Biphasic effects of zonisamide on serotonergic system in rat hippocampus

Zonisamide attenuates the severity of levodopa-induced dyskinesia via modulation of the striatal serotonergic system in a rat model of Parkinson's disease

Glutamate, GABA, acetylcholine, dopamine, and serotonin interact with each other to regulate the flow of neural information in the striatum. Serotonin type 1A receptor (5HT1A) is primarily expressed on glutamatergic nerve terminals, and 5HT1B is expressed on GABAergic medium spiny neurons (MSNs). Zonisamide (ZNS) reportedly improves the off period without worsening levodopa-induced dyskinesia (LID) in patients with advanced Parkinson's disease. In this study, LID model rats were prepared by administrating levodopa to unilaterally 6-OHDA-lesioned rats. We analyzed changes in serotonergic neurotransmission of LID model rats to elucidate the relationship between LID and the serotonergic system and pathomechanism of the anti-dyskinetic effects of ZNS. Abnormal involuntary movements (AIMs) were most severe in intermittently levodopa-treated rats but milder in rats intermittently medicated with levodopa and ZNS. Continuously levodopa-infused rats or intermittently ZNS-injected rats did not develop AIMs, and no differences in the expression of brain-derived neurotrophic factor, 5-HT transporter, 5HT1A, and 5HT1B mRNA between the lesioned striatum and normal side were observed. Expression of 5HT1B mRNA was elevated in the lesioned striatum of intermittently levodopa-treated rats, but this elevation was normalized by concomitant use of ZNS. The severity of AIMs was correlated with the ratio of 5HT1B to 5HT1A mRNA expression in the lesioned striatum, indicating that the anti-LID effect of ZNS is based on inhibition via 5HT1B receptors to direct pathway MSNs sensitized by intermittent levodopa treatment. Selectively acting serotonergic drugs, especially those that lower the 5HT1B to 5HT1A ratio, are promising new therapeutic agents to attenuate LID development.

Zonisamide effects on sleep problems and depressive symptoms in Parkinson's disease

BACKGROUND

We aimed to evaluate the effect of zonisamide (ZNS) on motor symptoms and nonmotor symptoms such as depressive symptoms and sleep problems in Parkinson's disease (PD) patients with or without tremor.

METHODS

We conducted a 3-month, open-label study to assess the effects of ZNS on motor symptoms, depressive symptoms and sleep problems. Twenty levodopa-treated PD patients with motor fluctuation completed the study. Patients received 25-50 mg/day of ZNS and were assessed for the Japanese version of the Movement Disorder Society Revision of the Unified PD Rating Scale (MDS-UPDRS) parts I, III, and IV, PD Sleep Scale (PDSS)-2, Beck depression inventory-2 (BDI-II), and PD Questionnaire (PDQ-8) at baseline and after 1, 2 and 3 months of treatment. Patients were categorized into the tremor group and nontremor group to assess changes in clinical parameters.

RESULTS

At 3 months, the scores on the MDS-UPDRS parts I, III and IV significantly improved and off-time reduced compared to baseline. Additionally, the PDSS-2 total score significantly decreased at 3 months. Although there were no significant differences in changes in UPDRS part I, III, or IV between the groups after ZNS treatment, the tremor group had significant improvements in PDSS-2 at 3 months and BDI-II at 1, 2 and 3 months compared with the nontremor group.

CONCLUSION

We showed the beneficial effects of ZNS on motor symptoms and sleep problems in levodopa-treated PD patients with motor fluctuation. ZNS may be more effective for several nonmotor symptoms in PD patients with tremor compared with those without tremor.

Astroglial Connexin43 as a Potential Target for a Mood Stabiliser

Mood disorders remain a major public health concern worldwide. Monoaminergic hypotheses of pathophysiology of bipolar and major depressive disorders have led to the development of monoamine transporter-inhibiting antidepressants for the treatment of major depression and have contributed to the expanded indications of atypical antipsychotics for the treatment of bipolar disorders. In spite of psychopharmacological progress, current pharmacotherapy according to the monoaminergic hypothesis alone is insufficient to improve or prevent mood disorders. Recent approval of esketamine for treatment of treatment-resistant depression has attracted attention in psychopharmacology as a glutamatergic hypothesis of the pathophysiology of mood disorders. On the other hand, in the last decade, accumulated findings regarding the pathomechanisms of mood disorders emphasised that functional abnormalities of tripartite synaptic transmission play important roles in the pathophysiology of mood disorders. At first glance, the enhancement of astroglial connexin seems to contribute to antidepressant and mood-stabilising effects, but in reality, antidepressive and mood-stabilising actions are mediated by more complicated interactions associated with the astroglial gap junction and hemichannel. Indeed, several depressive mood-inducing stress stimulations suppress connexin43 expression and astroglial gap junction function, but enhance astroglial hemichannel activity. On the other hand, monoamine transporter-inhibiting antidepressants suppress astroglial hemichannel activity and enhance astroglial gap junction function, whereas several non-antidepressant mood stabilisers activate astroglial hemichannel activity. Based on preclinical findings, in this review, we summarise the effects of antidepressants, mood-stabilising antipsychotics, and anticonvulsants on astroglial connexin, and then, to establish a novel strategy for treatment of mood disorders, we reveal the current progress in psychopharmacology, changing the question from "what has been revealed?" to "what should be clarified?".

