Adjunctive treatment of acute mania: a clinical overview

Lamotrigine as a mood stabilizer: insights from the pre-clinical evidence

INTRODUCTION

Lamotrigine (LTG) is a well-established anticonvulsant that is also approved for the prevention of mood relapses in bipolar disorder. However, the mechanisms underlying LTG mood stabilizing effects remain unclear. Areas covered: Herein, the pre-clinical evidence concerning LTG's' mode of action in depression and mania is reviewed. Bottlenecks and future perspectives for this expanding and promising field are also discussed. Pre-clinical studies have indicated that neurotransmitter systems, especially serotoninergic, noradrenergic and glutamatergic, as well as non-neurotransmitter pathways such as inflammation and oxidative processes might play a role in LTG's antidepressant effects. The mechanisms underlying LTG's anti-manic properties remain to be fully explored, but the available pre-clinical evidence points out to the role of glutamatergic neurotransmission, possibly through AMPA-receptors. Expert opinion: A major limitation of current pre-clinical investigations is that there are no experimental models that recapitulate the complexity of bipolar disorder. Significant methodological differences concerning time and dose of LTG treatment, administration route, animal strains, and behavioral paradigms also hamper the reproducibility of the findings, leading to contradictory conclusions. Moreover, the role of other mechanisms (e.g. inositol phosphate and GSK3β pathways) implicated in the mode of action of different mood-stabilizers must also be consolidated with LTG.

The preclinical discovery and development of quetiapine for the treatment of mania and depression

INTRODUCTION

Bipolar disorder is a chronic disabling condition characterized by alternating manic and depressive episodes. Bipolar disorder has been associated with functional impairment, poor quality of life, morbidity and mortality. Despite its significant clinical, social and economic burden, treatment options for bipolar disorder are still limited. Several clinical trials have shown efficacy of the atypical antipsychotic quetiapine (QTP) in the treatment of this condition. However, the mechanisms underlying the antidepressant and anti-manic effects of QTP remain poorly understood. Areas covered: The article provides the emerging evidence from pre-clinical studies regarding the antidepressant and anti-manic mechanisms of action of QTP. In combination with its primary active metabolite norquetiapine, QTP modulates several neurotransmitter systems, including serotonin, dopamine, noradrenaline and histamine. QTP also seems to influence mediators of the immune system. Expert opinion: Pre-clinical studies have provided valuable information on the potential antidepressant mechanisms of action of QTP, but pre-clinical studies on QTP's anti-manic effects are still scarce. A major problem refers to the lack of valid experimental models for bipolar disorder. Additionally, immune and genetic based studies are largely descriptive. The role of the QTP metabolite norquetiapine in modulating non-neurotransmitter systems also needs to be further addressed.

Animal models of bipolar mania: The past, present and future

Bipolar disorder (BD) is the sixth leading cause of disability in the world according to the World Health Organization and affects nearly six million (∼2.5% of the population) adults in the United State alone each year. BD is primarily characterized by mood cycling of depressive (e.g., helplessness, reduced energy and activity, and anhedonia) and manic (e.g., increased energy and hyperactivity, reduced need for sleep, impulsivity, reduced anxiety and depression), episodes. The following review describes several animal models of bipolar mania with a focus on more recent findings using genetically modified mice, including several with the potential of investigating the mechanisms underlying 'mood' cycling (or behavioral switching in rodents). We discuss whether each of these models satisfy criteria of validity (i.e., face, predictive, and construct), while highlighting their strengths and limitations. Animal models are helping to address critical questions related to pathophysiology of bipolar mania, in an effort to more clearly define necessary targets of first-line medications, lithium and valproic acid, and to discover novel mechanisms with the hope of developing more effective therapeutics. Future studies will leverage new technologies and strategies for integrating animal and human data to reveal important insights into the etiology, pathophysiology, and treatment of BD.

Pharmacotherapy of acute mania: monotherapy or combination therapy with mood stabilizers and antipsychotics?

The use of combination therapy with mood stabilizers and antipsychotics in acute mania in bipolar disorder (BD) is widespread, although most treatment guidelines recommend monotherapy as the first option, and reserve combination therapy, which is associated with more frequent and more severe side effects, for when patients do not respond to the former treatment option. Reasons to prescribe combination therapy include the lack of efficacy of the current treatment (either real or due to undisclosed poor adherence), psychiatric comorbidities, severe previous course of illness, slow cross-tapering during treatment switching, and potential benefits from particular combinations. The decision to start with monotherapy or combination therapy may depend on the patient characteristics, and is still under debate. Clinical trials designed to ascertain whether combination therapy or monotherapy is more advantageous for patients in acute mania and beyond, according to illness severity, are urgently needed. Adding a third monotherapy arm to the conventional two-arm, adjunctive-design trials or initiating combination therapy from the beginning may help to shed some light on the issue.

