Adjuvant topiramate administration: a pharmacologic strategy for addressing NMDA receptor hypofunction in schizophrenia

Pharmacological interventions for prevention of weight gain in people with schizophrenia

BACKGROUND

Antipsychotic-induced weight gain is an extremely common problem in people with schizophrenia and is associated with increased morbidity and mortality. Adjunctive pharmacological interventions may be necessary to help manage antipsychotic-induced weight gain. This review splits and updates a previous Cochrane Review that focused on both pharmacological and behavioural approaches to this problem.

OBJECTIVES

To determine the effectiveness of pharmacological interventions for preventing antipsychotic-induced weight gain in people with schizophrenia.

SEARCH METHODS

The Cochrane Schizophrenia Information Specialist searched Cochrane Schizophrenia's Register of Trials on 10 February 2021. There are no language, date, document type, or publication status limitations for inclusion of records in the register.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that examined any adjunctive pharmacological intervention for preventing weight gain in people with schizophrenia or schizophrenia-like illnesses who use antipsychotic medications.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data and assessed the quality of included studies. For continuous outcomes, we combined mean differences (MD) in endpoint and change data in the analysis. For dichotomous outcomes, we calculated risk ratios (RR). We assessed risk of bias for included studies and used GRADE to judge certainty of evidence and create summary of findings tables. The primary outcomes for this review were clinically important change in weight, clinically important change in body mass index (BMI), leaving the study early, compliance with treatment, and frequency of nausea. The included studies rarely reported these outcomes, so, post hoc, we added two new outcomes, average endpoint/change in weight and average endpoint/change in BMI.

MAIN RESULTS

Seventeen RCTs, with a total of 1388 participants, met the inclusion criteria for the review. Five studies investigated metformin, three topiramate, three H2 antagonists, three monoamine modulators, and one each investigated monoamine modulators plus betahistine, melatonin and samidorphan. The comparator in all studies was placebo or no treatment (i.e. standard care alone). We synthesised all studies in a quantitative meta-analysis. Most studies inadequately reported their methods of allocation concealment and blinding of participants and personnel. The resulting risk of bias and often small sample sizes limited the overall certainty of the evidence. Only one reboxetine study reported the primary outcome, number of participants with clinically important change in weight. Fewer people in the treatment condition experienced weight gains of more than 5% and more than 7% of their bodyweight than those in the placebo group (> 5% weight gain RR 0.27, 95% confidence interval (CI) 0.11 to 0.65; 1 study, 43 participants; > 7% weight gain RR 0.24, 95% CI 0.07 to 0.83; 1 study, 43 participants; very low-certainty evidence). No studies reported the primary outcomes, 'clinically important change in BMI', or 'compliance with treatment'. However, several studies reported 'average endpoint/change in body weight' or 'average endpoint/change in BMI'. Metformin may be effective in preventing weight gain (MD -4.03 kg, 95% CI -5.78 to -2.28; 4 studies, 131 participants; low-certainty evidence); and BMI increase (MD -1.63 kg/m2, 95% CI -2.96 to -0.29; 5 studies, 227 participants; low-certainty evidence). Other agents that may be slightly effective in preventing weight gain include H2 antagonists such as nizatidine, famotidine and ranitidine (MD -1.32 kg, 95% CI -2.09 to -0.56; 3 studies, 248 participants; low-certainty evidence) and monoamine modulators such as reboxetine and fluoxetine (weight: MD -1.89 kg, 95% CI -3.31 to -0.47; 3 studies, 103 participants; low-certainty evidence; BMI: MD -0.66 kg/m2, 95% CI -1.05 to -0.26; 3 studies, 103 participants; low-certainty evidence). Topiramate did not appear effective in preventing weight gain (MD -4.82 kg, 95% CI -9.99 to 0.35; 3 studies, 168 participants; very low-certainty evidence). For all agents, there was no difference between groups in terms of individuals leaving the study or reports of nausea. However, the results of these outcomes are uncertain given the very low-certainty evidence.

AUTHORS' CONCLUSIONS

There is low-certainty evidence to suggest that metformin may be effective in preventing weight gain. Interpretation of this result and those for other agents, is limited by the small number of studies, small sample size, and short study duration. In future, we need studies that are adequately powered and with longer treatment durations to further evaluate the efficacy and safety of interventions for managing weight gain.

