Effects of carbamazepine and valproate on haloperidol plasma levels and on psychopathologic outcome in schizophrenic patients

Drug-drug interactions between antiseizure medications and antipsychotic medications: a narrative review and expert opinion

INTRODUCTION

Antiseizure medications (ASMs) and antipsychotic drugs are frequently coadministered with the potential for drug-drug interactions. Interactions may either be pharmacokinetic or pharmacodynamic, resulting in a decrease or increase in efficacy and/or an increase or decrease in adverse effects.

AREAS COVERED

The clinical evidence for pharmacokinetic and pharmacodynamic interactions between ASMs and antipsychotics is reviewed based on the results of a literature search in MEDLINE conducted in April 2023.

EXPERT OPINION

There is now extensive published evidence for the clinical importance of interactions between ASMs and antipsychotics. Enzyme-inducing ASMs can decrease blood concentrations of many of the antipsychotics. There is also evidence that enzyme-inhibiting ASMs can increase antipsychotic blood concentrations. Similarly, there is limited evidence showing that antipsychotic drugs may affect the blood concentrations of ASMs through pharmacokinetic interactions. There is less available evidence for pharmacodynamic interactions, but these can also be important, as can displacement from protein binding. The lack of published evidence for an interaction should not be interpreted as meaning that the given interaction does not occur; the evidence is building continually. There is no substitute for careful patient monitoring and sound clinical judgment.

Pharmacokinetic Interactions Between Antiseizure and Psychiatric Medications

Antiseizure medications and drugs for psychiatric diseases are frequently used in combination. In this context, pharmacokinetic interactions between these drugs may occur. The vast majority of these interactions are primarily observed at a metabolic level and result from changes in the activity of the cytochrome P450 (CYP). Carbamazepine, phenytoin, and barbiturates induce the oxidative biotransformation and can consequently reduce the plasma concentrations of tricyclic antidepressants, many typical and atypical antipsychotics and some benzodiazepines. Newer antiseizure medications show a lower potential for clinically relevant interactions with drugs for psychiatric disease. The pharmacokinetics of many antiseizure medications is not influenced by antipsychotics and anxiolytics, while some newer antidepressants, namely fluoxetine, fluvoxamine and viloxazine, may inhibit CYP enzymes leading to increased serum concentrations of some antiseizure medications, including phenytoin and carbamazepine. Clinically relevant pharmacokinetic interactions may be anticipated by knowledge of CYP enzymes involved in the biotransformation of individual medications and of the influence of the specific comedication on the activity of these CYP enzymes. As a general rule, these interactions can be managed by careful evaluation of clinical response and, when indicated, individualized dosage adjustments guided by measurement of drugs serum concentrations, especially if pharmacokinetic interactions may cause any change in seizure control or signs of toxicity. Further studies are required to improve predictions of pharmacokinetic interactions between antiseizure medications and drugs for psychiatric diseases providing practical helps for clinicians in the clinical setting.

Pharmacokinetic drug interactions with oral haloperidol in adults: dose correction factors from a combined weighted analysis

INTRODUCTION

Pharmacokinetic (PK) drug-drug interactions (DDIs) of oral haloperidol, a first-generation antipsychotic, are systematically reviewed.

AREAS COVERED

After exclusions, the search for DDIs with oral haloperidol provided 47 articles as victim and 7 as perpetrator. Changes in mean haloperidol concentration-to-dose (C/D) ratios after weighting each study's size were used to calculate the effects of other drugs (inhibitors/inducers) on haloperidol. These changes of haloperidol C/D ratio were used to estimate dose-correction factors (<1 for inhibitors and >1 for inducers).

EXPERT OPINION

A box summarizes our recommendations for clinicians regarding our current knowledge of haloperidol PK DDIs, which will need to be updated as new information becomes available. Moderate to strong inducers (carbamazepine, phenobarbital, phenytoin, or rifampin) should be avoided since they required dose-correction factors of 2-5. Smoking appeared to be a weak inducer (dose-correction factor 1.2). Fluvoxamine, promethazine, and combinations of CYP3A4 and CYP2D6 inhibitors should be avoided. There are no long-term studies on fluoxetine to provide a dose correction factor. Limited information suggests that valproate may be an inhibitor (dose-correction factor 0.6). In most patients, haloperidol may not have clinically relevant effects as a perpetrator, but in vitro and clinical studies suggest it is a weak CYP2D6 inhibitor.

Efficacy of Carbamazepine and Its Derivatives in the Treatment of Bipolar Disorder

Background and Objectives: This review is dedicated to the use of carbamazepine and its derivatives oxcarbazepine and eslicarbazepine in bipolar disorder and their relative strengths in treating and preventing new depressive or manic episodes. This paper will discuss the evidence of their efficacy relative to the polarity of relapse from controlled acute and maintenance/relapse prevention studies in bipolar patients. Materials and Methods: A Medline search was conducted for controlled acute and maintenance studies with carbamazepine, oxcarbazepine, and eslicarbazepine in bipolar disorder. In addition, abstracts reporting on controlled studies with these medications from key conferences were taken into consideration. Results: Information was extracted from 84 articles on the acute and prophylactic efficacy of the medications under consideration. They all appear to have stronger efficacy in treating acute mania than depression, which also translates to better protection against manic than depressive relapses for carbamazepine. Still, there is a paucity of controlled acute studies on bipolar depression for all and, with the exception of carbamazepine, a lack of long-term monotherapy maintenance data. For eslicarbazepine, the efficacy in bipolar disorder remains largely unknown. Especially with carbamazepine, tolerability issues and drug-drug interactions need to be kept in mind. Conclusions: Two of the medications discussed in this review, carbamazepine and oxcarbazepine, match Class A criteria according to the criteria proposed by Ketter and Calabrese, meaning acute antimanic efficacy, prevention of manic relapses, and not causing or worsening depression.

How Can Drug Metabolism and Transporter Genetics Inform Psychotropic Prescribing?

Many genetic variants in drug metabolizing enzymes and transporters have been shown to be relevant for treating psychiatric disorders. Associations are strong enough to feature on drug labels and for prescribing guidelines based on such data. A range of commercial tests are available; however, there is variability in included genetic variants, methodology, and interpretation. We herein provide relevant background for understanding clinical associations with specific variants, other factors that are relevant to consider when interpreting such data (such as age, gender, drug-drug interactions), and summarize the data relevant to clinical utility of pharmacogenetic testing in psychiatry and the available prescribing guidelines. We also highlight areas for future research focus in this field.

Valproate for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with ordinary antipsychotic drug treatment. In these cases, various add-on medications are used, and valproate is one of these.

OBJECTIVES

To examine whether:1. valproate alone is an effective treatment for schizophrenia and schizoaffective psychoses; and2. valproate augmentation of antipsychotic medication is an effective treatment for the same illnesses.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Study-Based Register of Trials (July 2002; February 2007; July 2012; March 04, 2016). We also contacted pharmaceutical companies and authors of relevant studies in order to identify further trials.

SELECTION CRITERIA

We included all randomised controlled trials comparing valproate to antipsychotics or to placebo (or no intervention), whether as the sole agent or as an adjunct to antipsychotic medication for the treatment of people with schizophrenia or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

We independently inspected citations and, where possible, abstracts, ordered papers, and re-inspected and quality-assessed these. At least two review authors independently extracted data. We analysed dichotomous data using risk ratio (RR) and its 95% confidence intervals (CI). We analysed continuous data using mean differences (MD) and their 95% CI. We assessed risk of bias for included studies and used GRADE (Grading of Recommendations Assessment, Development and Evaluation) to create a 'Summary of findings' table.