Lithium as add-on to quetiapine XR in adult patients with acute mania: a 6-week, multicenter, double-blind, randomized, placebo-controlled study

Quetiapine extended release (XR) and lithium are treatments with proven efficacy in acute mania. This randomized study evaluated the efficacy and safety of lithium or placebo as add-on to quetiapine XR in adult patients with manic or mixed symptoms of bipolar I disorder. In this 6-week, double-blind study (Trial D144AC00003), adult patients with DSM-IV-TR-diagnosed bipolar I disorder (current episode manic or mixed), a Young Mania Rating Scale (YMRS) total score ≥20, and score ≥4 on two of four core YMRS items were administered quetiapine XR (400 to 800 mg/day) and randomly assigned to receive add-on lithium (600 to 1,800 mg/day) or placebo. The primary efficacy end point was change in the YMRS total score from baseline to day 43, analyzed using a mixed-model for repeated measures (MMRM) approach. Secondary efficacy and safety end points were also measured. Rating scales were administered by trained staff. Three hundred fifty-six patients treated with quetiapine XR were randomized to add-on lithium (n = 173) or placebo (n = 183). Two hundred ninety-one patients (81.7%) completed the study. At day 43, least squares mean change in YMRS total score was −22.8 for add-on lithium and −20.1 for add-on placebo, a statistically significant treatment group difference of −2.69 (p < 0.001). On secondary measures, add-on lithium was associated with significant improvements in response, remission, illness severity, and overall illness versus add-on placebo (p < 0.05). The number needed to treat was 9.1 for response and 7.9 for remission for add-on lithium compared with add-on placebo. Lithium in combination with quetiapine XR was generally well tolerated, with a similar profile to quetiapine XR in combination with placebo. The addition of lithium to quetiapine XR therapy was associated with significantly greater efficacy than placebo as add-on and was generally well tolerated in patients with acute bipolar I mania. This study was registered under Clinicaltrials.gov Identifier NCT00931723.

Genetic susceptibility for bipolar disorder and response to antidepressants in major depressive disorder

The high heterogeneity of response to antidepressant treatment in major depressive disorder (MDD) makes individual treatment outcomes currently unpredictable. It has been suggested that resistance to antidepressant treatment might be due to undiagnosed bipolar disorder or bipolar spectrum features. Here, we investigate the relationship between genetic susceptibility for bipolar disorder and response to treatment with antidepressants in MDD. Polygenic scores indexing risk for bipolar disorder were derived from the Psychiatric Genomics Consortium Bipolar Disorder whole genome association study. Linear regressions tested the effect of polygenic risk scores for bipolar disorder on proportional reduction in depression severity in two large samples of individuals with MDD, treated with antidepressants, NEWMEDS (n=1,791) and STAR*D (n=1,107). There was no significant association between polygenic scores for bipolar disorder and response to treatment with antidepressants. Our data indicate that molecular measure of genetic susceptibility to bipolar disorder does not aid in understanding non-response to antidepressants.

Predictive animal models of mania: hits, misses and future directions

Mania has long been recognized as aberrant behaviour indicative of mental illness. Manic states include a variety of complex and multifaceted symptoms that challenge clear clinical distinctions. Symptoms include over-activity, hypersexuality, irritability and reduced need for sleep, with cognitive deficits recently linked to functional outcome. Current treatments have arisen through serendipity or from other disorders. Hence, treatments are not efficacious for all patients, and there is an urgent need to develop targeted therapeutics. Part of the drug discovery process is the assessment of therapeutics in animal models. Here we review pharmacological, environmental and genetic manipulations developed to test the efficacy of therapeutics in animal models of mania. The merits of these models are discussed in terms of the manipulation used and the facet of mania measured. Moreover, the predictive validity of these models is discussed in the context of differentiating drugs that succeed or fail to meet criteria as approved mania treatments. The multifaceted symptomatology of mania has not been reflected in the majority of animal models, where locomotor activity remains the primary measure. This approach has resulted in numerous false positives for putative treatments. Recent work highlights the need to utilize multivariate strategies to enable comprehensive assessment of affective and cognitive dysfunction. Advances in therapeutic treatment may depend on novel models developed with an integrated approach that includes: (i) a comprehensive battery of tests for different aspects of mania, (ii) utilization of genetic information to establish aetiological validity and (iii) objective quantification of patient behaviour with translational cross-species paradigms.