Topiramate mitigates weight gain in antipsychotic-treated patients with schizophrenia: meta-analysis of randomised controlled trials

OBJECTIVE

Weight gain is one of the most challenging issues in patients with schizophrenia treated with antipsychotics. Several meta-analyses have been conducted to review the efficacy of topiramate in reducing weight, however, several issues regarding the methodology had arisen of which make the results remain ambiguous.

METHODS

We conducted a meta-analysis of randomised controlled trials about the use of topiramate in patients with schizophrenia for weight reduction. Ten double-blinded randomised placebo-controlled trials and seven open-label randomised controlled trials included 905 patients.

RESULTS

Patients treated with topiramate experienced a greater reduction in body weight and BMI. Patients in countries of the lower overweight population showed more significant BMI reduction. Besides, studies from the Middle East and South Asia showed the greatest effect in body weight change, followed by East Asia, then Europe/America. Topiramate group was outperformed control group with significant psychopathology improvement. No difference between two groups regarding the overall side effects.

CONCLUSIONS

Topiramate was significantly superior to control group in mitigating weight gain and psychopathology in antipsychotic-treated patients with schizophrenia. The effects of topiramate augmentation need further investigations in larger definitive studies using methodological rigor and thorough assessments.

Design, Synthesis, and X-ray of Selenides as New Class of Agents for Prevention of Diabetic Cerebrovascular Pathology

A series of novel selenides bearing benzenesulfonamide moieties was synthesized and investigated for their inhibition on six human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms such as the physiologically relevant hCA I, II, VA, VB, VII, and IX and the X-ray complex in adduct with hCA II for some of them investigated. These enzymes are involved in a variety of diseases including glaucoma, retinitis pigmentosa, epilepsy, arthritis, metabolic disorders, and cancer. The investigated compounds showed potent inhibitory action against hCA VA, VII, and IX, in the low nanomolar range, thus making them of interest for the development of isoform-selective inhibitors and as candidates for various biomedical applications.

Regulation of high glucose-induced apoptosis of brain pericytes by mitochondrial CA VA: A specific target for prevention of diabetic cerebrovascular pathology

Events responsible for cerebrovascular disease in diabetes are not fully understood. Pericyte loss is an early event that leads to endothelial cell death, microaneurysms, and cognitive impairment. A biochemical mechanism underlying pericyte loss is rapid respiration (oxidative metabolism of glucose). This escalation in respiration results from free influx of glucose into insulin-insensitive tissues in the face of high glucose levels in the blood. Rapid respiration generates superoxide, the precursor to all reactive oxygen species (ROS), and results in pericyte death. Respiration is regulated by carbonic anhydrases (CAs) VA and VB, the two isozymes expressed in mitochondria, and their pharmacologic inhibition with topiramate reduces respiration, ROS, and pericyte death. Topiramate inhibits both isozymes; therefore, in the earlier studies, their individual roles were not discerned. In a recent genetic study, we showed that mitochondrial CA VA plays a significant role in regulation of reactive oxygen species and pericyte death. The role of CA VB was not addressed. In this report, genetic knockdown and overexpression studies confirm that mitochondrial CA VA regulates respiration in pericytes, whereas mitochondrial CA VB does not contribute significantly. Identification of mitochondrial CA VA as a sole regulator of respiration provides a specific target to develop new drugs with fewer side effects that may be better tolerated and can protect the brain from diabetic injury. Since similar events occur in the capillary beds of other insulin-insensitive tissues such as the eye and kidney, these drugs may also slow the onset and progression of diabetic disease in these tissues.