MAIN RESULTS

The 2012 update search identified 19 further relevant studies, most of which were from China. Thus the review currently includes 26 studies with a total of 2184 participants. All trials examined the effectiveness of valproate as an adjunct to antipsychotics. With the exception of two studies, the studies were small, the participants and personnel were not blinded (neither was outcome assessment), and most were short-term and incompletely reported.For this update we prespecified seven main outcomes of interest: clinical response (clinically significant response, aggression/agitation), leaving the study early (acceptability of treatment, overall tolerability), adverse events (sedation, weight gain) and quality of life.Adding valproate to antipsychotic treatment resulted in more clinically significant response than adding placebo to antipsychotic drugs (14 RCTs, n = 1049, RR 1.31, 95% CI 1.16 to 1.47, I2 = 12%, low-quality evidence). However, this effect was removed after excluding open RCTs in a sensitivity analysis. In terms of acceptability of treatment (measured by the number of participants leaving the study early due to any reason) valproate was just as acceptable as placebo (11 RCTs, n = 951, RR 0.76, 95% CI 0.47 to 1.24, I2 = 55%). Also overall tolerability (measured by the number of participants leaving the study early for adverse events) between valproate and placebo was similar (6 RCTs, n = 974, RR 1.33, 95% CI 0.90 to 1.97, I2 = 0).Participants in the valproate group were found to be less aggressive than the control group based on the Modified Overt Aggression Scale (3 RCTs, n = 186, MD -2.55, 95% CI -3.92 to -1.19, I2 = 82%, very low-quality evidence). Participants receiving valproate more frequently experienced sedation (8 RCTs, n = 770, RR 1.38, 95% CI 1.07 to 1.79, I2 = 0, low-quality evidence) but were no more likely to gain weight than those receiving placebo (4 RCTs, n = 427, RR 1.17, 95% CI 0.76 to 1.82, I2 = 0, low-quality evidence). No study reported on the important outcome of quality of life.

AUTHORS' CONCLUSIONS

There is limited evidence, based on a number of trials, that the augmentation of antipsychotics with valproate may be effective for overall clinical response, and also for specific symptoms, especially in terms of excitement and aggression. However, this evidence was entirely based on open RCTs. Moreover, valproate was associated with a number of adverse events among which sedation and dizziness appeared significantly more frequently than in the control groups. Further randomised studies which are blinded are necessary before any clear recommendation can be made. Ideally these would focus on people with schizophrenia and aggression, on those with treatment-resistant forms of the illness and on those with schizoaffective disorders.

Pharmacokinetic considerations and recommendations in palliative care, with focus on morphine, midazolam and haloperidol

INTRODUCTION

A variety of medications are used for symptom control in palliative care, such as morphine, midazolam and haloperidol. The pharmacokinetics of these drugs may be altered in these patients as a result of physiological changes that occur at the end stage of life.

AREAS COVERED

This review gives an overview of how the pharmacokinetics in terminally ill patients may differ from the average population and discusses the effect of terminal illness on each of the four pharmacokinetic processes absorption, distribution, metabolism, and elimination. Specific considerations are also given for three commonly prescribed drugs in palliative care: morphine, midazolam and haloperidol).

EXPERT OPINION

The pharmacokinetics of drugs in terminally ill patients can be complex and limited evidence exists on guided drug use in this population. To improve the quality of life of these patients, more knowledge and more pharmacokinetic/pharmacodynamics studies in terminally ill patients are needed to develop individualised dosing guidelines. Until then knowledge of pharmacokinetics and the physiological changes that occur in the final days of life can provide a base for dosing adjustments that will improve the quality of life of terminally ill patients. As the interaction of drugs with the physiology of dying is complex, pharmacological treatment is probably best assessed in a multi-disciplinary setting and the advice of a pharmacist, or clinical pharmacologist, is highly recommended.

Significant Effect of Valproate Augmentation Therapy in Patients With Schizophrenia: A Meta-analysis Study

Valproate is an anticonvulsant, which is also widely used for treating psychiatric disorders. Some clinical trials have demonstrated benefits of valproate augmentation therapy in schizophrenia. Previous meta-analysis showed inconsistent findings because of limited literature at that time. The aim of this study is to update the newer published data by conducting a meta-analysis of clinical efficacy of valproate augmentation therapy in patients with schizophrenia or schizoaffective disorder. Data sources include electronic research through platform of PubMed. Study eligibility criteria, participants, and interventions were as follows: the inclusion criteria included articles discussing comparisons of the treatment effect in schizophrenic patients treated with antipsychotic augmented with valproate and antipsychotics with/without placebo; articles on clinical trials in humans. The exclusion criteria were case reports or series and nonclinical trials. We compared the effect between antipsychotic treatment with valproate augmentation and antipsychotic monotherapy. Data from clinical trials were pooled by random-effects model, and possible confounding variables were examined through meta-regression and subgroup analysis. Data from 11 articles including 889 patients were included into current meta-analysis. We found patients treated with antipsychotics with valproate augmentation showed significantly more improvement in total psychopathology than those treated with antipsychotics only (P = 0.02). Results from open trials, but not from randomized controlled trials (P = 0.20), showed significant improvement (P = 0.01). In addition, the significance only persisted in the studies conducted with a shorter treatment duration (P < 0.001) rather than longer treatment duration (P = 0.23). There is no difference in the dropout rate between valproate augmentation and antipsychotic treatment only (P = 0.14). We could not perform a detailed meta-analysis for every category of antipsychotics, long-term effect, and safety profiles of valproate augmentation therapy in maintenance treatment, safety in pregnant patients, and subtype of schizophrenia. Our meta-analysis highlights the significantly better treatment effect with valproate augmentation therapy in patients with schizophrenia or schizoaffective disorder, and provides important evidence for supporting the practice of valproate augmentation therapy in these patients.

Carbamazepine for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with just antipsychotic drug treatment and various adjunct medications are used to promote additional response. The antiepileptic carbamazepine is one such drug.

OBJECTIVES

To examine whether carbamazepine or oxcarbazepine alone is an effective treatment for schizophrenia and schizoaffective psychoses and whether carbamazepine or oxcarbazepine augmentation of neuroleptic medication is an effective treatment for the same illnesses.

SEARCH METHODS

For the original version we searched The Cochrane Schizophrenia Group's Register of Trials (December 2001), The Cochrane Library (Issue 3, 2001), MEDLINE (1966-2001), EMBASE (1980-2001), Biological Abstracts (1980-2001), PsycLIT (1886-2001) and PSYNDEX (1974-2001). For the most recent update we searched the Cochrane Schizophrenia Group's Register of Trials in July 2012. We also inspected references of all identified studies for further trials and contacted relevant pharmaceutical companies and authors for additional data.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing carbamazepine or compounds of the carbamazepine family with placebo or no intervention, whether as sole treatment or as an adjunct to antipsychotic medication for the treatment of schizophrenia and/or schizoaffective psychoses.

DATA COLLECTION AND ANALYSIS

We extracted data independently. For homogenous dichotomous data we calculated fixed-effect, risk ratio (RR), with 95% confidence intervals (CIs) on an intention-to-treat basis. For continuous data, we calculated mean differences (MD). We assessed the risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

The updated search did not reveal any further studies that met our inclusion criteria. The number of included studies therefore remains at 10 with the number of participants randomised still 283.One study comparing carbamazepine with placebo as the sole treatment for schizophrenia was abandoned early due to high relapse rate with 26 out of 31 participants relapsing by three months. No effect of carbamazepine was evident with no difference in relapse between the two groups (1 RCT n = 31, RR 1.07 CI 0.78 to 1.45). Another study compared carbamazepine with antipsychotics as the sole treatment for schizophrenia. No differences in terms of mental state were found when comparing 50% reduction in Brief Psychiatric Rating Scale (BPRS) scores (1 RCT n = 38, RR 1.23 CI 0.78 to 1.92). A favourable effect for carbamazepine was found when more people who received the antipsychotic (perphenazine) had parkinsonism (1 RCT n = 38, RR 0.03 CI 0.00 to 0.043). Eight studies compared adjunctive carbamazepine versus adjunctive placebo, we were able use GRADE for quality of evidence for these results. Adding carbamazepine to antipsychotic treatment was as acceptable as adding placebo with no difference between the numbers leaving the study early from each group (8 RCTs n = 182, RR 0.47 CI 0.16 to 1.35, very low quality evidence). Carbamazepine augmentation was superior compared with antipsychotics alone in terms of overall global improvement, but participant numbers were low (2 RCTs n = 38, RR 0.57 CI 0.37 to 0.88). There were no differences for the mental state outcome of 50% reduction in BPRS scores (6 RCTs n = 147, RR 0.86 CI 0.67 to 1.12, low quality evidence). Less people in the carbamazepine augmentation group had movement disorders than those taking haloperidol alone (1 RCT n = 20, RR 0.38 CI 0.14 to 1.02). No data were available for the effects of carbamazepine on subgroups of people with schizophrenia and aggressive behaviour, negative symptoms or EEG abnormalities or with schizoaffective disorder.