Reformulation of current recommendations for target serum lithium concentration according to clinical indication, age and physical comorbidity

BACKGROUND

There have been significant changes in the nature of psychiatric patient populations and patterns of drug prescribing in mood disorders since serum lithium monitoring was introduced. It seems opportune to review current guidelines for target lithium concentration given the decline in lithium monotherapy and increase in the numbers of older people and those with comorbid physical disease administered lithium.

METHOD

A review was made of the literature of lithium monitoring and target serum concentration in mood disorders, older people, and comorbid physical illness.

RESULTS

Current guidelines, which generally recommend a target serum concentration of 0.5/0.6 to 1.1/1.2 mmol/L, have a number of limitations. A target lithium level of > 0.8 mmol/L is inappropriate given poor tolerability, and adequate efficacy when combination lithium-antipsychotic therapy is used at this or lower levels. Guidelines have largely failed to match specific clinical indications to serum levels, and to consider comorbid physical illness factors known to be associated with lithium toxicity.

CONCLUSION

For most patients, a target serum lithium concentration range of 0.5-0.8 mmol/L, varying according to clinical indication, age and concurrent physical status, seems most appropriate in enhancing efficacy and minimizing adverse effects. The lower end of this range (0.5-0.6 mmol/L) is recommended for patients 50 years and over; those with diabetes insipidus, renal impairment or thyroid dysfunction; those administered diuretics, angiotensin converting enzyme (ACE) inhibitors or non-steroidal anti-inflammatory drugs (NSAIDs)/COX-2 inhibitors; and in the prophylaxis of bipolar depression and management of acute unipolar depression. The higher end of this range (0.7-0.8 mmol/L) is recommended in the management of acute mania and prophylaxis of mania.

Antiepileptic drugs in the treatment of psychiatric disorders

The clinical interface between psychiatry and neurology is epilepsy; the pharmacological expression of this interface is antiepileptic drugs (AEDs), as they are used to treat both epilepsy and psychiatric disorders, especially bipolar disorders. The prevalence of psychiatric comorbidity and the risk of suicidal behavior/ideation/suicide are markedly increased in patients with epilepsy (PWE). Though AEDs receive initial indications for the treatment of epilepsy, currently the majority of AEDs are used to treat pain and psychiatric disorders. Thus in selecting the appropriate AEDs for treatment of PWE, consideration should be given to which AEDs best treat the epileptic disorder and the psychiatric comorbidity. This review is an overview of 21 AEDs in which negative psychotropic properties, approved indications in psychiatry, off-label studied uses in psychiatry, and principal uses in psychiatry are presented with literature review. A total of 40 psychiatric uses have been identified. Of the 21 AEDs reviewed, only 5 have U.S. Food and Drug Administration and/or European Medicines Agency psychiatric approval for limited uses; the majority of AEDs are used off-label. Many of these off-label uses are based on case reports, open-label studies, and poorly controlled or small-sample-size studies. In some instances, off-label use persists in the face of negative pivotal trials. Further placebo-controlled (augmentation and monotherapy) parallel-arm research with active comparators is required in the complex field of AED treatment of psychiatric disorders to minimize the treatment gap not only for PWE with psychiatric disorders, but also for psychiatric patients who would benefit from properly studied AEDs while minimizing adverse effects.

Successful combined therapy with tamoxifen and lithium in a paradoxical sleep deprivation-induced mania model

BACKGROUND

Previous studies have suggested that manic states and sleep deprivation could contribute to the pathophysiology of bipolar disorder (BD) through protein kinase C (PKC) signaling abnormalities. Moreover, adjunctive therapy has become a standard strategy in the management of BD patients who respond poorly to current pharmacological treatments.

AIM

Thus, the aim of this study was to investigate the possible involvement of PKC inhibition by tamoxifen both separately or in combination with lithium, in paradoxical sleep deprivation (PSD)-induced hyperactivity, one facet of mania-like behavior.

MATERIALS & METHODS

Adult male C57BL/6J mice were randomly distributed (n = 7/group) in 24-h PSD or control groups and injected intraperitoneally (i.p.) with vehicle, lithium (50, 100, or 150 mg/kg) or tamoxifen (0.5, 1.0, or 2.0 mg/kg - experiment 1). In a second experiment, mice were injected i.p. with vehicle or a combination of subeffective doses of lithium and tamoxifen. Animals were subjected to a protocol based on repetitive PSD conditions, followed by assessment of locomotion activity in the open-field task.