Topiramate Protects Pericytes from Glucotoxicity: Role for Mitochondrial CA VA in Cerebromicrovascular Disease in Diabetes

Hyperglycemia in diabetes mellitus causes oxidative stress and pericyte depletion from the microvasculature of the brain thus leading to the Blood-Brain Barrier (BBB) disruption. The compromised BBB exposes the brain to circulating substances, resulting in neurotoxicity and neuronal cell death. The decline in pericyte numbers in diabetic mouse brain and pericyte apoptosis in high glucose cultures are caused by excess superoxide produced during enhanced respiration (mitochondrial oxidative metabolism of glucose). Superoxide is precursor to all Reactive Oxygen Species (ROS) which, in turn, cause oxidative stress. The rate of respiration and thus the ROS production is regulated by mitochondrial carbonic anhydrases (mCA) VA and VB, the two isoforms expressed in the mitochondria. Inhibition of both mCA: decreases the oxidative stress and restores the pericyte numbers in diabetic brain; and reduces high glucose-induced respiration, ROS, oxidative stress, and apoptosis in cultured brain pericytes. However, the individual role of the two isoforms has not been established. To investigate the contribution of mCA VA in ROS production and apoptosis, a mCA VA overexpressing brain pericyte cell line was engineered. These cells were exposed to high glucose and analyzed for the changes in ROS and apoptosis. Overexpression of mCA VA significantly increased pericyte ROS and apoptosis. Inhibition of mCA VA with topiramate prevented increases both in glucose-induced ROS and pericyte death. These results demonstrate, for the first time, that mCA VA regulates the rate of pericyte respiration. These findings identify mCA VA as a novel and specific therapeutic target to protect the cerebromicrovascular bed in diabetes.

Topiramate as an adjuvant treatment for obsessive compulsive symptoms in patients with bipolar disorder: a randomized double blind placebo controlled clinical trial

BACKGROUND

It has not been examined trialed whether obsessive compulsive symptoms in patients with bipolar disorder respond to topiramate as an adjuvant treatment.

METHODS

This 4-month double-blind placebo-controlled randomized clinical trial examined the efficacy and safety of augmentation with topiramat for treating the patients with bipolar disorder, manic phase type-I, and obsessive compulsive disorder symptoms. Both groups received lithium+olanzapine+clonazepam. However, one group received topiramate and the other group placebo as adjuvant medications. Yale Brown obsessive compulsive behavior scale was used to assess the outcome. Adverse effects were also recorded.

RESULTS

A total of 32 patients completed this trial. The mean score decreased from 24.2(4.8) to 17.6(8.7) in the topiramate group (P<0.003) and from 20.9(2.9) to 9.6(3.5) in the placebo group during this trial (P<0.0001). Additionally, 9(52.9%) out of 17 patients in the topiramate group and 2(12.5%) out of 16 patients in the placebo group showed more than 34% decline in YBOC score (x2=6.0, df=1, P<0.01). No serious adverse effects were detected.

LIMITATIONS

The limitations of the present study were its small sample size and the fact that it was conducted in a single center.

CONCLUSIONS

The combination of lithium+olanzapine+clonazepam decreased the symptoms of obsessive compulsive disorder in the patients with bipolar disorder type I. However, topiramate had a more significant effect than placebo on improvement of the patients with bipolar disorder and obsessive compulsive symptoms. This combination seems to be without serious adverse effects.

Modulation of ion channels in clinical psychopharmacology: adults and younger people

This review focuses on the use of Na(+), Ca(2+) and Cl(-) channel modulators in psychiatric disease. Drugs that modulate ion channels have been used in psychiatry for more than a century, and in this review we critically evaluate clinical research that reports the therapeutic effects of drugs acting on GABA(A), voltage-gated Na(+) and voltage-gated Ca(2+) channels in pediatric and adult patients. As in other fields, the evidence underpinning the use of medicines in younger people is far less robust than for adults. In addition, we discuss some current developments and highlight clinical disorders in which current molecules could be further tested. Notable success stories, such as benzodiazepines (in sleep and anxiety disorders) and antiepileptics (in bipolar disorder), have been the result of serendipitous discoveries or refinements of serendipitous discoveries, as in all other major treatments in psychiatry. Genomic, high-throughput screening and molecular pharmacology discoveries may, however, guide further developments in the future. This could include increased research in promising targets that have been perceived as commercially risky, such as selective α-subunit GABA(A) receptors.