AUTHORS' CONCLUSIONS

Based on currently available randomised trial-derived evidence, carbamazepine cannot be recommended for routine clinical use for treatment or augmentation of antipsychotic treatment of schizophrenia. At present large, simple well-designed and reported trials are justified - especially if focusing on people with violent episodes and people with schizoaffective disorders or those with both schizophrenia and EEG abnormalities.

Predictive validity of a MK-801-induced cognitive impairment model in mice: implications on the potential limitations and challenges of modeling cognitive impairment associated with schizophrenia preclinically

Cognitive impairment associated with schizophrenia (CIAS) is a major and disabling symptom domain of the disease that is generally unresponsive to current pharmacotherapies. Critically important to the discovery of novel therapeutics for CIAS is the utilization of preclinical models with robust predictive validity. We investigated the predictive validity of MK-801-induced memory impairments in mouse inhibitory avoidance (MK-IA) as a preclinical model for CIAS by investigating compounds that have been tested in humans, including antipsychotics, sodium channel blocker mood stabilizers, and putative cognitive enhancers. The atypical antipsychotic clozapine, as well as risperidone and olanzapine (see Brown et al., 2013), had no effect on MK-801-induced memory impairments. For sodium channel blockers, carbamazepine significantly attenuated memory impairments induced by MK-801, whereas lamotrigine had no effect. Nicotine, donepezil, modafinil, and xanomeline all significantly attenuated MK-801-induced memory impairments, but the magnitude of effects and the dose-responses observed varied across compounds. Clinically, only acute administration of nicotine has demonstrated consistent positive effects on CIAS, while inconsistent results have been reported for lamotrigine, donepezil, and modafinil; atypical antipsychotics produce only moderate improvements at best. A positive clinical signal has been observed with xanomeline, but only in a small pilot trial. The results presented here suggest that the MK-IA model lacks robust predictive validity for CIAS as the model is likely permissive and may indicate false positive signals for compounds and mechanisms that lack clear clinical efficacy for CIAS. Our findings also highlight the potential limitations and challenges of using NMDA receptor antagonists in rodents to model CIAS.

World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for Biological Treatment of Schizophrenia, part 1: update 2012 on the acute treatment of schizophrenia and the management of treatment resistance

These updated guidelines are based on a first edition of the World Federation of Societies of Biological Psychiatry Guidelines for Biological Treatment of Schizophrenia published in 2005. For this 2012 revision, all available publications pertaining to the biological treatment of schizophrenia were reviewed systematically to allow for an evidence-based update. These guidelines provide evidence-based practice recommendations that are clinically and scientifically meaningful and these guidelines are intended to be used by all physicians diagnosing and treating people suffering from schizophrenia. Based on the first version of these guidelines, a systematic review of the MEDLINE/PUBMED database and the Cochrane Library, in addition to data extraction from national treatment guidelines, has been performed for this update. The identified literature was evaluated with respect to the strength of evidence for its efficacy and then categorised into six levels of evidence (A-F; Bandelow et al. 2008b, World J Biol Psychiatry 9:242). This first part of the updated guidelines covers the general descriptions of antipsychotics and their side effects, the biological treatment of acute schizophrenia and the management of treatment-resistant schizophrenia.

The acute and chronic effects of combined antipsychotic-mood stabilizing treatment on the expression of cortical and striatal postsynaptic density genes

The detection of changes in postsynaptic gene expression after the administration of mood stabilizers, alone or in combination with antipsychotics, and antidepressants in animal models of drug treatment, may represent a valuable strategy to explore the molecular targets of the mainstay treatments for bipolar disorder. In this study we investigated, in both acute and chronic paradigms, the expression of specific postsynaptic density genes (Homer1a, Homer1b/c, and PSD95) and genes putatively implicated in mood stabilizers mechanism of action (GSK3b, ERK) after administration of first (haloperidol) or second generation antipsychotics (quetiapine 30 mg/kg), alone or in combination with valproate. Moreover, we compared the effects of an antidepressant agent widely used in bipolar depression (citalopram) with a low dose of quetiapine (15 mg/kg), which has been demonstrated to display antidepressant action in bipolar depression. In striatal regions, Homer1a expression was strongly induced by haloperidol compared to all the other treatments. Haloperidol plus valproate also markedly induced Homer1a, but to a significant lesser extent than haloperidol alone. Also in the chronic paradigm haloperidol, but not haloperidol plus valproate, induced Homer1a expression in all the subregions of the caudate-putamen and in the nucleus accumbens core. The high dose of quetiapine significantly induced Homer1a in anterior cingulated, premotor and motor subregions of the cortex, and the extent of induction was significantly higher as compared to the lower dose. Oppositely, Homer1a expression was decreased in the cortex by citalopram acute administration. ERK gene was upregulated in cortex and striatum by the acute treatment with valproate and with the combination of haloperidol or quetiapine plus valproate, whereas no significant differences were noticed in GSK3b expression among treatments. PSD95 showed a significant upregulation by acute citalopram and by haloperidol plus valproate in both cortical and subcortical regions. Haloperidol and quetiapine 30 mg/kg, oppositely, significantly reduced the expression of the gene in the cortex. In conclusion, these results suggest that the combined treatment with a typical or an atypical antipsychotic plus valproate may induce differential modulation of postsynaptic genes expression when compared to the effects of these drugs individually administered.

Valproate for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with ordinary antipsychotic drug treatment. In these cases, various add-on medications are used; valproate is one of these.

OBJECTIVES

To review the effects of valproate for the treatment of schizophrenia and schizophrenia-like psychoses.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group's register (last update February 2007). This register is compiled by methodical searches of BIOSIS, CINAHL, Dissertation abstracts, EMBASE, LILACS, MEDLINE, PSYNDEX, PsycINFO, RUSSMED, Sociofile, supplemented with hand searching of relevant journals and numerous conference proceedings. We also contacted a pharmaceutical company and authors of relevant studies in order to identify further trials.

SELECTION CRITERIA

We included all randomised controlled trials comparing valproate to antipsychotics or to placebo (or no intervention), whether as the sole agent or as an adjunct to antipsychotic medication for the treatment of schizophrenia and/or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

We independently inspected citations and, where possible, abstracts, ordered papers and re-inspected and quality assessed these. Data were extracted independently by at least two reviewers. We analysed dichotomous data using relative risks (RR) and the 95% confidence intervals (CI). We analysed continuous data using weighted mean differences. Where possible we calculated the number needed to treat (NNT) or number needed to harm statistics.

MAIN RESULTS

The update search identified two further relevant studies, thus the review currently includes seven studies with a total of 519 participants. All trials examined the effectiveness of valproate as an adjunct to antipsychotics. With one exception the studies were small, short-term and incompletely reported. Adding valproate was as acceptable as adding placebo to antipsychotic drugs (6 RCT, n=270, RR leaving the study early 1.7 CI 0.9 to 3.2). No significant effect of valproate as an adjunct to antipsychotic medication on the participants' global state or the general mental state at the endpoint was evident. However, one study showed a quicker onset of action in the combination group (Casey 2003). A single small study found the participants in the valproate group to be less aggressive than the control group (n=30, WMD -3.8, CI -5.1 to -2.5). Participants receiving valproate more frequently experienced sedation than those in the placebo group. In a single small study valproate significantly reduced tardive dyskinesia (n=30, WMD -3.3, CI -4.9 to -1.7). The effects of valproate on important subgroups such as those with schizophrenia and aggressive behaviour or those with schizoaffective disorder are unknown.

AUTHORS' CONCLUSIONS

Based on currently available randomised trial-derived evidence, there are no data to support or to refute valproate as a sole agent for schizophrenia. There is some evidence for positive effects on aggression and tardive dyskinesia, but given that these results were based on only a single small study they cannot be considered robust. Given the paucity of the available database further large, simple well-designed and reported trials are necessary. Ideally these would focus on people with schizophrenia and aggression, on those with treatment resistant forms of the disorder and on those with schizoaffective disorders.