RESULTS

PSD significantly increased locomotor activity in both experiments. These behavioral changes were prevented by a treatment with lithium or tamoxifen, or a combined treatment with both lithium and tamoxifen.

DISCUSSION

Therefore, our findings suggest that lithium and tamoxifen exert reversal effects against PSD-induced hyperactivity in mice.

CONCLUSION

Furthermore, tamoxifen as an adjunct to lithium therapy provides support for an alternative treatment of individuals who either do not respond adequately or cannot tolerate the adverse effects associated with therapeutic doses of lithium.

In vivo evidence of differential impact of typical and atypical antipsychotics on intracortical myelin in adults with schizophrenia

CONTEXT

Imaging and post-mortem studies provide converging evidence that patients with schizophrenia have a dysregulated developmental trajectory of frontal lobe myelination. The hypothesis that typical and atypical medications may differentially impact brain myelination in adults with schizophrenia was previously assessed with inversion recovery (IR) images. Increased white matter (WM) volume suggestive of increased myelination was detected in the patient group treated with an atypical antipsychotic compared to a typical one.

OBJECTIVE

In a follow-up reanalysis of MRI images from the original study, we used a novel method to assess whether the difference in WM volumes could be caused by a differential effect of medications on the intracortical myelination process.

DESIGN, SETTING, AND PARTICIPANTS

Two different male cohorts of healthy controls ranging in age from 18-35 years were compared to cohorts of subjects with schizophrenia who were treated with either oral risperidone (Ris) or fluphenazine decanoate (Fd).

MAIN OUTCOME MEASURE

A novel MRI method that combines the distinct tissue contrasts provided by IR and proton density (PD) images was used to estimate intracortical myelin (ICM) volume.

RESULTS

When compared with their pooled healthy control comparison group, the two groups of schizophrenic patients differed in the frontal lobe ICM measure with the Ris group having significantly higher volume.

CONCLUSIONS

The data suggest that in adults with schizophrenia antipsychotic treatment choice may be specifically and differentially impacting later-myelinating intracortical circuitry. In vivo MRI can be used to dissect subtle differences in brain tissue characteristics and thus help clarify the effect of pharmacologic treatments on developmental and pathologic processes.

Advantages and disadvantages of combination treatment with antipsychotics ECNP Consensus Meeting, March 2008, Nice

TERMINOLOGY AND PRINCIPLES OF COMBINING ANTIPSYCHOTICS WITH A SECOND MEDICATION: The term "combination" includes virtually all the ways in which one medication may be added to another. The other commonly used terms are "augmentation" which implies an additive effect from adding a second medicine to that obtained from prescribing a first, an "add on" which implies adding on to existing, possibly effective treatment which, for one reason or another, cannot or should not be stopped. The issues that arise in all potential indications are: a) how long it is reasonable to wait to prove insufficiency of response to monotherapy; b) by what criteria that response should be defined; c) how optimal is the dose of the first monotherapy and, therefore, how confident can one be that its lack of effect is due to a truly inadequate response? Before one considers combination treatment, one or more of the following criteria should be met; a) monotherapy has been only partially effective on core symptoms; b) monotherapy has been effective on some concurrent symptoms but not others, for which a further medicine is believed to be required; c) a particular combination might be indicated de novo in some indications; d) The combination could improve tolerability because two compounds may be employed below their individual dose thresholds for side effects. Regulators have been concerned primarily with a and, in principle at least, c above. In clinical practice, the use of combination treatment reflects the often unsatisfactory outcome of treatment with single agents. ANTIPSYCHOTICS IN MANIA: There is good evidence that most antipsychotics tested show efficacy in acute mania when added to lithium or valproate for patients showing no or a partial response to lithium or valproate alone. Conventional 2-armed trial designs could benefit from a third antipsychotic monotherapy arm. In the long term treatment of bipolar disorder, in patients responding acutely to the addition of quetiapine to lithium or valproate, this combination reduces the subsequent risk of relapse to depression, mania or mixed states compared to monotherapy with lithium or valproate. Comparable data is not available for combination with other antipsychotics. ANTIPSYCHOTICS IN MAJOR DEPRESSION: Some atypical antipsychotics have been shown to induce remission when added to an antidepressant (usually a SSRI or SNRI) in unipolar patients in a major depressive episode unresponsive to the antidepressant monotherapy. Refractoriness is defined as at least 6 weeks without meeting an adequate pre-defined treatment response. Long term data is not yet available to support continuing efficacy. SCHIZOPHRENIA: There is only limited evidence to support the combination of two or more antipsychotics in schizophrenia. Any monotherapy should be given at the maximal tolerated dose and at least two antipsychotics of different action/tolerability and clozapine should be given as a monotherapy before a combination is considered. The addition of a high potency D2/3 antagonist to a low potency antagonist like clozapine or quetiapine is the logical combination to treat positive symptoms, although further evidence from well conducted clinical trials is needed. Other mechanisms of action than D2/3 blockade, and hence other combinations might be more relevant for negative, cognitive or affective symptoms. OBSESSIVE-COMPULSIVE DISORDER: SSRI monotherapy has moderate overall average benefit in OCD and can take as long as 3 months for benefit to be decided. Antipsychotic addition may be considered in OCD with tic disorder and in refractory OCD. For OCD with poor insight (OCD with "psychotic features"), treatment of choice should be medium to high dose of SSRI, and only in refractory cases, augmentation with antipsychotics might be considered. Augmentation with haloperidol and risperidone was found to be effective (symptom reduction of more than 35%) for patients with tics. For refractory OCD, there is data suggesting a specific role for haloperidol and risperidone as well, and some data with regard to potential therapeutic benefit with olanzapine and quetiapine. ANTIPSYCHOTICS AND ADVERSE EFFECTS IN SEVERE MENTAL ILLNESS: Cardio-metabolic risk in patients with severe mental illness and especially when treated with antipsychotic agents are now much better recognized and efforts to ensure improved physical health screening and prevention are becoming established.