Effects of Carbamazepine, Lacosamide and Zonisamide on Gliotransmitter Release Associated with Activated Astroglial Hemichannels

Recent studies using the genetic partial epilepsy model have demonstrated that hyperfunction of astroglial hemichannels contributes to pathomechanism of epileptic seizure. Therefore, to explore the novel anticonvulsive mechanisms, the present study determined the effects of voltage-dependent Na⁺ channel (VDSC)-inhibiting anticonvulsants, carbamazepine (CBZ), lacosamide (LCM), and zonisamide (ZNS) on the astroglial release of l-glutamate and adenosine triphosphate (ATP). The effects of subchronic administration of therapeutic-relevant dose of three anticonvulsants on the release of l-glutamate and ATP in the orbitofrontal cortex (OFC) were determined using microdialysis. The concentration-dependent effects of acute and subchronic administrations of anticonvulsants on astroglial gliotransmitter release were determined using primary cultured astrocytes. The concentration-dependent effects of subchronic administrations of anticonvulsants on connexin43 (Cx43) expression in the plasma membrane of primary cultured astrocytes were determined using the Simple Western system. An increase in the levels of extracellular K⁺ resulted in a concentration-dependent increase in the astroglial release of l-glutamate and ATP. The depleted levels of extracellular Ca²⁺ alone did not affect astroglial gliotransmitter release but did accelerate K⁺-evoked gliotransmitter release via activation of astroglial hemichannels. Both non-selective hemichannel inhibitor carbenoxolone (CBX) and selective Cx43 inhibitor GAP19 prevented both gliotransmitter release through activated astroglial hemichannels and the hemichannel-activating process induced by elevation of the levels of extracellular K⁺ with depletion of the levels of extracellular Ca²⁺. ZNS subchronically decreased Cx43 expression and acutely/subchronically inhibited Cx43 hemichannel activity. LCM acutely inhibited hemichannel activity but did not subchronically affect Cx43 expression. Therapeutic-relevant concentration of CBZ did not affect hemichannel activity or Cx43 expression, but supratherapeutic concentration of CBZ decreased Cx43 expression and hemichannel activity. Therefore, the present study demonstrated the distinct effects of CBZ, LCM, and ZNS on gliotransmitter release via modulation of astroglial hemichannel function. The different features of the effects of three VDSC-inhibiting anticonvulsants on astroglial transmission associated with hemichannels, at least partially, possibly contributing to the formation of the properties of these three anticonvulsants, including the antiepileptic spectrum and adverse effects regarding mood and cognitive disturbance.

The effect of zonisamide on memory processes - A preclinical study

OBJECTIVE

Zonisamide is an antiepileptic drug with a perspective of a broader use. Although it is regarded as a relatively safe drug, zonisamide might cause disorders of the central nervous system. The study assessed the influence of zonisamide on spatial and emotional memory in adult Wistar rats.

METHODS

Morris water maze test was used to examine the effect of zonisamide administered p.o. as single dose (50 mg/kg or 100 mg/kg) or repeatedly (50 mg/kg) on spatial memory. The impact of zonisamide administered as above on emotional memory was assessed in the Passive avoidance test.

RESULTS

Zonisamide mainly in a high acute dose impaired the spatial memory, whereas when administered repeatedly, its effect was observed only in the initial phase of the study. Emotional memory disturbances were noted only during repeated administration of zonisamide.

CONCLUSION

Zonisamide may impair memory and learning processes in rats but the results are varied and depend on the type of memory.

Vortioxetine Subchronically Activates Serotonergic Transmission via Desensitization of Serotonin 5-HT1A Receptor with 5-HT3 Receptor Inhibition in Rats

Vortioxetine is a novel, multimodal antidepressant with unique targets, including the inhibition of the serotonin transporter (SET), of serotonin 5-HT₃ (5-HT3R), and of 5-HT₇ (5-HT7R) receptors and partial agonism to serotonin 5-HT_1A (5-HT1AR) receptors in humans. Vortioxetine has a lower affinity to 5-HT1AR and 5-HT7R in rats compared with humans, but several behavior studies have demonstrated its powerful antidepressant-like actions. In spite of these efforts, detailed effects of the subchronic administration of vortioxetine on serotonergic transmission remain to be clarified. This study examined the mechanisms underlying the clinical effects of vortioxetine by measuring the releases of 5-HT and GABA in the medial prefrontal cortex (mPFC) of freely moving rats compared with the selective SET inhibitor, escitalopram. Inhibition of 5-HT3R in the mPFC enhanced regional 5-HT release via GABAergic disinhibition. Activation of somatodendritic 5-HT1AR in the dorsal raphe nucleus (DRN) and presynaptic 5-HT1AR in the mPFC inhibited 5-HT release in the mPFC. Escitalopram subchronically activated mesocortical serotonergic transmission via desensitization of 5-HT1AR in the mPFC and DRN and of 5-HT3R in the mPFC; however, vortioxetine also subchronically activated mesocortical serotonergic transmission via desensitization of 5-HT1AR in the mPFC and DRN but not of 5-HT3R in the mPFC. These demonstrations, the desensitization of 5-HT1AR with the inhibition of 5-HT3R (without 5-HT3R desensitization), at least partially, contribute to the multimodal antidepressant action of vortioxetine in rats.

Pharmacometabolomics applied to zonisamide pharmacokinetic parameter prediction

INTRODUCTION

Zonisamide is a new-generation anticonvulsant antiepileptic drug metabolized primarily in the liver, with subsequent elimination via the renal route.

OBJECTIVES

Our objective was to evaluate the utility of pharmacometabolomics in the detection of zonisamide metabolites that could be related to its disposition and therefore, to its efficacy and toxicity.

METHODS

This study was nested to a bioequivalence clinical trial with 28 healthy volunteers. Each participant received a single dose of zonisamide on two separate occasions (period 1 and period 2), with a washout period between them. Blood samples of zonisamide were obtained from all patients at baseline for each period, before volunteers were administered any medication, for metabolomics analysis.

RESULTS

After a Lasso regression was applied, age, height, branched-chain amino acids, steroids, triacylglycerols, diacyl glycerophosphoethanolamine, glycerophospholipids susceptible to methylation, phosphatidylcholines with 20:4 FA (arachidonic acid) and cholesterol ester and lysophosphatidylcholine were obtained in both periods.

CONCLUSION

To our knowledge, this is the only research study to date that has attempted to link basal metabolomic status with pharmacokinetic parameters of zonisamide.