The effectiveness of anticonvulsants in psychiatric disorders

Anticonvulsant drugs are widely used in psychiatric indications. These include mainly alcohol and benzodiazepine withdrawal syndromes, panic and anxiety disorders, dementia, schizophrenia, affective disorders, bipolar affective disorders in particular, and, to some extent, personality disorders, A further area in which neurology and psychiatry overlap is pain conditions, in which some anticonvulsants, and also typical psychiatric medications such as antidepressants, are helpful. From the beginning of their psychiatric use, anticonvulsants have also been used to ameliorate specific symptoms of psychiatric disorders independently of their causality and underlying illness, eg, aggression, and, more recently, cognitive impairment, as seen in affective disorders and schizophrenia. With new anticonvulsants currently under development, it is likely that their use in psychiatry will further increase, and that psychiatrists need to learn about their differential efficacy and safety profiles to the same extent as do neurologists.

Pharmacodynamic and pharmacokinetic interactions of psychotropic drugs with antiepileptic drugs

Co-morbid psychiatric disorders are relatively frequent in patients with epilepsy. The prevalence rates of mood and anxiety disorders, psychotic disorders and attention deficit/hyperactivity disorder have been found to be significantly higher in patients with epilepsy than in the general population. While co-morbid psychiatric disorders have frequently been considered as complications of the seizure disorder, there is an increasing body of literature that points to a complex relationship between psychiatric and seizure disorders. Because of this, it is crucial that clinicians consider the presence of co-morbid psychiatric disorders when planning the treatment of patients with epilepsy. Having a clear understanding of the pharmacodynamic and pharmacokinetic interactions between antiepileptic drugs and psychotropic drugs is of the essence to avert unnecessary adverse events and loss of efficacy of psychotropic drugs. This chapter provides a practical review on the use of psychotropic drugs for the treatment of these psychiatric co-morbidities in patients with epilepsy.

Update: new uses for lithium and anticonvulsants

Anticonvulsants are being used clinically as monotherapy and adjuncts in mental illnesses other than affective disorders. This review focuses on the literature for anticonvulsants and lithium in substance use disorders, anxiety disorders, and schizophrenia. Given the abuse potential and other difficulties with prescribing benzodiazepines for alcohol and benzodiazepine withdrawal, anticonvulsants have been considered as an alternative. Promising therapeutic effects have been demonstrated in many of the anxiety disorders, with the greatest number of trials and positive results in posttraumatic stress disorder. Although anticonvulsant and lithium augmentation for schizophrenia is common in practice and has been studied in double-blind, randomized, controlled trials, the sum of the evidence has been inconclusive.

Perazine and carbamazepine in comparison to olanzapine in schizophrenia

Atypical antipsychotics like olanzapine are more efficacious in treating negative symptoms and have less side effects. Nevertheless, important adverse effects of olanzapine are, for example, weight gain and hyperglycemia. Perazine in combination with carbamazepine has shown satisfying results in several single-schizophrenia patients, leading to the hypothesis of being equal or even superior to atypical antipsychotic monotherapy. The aim of the present study was to survey the hypothesis that perazine in combination with carbamazepine have an outcome and risk of side effects comparable to olanzapine. Eleven patients with DSM-IV schizophrenia received 14.0 +/- 5.0 mg/day olanzapine and 12 patients received 360.0 +/- 196.0 mg/day perazine in combination with 404.0 +/- 229.0 mg/day carbamazepine. Symptoms and neuropsychological state were assessed 3 times (days 0, 7, 21) using the Positive and Negative Syndrome Scale and the Brief Psychiatric Rating Scale. The neuropsychological state was assessed by the following neuropsychological tests: Benton, d2, ZVT, VLMT and MWT-B. Data were analyzed of variance for multiple dependent variables and repeated-measures multivariate analysis of variance. Positive and Negative Syndrome Scale and Brief Psychiatric Rating Scale scores showed superior improvement in the group receiving olanzapine. Olanzapine offers a more favorable response in positive symptoms than does perazine in combination with carbamazepine. The effect on negative symptoms is favorable in both forms of therapy and no significant differences between the groups could be determined. In both groups, treatment was associated with improved performance in cognitive tests; however, no differences were determined in the effects of the drugs. Results suggest that olanzapine offers a better response in positive symptoms than perazine in combination with carbamazepine.

Carbamazepine for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with just antipsychotic drug treatment and various adjunct medications are used to promote additional response. The antiepileptic carbamazepine is one such drug.

OBJECTIVES

To evaluate the effects of carbamazepine and its derivatives for the treatment of schizophrenia and related psychoses.

SEARCH STRATEGY

For the original version we searched Biological Abstracts (1980-2001), The Cochrane Library (Issue 3, 2001), The Cochrane Schizophrenia Group's Register of Trials (December 2001), EMBASE (1980-2001), MEDLINE (1966-2001), PsycLIT (1886-2001) and PSYNDEX (1974-2001). For the current update we searched the Cochrane Schizophrenia Group's Register of Trials in March 2005 and in December 2006. We also inspected references of all identified studies for further trials and contacted relevant pharmaceutical companies and authors for additional data.

SELECTION CRITERIA

We included all randomised controlled trials comparing carbamazepine or compounds of the carbamazepine family to placebo or no intervention, whether as sole treatment or as an adjunct to antipsychotic medication for the treatment of schizophrenia and/or schizoaffective psychoses.

DATA COLLECTION AND ANALYSIS

We extracted data independently. For homogenous dichotomous data we calculated random effects, relative risk (RR), 95% confidence intervals (CI) and, where appropriate, numbers needed to treat (NNT) on an intention-to-treat basis. For continuous data, we calculated weighted mean differences (WMD).

MAIN RESULTS

The update search did not reveal any further studies that met our inclusion criteria. The number of included studies therefore remains at ten with the number of participants randomised still 258. One study comparing carbamazepine with placebo as the sole treatment for schizophrenia was abandoned early due to high relapse rate with 26 out of 31 participants relapsing by three months. No effect of carbamazepine was evident with no difference in relapse between the two groups (1 RCT n=31, RR 4.1 CI 0.8 to 1.5). Another study compared carbamazepine with antipsychotics as the sole treatment for schizophrenia. No differences in terms of mental state were found when comparing 50% reduction in BPRS scores (1 RCT n=38, RR 1.2 CI 0.8 to 1.9). A favourable effect for carbamazepine was found when more people who received the antipsychotic (perphenazine) had parkinsonism (1 RCT n=38, RR 0.03 CI 0.00 to 0.04, NNH 1 CI 0.9 to 1.4). Eight studies compared adjunctive carbamazepine versus adjunctive placebo. Adding carbamazepine to antipsychotic treatment was as acceptable as adding placebo with no difference between the numbers leaving the study early from each group (8 RCTs n=182, RR 0.5 CI 0.2 to 1.4). Carbamazepine augmentation was superior compared with antipsychotics alone in terms of overall global improvement, but participant numbers were low (2RCTs n=38, RR 0.6 CI 0.4 to 0.9, NNT 2 CI 1 to 5). There were no differences for the mental state outcome of 50% reduction in BPRS scores (6 RCTs n=147, RR 0.9 CI 0.7 to 1.1). Less people in the carbamazepine augmentation group had movement disorders than those taking haloperidol alone (1 RCT n=20, RR 0.4 CI 0.1 to 1.0). No data were available for the effects of carbamazepine on subgroups of people with schizophrenia and aggressive behaviour, negative symptoms or EEG abnormalities or with schizoaffective disorder.

AUTHORS' CONCLUSIONS

Based on currently available randomised trial-derived evidence, carbamazepine cannot be recommended for routine clinical use for treatment or augmentation of antipsychotic treatment of schizophrenia. At present large, simple well-designed and reported trials are justified especially if focusing on those with violent episodes and people with schizoaffective disorders or those with both schizophrenia and EEG abnormalities.

Thirty years of clinical experience with carbamazepine in the treatment of bipolar illness: principles and practice

Carbamazepine began to be studied in a systematic fashion in the 1970s and became more widely used in the treatment of bipolar disorder in the 1980s. Interest in carbamazepine has been renewed by (i) the recent US FDA approval of a long-acting preparation for the treatment of acute mania; (ii) studies suggesting some efficacy in bipolar depression; and (iii) evidence of prophylactic efficacy in some difficult-to-treat subtypes of bipolar illness. A series of double-blind controlled studies of the drug were conducted at the US National Institute of Mental Health from the mid-1970s to the mid-1990s. This review summarises our experience in the context of the current literature on the clinical efficacy, adverse effects and pharmacokinetic interactions of carbamazepine. Carbamazepine has an important and still evolving place in the treatment of acute mania and long-term prophylaxis. It may be useful in individuals with symptoms that are not responsive to other treatments and in some subtypes of bipolar disorder that are not typically responsive to a more traditional agent such as lithium. These subtypes might include those patients with bipolar II disorder, dysphoric mania, substance abuse co-morbidity, mood incongruent delusions, and a negative family history of bipolar illness in first-degree relatives. In addition, carbamazepine may be useful in patients who do not adequately tolerate other interventions as a result of adverse effects, such as weight gain, tremor, diabetes insipidus or polycystic ovarian syndrome. We review our clinical and research experience with carbamazepine alone and in combination with lithium, valproic acid and other agents in complex combination treatment of bipolar illness. More precise clinical and biological predictors and correlates of individual clinical responsiveness to carbamazepine and other mood stabilisers are eagerly awaited.