Topiramate treatment protects blood-brain barrier pericytes from hyperglycemia-induced oxidative damage in diabetic mice

Diabetes mellitus causes cerebral microvasculature deterioration and cognitive decline. The specialized endothelial cells of cerebral microvasculature comprise the blood-brain barrier, and the pericytes (PC) that are in immediate contact with these endothelial cells are vital for blood-brain barrier integrity. In diabetes, increased mitochondrial oxidative stress is implicated as a mechanism for hyperglycemia-induced PC loss as a prerequisite leading to blood-brain barrier disruption. Mitochondrial carbonic anhydrases (CA) regulate the oxidative metabolism of glucose and thus play an important role in the generation of reactive oxygen species and oxidative stress. We hypothesize that the inhibition of mitochondrial CA would reduce mitochondrial oxidative stress, rescue cerebral PC loss caused by diabetes-induced oxidative stress, and preserve blood-brain barrier integrity. We studied the effects of pharmacological inhibition of mitochondrial CA activity on streptozotocin-diabetes-induced oxidative stress and PC loss in the mouse brain. At 3 wk of diabetes, there was significant oxidative stress; the levels of reduced glutathione were lower and those of 3-nitrotyrosine, 4-hydroxy-2-trans-nonenal, and superoxide dismutase were higher. Treatment of diabetic mice with topiramate, a potent mitochondrial CA inhibitor, prevented the oxidative stress caused by 3 wk of diabetes. A significant decline in cerebral PC numbers, at 12 wk of diabetes, was also rescued by topiramate treatment. These results provide the first evidence that inhibition of mitochondrial CA activity reduces diabetes-induced oxidative stress in the mouse brain and rescues cerebral PC dropout. Thus, mitochondrial CA may provide a new therapeutic target for oxidative stress related illnesses of the central nervous system.

Topiramate augmentation of clozapine in schizophrenia: a double-blind, placebo-controlled study

The persistence of psychotic, affective, cognitive, and psychosocial symptoms despite medications is commonly observed in schizophrenic patients. The present study was a 24-week double-blind, randomized, placebo-controlled trial aimed to explore the efficacy of topiramate add-on pharmacotherapy on clinical symptomatology and cognitive functioning in a sample of treatment-resistant schizophrenic patients receiving clozapine. After clinical and cognitive assessments were randomly allocated to receive either up to 200 mg/day of topiramate or a placebo. A final sample of 43 patients completed the study. The results obtained indicate that topiramate appeared to be scarcely effective for reducing clinical symptomatology in schizophrenic patients who have had an incomplete clinical response to clozapine. Regarding cognitive functioning, in our sample a trend to experience cognitive impairment in the examined domains was observed, as the patients included in the topiramate groups expressed cognitive complaints partially confirmed by a mild worsening of performances on certain cognitive tasks. Schizophrenia is a heterogeneous disorder with regard to pathophysiology; therefore, data reflecting the mean response of a sample of patients may fail to reveal therapeutic effects. More research is needed to better identify subgroups of patients with peculiar features which may account for responsivity to experimental medications and augmentation strategies.

Pharmacotherapy for treatment-resistant schizophrenia

Schizophrenia is a disabling mental illness with a lifetime prevalence of 0.7% worldwide and significant, often devastating, consequences on social and occupational functioning. A range of antipsychotic medications are available; however, suboptimal therapeutic response in terms of psychotic symptoms is common and affects up to one-third of people with schizophrenia. Negative symptoms are generally less amenable to treatment. Because of the consequences of inadequate symptom control, effective treatment strategies are required for people with treatment-resistant schizophrenia. Clozapine has been shown to be more effective than other antipsychotics in treatment-resistant populations in several studies; however, the occurrence of adverse effects, some of which are potentially life-threatening, are important limitations. In addition to those who are intolerant to clozapine, only 30% to 50% experience clinically significant symptom improvement. This review describes the recent evidence for treatment strategies for people not responding to nonclozapine antipsychotic agents and people not responding or only partially responding to clozapine.