Efficacy, tolerability, and retention rates of zonisamide in older adult patients with focal-onset epilepsy: Experiences from two tertiary epilepsy centers

OBJECTIVE

The objective of this study was to evaluate the efficacy, tolerability, and retention rates for zonisamide (ZNS) in older adult patients with focal-onset epilepsy.

PATIENTS AND METHODS

Chart reviews of patients aged 60years and older with focal-onset epilepsy treated with ZNS in two tertiary epilepsy centers were analyzed retrospectively.

RESULTS

Eighty-five patients (41 males, 44 females) aged over 60years (range: 60-81) with focal-onset epilepsy treated with ZNS were identified; 55.3% of the patients (n=47) were on monotherapy. The median and average doses of ZNS doses were 200mg/day (range: 100-400) and 212.9±84.2mg/day, respectively. With ZNS treatment, 67.1% of the patients (n=57) were seizure-free for a median of 28months (range: 10-56) whereas 20% (n=17) of the patients had seizures that were unresponsive to ZNS treatment. Best seizure control was achieved in patients with poststroke epilepsy; seizure freedom was 80% in this subgroup. Overall retention rate was found to be 83.5%. There was no significant relation between receiving poly- or monotherapy and discontinuation of ZNS (p=0.18). Thirty-two of the patients (37.6%) lost weight. Median weight loss was 8kg (range: 2-16). There was no significant correlation between weight loss and the administered doses of ZNS (r=0.34; p=0.12).

CONCLUSION

Despite limitations due to the retrospective design of the study, the results show that ZNS is a well-retained drug with high efficacy in older adult patients with epilepsy.

Prevention of the adverse effects of olanzapine on lipid metabolism with the antiepileptic zonisamide

BACKGROUND

Atypical antipsychotic drugs, particularly olanzapine, represent a mainstay in the treatment of psychoses; however, their use is commonly associated with weight gain and diabetes. The aim of this study was to determine whether combined administration of olanzapine and zonisamide can be used to prevent olanzapine-induced metabolic disturbances.

METHODS AND RESULTS

These experiments involved female Sprague Dawley rats (n = 6-8/group) that were administered olanzapine, either acutely (6 mg/kg, s. c) or via continuous osmotic minipump infusion (6 mg/kg/day for 6 or 14 days), in combination with zonisamide (26 mg/kg/day,i.p.). Continuous infusion of olanzapine induced accumulation of adipose tissue and an associated reduction in stimulated lipolysis and reduced protein expression of CGI-58, a critical co-activator of ATGL. Olanzapine treatment caused a preferential shift toward carbohydrate oxidation (or reduced fat oxidation), elevated blood triglycerides and a reduction in locomotor activity. Olanzapine had a direct effect on glucose regulation, causing rapid hyperglycemia, and a reduction in glucose tolerance and insulin sensitivity. Continuous administration of olanzapine caused significant hyperinsulinemia and a significant reduction in insulin sensitivity. Zonisamide did not affect the impact of olanzapine on glucose homeostasis. On the other hand, co-administration of olanzapine with zonisamide completely ameliorated olanzapine-mediated shifts in lipid metabolism resulting in a normalization of olanzapine-induced weight gain.

CONCLUSION

These data collectively show an impact of olanzapine on body weight and lipid metabolism, which is ameliorated by co-administration with zonisamide. These findings suggest that a combined olanzapine and zonisamide approach might reduce weight gain, but will not provide protection against olanzapine-induced glucose intolerance.

Zonisamide attenuates lactacystin-induced parkinsonism in mice without affecting system xc<sup/>

Zonisamide (ZNS), an anticonvulsant drug exhibiting symptomatic effects in Parkinson's disease (PD), was recently reported to exert neuroprotection in rodent models. One of the proposed neuroprotective mechanisms involves increased protein expression of xCT, the specific subunit of the cystine/glutamate antiporter system x_c^-, inducing glutathione (GSH) synthesis. Here, we investigated the outcome of ZNS treatment in a mouse model of PD based on intranigral proteasome inhibition, and whether the observed effects would be mediated by system x_c^-. The proteasome inhibitor lactacystin (LAC) was administered intranigrally to male C57BL/6J mice receiving repeated intraperitoneal injections of either ZNS 30mgkg^-1 or vehicle. Drug administration was initiated three days prior to stereotaxic LAC injection and was maintained until six days post-surgery. One week after lesion, mice were behaviorally assessed and investigated in terms of nigrostriatal neurodegeneration and molecular changes at the level of the basal ganglia, including expression levels of xCT. ZNS reduced the loss of nigral dopaminergic neurons following LAC injection and the degree of sensorimotor impairment. ZNS failed, however, to modulate xCT expression in basal ganglia of lesioned mice. In a separate set of experiments, the impact of ZNS treatment on system x_c^- was investigated in control conditions in vivo as well as in vitro. Similarly, ZNS did not influence xCT or glutathione levels in naive male C57BL/6J mice, nor did it alter system x_c^- activity or glutathione content in vitro. Taken together, these results demonstrate that ZNS treatment provides neuroprotection and behavioral improvement in a PD mouse model based on proteasome inhibition via system x_c^- independent mechanisms.

