Efectividad de la ketamina en depresión bipolar: revisión sistemática de la literatura

Introducción: Aunque el hallazgo clínico más distintivo del Trastorno Afectivo Bipolar es el ánimo patológicamente elevado, este no suele ser el estado de ánimo prevalente de la enfermedad. La fase depresiva del trastorno o depresión bipolar es más crónica, conlleva a un mayor deterioro de la funcionalidad y representa un reto terapéutico habitual. En la actualidad, el manejo farmacológico de la depresión bipolar suele consistir en combinaciones de al menos dos medicamentos distintos, incluyendo estabilizadores del afecto (litio y anticonvulsivantes), antipsicóticos atípicos y antidepresivos. El objetivo central de este trabajo es evaluar la efectividad de la Ketamina en la depresión bipolar. Métodos: Revisión sistemática de la literatura de artículos que proporcionen información sobre la eficacia de la Ketamina en la fase depresiva del Trastorno Bipolar. Resultados: De los 147 artículos arrojados por la búsqueda, dos cumplieron los criterios de selección (n=33). En comparación con placebo, ketamina tiene un efecto antidepresivo rápido y duradero, incluso en pacientes que han recibido más de 3 medicamentos previamente. No se reportaron efectos adversos severos durante los estudios. Discusión. La evidencia actual apunta a que la ketamina es útil para el manejo de la depresión bipolar, incluso cuando es resistente al tratamiento, es segura y puede tener cierto efecto antisuicida. Es necesario ampliar la evidencia existente.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targetsof reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Common structural basis for central nervous system drug design

The main theme of this thesis is that there is a common structural basis for drugs acting on the central nervous system (CNS), and that this concept may be used to design new CNS-active drugs which have greater specificity and hence less side-effects. To develop these ideas, the biological basis of how drugs modify CMS neurotransmission is described, and illustrated using dopaminergic pathways. An account is then given of the use of physicochemical concepts in contemporary drug design. The complete conformational analysis of several antipsychotic drugs is used to illustrate some of these techniques in the development of a model for antipsychotic drug action. After reviewing current structure-activity studies in several classes of CNS drugs (antipsychotics, anti-depressants, stimulants, hal1ucinogens, anticonvulsants and analgesics), a hypothesis for a common structural basis of CNS drug action is proposed- This is based on a topographical comparison of the X-ray structures of eight representative CNS-active drugs, and consists of three parts: 1.there is a common structural basis for the activity of many different CNS-active drug classes; 2. an aromatic ring and a nitrogen atom are the primary binding groups whose topographical arrangement is fundamental to the activity of these drug classes; 3. the nature and placement of secondary binding determines different classes of CNS drug activity. A four-Point model for this common structural basis is then defined using 14- CNS-active drug structures that include the original eight used in proposing the hypothesis. The coordinates of this model are: R1 (0. 3.5, 0), R2 (0, -3.5, O), N (4.8. -0.3, 1.4), and R3 (6.3, 1.3, 0), where R1 and R2 represent the point locations of a hydrophobic interaction of the common aromatic ring with a receptor, and R3 locates the receptor point for a hydrogen bond involving the common nitrogen, N. Extended structures were used to define the receptor points R1, R2 and R3, and the complete conformational space of each of the 14 molecules was considered. It is then shoun that the model may be used to predict whether a given structure is likely to show CNS activity: a search over 1,000 entries in the current Merck Index shows a high probability (82%) of CNS activity in compounds fitting the structural model. Analysis of CNS neurotransmitters and neuropeptides shows that these fit the common model well. Based on the available evidence supporting chemical evolution, protein evolution, and the evolution of neurotransmitter functions, it is surmised that the aromatic ring/nitrogen atom pharmacophore proposed in the common model supports the idea of the evolution of CNS receptors and their neurotransmitters, possibly from an aromatic amine or acety1cho1ine acting as a primaeval communicating molecule. The third point in the hypothesis trilogy is then addressed. The extensive conformation-activity analyses that have resulted in well-defined models for five separate CNS drug classes are used to map out the locations of secondary binding groups relative to the common model for anti-psychotics, antidepressants, analgesics, anticholinergics, and anticonvulsants. With this information, and knowledge derived from receptor-binding data, it is postulated that drugs having specified activity could be designed. In order to generate novel structures having a high probability of CNS-activity, a process of drug design is described in which known CNS structures are superimposed topographically using the common model as a template. Atoms regarded as superfluous may be selectively deleted and the required secondary binding groups added in predicted locations to give novel structures. It is concluded that this process provides the basis for the rational design of new lead compounds which could further be optimized for potent and specific CNS activity.