A review of the preclinical and clinical evidence for protein kinase C as a target for drug development for bipolar disorder

In this article, we review preclinical studies investigating the role of protein kinase C (PKC) as it pertains to mania and effective antimanic agents. We then discuss clinical studies conducted with tamoxifen, a relatively selective PKC inhibitor, in acute bipolar mania. We conclude that PKC is an important target-arguably the first mechanistically distinct drug target for bipolar disorder. PKC holds considerable promise as a novel target for developing a new line of treatments for bipolar disorder.

Changes in outpatient lithium treatment in the Netherlands during 1996-2005

BACKGROUND

The objectives of the present study were to investigate in outpatients in the Netherlands between 1996 and 2005, changes in 1) the incidence and prevalence of lithium use and 2) lithium use patterns (discontinuation, add-on, and switch).

METHODS

Incidence and prevalence of lithium use were determined for each year between 1996 and 2005. In addition, we determined cumulative changes in lithium use (discontinuation, add-on, and switching) at three, six, 12 and 24 months for three separate time-cohorts (1998-1999, 2000-2001 and 2002-2003). Lastly, concomitant use of other drugs used in the treatment of bipolar disorders next to lithium during the 24 months after the first lithium prescription was determined for the three time-cohorts.

RESULTS

Incidence of lithium use was constant at approximately 0.2 per 1000 person-years, prevalence increased with 26% from 0.95 to 1.2 per 1000 persons. The percentage of patients receiving an add-on drug used in the treatment of bipolar disorders was constant over the three time-cohorts, with a significant decrease in use of tricyclic antidepressants. Within the patient group that stopped using lithium, more patients switched from lithium to another agent used in the treatment of bipolar disorders over calendar time, and fewer patients discontinued lithium. There was a significant increase in the use of atypical antipsychotics and valproic acid next to lithium.

LIMITATIONS

We did not know the specific diagnosis for which lithium treatment was instituted.

CONCLUSION

The changes were in line with the increase in alternatives during the last decade and in line with Dutch guidelines.

Differential effects of olanzapine, haloperidol and risperidone on calcitonin gene-related peptide in the rat brain

Calcitonin gene-related peptide (CGRP) is a 37 amino acid peptide which acts on central nervous system (CNS) neurons and is involved in activities related to dopamine. These effects of CGRP suggest that the peptide may have a role in pathophysiology and treatment of schizophrenia where dopaminergic system hypoactivity in the frontal cortex and hyperactivity in the subcortical structures have been demonstrated. In this study we measured by radioimmunoassay (RIA) the brain levels of CGRP-like immunoreactivity (CGRP-LI) in rats treated with either classical (haloperidol) or atypical (risperidone and olanzapine) antipsychotic drugs. Both haloperidol and risperidone decreased CGRP-LI in the striatum. Risperidone also decreased CGRP-LI in the occipital cortex. On the other hand, olanzapine increased CGRP-LI in the striatum, the frontal cortex and hypothalamus. The differential effects on CGRP could reflect a different profile of side effects and further suggest that CGRP is involved in CNS functions related to psychiatric disorders.