Anticonvulsants for the treatment of alcohol withdrawal syndrome and alcohol use disorders

Alcoholic patients suffer from harmful allostatic neuroplastic changes in the brain causing an acute withdrawal syndrome upon cessation of drinking followed by a protracted abstinence syndrome and an increased risk of relapse to heavy drinking. Benzodiazepines have long been the treatment of choice for detoxifying patients and managing alcohol withdrawal syndrome (AWS). Non-benzodiazepine anticonvulsants (NBACs) are increasingly being used both for alcohol withdrawal management and for ongoing outpatient treatment of alcohol dependence, with the goal of either abstinence or harm reduction. This expert narrative review summarizes the scientific basis and clinical evidence supporting the use of NBACs in treating AWS and for reducing harmful drinking patterns. There is less evidence in support of NBAC therapy for AWS, with few placebo-controlled trials. Carbamazepine and gabapentin appear to be the most promising adjunctive treatments for AWS, and they may be useful as monotherapy in select cases, especially in outpatient settings and for the treatment of mild-to-moderate low-risk patients with the AWS. The body of evidence supporting the use of the NBACs for reducing harmful drinking in the outpatient setting is stronger. Topiramate appears to have a robust effect on reducing harmful drinking in alcoholics. Gabapentin is a potentially efficacious treatment for reducing the risk of relapse to harmful drinking patterns in outpatient management of alcoholism. Gabapentin's ease of use, rapid titration, good tolerability, and efficacy in both the withdrawal and chronic phases of treatment make it particularly appealing. In summary, several NBACs appear to be beneficial in treating AWS and alcohol use disorders.

Zonisamide: a review of the clinical and experimental evidence for its use in Parkinson's disease

The limitations of currently available therapies in addressing the non motor symptoms of Parkinson's disease (PD) have egged on the search for newer options. Zonisamide has been in use for epilepsy and it was serendipitously found to improve the symptoms of PD in a patient who had both epilepsy and PD. Thereafter, various trials were designed to assess the use of zonisamide in PD. The present article investigates the evidence for use of zonisamide in PD from the various clinical trials that were designed to address this issue. Furthermore, the article also summarizes the various mechanisms of its use in PD as described in various animal experiments. A search protocol was designed with predefined inclusion and exclusion criteria. The databases searched were Pubmed, Ovid medline, Cochrane and clinicaltrials.gov. The data thus generated, was fed into a predesigned format. Most of the clinical trials on zonisamide in PD have come from Japan. Most of these trials used the changes in the Unified Parkinson's Disease Rating Scale (UPDRS) score as the endpoints and the most conclusive evidence is for a dose of 25-50 mg, which caused a change in UPDRS part III (motor symptoms). These patients were on levodopa and other drugs used for PD during the trials. One of the clinical trials conducted in Spain investigates the use of zonisamide in impulse control disorders among 15 patients of PD. Among the many mechanisms postulated, a reduction in levodopa induced quinone formation, protection against mitochondrial impairment and an increase in astroglial cysteine transport, an inhibition of microglial activation, monoamine oxidase-B (MAO-B) inhibition, an increased dopamine release and blockade of calcium channels are the most cited. There is evidence for use of zonisamide in PD in addition to levodopa and other therapies for control of motor symptoms. For now, the evidence for its use in control of non motor symptoms in PD is not enough and needs to be investigated further.

The effect of zonisamide on antipsychotic-associated weight gain in patients with schizophrenia: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Many patients with schizophrenia suffer from metabolic symptoms and weight gain in which predispose them to obesity, diabetes, and cardiovascular problems. This trial examines the efficacy and safety of zonisamide on weight and body mass index in patients with schizophrenia being administered with atypical antipsychotics.

METHOD

In this 10-week, double blind randomized placebo controlled clinical trial, forty one patients with schizophrenia diagnosed according to DSM-IV-TR criteria who were taking a stable dose of atypical antipsychotic are allocated into one of the two groups of zonisamide or placebo group. Weight, body mass index, waist circumference, and adverse effects were assessed.

RESULTS

The two groups were not statistically different regarding baseline characteristics on age, gender, education, diagnosis, weight, body mass index, daily cigarette smoking, and the duration of illness. After 10 weeks, the patients in the placebo group had significantly gained weight, while the patients in the zonisamide group lost weight (mean=1.9, SD=2.2 versus mean=-1.1 kg, SD=1.4). The changes of body mass index in the two groups were significantly different. Body mass index decreased in the zonisamide group (mean=-0.3, SD=0.4) while it increased in the placebo group (mean=2.2, SD=6.9). There was a significance difference between the two groups regarding waist circumference at the end of trial (P<0.0001), too. The waist increased in the placebo group while it decreased in the zonisamide group (mean=1.1, SD=1.7 versus mean=-0.7, SD=1.2, respectively), as well. The frequencies of adverse effects were not significantly different between the two groups and zonisamide was tolerated well.

CONCLUSION

Zonisamide as an adjuvant treatment is tolerated well and markedly affect on the weight loss of patients with schizophrenia being treated with atypical antipsychotics.

Antiepileptic drug effects on mood and behavior: molecular targets

With almost 100 years of clinical experience, antiepileptic drugs (AEDs) remain the mainstay of epilepsy treatment. They suppress epileptic seizures by acting on a variety of mechanisms and molecular targets involved in the regulation of neuronal excitability. These include inhibitory-GABAergic and excitatory-glutamatergic neurotransmission, as well as ion (sodium and calcium) conductance through voltage-gated channels. On the other hand, accruing evidence indicates that these mechanisms and targets are also implicated in the regulation of mood and behavior, which may explain why each AED is associated with specific psychotropic effects. These effects, however, cannot be explained solely on the basis of the known mode of action of each AED, and other mechanisms or targets are likely to be implicated. In this article, we review positive and negative effects of AEDs on mood and behavior, discuss putative underlying mechanisms, and highlight knowledge gaps which should be addressed in future studies.

Characteristics of selected second-generation antiepileptic drugs used in dogs

A significant number of cases of clinical canine epilepsy remain difficult to control in spite of the applied treatment. At the same time, the range of antiepileptic drugs is increasingly wide, which allows efficient treatment. In the present paper we describe the pharmacodynamics and pharmacokinetics of the newer antiepileptic drugs which were licensed after 1990 but are still not widely used in veterinary medicine. The pharmacokinetic profiles of six of these drugs were tested on dogs. The results of experimental studies suggest that second generation antiepileptic drugs may be applied in mono- as well as in poli- treatment of canine epilepsy because of the larger safety margin and more advantageous pharmacokinetic parameters. Knowledge of the drugs' pharmacokinetics allows its proper clinical appliance, which, in turn, gives the chance to improve the efficiency of pharmacotherapy of canine epilepsy.