Do NMDA receptor antagonist models of schizophrenia predict the clinical efficacy of antipsychotic drugs?

N-methyl-D-aspartate (NMDA) receptor antagonists, such as ketamine and phencyclidine, induce perceptual abnormalities, psychosis-like symptoms, and mood changes in healthy humans and patients with schizophrenia. The similarity between NMDA receptor antagonist-induced psychosis and schizophrenia has led to the widespread use of the drugs to provide models to aid the development of novel treatments for the disorder. This review investigates the predictive validity of NMDA receptor antagonist models based on a range of novel treatments that have now reached clinical trials. Furthermore, it considers the extent to which the different hypotheses that have been proposed to account for the psychotomimetic effects of NMDA receptor antagonist have been validated by the results of these trials. Finally, the review discusses some of the caveats associated with use of the models and some suggestions as to how a greater use of translational markers might ensure progress in understanding the relationship between the models and schizophrenia.

Involvement of adenosine in the neurobiology of schizophrenia and its therapeutic implications

Based on the neuromodulatory and homeostatic actions of adenosine, adenosine dysfunction may contribute to the neurobiological and clinical features of schizophrenia. The present model of adenosine dysfunction in schizophrenia takes into consideration the dopamine and glutamate hypotheses, since adenosine exerts neuromodulatory roles on these systems, and proposes that adenosine plays a role in the inhibitory deficit found in schizophrenia. Given the role of adenosine activation of adenosine A1 receptor (A1R) in mediating neurotoxicity in early stages of brain development, pre- and peri-natal complications leading to excessive adenosine release could induce primary brain changes (i.e., first hit). These events would lead to an adenosine inhibitory deficit through a partial loss of A1R that may emerge as reduced control of dopamine activity and increased vulnerability to excitotoxic glutamate action in the mature brain (i.e., second hit). Adenosine dysfunction is reasonably compatible with symptoms, gray and white matter abnormalities, progressive brain loss, pre- and peri-natal risk factors, age of onset, response to current treatments, impaired sensory gating and increased smoking in schizophrenia. Pharmacological treatments enhancing adenosine activity could be effective for symptom control and for alleviating deterioration in the course of the illness. Accordingly, allopurinol, which may indirectly increase adenosine, has been effective and well tolerated in the treatment of schizophrenia. Since much of the evidence for the adenosine hypothesis is preliminary and theoretical, further investigation in the field is warranted.

Use of psychotropic drugs in patients with epilepsy: interactions and seizure risk

It is now accepted that patients with epilepsy are more prone than the general population to develop psychiatric disorders, being significantly at risk due to psychosocial reasons, the presence of electrophysiologic and anatomopathologic abnormalities mainly in the limbic system, and because they are taking antiepileptic drugs which may have negative psychotropic effects. It is also known that many patients with epilepsy sometimes receive psychotropic medications on account of their psychiatric symptoms. This review focuses on the main problems that a clinician may encompass when treating psychiatric disorders in patients with epilepsy. On one hand, the effects of antiepileptic drugs on mood and behavior for a correct differential diagnosis of psychiatric symptoms. On the other hand, the main factors that may affect choice of therapy, patients' response and compliance, when prescribing antidepressants or antipsychotic drugs, drug interactions and the potential proconvulsive risk are reviewed.

Sensitive Determination of 4-(4-Bromophenyl)-4-hydroxypiperidine, a Metabolite of Bromperidol, in Rat Plasma by HPLC with Fluorescence Detection after Pre-column Derivatization Using 4-Fluoro-7-nitro-2,1,3-benzoxadiazole

The purpose of this study was to determine the level of 4-(4-bromophenyl)-4-hydroxypiperidine (BPHP), a bromperidol (BRO) metabolite, in rat plasma by HPLC with fluorescence detection after pre-column derivatization using 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). After basic extraction of the samples with benzene, derivatization with NBD-F was conducted in borate buffer (pH 8.0) at 60 degrees C for 3 min. Mexiletine was utilized through the procedure as an internal standard (IS). Retention times of the BPHP and IS derivatives were 7.7 and 11.5 min, respectively. The regression equation for BPHP showed good linearity in the range of 0.01-1 mg/ml with the detection limit of 0.003 microg/ml. The coefficient of variation was less than 12.0%. The recovery was satisfactory. This method was applied for a pharmacokinetic study of BPHP in comparison with 4-(4-chlorophenyl)-4-hydroxypiperidine (CPHP), the corresponding haloperidol (HAL) metabolite, in rats. The ratio of the area under the plasma concentration curve (AUC) after p.o. administration of BPHP to the AUC after i.p. administration of BPHP (46%) was lower than that of CPHP (56%), indicating that intestinal absorption of BPHP is lower than that of CPHP. The ratio of BRO metabolism to BPHP (48%) was 1.8-fold higher than that of HAL metabolism to CPHP (27%); the ratio was estimated as (AUCp.o.,A-->B/AUCp.o.,B)x100, where AUCp.o.,A-->B is the AUC value of BPHP or CPHP after p.o. administration of BRO or HAL, and AUCp.o.,B is the AUC of BPHP or CPHP after administration of BPHP or CPHP, respectively. Our method provides a sensitive procedure for determination of BPHP in rat plasma and is suitable for pharmacokinetic studies of BPHP after BRO administration.

Interactions between Antiepileptic and Antipsychotic Drugs

Antiepileptic and antipsychotic drugs are often prescribed together. Interactions between the drugs may affect both efficacy and toxicity. This is a review of human clinical data on the interactions between the antiepileptic drugs carbamazepine, valproic acid (sodium valproate), vigabatrin, lamotrigine, gabapentin, topiramate, tiagabine, oxcarbazepine, levetiracetam, pregabalin, felbamate, zonisamide, phenobarbital and phenytoin with the antipsychotic drugs risperidone, olanzapine, quetiapine, clozapine, amisulpride, sulpiride, ziprasidone, aripiprazole, haloperidol and chlorpromazine; the limited information on interactions between antiepileptic drugs and zuclopenthixol, periciazine, fluphenazine, flupenthixol and pimozide is also presented. Many of the interactions depend on the induction or inhibition of the cytochrome P450 isoenzymes, but other important mechanisms involve the uridine diphosphate glucuronosyltransferase isoenzymes and protein binding. There is some evidence for the following effects. Carbamazepine decreases the plasma concentrations of both risperidone and its active metabolite. It also decreases concentrations of olanzapine, clozapine, ziprasidone, haloperidol, zuclopenthixol, flupenthixol and probably chlorpromazine and fluphenazine. Quetiapine increases the ratio of carbamazepine epoxide to carbamazepine and this may lead to toxicity. The data on valproic acid are conflicting; it may either increase or decrease clozapine concentrations, and it appears to decrease aripiprazole concentrations. Chlorpromazine possibly increases valproic acid concentrations. Lamotrigine possibly increases clozapine concentrations. Phenobarbital decreases clozapine, haloperidol and chlorpromazine concentrations. Phenytoin decreases quetiapine, clozapine, haloperidol and possibly chlorpromazine concentrations. There are major gaps in the data. In many cases there are no published clinical data on interactions that would be predicted on theoretical grounds.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for biological treatment of schizophrenia, Part 1: acute treatment of schizophrenia

These guide lines for the biological treatment of schizophrenia were developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBO). The goal during the development of these guidelines was to review systematically all available evidence pertaining to the treatment of schizophrenia, and to reach a consensus on a series of practice recommendations that are clinically and scientifically meaningful based on the available evidence. These guidelines are intended for use by all physicians seeing and treating people with schizophrenia. The data used for developing these guidelines have been extracted primarily from various national treatment guidelines and panels for schizophrenia, as well as from meta-analyses, reviews and randomised clinical trials on the efficacy of pharmacological and other biological treatment interventions identified by a search of the MEDLINE database and Cochrane Library. The identified literature was evaluated with respect to the strength of evidence for its efficacy and then categorised into four levels of evidence (A-D). This first part of the guidelines covers disease definition, classification, epidemiology and course of schizophrenia, as well as the management of the acute phase treatment. These guidelines are primarily concerned with the biological treatment (including antipsychotic medication, other pharmacological treatment options, electroconvulsive therapy, adjunctive and novel therapeutic strategies) of adults suffering from schizophrenia.