Topiramate augmentation in clozapine-treated patients with schizophrenia: clinical and metabolic effects

Clozapine represents the treatment of choice for refractory psychosis, although a significant number of individuals demonstrate suboptimal response to it as well, leading to clozapine augmentation strategies. A variety of agents have been investigated in this regard, including mood stabilizers, such as anticonvulsants. Within this group of medications, topiramate is unique in that it is associated with weight loss, making it an attractive option because of clozapine's notable risk for associated metabolic disturbance. A 12-week naturalistic, open study was carried out to examine the potential benefits of topiramate in clozapine-treated individuals with schizophrenia demonstrating a suboptimal clinical response. We were specifically interested in clinical symptoms, changes in metabolic parameters, and tolerability. A total of 20 subjects were enrolled, and 16 completed the study, including 5 individuals with type 2 diabetes. Topiramate augmentation led to a 14% improvement in total Brief Psychiatric Rating Scale scores (P = 0.0003), a 2.5% decrease in body weight (P = 0.015), and was generally well tolerated, paraesthesia being the most common side effect. These findings support topiramate as a viable augmentation strategy in clozapine partial responders, with evidence of both clinical and metabolic benefits.

Longitudinal studies of cognition in schizophrenia: meta-analysis

BACKGROUND

A wide range of cognitive deficits have been demonstrated in schizophrenia, but their longitudinal course remains unclear.

AIMS

To bring together all the available information from longitudinal studies of cognitive performance in people with schizophrenia.

METHOD

We carried out a meta-analysis of 53 studies. Unlike previous reviewers, we included all studies (regardless of the type of medication), analysed each variable separately and compared results with data from controls.

RESULTS

Participants with schizophrenia showed a significant improvement in most cognitive tasks. The available data for controls showed, with one exception (the Stroop test), a similar or greater improvement. Performance in semantic verbal fluency remained stable in both individuals with schizophrenia and controls.

CONCLUSIONS

Participants with schizophrenia displayed improvement in most cognitive tasks, but practice was more likely than cognitive remediation to account for most of the improvements observed. Semantic verbal fluency may be the best candidate cognitive endophenotype.

Effects of topiramate on the prepulse inhibition of the acoustic startle in rats

The anticonvulsant topiramate (TPM) has been recently proposed as a novel adjuvant therapy for bipolar disorder and schizophrenia, yet its efficacy remains controversial. As both disorders are characterized by gating deficits, we tested the effects of TPM on the behavioral paradigm of prepulse inhibition (PPI) of the acoustic startle response, a validated animal model of sensorimotor gating. TPM (10, 18, 32, 58, 100 mg/kg, intraperitoneal, i.p.) enhanced PPI in rats in a dose-dependent fashion, prevented the PPI reduction mediated by the dopaminergic agonist apomorphine (0.25 mg/kg, subcutaneous, s.c.) and potentiated the effects of the antipsychotic drugs haloperidol (0.05, 0.1 mg/kg, i.p.) and clozapine (2.5, 5 mg/kg, i.p.). Conversely, TPM elicited no significant effect on the PPI disruption mediated by the NMDA receptor antagonist dizocilpine (0.05, 0.1 mg/kg, s.c.) and surprisingly antagonized the attenuation of dizocilpine-induced PPI disruption mediated by clozapine (5 mg/kg, i.p.). Our results suggest that TPM may exert diverse actions on the neural substrates of sensorimotor gating. While the pharmacological mechanisms of such effects are still elusive, our findings might contribute to shed light on some controversies on the therapeutic action of TPM, and point to this drug as a putative novel adjuvant therapy for some clusters of gating disturbances.

Effects of topiramate on methamphetamine-induced changes in attentional and perceptual-motor skills of cognition in recently abstinent methamphetamine-dependent individuals

Methamphetamine-dependent individuals often cite the need to maintain enhanced cognitive performance and attention as a reason for continuing or relapsing to drug-taking. Further, methamphetamine addicts might not comply with taking a potentially therapeutic medication if it had a profound effect on these cognitive processes. Topiramate, a sulfamate-substituted fructopyranose derivative, has been suggested as a putative therapeutic medication for treating methamphetamine dependence. Examination of topiramate's effects on cognitive performance and attention is a clinically and scientifically important component of understanding its potential therapeutic profile. In 10 male and female individuals who met DSM-IV criteria for methamphetamine dependence, we examined the effects of low (50 mg b.i.d.)- and high (100 mg b.i.d.)-dose topiramate - in both the presence and absence of low (15 mg)- and high (30 mg)-dose intravenous methamphetamine--on cognitive performance, attention, and concentration on the rapid visual information processing task and the digit symbol substitution test. Intravenous methamphetamine enhanced cognitive performance, attention, and concentration among recently withdrawn methamphetamine addicts--an effect that hitherto had not been well characterized. Topiramate's cognitive effects were mixed and rather paradoxical, with a tendency to improve attention and concentration both alone and in the presence of methamphetamine while worsening psychomotor retardation. No deleterious interaction occurred between topiramate and methamphetamine on any of these cognitive processes. While clinical studies with topiramate should prepare participants for possible psychomotor retardation, the cognitive effects profile observed would not likely present an important obstacle to compliance in motivated patients. Topiramate's complicated cognitive effects among methamphetamine addicts need more comprehensive examination.