Zonisamide: its pharmacology, efficacy and safety in clinical trials

Zonisamide is a benzisoxazole derivative, chemically unrelated to other antiepileptic drugs, that appears to have multiple mechanisms of action, including inhibition of Na(+) channels and reduction of T-type Ca(2+) currents. It is currently licensed in Europe and the USA for adjunctive treatment of partial seizures in adults, and in Europe as monotherapy for treatment of partial seizures in adults with newly diagnosed epilepsy. Zonisamide displays predictable, dose-dependent pharmacokinetics and has a half-life of ~60 h, allowing once- or twice-daily administration. It has a low potential for interactions with other medications, including oral contraceptives. The clinical efficacy of adjunctive zonisamide therapy has been established in four pivotal, phase III, randomized, double-blind, placebo-controlled trials, which together included approximately 850 patients, aged 12-77 years, with refractory partial epilepsy. In all four trials, zonisamide 300-600 mg/day resulted in significant reductions in median total seizure rates vs placebo, and zonisamide was generally well tolerated; the most frequently reported adverse events being somnolence, dizziness and anorexia/weight loss. Subanalysis of the primary European trial indicated that zonisamide was effective when administered as first-line adjunctive treatment, and a long-term extension to the same trial demonstrated that the efficacy and safety/tolerability of adjunctive zonisamide was sustained for up to 36 months. Once-daily monotherapy with zonisamide (200-500 mg/day) has been shown to be non-inferior to, and as well tolerated as, twice-daily monotherapy with controlled-release carbamazepine (400-1200 mg/day) in adults with newly diagnosed partial epilepsy. Zonisamide has also been shown to have favourable long-term retention rates, an important indication of its overall effectiveness.

An open pilot study of zonisamide augmentation in major depressive patients not responding to a low dose trial with duloxetine: preliminary results on tolerability and clinical effects

BACKGROUND

Despite multiple antidepressant options, major depressive disorder (MDD) still faces high non-response rates, eventually requiring anticonvulsant augmentation strategies too. The aim of this study was to explore such a potential role for zonisamide.

METHODS

A total of 40 MDD outpatients diagnosed using the Diagnostic and Statistical Manual for Mental Disorders, fourth edition criteria entered a 24 week open trial receiving duloxetine 60 mg/day for the first 12 weeks and subsequently (weeks 12 to 24) augmentation with zonisamide 75 mg/day if they did not respond to the initial monotherapy. Efficacy and tolerability were assessed using the Hamilton Scales for Anxiety and Depression (a 12 week score ≥50% vs baseline defined 'non-response'), the Arizona Sexual Experience Scale, the Patient Rated Inventory of Side Effects and the Young Mania Rating Scale.

RESULTS

At week 12, 15 patients out of 39 (38.5%) were responders, and 1 had dropped out; remarkably, 14 patients out of 24 (58.3%) had achieved response by week 24. Poor concentration and general malaise were associated with non-response both at week 12 and 24 (P = 0.001), while loss of libido and reduced energy were prominent among final timepoint non-responders. Patients receiving zonisamide also experienced weight reduction (2.09 ± 12.14 kg; P = 0.001) independently of the outcome.

CONCLUSIONS

Although only a preliminary study due to strong methodological limitations, and thus requiring confirmation by further controlled investigations, the current results indicate zonisamide may be a potential augmentation option for some depressed patients receiving low doses of duloxetine.

Moderate toxic effects following acute zonisamide overdose

Zonisamide is an antiepileptic drug that acts on voltage-sensitive sodium and calcium channels, with a modulatory effect on GABA-mediated neuronal inhibition and an inhibitory effect on carbonic anhydrase. It is used mainly for the treatment of partial seizures, and is generally well tolerated at therapeutic doses. The most common reported adverse effects are somnolence, anorexia, dizziness, and headache. There are limited data on zonisamide overdose in the literature, and no case of zonisamide mono-intoxication has been published to date. We describe the first case of zonisamide mono-intoxication in a 25-year-old woman who ingested 12.6 g of this substance with suicidal intent. Despite a plasma zonisamide concentration of 182 mg/L on admission, the patient exhibited a benign clinical course with vomiting and central nervous system depression, requiring brief intubation. Somnolence persisted for 50 hours, and normal-anion-gap metabolic acidosis and polyuria for several days. Complete recovery may be expected with supportive care, even after ingestion of large zonisamide overdoses.

Present and future: pharmacologic treatment of obesity

Obesity now presents one of the biggest health problems of our times. Diet and exercise are best for both prevention and treatment; unfortunately, both require much discipline and are difficult to maintain. Medications offer a possible adjunct, but their effect is modest, they are limited by side effects, and the weight loss lasts only as long as the drug is being taken, since as soon as treatment is stopped, the weight is regained. Sibutramine, a sympathomimetic medication which was available for long-term treatment, is the most recent of the drugs to be withdrawn from the market due to side effects; in this case it was an increased risk of cardiovascular events. This paper reviews those medications which are available for treatment of obesity, including many of those recently taken off the market. It also discusses some of the newer treatments that are currently being investigated.

Zonisamide discontinuation due to psychiatric and cognitive adverse events: a case-control study

OBJECTIVES

Zonisamide (ZNS) is an antiepileptic drug (AED) that has been associated with psychiatric adverse events (PAE) and cognitive adverse events (CAE); controlled studies evaluating these adverse events are limited. Our objectives were to 1) determine the incidence of PAE and CAE leading to the discontinuation of ZNS and 2) identify risk factors for PAE and CAE associated with the discontinuation of ZNS.

METHODS

All patients exposed to ZNS at MINCEP Epilepsy Care between March 2000 and September 2008 were identified. Reasons for discontinuing ZNS were documented. Separate case-control studies were performed to identify risk factors associated with the discontinuation of ZNS due to PAE or CAE via multivariate binary logistic regression.