An overview of psychotropic drug-drug interactions

The psychotropic drug-drug interactions most likely to be relevant to psychiatrists' practices are examined. The metabolism and the enzymatic and P-glycoprotein inhibition/induction profiles of all antidepressants, antipsychotics, and mood stabilizers are described; all clinically meaningful drug-drug interactions between agents in these psychotropic classes, as well as with frequently encountered nonpsychotropic agents, are detailed; and information on the pharmacokinetic/pharmacodynamic results, mechanisms, and clinical consequences of these interactions is presented. Although the range of drug-drug interactions involving psychotropic agents is large, it is a finite and manageable subset of the much larger domain of all possible drug-drug interactions. Sophisticated computer programs will ultimately provide the best means of avoiding drug-drug interactions. Until these programs are developed, the best defense against drug-drug interactions is awareness and focused attention to this issue.

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.

Evaluation of the effects of lamotrigine, valproate and carbamazepine in a rodent model of mania

Bipolar disorder is a psychiatric condition characterised by episodes of mania, depression, and underlying mood instability. Anticonvulsant drugs have an established place in the treatment of the disorder, but identifying novel drugs in this class is complicated by the absence of validated animal models. We have evaluated the efficacy of three anticonvulsant mood stabilising drugs (lamotrigine, valproate, and carbamazepine) in a model of mania, in which hyperactivity is induced by the combination of D-amphetamine and chlordiazepoxide. All three drugs were effective at preventing the hyperactivity. Lower doses of valproate and carbamazepine were required to prevent hyperactivity compared to doses required to block tonic-clonic seizures induced by pentylenetetrazole. Lamotrigine was equipotent in the two models. However, the complex pharmacology of the D-amphetamine/chlordiazepoxide model means that there may be several mechanisms by which hyperactivity can be reduced, and these may have more or less relevance to the treatment of bipolar disorder. To address this issue, we also evaluated effects of the three anticonvulsants on baseline locomotion, on activity in the presence of chlordiazepoxide alone, or on activity induced by D-amphetamine alone. Based on the results, we propose that hyperactivity induced by D-amphetamine/chlordiazepoxide may arise through dopaminergic drive coupled with disinhibition caused by low doses of the benzodiazepine. The efficacy of lamotrigine may then arise through a reduction in neuronal excitability or increased glutamate transmission, these latter a consequence of the disinhibition. Carbamazepine may also reduce excitability and glutamate release, but its broader pharmacology, manifested by sedation at higher doses complicates interpretation of its efficacy and reflects its poorer tolerability in the clinic. Valproate may be effective, at least in part, through an enhancement of GABAergic transmission. The predictive validity of the D-amphetamine/chlordiazepoxide model for efficacy in bipolar disorder remains to be established, and research with a wider range of clinically tested drugs is warranted to help validate the model further. In the meantime, the model may be useful for distinguishing novel anticonvulsant drugs with different mechanisms of action.

Toward convergence in the medication treatment of bipolar disorder and schizophrenia

Reaching a correct differential diagnosis among patients with psychotic symptoms was especially important during the era of first-generation antipsychotics, when treatments for the different disorders varied in terms of adverse events and likelihood of response. The historical "overdiagnosis" of schizophrenia and "underdiagnosis" of bipolar disorder in the United States was blamed for an increased exposure to neuroleptics among patients who might have benefited from lithium. With the recognition that second-generation antipsychotics are useful in the treatment of both schizophrenia and bipolar mania, and that combining them with classic mood stabilizers such as valproate may results in increased efficacy, the field is witnessing a convergence of pharmacological approaches to the treatment of schizophrenia and bipolar disorder. Substantially more data is available regarding combination treatments for bipolar disorder than for schizophrenia, and appropriate diagnosis remains important in predicting prognosis, but until the precise pathophysiology of psychotic disorders can be elucidated, and specific targeted treatments crafted, we will continue to see similar blended treatments for these two disease states.

Valproate as an adjunct to antipsychotics for schizophrenia: a systematic review of randomized trials

Randomized controlled trials comparing valproate (as a sole, or as an adjunctive compound) to placebo for patients with schizophrenia or schizophrenia-like disorders were summarized in a metaanalysis. It was possible to include only five trials (n = 379) examining valproate as add-on to antipsychotics in this review. Some of the single studies showed inconsistent beneficial effects on some aspects of response, but no overall superiority of valproate augmentation at study endpoints was shown.

The World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for the biological treatment of bipolar disorders, part III: maintenance treatment

As with the two preceding guidelines of this series, these practice guidelines for the pharmacological maintenance treatment of bipolar disorder were developed by an international task force of the World Federation of Societies of Biological Psychiatry (WFSBP). Their purpose is to supply a systematic overview of all scientific evidence relating to maintenance treatment. The data used for these guidelines were extracted from a MEDLINE and EMBASE search, from recent proceedings from key conferences and various national and international treatment guidelines. The scientific justification of support for particular treatments was categorised into four levels of evidence (A-D). As these guidelines are intended for clinical use, the scientific evidence was not only graded, but also reviewed by the experts of the task force to ensure practicality.

Valproate for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with ordinary antipsychotic drug treatment. In these cases, various add-on medications are used, among them valproate.

OBJECTIVES

To review the effects of valproate for the treatment of schizophrenia and schizophrenia-like psychoses.

SEARCH STRATEGY

The reviewers searched the Cochrane Schizophrenia Group's register (July 2002). This register is compiled of methodical searches of BIOSIS, CINAHL, Dissertation abstracts, EMBASE, LILACS, MEDLINE, PSYNDEX, PsycINFO, RUSSMED, Sociofile, supplemented with hand searching of relevant journals and numerous conference proceedings. We also contacted a pharmaceutical company and authors of relevant studies in order to identify further trials.

SELECTION CRITERIA

All randomised controlled trials comparing valproate to antipsychotics or to placebo (or no intervention), whether as the sole agent or as an adjunct to antipsychotic medication for the treatment of schizophrenia and/or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were extracted independently by at least two reviewers. Dichotomous data were analysed using relative risks (RR) and the 95% confidence intervals (CI). Continuous data were analysed using weighted mean differences. Where possible the number needed to treat (NNT) or number needed to harm statistics were calculated.

MAIN RESULTS

Five studies with a total of 379 participants were included. All trials examined the effectiveness of valproate as an adjunct to antipsychotics. With one exception the studies were small, short-term and incompletely reported. Adding valproate was as acceptable as adding placebo to antipsychotic drugs (n=130, RR leaving the study early 1.6 CI 0.8 to 3.1). No significant effect of using valproate as an adjunct to antipsychotic medication on the participants' global state or general mental state at the endpoint studies was evident. However, one study showed a quicker onset of action in the combination group. Participants receiving valproate more frequently experienced sedation than those in the placebo group. The effects of valproate on important subgroups such as those with schizophrenia and aggressive behaviour or those with schizoaffective disorder are unknown.

REVIEWER'S CONCLUSIONS

Based on randomised trial-derived evidence which is currently available, there are no data to support or to refute the use of valproate as a sole agent for schizophrenia. There is some evidence for a more rapid improvement with valproate augmentation, but this effect vanished over time. Given this limited evidence, further large, simple well-designed and reported trials are necessary. These might focus on people with schizophrenia and violent episodes, on those with treatment resistant forms of the disorder and on people with schizoaffective disorders.

GABA and schizophrenia: a review of basic science and clinical studies

BACKGROUND

A converging body of evidence implicates the gamma-aminobutyric acid (GABA) neurotransmitter system in the pathogenesis of schizophrenia.