Restless leg syndrome caused by olanzapine: a case series

Restless leg syndrome (RLS) is a common disorder associated with significant distress. We report three cases of drug induced RLS caused by olanzapine. In each case, RLS commenced after initiation of treatment with olanzapine and resolved after ceasing olanzapine. All three patients were subsequently treated with other atypical antipsychotics, risperidone, quetiapine or aripiprazole, without re-emergence of RLS. RLS is associated with central dopaminergic dysfunction. Dopamine agonists and l-dopa reduce the symptoms of RLS, and some agents that block the dopaminergic system aggravate RLS. Greater awareness of potential causes of RLS, and its differentiation from akathisia and illness related agitation might help in reducing the distress associated with it and improving patient compliance.

The management of bipolar disorder in primary care : a review of existing and emerging therapies

Recent evidence suggests that the prevalence of bipolar disorder is as much as fivefold higher than previously believed, and may amount to nearly 5% of the population, making it almost as common as unipolar major depression. It is, therefore, not unrealistic to assume that primary care or family physicians will frequently encounter bipolar patients in their practice. Such patients may present with a depressive episode, for a variety of medical reasons, for longer-term maintenance after stabilization, and even with an acute manic episode. Whatever the reason, a working knowledge of current trends in the acute and longer-term management of bipolar disorder would be helpful to the primary care physician. In addition, an understanding of important side-effects and drug interactions that occur with drugs used to treat bipolar disorder, which may be encountered in the medical setting, are paramount. This paper will attempt to review existing and emerging therapies in bipolar disorder, as well as their common drug interactions and side-effects.

Health-related quality of life and functioning in bipolar disorder : the impact of pharmacotherapy

Bipolar disorder has a major deleterious impact on many aspects of a patient's functioning and health-related quality of life. Although the formal measurement of these deficits has been neglected until recently, many well-designed trials now include an assessment of functioning and health-related quality of life using one or more rating scales. This review describes recent developments in the measurement of functioning and health-related quality of life in bipolar disorder, and discusses the evidence that medications that improve symptoms in bipolar disorder also offer clinically relevant benefits in functioning and health-related quality of life. Direct comparisons of the benefits of medications including atypical antipsychotics are problematic due to differences in trial populations, study durations and rating scales. Data from quetiapine trials indicate that this medication offers prompt and sustained improvement of functioning in patients with mania and enhancement of health-related quality of life in patients with bipolar depression, to accompany the significant improvements in mood episodes.

The safety of medications for the treatment of bipolar disorder during pregnancy and the peurperium

Risks associated with pharmacological treatment of bipolar disorder are heightened during reproductive events. Treatments need to be planned with the mutual agreement of both the treating physician and the patient and tailored to the needs of the individual so as to minimise risk while providing adequate treatment. Conventional treatments have all been associated with teratogeny in first trimester exposure, lithium with cardiac malformation and valproate and carbamazepine with neural tube malformations. There have been an insufficient number of first trimester exposures to the newer anticonvulsant mood stabilisers, lamotrigine and oxcarbazepine, to determine whether there is a safety advantage in switching to these agents. Increasingly, atypical antipsychotics are being suggested as useful agents for the treatment of bipolar disorder. While not known to be teratogenic, there are other reproductive safety concerns associated with these agents. Bipolar disorder patients may be prescribed antidepressants, and many of these agents are associated with a low safety risk during reproductive events, however data regarding use of these agents are currently equivocal. Adverse outcomes from inadequate pharmacological prophylaxis have been documented for both the mother and the baby. Risks and benefits need to be carefully balanced based on an accurate review of the evidence.