RESULTS

A total of 544 patients were exposed to ZNS during the study period. PAE and CAE were the most frequently identified reasons for terminating ZNS therapy. The incidence of PAE severe enough to be associated with the discontinuation of ZNS was 6.9%; the incidence of CAE was 5.8%. Factors associated with termination of ZNS therapy due to PAE were past psychiatric history (p = 0.005), symptomatic generalized epilepsy (p = 0.027), and lower maximum ZNS serum concentration (mean = 17.9 mg/L vs 34.7 mg/L, p < 0.001). Independent variables associated with discontinuing ZNS due to CAE were greater number of concomitant AEDs (p = 0.011) and lower maximum ZNS serum concentration (mean = 16.6 mg/L vs 30.6 mg/L, p = 0.002).

CONCLUSIONS

We have identified clinically relevant risk factors associated with the discontinuation of ZNS. Our findings support the concept that selected patients are relatively more vulnerable to CNS adverse events when exposed to ZNS.

Zonisamide ameliorates symptoms of secondary paroxysmal dystonia

A number of medications have been used with varying success to treat the symptoms of generalized, focal, and paroxysmal dyskinesias; these agents include anticonvulsant, benzodiazepine, neuroleptic, dopaminergic, dopamine antagonist, and carbonic anhydrase inhibitor types. The carbonic anhydrase inhibitor drug group is best represented by acetazolamide, which has been widely applied in the treatment of paroxysmal dyskinesias. Zonisamide, which has several putative pharmacologic mechanisms of action, is a member of the carbonic anhydrase inhibitor drug group. Zonisamide was chosen for treatment of secondary paroxysmal dystonia in a patient with pyruvate dehydrogenase deficiency (case 1) and in two patients with neonatal hemochromatosis and family history of neonatal hemochromatosis (cases 2 and 3). Although zonisamide ameliorated the symptoms of secondary paroxysmal dystonia in these three patients, the precise biochemical mechanism remains unclear, and further studies are needed to substantiate and explain this finding.

New approaches to the pharmacological treatment of obesity: can they break through the efficacy barrier?

In this review we assess the range of centrally active anorectics that are either in human clinical trials, or are likely to be so in the near future. We describe their weight loss efficacy, mode of action at both pharmacological and behavioural levels, where understood, together with the range of side effects that might be expected in clinical use. We have however evaluated these compounds against the considerably more rigorous criteria that are now being used by the Federal Drugs Agency and European Medicines Agency to decide approvals and market withdrawals. Several trends are evident. Recent advances in the understanding of energy balance control have resulted in the exploitation of a number of new targets, some of which have yielded promising data in clinical trials for weight loss. A second major trend is derived from the hypothesis that improved weight loss efficacy over current therapy is most likely to emerge from treatments targeting multiple mechanisms of energy balance control. This reasoning has led to the development of a number of new treatments for obesity where multiple mechanisms are targeted, either by a single molecule, such as tesofensine, or through drug combinations such as qnexa, contrave, empatic, and pramlintide+metreleptin. Many of these approaches also utilise advances in formulation technology to widen safety margins. Finally, the practicality of peptide therapies for obesity has become better validated in recent studies and this may allow more rapid exploitation of novel targets, rather than awaiting the development of orally available small molecules. We conclude that novel, more efficacious and better tolerated treatments for obesity may become available in the near future.

Neuropsychiatric adverse effects of centrally acting antiobesity drugs

INTRODUCTION

Central neurochemical systems including the monoamine, opioid, and cannabinoid systems have been promising targets for antiobesity drugs that modify behavioral components of obesity. In addition to modulating eating behavior, centrally acting antiobesity drugs are also likely to alter emotional behavior and cognitive function due to the high expression of receptors for the neurochemical systems targeted by these drugs within the fronto-striatal and limbic circuitry.

METHODS

This paper reviewed the neuropsychiatric adverse effects of past and current antiobesity drugs, with a central mechanism of action, linking the adverse effects to their underlying neural substrates and neurochemistry.

RESULTS

Antiobesity drugs were found to have varying neuropsychiatric adverse event profiles. Insomnia was the most common adverse effect with drugs targeting monoamine systems (sibutramine, bupropion and tesofensine). These drugs had some positive effects on mood and anxiety and may have added therapeutic benefits in obese patients with comorbid depression and anxiety symptoms. Sedation and tiredness were the most common adverse effects reported with drugs targeting the m-opioid receptors (i.e., naltrexone) and combination therapies targeting the opioid and monoamine systems (i.e., Contrave™). Cognitive impairments were most frequently associated with the antiepileptic drugs, topiramate and zonisamide, consistent with their sedative properties. Drugs targeting the cannabinoid system (rimonabant and taranabant) were consistently associated with symptoms of anxiety and depression, including reports of suicidal ideation. Similar adverse events have also been noted for the D₁/D₅ antagonist ecopipam.

CONCLUSION

These findings highlight the need to assess neuropsychiatric adverse events comprehensively using sensitive and validated methods early in the clinical development of candidate antiobesity drugs with a central mechanism of action.

Placebo-controlled trial of zonisamide for the treatment of alcohol dependence

INTRODUCTION

Zonisamide is an anticonvulsant medication with GABAergic, glutamatergic, and monoaminergic effects. Zonisamide has also been shown to reduce alcohol intake in rodents and in risky drinkers in the context of a laboratory study. This pilot clinical trial evaluated the safety, tolerability, and efficacy of zonisamide for the treatment of alcohol dependence.

METHODS

Forty alcohol-dependent subjects (23 men) were randomly assigned to receive treatment with either placebo or zonisamide in a 12-week double-blind trial. Zonisamide was initiated at a dosage of 100 mg/d, which was increased by 100 mg/d every 2 weeks for 8 weeks to a maximum dosage of 500 mg/d. The medication was continued for 4 weeks at the target dosage and then tapered and discontinued. The primary outcomes were drinks per week, heavy drinking days per week, and abstinent days per week, which were measured using the Timeline Follow-Back method.