Topiramate-induced psychotic exacerbation: case report and review of literature

Background. Topiramate (TPM) is a new antiepileptic drug that is used mainly in the treatment of refractory partial epileptic seizures. There are some studies reporting TPM's effectiveness in the treatment and maintenance of some psychiatric illnesses such as acute mania, some other affective disorders, post-traumatic stress disorder and binge-eating disorder. On the other hand, it has been shown that TPM may cause mild to moderate cognitive impairment and is thought to be responsible for a series of neuro-psychiatric signs and symptoms. Some of the available articles that have mentioned the relationship of psychotic symptoms and topiramate usage are discussed. Objective. The present paper aims to discuss a case of psychotic exacerbation purported to occur after TPM administration and to review specifically the literature on TPM's potential for inducing psychotic symptoms. The patient presented here is thought to be an undiagnosed schizophrenia patient until his admission to our clinic (Department of Psychiatry, Gazi University Medical School) with TPM-exacerbated psychotic symptoms. Conclusions. The current findings are still subject to controversy because of the presence of both individual case reports and case series on the association between appearance of psychotic symptoms and TPM usage.

Efficacy of topiramate, valproate, and their combination on aggression/agitation behavior in patients with psychosis

Topiramate is an antiepileptic drug, recently also used in the treatment of psychiatric diseases. Inasmuch as topiramate and valproate, which are currently used for aggressive behavior, share several pharmacological mechanisms (positive modulatory effect on the GABA activity and negative modulatory effect on glutamatergic neurotransmission), the objective of the present study was to compare the pharmacological effects of topiramate with those of valproate and their combination in patients with psychiatric disorders showing marked aggression and agitation. A retrospective, case-controlled, mirror-image study was carried out in a sample of 45 inpatients affected by schizophrenia, schizoaffective and bipolar disorder, and hospitalized in a maximum-security Canadian psychiatry hospital. Overt Aggression Scale, Agitation-Calmness Evaluation Scale, number and intensity of psychotic episodes, number of episodes of withdrawal from group activities per week, and number of therapeutic isolation per week and of strict surveillance intervention per week were evaluated before and after the treatments. Results indicate that patients treated with topiramate show a decrease in the average score of the Overt Aggression Scale, a decrease of episodes of agitation and of strict surveillance interventions. This effect was similar to the group treated with valproate or with the combination of valproate-topiramate. However, valproate therapy, but not topiramate therapy, decreased the intensity of agitation episodes measured by the Agitation-Calmness Evaluation Scale; valproate and the combination topiramate-valproate decreased the number of psychotic disorganization episodes as well. These results suggest that topiramate could be a valid medicine in the control of aggression in psychosis. Double-blind, randomized, placebo-controlled studies need to further assess this pharmacological indication.

Topiramate augments the antipsychotic-like effect and cortical dopamine output of raclopride