The management of individuals with bipolar disorder : a review of the evidence and its integration into clinical practice

Bipolar disorder is a common, debilitating, chronic illness that emerges early in life and has serious consequences such as long-term unemployment and suicide. It confers considerable functional disability to the individual, their family and society as a whole and yet it is often undetected, misdiagnosed and treated poorly. In the past decade, many new treatment strategies have been trialled in the management of bipolar disorder with variable success. The emerging evidence, for pharmacological agents in particular, is promising but when considered alone does not directly translate to real-world clinical populations of bipolar disorder. Data from drug trials are largely based on findings that identify difterences between groups determined in a time-limited manner, whereas clinical management concerns the treatment of individuals over the life-long course of the illness. Considering the findings in the context of the individual and their particular needs perhaps besl bridges the gap between the evidence from research studies and their application in clinical practice. Specifically, only lithium and valproate have moderate or strong evidence for use across all three phases of bipolar disorder, Anticonvulsants, such as lamotrigine. have strong evidence in maintenance; whereas antipsychotics largely have strong evidence in acute mania, with the exception of quetiapine, which has strong evidence in bipolar depression. Maintenance data for antipsychotics is emerging but at present remains weak. Combinations have strong evidence in acute phases of illness but maintenance data is urgently needed. Conventional antidepressants only have weak evidence in bipolar depression and do not have a role in maintenance therapy. Therefore, this paper summarizes the efficacy data for treating bipolar disorder and also applies clinical considerations to these data when

Melatonin : an overlooked factor in schizophrenia and in the inhibition of anti-psychotic side effects

This paper reviews melatonin as an overlooked factor in the developmental etiology and maintenance of schizophrenia; the neuroimmune and oxidative pathophysiology of schizophrenia; specific symptoms in schizophrenia, including sleep disturbance; circadian rhythms; and side effects of antipsychotics, including tardive dyskinesia and metabolic syndrome. Electronic databases, i.e. PUBMED, Scopus and Google Scholar were used as sources for this review using keywords: schizophrenia, psychosis, tardive dyskinesia, antipsychotics, metabolic syndrome, drug side effects and melatonin. Articles were selected on the basis of relevance to the etiology, course and treatment of schizophrenia. Melatonin levels and melatonin circadian rhythm are significantly decreased in schizophrenic patients. The adjunctive use of melatonin in schizophrenia may augment the efficacy of antipsychotics through its anti-inflammatory and antioxidative effects. Further, melatonin would be expected to improve sleep disorders in schizophrenia and side effects of anti-psychotics, such as tardive dyskinesia, metaboilic syndrome and hypertension. It is proposed that melatonin also impacts on the tryptophan catabolic pathway via its effect on stress response and cortisol secretion, thereby impacting on cortex associated cognition, amygdala associated affect and striatal motivational processing. The secretion of melatonin is decreased in schizophrenia, contributing to its etiology, pathophysiology and management. Melatonin is likely to have impacts on the metabolic side effects of anti-psychotics that contribute to subsequent decreases in life-expectancy.

Treatment and outcomes of an Australian cohort of outpatients with bipolar 1 or schizoaffective disorder over twenty-four months : implications for clinical practice

Background The Bipolar Comprehensive Outcomes Study (BCOS) is a 2-year, prospective, non-interventional, observational study designed to explore the clinical and functional outcomes associated with ‘real-world’ treatment of participants with bipolar I or schizoaffective disorder. All participants received treatment as usual. There was no study medication.