RESULTS

There was a significant medication by treatment week interaction effect favoring the zonisamide group for heavy drinking days (HDD; P = 0.012), drinks per week (P = 0.004), and alcohol urge scores (P = 0.006). There was not a significant effect on the number or rate of increase in abstinent days. There were no serious adverse events reported and zonisamide treatment was well tolerated.

CONCLUSION

The findings provide preliminary support for the use of zonisamide to treat alcohol dependence. Efforts to replicate and extend these findings are warranted.

Zonisamide enhances delta receptor-associated neurotransmitter release in striato-pallidal pathway

A recent randomized control study demonstrated that zonisamide (ZNS), an antiepileptic drug, is effective in Parkinson's disease at the lower than the therapeutic doses against epilepsy (25-50 mg/day); however, the detailed mechanism of antiparkinsonian effects of ZNS remains to be clarified. To determine the mechanism of antiparkinsonian effect of ZNS, we investigated the effects of ZNS on extracellular levels of dopamine in the striatum (STR), glutamate in substantia nigra pars reticulata (SNr), GABA in globus pallidus (GP), subthalamic nucleus (STN) and SNr, using multiple microdialysis probes. Striatal perfusion of 1000 microM ZNS (within therapeutic-relevant concentration against epilepsy) increased extracellular levels of dopamine in STR, whereas 100 microM ZNS (lower than the therapeutic-relevant concentration against epilepsy but within the therapeutic rage against Parkinson's disease) did not affect it. Striatal perfusion of ZNS (100 and 1000 microM) decreased the extracellular levels of GABA in STN and glutamate in SNr, but decreased extracellular GABA level in GP without affecting GABA level in SNr. These concentration-dependent effects of ZNS on extracellular neurotransmitter levels were independent of dopamine and delta(2) receptors; however, blockade of delta(1) receptor inhibited the effects of ZNS. Furthermore, activation of delta(1) receptor enhanced the effects of ZNS on neurotransmitter level. These results suggest that ZNS does not affect the direct pathway but inhibits the indirect pathway, which is mediated by delta(1) receptor. Therefore, the antiparkinsonian effects of ZNS seem to be mediated through the interaction between lower than therapeutically-relevant concentration against epilepsy of ZNS (100 microM) and delta(1) receptor.

Topiramate and zonisamide prevent paradoxical intoxication induced by carbamazepine and phenytoin

The mechanisms of paradoxical aggravation of epileptic seizures induced by selected antiepileptic drugs (AEDs) remain unclear. The present study addressed this issue by determining the seizure-threshold doses of carbamazepine (CBZ) and phenytoin (PHT), as well the dose-dependent effects of CBZ, PHT, and carbonic anhydrase-inhibiting AEDs, acetazolamide (AZM), topiramate (TPM), and zonisamide (ZNS), on neurotransmitter release in rat hippocampus. The dose-dependent effects of AEDs on hippocampal extracellular levels of glutamate (Glu), GABA, norepinephrine (NE), dopamine (DA), and serotonin (5-HT) were determined by microdialysis with high-speed and high-sensitive extreme liquid chromatography. Proconvulsive effects of AEDs were determined by telemetric-electrocorticography. Therapeutically relevant doses of AZM, CBZ, TPM, and ZNS increased hippocampal extracellular levels of GABA, NE, DA, and 5-HT, while PHT had no effect. Supratherapeutic doses of AZM, CBZ, PHT, TPM, and ZNS decreased extracellular levels of GABA, NE, DA, and 5-HT, without affecting Glu levels. Toxic doses of CBZ and PHT produced seizures (paradoxical intoxication), markedly increasing all transmitter levels, but TPM and ZNS even at toxic doses did not produce seizure. Co-administration experiments showed that therapeutically relevant doses of CBZ or PHT reduced the seizure-threshold doses of PHT or CBZ, respectively. In contrast, therapeutically relevant doses of AZM, TPM, and ZNS elevated the seizure-threshold doses of CBZ and PHT. These results suggested that blockade of high percentage of the population of voltage-dependent sodium channels by CBZ and PHT might be important in inducing paradoxical intoxication/reaction, and that inhibition of carbonic anhydrase inhibits this effect. TPM and ZNS are candidate first-choice agents in treatment of epilepsy when first-line AEDs are ineffective.

Clinical pharmacology and mechanism of action of zonisamide

Antiepileptic drugs (AEDs) suppress seizures by selectively modifying the excitability of neurons and blocking seizure firing with minimal disturbance of nonepileptic activity. All AEDs have been shown to work by at least one of 3 main mechanisms of action: through modulation of voltage-gated ion channels, enhancement of synaptic inhibition, and inhibition of synaptic excitation. Zonisamide is a novel AED that has a broad combination of complementary mechanisms of action, which may offer a clinical advantage over other antiepileptic agents. By altering the fast inactivation threshold of voltage-dependent sodium channels, zonisamide reduces sustained high-frequency repetitive firing of action potentials. Zonisamide also inhibits low-threshold T-type calcium channels in neurons, which may prevent the spread of seizure discharge across cells. In addition, zonisamide is a weak inhibitor of carbonic anhydrase. However, this mechanism is not believed to contribute to the antiepileptic activity of zonisamide. Although zonisamide also seems to alter dopamine, serotonin, and acetylcholine metabolism, it is not clear to what extent these effects on neurotransmitters are involved in the clinical actions of the drug. In addition to these actions, recent evidence suggests that zonisamide may exert neuroprotective actions, independent of its antiepileptic activity. These potential effects may be important in preventing neuronal damage caused by recurrent seizures. Therefore, it seems that the multiple pharmacological actions of zonisamide may contribute to the seizure reductions observed in a wide range of epilepsies and may help to preserve efficacy in individual patients despite possible changes in electrophysiological status.