Recent clinical studies have shown that the anticonvulsant drug topiramate may improve negative symptoms in schizophrenia when added to a stable regimen of neuroleptic medication. It has also been shown that addition of topiramate to neuroleptics might be beneficial in treatment-resistant schizophrenia. Clinically effective doses of antipsychotic drugs (APDs) have been found to suppress conditioned avoidance response behavior (CAR), a preclinical test of antipsychotic activity with high predictive validity, in rats. Therefore, we investigated the putative antipsychotic-like activity of topiramate when added to the selective dopamine (DA) D2 receptor antagonist raclopride, using the CAR model in the rat. Extrapyramidal side effect liability of the drug combination was evaluated in parallel by means of the catalepsy test. We also examined the effect of this drug treatment on DA release in the medial prefrontal cortex (mPFC) and the nucleus accumbens (NAC), using in vivo microdialysis in freely moving animals. Topiramate (40 mg/kg), while ineffective when given alone, significantly augmented the antipsychotic-like effect of raclopride (0.075 mg/kg) on CAR without any concomitant catalepsy. Addition of topiramate to rats treated with raclopride generated a large increase in DA output in the mPFC, whereas no additional effect on the raclopride-induced DA release in the NAC was obtained. These data support the adjunctive use of topiramate in schizophrenia to ameliorate negative symptoms and suggest that this treatment may increase the efficacy, but not the extrapyramidal side effect liability, of the APDs used.

Topiramate as an Adjuvant Treatment With Atypical Antipsychotics in Schizophrenic Patients Experiencing Weight Gain

Schizophrenic patients commonly suffer weight gain, which is often associated with widely prescribed antipsychotic medicines. It is distressing to most patients who experience it and may affect their response to treatment of schizophrenia. Weight gain is also associated with treatment noncompliance and several medical conditions. This study explored the efficacy and tolerability of topiramate as an adjuvant treatment of patients with schizophrenia who were carrying excess weight. In this 12-week, randomized, placebo-controlled prospective study, 66 hospitalized patients with schizophrenia who were carrying excess weight were given topiramate at doses of 100 mg/day or 200 mg/day, or a placebo. The primary measures made were body weight, body mass index, waist measurement, hip measurement, and waist-to-hip ratio. Safety measures included physical examinations and the monitoring of adverse effects, clinical laboratory data, and vital signs. The Clinical Global Impression-Severity of Illness scale (CGI-S) and the Brief Psychiatric Rating Scale (BPRS) were used to quantify changes in schizophrenic symptoms and signs. In the 200-mg/day topiramate group, body weight, body mass index, waist measurement, and hip measurement decreased significantly compared with the 100-mg/day topiramate and placebo groups over 12 weeks. However, the waist-to-hip ratio did not change in any group. Scores on the CGI-S and BPRS decreased significantly over the 12-week period in both topiramate groups, but the decrease was not clinically meaningful. These results suggest that a higher dose of topiramate is efficacious as an adjuvant treatment of patients with schizophrenia experiencing excess weight gain. Further clinical research is required to establish guidelines for the use of topiramate as an antiobesity agent in schizophrenic patients.

Novel antipsychotics in schizophrenia

Several atypical antipsychotics have become available for the treatment of schizophrenia that are at least as effective as conventional treatment and with fewer extrapyramidal side effects. Their presumed mechanisms of therapeutic action vary and are no longer limited to dopamine D2 receptor antagonism. Numerous novel drugs are in development, with a variety of receptor affinities and other supposed therapeutic effects. This article will review current developments in drug discovery alongside contemporary evidence for potential substrates and mechanisms of antipsychotic action. Despite many promising developments there is no ideal antipsychotic to date. Progress in drug treatment for schizophrenia is confronted by several areas of difficulty which, barring serendipity, must be resolved before real advances can be anticipated.

Effects of acute topiramate dosing on open field behavior in mice

Although topiramate (TPM) has been used to treat human disease, there are few studies of its effects on the behavior of animal models. Objective. This study aimed to assess the effect of acute TPM administration on the behavior of mice undergoing the open-field test. Method. The animals were divided in two groups: the treatment group (n = 10), which received 10 mg/kg TPM intraperitoneally, and the control group (n = 10), which received saline. 30 minutes after drug administration, the animals were assessed for 5 minutes in the open-field. The following parameters were analyzed: number of squares explored, immobility time, central area permanence time, peripheral apparatus permanence time, rearing frequency and time, grooming frequency and time, rearing frequency during the last minute, number of fecal boli, and estimated speed. Results. The treatment group had a higher number of squares explored (p = 0.02) and greater estimated speed (p = 0.01). Conclusion. The results suggest that acute TPM administration increases the locomotor activity of mice without interfering with learning, anxiety, stress, and exploratory behavior.