of schizophrenia. However, despite advances, no treatments have been established for patients who fail to improve with the most effective of these, clozapine. The inhibition of dopamine transmission through blockade of dopamine D2 receptors is considered to be essential for antipsychotic efficacy, but it is postulated that modulation of glutamate transmission may be equally important. In support of this, symptoms similar to schizophrenia can be induced in healthy volunteers using N-methyl-D-aspartate (NMDA) antagonist drugs that are also known to enhance glutamate transmission. Furthermore, lamotrigine, which can modulate glutamate release, may add to or synergise with atypical antipsychotic drugs, some of which may themselves modulate glutamate transmission.

OBJECTIVES

We examine the evidence for the efficacy of lamotrigine. We consider how this fits with a glutamate neuron dysregulation hypothesis of the disorder. We discuss mechanisms by which lamotrigine might influence neuronal activity and glutamate transmission, and possible ways in which the drug might interact with antipsychotic medications.

RESULTS

Data from four clinical studies support the efficacy of adjunctive lamotrigine in the treatment of schizophrenia. In addition, and consistent with a glutamate neuron dysregulation hypothesis of schizophrenia, lamotrigine can prevent the psychotic symptoms or behavioural disruption induced by NMDA receptor antagonists in healthy volunteers or rodents.

CONCLUSIONS

The efficacy of lamotrigine is most likely explained within the framework of a glutamate neuron dysregulation hypothesis, and may arise primarily through the drugs ability to influence glutamate transmission and neural activity in the cortex. The drug is likely to act through inhibition of voltage-gated sodium channels, though other molecular interactions cannot be ruled out. Lamotrigine may add to or synergise with some atypical antipsychotic drugs acting on glutamate transmission; alternatively, they may act independently on glutamate and dopamine systems to bring about a combined therapeutic effect. We propose new strategies for the treatment of schizophrenia using a combination of anti-dopaminergic and anti-glutamatergic drugs.

Calcium channel blockers for neuroleptic-induced tardive dyskinesia

BACKGROUND

Tardive dyskinesia is a disfiguring movement disorder of the orofacial region often caused by antipsychotic drugs. A wide range of strategies has been used to help manage tardive dyskinesia and, for people who are unable to have their antipsychotic medication stopped or substantially changed, the calcium-channel blocking group of drugs (diltiazem, nifedipine, nimodipine, verapamil) has been suggested as a useful adjunctive treatment.

OBJECTIVES

To determine the effects of calcium-channel blocker drugs (diltiazem, nifedipine, nimodipine, verapamil) for treatment of neuroleptic-induced tardive dyskinesia in people with schizophrenia, schizoaffective disorder or other chronic mental illnesses.

SEARCH STRATEGY

We updated previous searches of the Cochrane Schizophrenia Group Register (1982-2000), Cochrane Library (Issue 4, 2000), Cochrane Schizophrenia Group's register of trials (November 2000), EMBASE (1980-2000), LILACS (1982-2000), MEDLINE (1966-2000), PsycLIT (1974-2000), and SCISEARCH by searching the Cochrane Schizophrenia Group Register (September 2003). We searched references of all identified studies for further trial citations and contacted authors of trials.

SELECTION CRITERIA

Randomised clinical trials comparing calcium-channel blockers to placebo or no intervention for people with both tardive dyskinesia and schizophrenia or serious mental illness.

DATA COLLECTION AND ANALYSIS

Data were to have been independently extracted and analysed on an intention-to-treat basis. The relative risk (RR) and 95% confidence intervals (CI) of homogeneous dichotomous data were to have been calculated using a random effects model, and, where possible, the number needed to treat calculated. Weighted mean differences (WMD) were to have been calculated for continuous data.

MAIN RESULTS

No trials were included. We excluded fourteen studies; eight were not randomised, one did not use calcium channel blockers and five small, randomised, studies reported no usable data.

REVIEWER'S CONCLUSIONS

The effects of calcium-channel blockers for antipsychotic induced tardive dyskinesia are unknown. Their use is experimental and should only be given in the context of well designed randomised studies.