Methods Participants prescribed either conventional mood stabilizers (CMS; n = 155) alone, or olanzapine with, or without, CMS (olanzapine ± CMS; n = 84) were assessed every 3 months using several measures, including the Young Mania Rating Scale, 21-item Hamilton Depression Rating Scale, Clinical Global Impressions Scale – Bipolar Version, and the EuroQol Instrument. This paper reports 24-month longitudinal clinical, pharmacological, functional, and socioeconomic data.

Results On average, participants were 42 (range 18 to 79) years of age, 58%; were female, and 73%; had a diagnosis of bipolar I. Polypharmacy was the usual approach to pharmacological treatment; participants took a median of 5 different psychotropic medications over the course of the study, and spent a median proportion of time of 100%; of the study on mood stabilizers, 90%; on antipsychotics, 9%; on antidepressants, and 5%; on benzodiazepines/hypnotics. By 24 months, the majority of participants had achieved both symptomatic and syndromal remission of both mania and depression. Symptomatic relapse rates were similar for both the CMS alone (65%;) and the olanzapine ± CMS (61%;) cohorts.

Conclusions Participants with bipolar I or schizoaffective disorder in this study were receiving complex medication treatments that were often discordant with recommendations made in contemporary major treatment guidelines. The majority of study participants demonstrated some clinical and functional improvements, but not all achieved remission of symptoms or syndrome.

Mania : diagnosis and treatment recommendations

This article provides recommendations for the diagnosis and treatment of mania, which characterizes bipolar I disorder (BD I). Failure to detect mania leads to misdiagnosis and suboptimal treatment. To diagnose mania, clinicians should include a detailed mood history within their assessment of patients presenting with depression, agitation, psychosis or insomnia. With regards to treatment, by synthesizing the findings from recent treatment guidelines, and reviewing relevant literature, this paper has distilled recommendations for both acute and long-term management. Antimanic agents including atypical antipsychotics and traditional mood stabilizers are employed to reduce acute manic symptoms, augmented by benzodiazepines if needed, and in refractory or severe cases with behavioural and/or psychotic disturbance, electroconvulsive therapy may occasionally be necessary. Maintenance/prophylaxis therapy aims to reduce recurrences/relapse, for which the combination of psychological interventions with pharmacotherapy is beneficial as it ensures adherence and monitoring of tolerability.

Medicating mood with maintenance in mind : bipolar depression pharmacotherapy

Objectives:  Bipolar depression is a core feature of bipolar disorder, a phase in which many patients spend the majority of time and one that confers a significant degree of burden and risk. The purpose of this paper is to briefly review the evidence base for the pharmacotherapy of bipolar depression and to discuss the recommendations for its optimal management.Methods:  A detailed literature review was undertaken with a particular emphasis on pharmacological treatment strategies for bipolar depression across the acute and maintenance phases of the illness. Electronic library and Web-based searches were performed using recognised tools (MEDLINE, PubMED, EMBASE and PsychINFO) to identify the pertinent literature. A summary of the evidence base is outlined and then distilled into broad clinical recommendations to guide the pharmacological management of bipolar depression.Results:  Partitioning treatment into acute and maintenance therapy is difficult based on the paucity of current evidence. The evidence from treatment trials favours the use of lithium and lamotrigine as first-line treatment in preference to valproate, and indicates that, for acute episodes, quetiapine and olanzapine have perhaps achieved equivalence at least in terms of efficacy. However, the effectiveness of the atypical antipsychotics in maintenance therapy is constrained by the potential for significant side effects of individual agents and the lack of both long-term research data and clinical experience in treating bipolar disorder as compared to other agents. Conversely, lithium and the anticonvulsants are generally slower to effect symptomatic change, and this limits their usefulness.Conclusions:  There has been a tendency for research trials of bipolar depression to differentiate the illness cross-sectionally into the acute and maintenance phases of bipolar depression; however, in clinical terms, bipolar depression invariably follows a longitudinal course in which the phases of illness are inextricably linked, and useful acute treatments are typically continued in maintenance. Therefore, when medicating mood in acute bipolar depression it is imperative to keep maintenance in mind as it is this aspect of treatment that determines long-term success.