METHODS

The authors review neuroscience literature and clinical studies investigating the role of the GABA system in the pathophysiology of schizophrenia. First, a background on the GABA system is provided, including GABA pharmacology and neuroanatomy of GABAergic neurons. Results from basic science schizophrenia animal models and human studies are reviewed. The role of GABA in cognitive dysfunction in schizophrenia is then presented, followed by a discussion of GABAergic compounds used in monotherapy or adjunctively in clinical schizophrenia studies.

RESULTS

In basic studies, reductions in GABAergic neuronal density and abnormalities in receptors and reuptake sites have been identified in several cortical and subcortical GABA systems. A model has been developed suggesting GABA's role (including GABA-dopamine interactions) in schizophrenia. In several clinical studies, the use of adjunctive GABA agonists was associated with greater improvement in core schizophrenia symptoms.

CONCLUSIONS

Alterations in the GABA neurotransmitter system are found in clinical and basic neuroscience schizophrenia studies as well as animal models and may be involved in the pathophysiology of schizophrenia. The interaction of GABA with other well-characterized neurotransmitter abnormalities remains to be understood. Future studies should elucidate the potential therapeutic role for GABA ligands in schizophrenia treatment.

Management of the negative symptoms of schizophrenia: new treatment options

This article presents a systematic review of pharmacological treatment for negative symptoms of schizophrenia, based on MEDLINE searches from 1995 to September 2002 to identify pertinent clinical trials. The pharmacotherapy of negative symptoms in schizophrenia includes novel/atypical antipsychotics and classical antipsychotics, as well as antidepressants, glutamatergic compounds, antiepileptic drugs and estrogens. In the assessment of therapy for negative symptoms of schizophrenia, it is imperative that better studies of sound methodology are performed. In such studies, some important aspects to be considered include an accurate definition and assessment of negative symptoms (including well designed, valid and reliable rating scales), the differentiation between primary and secondary negative symptoms, an appropriate selection of standard comparators, adequate dosages of comparators (e.g. haloperidol dosages) and an overall optimal study design. Most of the available studies on treating negative symptoms in schizophrenia have focused on the atypical antipsychotics, while other potential candidates, mostly in the context of add-on therapy, have not been so intensively investigated. Atypical antipsychotics have been proven in placebo-controlled trials to be effective in treating negative symptoms of acute schizophrenic episodes. In many of the comparator studies, they showed efficacy in treating negative symptoms that was superior to that of typical antipsychotics. Data on stable, predominant negative symptoms in subchronic or chronic cases of schizophrenia, although limited, have demonstrated the efficacy of atypical antipsychotics. If the beneficial tolerability profile with respect to extrapyramidal symptoms is also taken into account during clinical decision making, the atypical antipsychotics should be preferred for the treatment of negative symptoms. It is also worth noting that the traditional antipsychotics have the risk of inducing negative symptoms in the context of akinesia. The benefits of add-on therapy with SSRIs or a glutamatergic compound are well documented. Estrogen add-on therapy seems promising. Other traditionally suggested approaches, such as comedication with an antiepileptic drug, lithium or beta-adrenoceptor antagonist, cannot generally be recommended on the basis of the available data.

Significant dose effect of carbamazepine on reduction of steady-state plasma concentration of haloperidol in schizophrenic patients

A reduction in haloperidol concentration induced by carbamazepine coadministration has been consistently reported. However, the degree of this reduction is very different among individuals treated with various doses of carbamazepine. Thus, we investigated dose effect of carbamazepine on the steady-state plasma concentration of haloperidol. Eleven excited schizophrenic inpatients, despite receiving haloperidol 12 mg/d, were treated with incremental doses of carbamazepine for 6 weeks (100, 300, 600 mg/d for 2 weeks each). Plasma drug concentrations were monitored together with clinical assessments before and after each phase of the 3 carbamazepine doses. Mean haloperidol concentrations during coadministration of carbamazepine 100, 300, and 600 mg/d were 75%, 39%, and 15%, respectively, of corresponding variables before carbamazepine coadministration. Negative linear correlations were observed between dose or plasma concentration of carbamazepine and the degree of reduction in haloperidol concentration. Mean carbamazepine dose and plasma carbamazepine concentrations at 50% reduction of haloperidol concentration were 240 mg/d and 3.5 microg/mL, respectively. Scores in total and excitement symptoms were significantly reduced after carbamazepine coadministration, whereas no changes were observed in other clinical symptoms or any of the subgroup side effects. Therefore, this study indicates that carbamazepine decreases plasma haloperidol concentration in a dose-dependent or concentration-dependent manner, and that reduction in haloperidol concentration is apparent even at subtherapeutic dose of carbamazepine.

Clinically important drug interactions in epilepsy: interactions between antiepileptic drugs and other drugs

Antiepileptic drugs (AEDs) are commonly prescribed for long periods, up to a lifetime, and many patients will require treatment with other agents for the management of concomitant or intercurrent conditions. When two or more drugs are prescribed together, clinically important interactions can occur. Among old-generation AEDs, carbamazepine, phenytoin, phenobarbital, and primidone are potent inducers of hepatic enzymes, and decrease the plasma concentration of many psychotropic, immunosuppressant, antineoplastic, antimicrobial, and cardiovascular drugs, as well as oral contraceptive steroids. Most new generation AEDs do not have clinically important enzyme inducing effects. Other drugs can affect the pharmacokinetics of AEDs; examples include the stimulation of lamotrigine metabolism by oral contraceptive steroids and the inhibition of carbamazepine metabolism by certain macrolide antibiotics, antifungals, verapamil, diltiazem, and isoniazid. Careful monitoring of clinical response is recommended whenever a drug is added or removed from a patient's AED regimen.

The World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for the Biological Treatment of Bipolar Disorders, Part II: Treatment of Mania

Identical to the preceding guidelines of this series, these practice guidelines for the biological, mainly pharmacological treatment of acute bipolar mania were developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). Their purpose is to supply a systematic overview of all scientific evidence pertaining to the treatment of acute mania. The data used for these guidelines have been extracted from a MEDLINE and EMBASE search, from recent proceedings of key conferences, and from various national and international treatment guidelines. Their scientific rigor was categorised into four levels of evidence (A-D). As these guidelines are intended for clinical use, the scientific evidence was finally not only graded, but has also been commented by the experts of the task force to ensure practicability. Key words: bipolar disorder, mania, acute treatment, evidence-based guidelines, pharmacotherapy, antipsychotics, mood stabiliser, electroconvulsive therapy.

Effect of divalproex combined with olanzapine or risperidone in patients with an acute exacerbation of schizophrenia

This double-blind, randomized, multicenter study investigated the use of divalproex with an antipsychotic agent in patients hospitalized for acute exacerbation of schizophrenia. Patients (n = 249) who met DSM-IV criteria for schizophrenia were randomly assigned to receive olanzapine monotherapy, risperidone monotherapy, divalproex plus olanzapine, or divalproex plus risperidone for 28 days. Divalproex was initiated at 15 mg/kg/day and titrated over 12 days to a maximum dosage of 30 mg/kg/day. Olanzapine and risperidone, were, respectively, initiated at 5 and 2 mg/day and were titrated over the first 6 days to respective target fixed daily dosages of 15 and 6 mg/day. Improvements from baseline were observed at all evaluation points throughout the 28-day treatment period in the two combination therapy and the two antipsychotic monotherapy groups, with statistically significant treatment differences favoring combination therapy as soon as day 3 for Positive and Negative Syndrome Scale (PANSS) total score, derived Brief Psychiatric Rating Scale (BPRSd) total score, as well as PANSS and BPRSd subscales. These findings were confirmed in post hoc repeated-measures analyses of variance in which treatment differences favoring combination therapy were observed for PANSS total (p = 0.020) and PANSS positive scale scores (p = 0.002). Both combination therapy and antipsychotic monotherapy were well tolerated. Treatment with divalproex in combination with an atypical antipsychotic agent resulted in earlier improvements in a range of psychotic symptoms among acutely hospitalized patients with schizophrenia. Further evaluation is warranted to confirm these findings.