NMDA receptor antagonist effects, cortical glutamatergic function, and schizophrenia: toward a paradigm shift in medication development

There is an urgent need to improve the pharmacotherapy of schizophrenia despite the introduction of important new medications. New treatment insights may come from appreciating the therapeutic implications of model psychoses. In particular, basic and clinical studies have employed the N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, ketamine, as a probe of NMDA receptor contributions to cognition and behavior. These studies illustrate a translational neuroscience approach for probing mechanistic hypotheses related to the neurobiology and treatment of schizophrenia and other disorders. Two particular pathophysiologic themes associated with schizophrenia, the disturbance of cortical connectivity and the disinhibition of glutamatergic activity may be modeled by the administration of NMDA receptor antagonists. The purpose of this review is to consider the possibility that agents that attenuate these two components of NMDA receptor antagonist response may play complementary roles in the treatment of schizophrenia.

Diltiazem, nifedipine, nimodipine or verapamil for neuroleptic-induced tardive dyskinesia

BACKGROUND

Tardive dyskinesia (TD) is a potentially disfiguring movement disorder of the orofacial region often caused by use of neuroleptic drugs. A wide range of strategies have been used to help manage TD and, for those who are unable to have their antipsychotic medication stopped or substantially changed, the calcium-channel blocking group of drugs (diltiazem, nifedipine, nimodipine, verapamil) has been suggested as a useful adjunctive treatment.

OBJECTIVES

To determine the clinical efficacy of calcium-channel blockers in people with neuroleptic-induced tardive dyskinesia (TD) and schizophrenia or other chronic mental illnesses.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1982-1995), Cochrane Schizophrenia Group's Register of trials (1995), EMBASE (1980-1995), LILACS (1982-1996), MEDLINE (1966-1995), PsycLIT (1974-1995), and SCISEARCH were undertaken. References of all identified studies were searched for further trial citations. Principal authors of trials were contacted.

SELECTION CRITERIA

The inclusion criteria for all relevant randomised studies were that they should focus on people with schizophrenia or other chronic mental illnesses, with neuroleptic-induced TD and compare the use of calcium-channel blockers to placebo or no intervention.

DATA COLLECTION AND ANALYSIS

No data could be extracted from the two randomised controlled trials that are currently awaiting assessment. The authors have been contacted to provide the relevant information.

MAIN RESULTS

No studies met the entry criteria. No data were synthesized.

REVIEWER'S CONCLUSIONS

Based on currently available information, no confident statement can be made about the effectiveness of calcium-channel blockers for treating people with neuroleptic-induced tardive dyskinesia. Before evaluation of these drugs in larger randomised controlled trials, clinicians should carefully weigh up their possible benefits against their potential adverse effects.

Verapamil for severe hyperkinetic movement disorders

The use of verapamil in three cases of severe hyperkinetic movement disorders resulted in dramatic improvement in patients who had been refractory to many other treatments over a prolonged period. A videotape illustration of one of the patients is provided. The mechanism of action and evidence of efficacy of calcium-channel blockers for abnormal movements are discussed.

Pharmacological options for the management of dyskinesias

Dyskinesias are abnormal involuntary movements characterised by an excessive amount of movement. Typically, these movements are choreiform in nature. They may be caused by systemic, metabolic, endocrinologic, structural, vascular, infectious or inherited degenerative conditions, or be toxin- or drug-induced. With many non-drug-induced dyskinesias, treatment of the underlying condition may be sufficient to eliminate the movements, although temporary treatment may be required to control the movements if they are severe. Drug-induced dyskinesias often resolve when the offending drug is discontinued. A notable exception is tardive dyskinesia, which is caused by exposure to dopamine receptor blocking drugs, the majority of which are antipsychotic agents. Tardive dyskinesias will persist, or may even develop after the causative agent has been stopped and may not spontaneously remit. Another commonly encountered form of drug-induced dyskinesia is seen in patients with Parkinson's disease who are receiving levodopa. Medications which deplete dopamine are most successful in treating choreiform dyskinesias, although anticholinergics, GABAergics, serotonergics, and calcium channel blocking agents have been reportedly beneficial in some cases. Treatment of levodopa-induced dyskinesias requires manipulation of the patient's antiparkinsonian drug regimen.

Nilvadipine is effective for chronic schizophrenia in a double-blind placebo-controlled study. off

We investigated the efficacy of nilvadipine, a calcium channel inhibitor, for psychiatric symptoms and tardive dyskinesia in 30 patients with chronic schizophrenia in a placebo-controlled double-blind crossover study. The total scores of the Brief Psychiatric Rating Scale decreased significantly when the patients were on nilvadipine compared with placebo. Improvement was particularly significant in emotional withdrawal and uncooperativeness. Nilvadipine was not effective, however, for tardive dyskinesia. No adverse effects, such as hypotension, occurred.