Antiepileptic-antipsychotic drug interactions: a critical review of the evidence

The potential for drug-drug interactions in psychiatry and patients with epilepsy is very high. Moreover, antiepileptic drugs are widely used outside epilepsy as psychotropic agents and their spectrum of activity on behavior is of considerable interest to psychopharmacology. In both neurologic and psychiatric practice, pharmacotherapy combinations are commonly used to treat comorbid psychiatric and neurologic disorders, to reduce or control the adverse effects of a medication or to increase its efficacy. This paper focuses on the metabolic pharmacokinetic interactions between two classes of psychotropic drugs: antiepileptic and antipsychotic drugs. The degree of documentation varies for many interactions from clinical case-report experiences to well established research outcomes. The evidence and the clinical significance of these interactions are reviewed. In general, it is better to use as few drugs as possible, as multicolored politherapies increase the possible adverse effects of drug interactions and reduce patient compliance.

Inhibitory deficit in schizophrenia is not necessarily a GABAergic deficit

1. Current evidence strongly supports the idea of an inhibitory deficit as a central pathophysiological mechanism in schizophrenia. This deficit has been well documented in sensory gating and paired-pulse studies and may be related to decreases in inhibitory interneurons found in schizophrenic patients. 2. The GABAergic system has been repeatedly postulated to mediate this deficit, but the findings are controversial, at least in some areas, and mostly negative regarding treatment with drugs enhancing GABAergic activity. Therefore, the scope of mediators of this inhibitory deficit should be widened and the neuromodulator adenosine is proposed as a candidate to be further studied. 3. A state of adenosinergic hypoactivity in schizophrenia is compatible not only with the inhibitory deficit but also with symptoms, clinical response to antipsychotics, impaired sensory gating, deteriorating course, increased smoking, and sleep alterations reported in schizophrenia. 4. It is concluded that although the GABAergic system should be further studied, especially in sensory gating model in humans, emphasis on other inhibitory mechanisms may prove useful and provide more effective treatment.

Clinical relevance and treatment possibilities of bipolar rapid cycling

Bipolar rapid cycling (RC) is defined as 4 or more affective episodes within 1 year. It has been postulated that RC is related to a poor response to lithium, to the same extent as mixed episodes or other atypical symptoms of the illness. This article reviews the current status of alternative pharmacological or otherwise supportive therapies of RC. Biological parameters and characteristics of the illness associated with RC like gender prevalence in women, hyperthyroidism, catecholamine-O-methyltransferase allele, the influence of sleep, different subtypes of bipolar disorder and the risk of antidepressant-induced cycling will be discussed in detail.

Carbamazepine for schizophrenia and schizoaffective psychoses

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with ordinary antipsychotic drug treatment and various additional medications are used to promote additional response. The antiepileptic carbamazepine is one such drug.

OBJECTIVES

To review the effects of carbamazepine and its derivatives for the treatment of schizophrenia and schizoaffective psychoses.

SEARCH STRATEGY

We searched Biological Abstracts (1980-2001), The Cochrane Library (Issue 3, 2001), The Cochrane Schizophrenia Group's Register of Trials (December 2001), EMBASE (1980-2001), MEDLINE (1966-2001), PsycLIT (1886-2001) and PSYNDEX (1974-2001). Citations from included trials were also inspected and relevant companies and authors contacted for additional data.

SELECTION CRITERIA

All randomised controlled trials comparing carbamazepine or compounds of the carbamazepine family to placebo or no intervention, whether as sole treatment or as an adjunct to antipsychotic medication for the treatment of schizophrenia and/or schizoaffective psychoses.

DATA COLLECTION AND ANALYSIS

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were extracted independently by at least two reviewers. Dichotomous data were analysed using Peto odds ratio (OR) and the 95% confidence interval (CI) estimated. Where possible the number needed to treat (NNT) or number needed to harm statistics were calculated.

MAIN RESULTS

Ten studies with a total of 258 participants were included. One study comparing carbamazepine with placebo as the sole treatment for schizophrenia (n=31) was stopped early due to high relapse rate. No effect of carbamazepine was evident (OR relapse 1.5 CI 0.2 to 9.7). Another study (n=38) compared carbamazepine with antipsychotics as the sole treatment for schizophrenia. No differences in terms of mental state were found (OR 50% BPRS reduction 1.9 CI 0.5 to 7.2). More people who received the antipsychotic (perphenazine) had parkinsonism (OR 0.03 CI 0.01 to 0.1, NNH 1 CI 0.9 to 1.4). Eight studies compared adjunctive carbamazepine plus antipsychotics versus placebo plus antipsychotics. Adding carbamazepine was as acceptable as adding placebo (n=182, OR leaving the study early 0.4 CI 0.1 to 1.4). Carbamazepine augmentation of antipsychotics was superior compared with antipsychotics alone, but participant numbers were low (n=38, OR 0.1 CI 0.02 to 0.4, NNT 2 CI 1 to 5). There were no differences for mental state outcomes (6 RCTs, n=147, OR 50% BPRS reduction 0.99 CI 0.2 to 6.0). Less people in the carbamazepine augmentation group had movement disorders than those taking haloperidol alone (1 RCT, n=20, OR 0.15 CI 0.03 to 0.8). The effects of carbamazepine on subgroups of people with schizophrenia and aggressive behaviour, negative symptoms or EEG abnormalities or with schizoaffective disorder are unknown.

REVIEWER'S CONCLUSIONS

Based on currently available evidence from randomised trials, carbamazepine cannot be recommend for routine clinical use for sole treatment, or augmentation of antipsychotic treatment, of schizophrenia. Large, simple well-designed and reported trials are justified especially if focusing on those with violent episodes and people with schizoaffective disorders or on those with both schizophrenia and EEG abnormalities.

Augmentation strategies in the treatment of schizophrenia

Use of augmenting agents in schizophrenia is a common practice in response to resistant symptoms or comorbid illness. Increasingly, clinicians are combining more than one antipsychotic agent, despite a lack of evidence from controlled studies to support this approach. A rationale can be made for adding higher-potency agents to clozapine in an attempt to optimize D2 dopamine receptor blockade, but this strategy requires further study before it should be adopted in clinical practice. Older reports have explored the use of antidepressants, mood stabilizers, and anxiolytics as augmenting agents. These agents appear to improve comorbid affective or anxiety symptoms, but earlier evidence of improvement in psychotic or negative symptoms has not been replicated consistently. Glutamatergic agents acting at the glycine coagonist site of the N-methyl-d-aspartate receptor, including glycine, d-cycloserine, and d-serine, have demonstrated impressive therapeutic effects for negative symptoms when added to conventional neuroleptic agents, but do not appear to enhance clozapine efficacy. Given the high rates of symptom persistence and disability associated with schizophrenia, the need for augmentation strategies is great, but no approach has clearly emerged as effective for a substantial portion of patients. Although certain approaches may prove helpful for individual patients, augmentation should not be used unless monotherapy has been optimized, and should not be continued long-term unless benefits are clear.

In vitro evaluation of valproic acid as an inhibitor of human cytochrome P450 isoforms: preferential inhibition of cytochrome P450 2C9 (CYP2C9)

AIMS

To evaluate the potency and specificity of valproic acid as an inhibitor of the activity of different human CYP isoforms in liver microsomes.

METHODS

Using pooled human liver microsomes, the effects of valproic acid on seven CYP isoform specific marker reactions were measured: phenacetin O-deethylase (CYP1A2), coumarin 7-hydroxylase (CYP2A6), tolbutamide hydroxylase (CYP2C9), S-mephenytoin 4'-hydroxylase (CYP2C19), dextromethorphan O-demethylase (CYP2D6), chlorzoxazone 6-hydroxylase (CYP2E1) and midazolam 1'-hydroxylase (CYP3A4).

RESULTS

Valproic acid competitively inhibited CYP2C9 activity with a Ki value of 600 microM. In addition, valproic acid slightly inhibited CYP2C19 activity (Ki = 8553 microM, mixed inhibition) and CYP3A4 activity (Ki = 7975 microM, competitive inhibition). The inhibition of CYP2A6 activity by valproic acid was time-, concentration- and NADPH-dependent (KI = 9150 microM, Kinact=0.048 min(-1)), consistent with mechanism-based inhibition of CYP2A6. However, minimal inhibition of CYP1A2, CYP2D6 and CYP2E1 activities was observed.

CONCLUSIONS

Valproic acid inhibits the activity of CYP2C9 at clinically relevant concentrations in human liver microsomes. Inhibition of CYP2C9 can explain some of the effects of valproic acid on the pharmacokinetics of other drugs, such as phenytoin. Co-administration of high doses of valproic acid with drugs that are primarily metabolized by CYP2C9 may result in significant drug interactions.