Zonisamide for the treatment of Parkinson's disease

Zonisamide is an antiepileptic drug widely used to treat seizures worldwide. In addition to epilepsy, zonisamide may have beneficial efficacy in various neurological or psychiatric diseases. This article reviews the structure, mechanism of action, pharmacokinetics and possible antiparkinsonian action of zonisamide. A multicentered, randomized, double-blind, placebo-controlled study conducted in Japan provided data suggesting that zonisamide, as an add-on treatment, has efficacy in treating motor symptoms in patients with Parkinson's disease (PD). Zonisamide may be effective in reducing the duration of 'off' time in patients with PD treated with L-DOPA. The therapeutic doses of zonisamide for the treatment of PD are 50-100 mg/day, considerably lower than those for the treatment of epilepsy (200-400 mg/day). It is expected that zonisamide will be safe and tolerated in patients with PD, as it has been used as an antiepileptic for more than 15 years; however, further studies are required to evaluate its safety and tolerability in the treatment of PD. The pharmacological mechanisms of the beneficial actions of zonisamide in PD remain unclear. Various hypotheses have been proposed, but the supporting data are not yet sufficient to draw any conclusions. Further basic research is required to advance our understanding of the antiparkinsonian mechanism of zonisamide.

Serotonin but not zonisamide inhibits theophylline-induced epileptiform activity in guinea pig hippocampal CA3 neurons

To test the putative serotonin (5-HT)-like effect of zonisamide (ZNS) we employed xanthine-induced epileptiform activity in the hippocampus slice preparation from guinea pigs. In this model Na(+)- and T-type Ca(2+) channel blockers are hardly effective while 5-HT should be inhibitory. Bath application of 5-HT hyperpolarized neurons and abolished theophylline-induced epileptiform activity. In contrast, ZNS failed to alter epileptiform bursting. We conclude that 5-HT augmenting effects of ZNS are missing or are not sufficient to inhibit epileptiform activity in hippocampal slice preparations.

Adjunctive zonisamide for treatment refractory anxiety

The aim of the study was to assess the use of a novel anticonvulsant, zonisamide, in patients with treatment refractory anxiety. Pilot and open study of a cohort of patients with anxiety (n = 10), who were deemed partial or non-responders to anxiolytic therapy, and received adjunctive zonisamide in a naturalistic fashion. The primary outcome measures were the Hamilton Anxiety Scale (HAM-A), the Clinical Global Impression of Severity (CGI-S) and the Clinical Global Impression of Improvement (CGI-I). Patients included were markedly ill with a mean number of previous medication trials of 4.9 +/- 1.9, a baseline HAM-A score of 27.9 +/- 3.8, and a baseline CGI-S score of 5.7 +/- 0.5. Patients improved significantly with an end-point HAM-A score of 12.6 +/- 7.4 (p < 0.001), CGI-S score of 3.6 +/- 1.3 (p < 0.002) and CGI-I score of 2.5 +/- 1.3. Zonisamide at a mean +/- SD dose of 160 +/- 70 mg/day for 9.2 +/- 4.5 weeks was generally well tolerated. Adverse events were generally mild, and no patients discontinued zonisamide because of side effects. Six patients (60%) met responder criteria at end-point (CGI-I <or= 2). Results from this pilot and open naturalistic study suggest that zonisamide may effectively augment response to anxiolytic medications in patients with treatment refractory anxiety. Larger and controlled studies are warranted to confirm these preliminary findings.

Seizure activity selectively reduces 5-HT1A receptor immunoreactivity in CA1 interneurons in the hippocampus of seizure-prone gerbils

Since the correlation between the serotonin (5-hydroxytryptamine, 5-HT) system and seizure activity remains to be clarified, we investigated the 5-HT system in the hippocampus of seizure-resistant (SR) and seizure-sensitive (SS) gerbils. There was no difference of the 5-HT system in the hippocampi of young animals (predisposed and juvenile gerbils) in both SR and SS gerbils. 5-HT immunoreactivity in the dorsal raphe nucleus and the median raphe nucleus was also similarly detected in both animal groups. As compared to SR adult gerbils, only 5-HT1A receptor immunoreactivity was selectively reduced in CA1 interneurons within SS adult gerbils. (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (a 5-HT1A receptor agonist, 1 and 2 mg/kg) markedly reduced paired-pulse inhibition in the CA1 region of SS adult gerbils only. These findings suggest that the selective reduction in 5-HT1A receptor expression on CA1 interneurons of SS adult gerbil may not be developmental defects, but be an acquired compensatory change induced by repeated seizure activity.

Interactions between zonisamide and conventional antiepileptic drugs in the mouse maximal electroshock test model

Despite the major advances in antiepileptic drug (AED) therapeutics, about one third of patients with epilepsy still do not have adequate seizure control with currently available AEDs when prescribed as monotherapy. Typically, in this setting polytherapy with two or more AEDs is used. Zonisamide (ZNS) is a new AED effective in the treatment of refractory epilepsy and since it is only prescribed in polytherapy regimens, its interactions with other AEDs is of particular importance. The aim of this study was to isobolographically determine interactions between ZNS and four conventional AEDs: carbamazepine (CBZ), phenytoin (PHT), phenobarbital (PB), and valproate (VPA), in the mouse maximal electroshock (MES)-induced seizure model. The total brain concentrations of conventional AEDs and ZNS were measured with immunofluorescence and high-pressure liquid chromatography (HPLC), respectively, in order to determine any pharmacokinetic contribution in any observed interactions. With isobolography, synergistic interactions were observed for the combination of ZNS plus VPA and ZNS plus PHT at the fixed-ratio of 1:1, while additivity was observed for their combinations at the remaining dose ratios of 1:3 and 3:1. In contrast, the interactions between ZNS and PB and between ZNS and CBZ, applied at the fixed-ratios of 1:3, 1:1 and 3:1 proved to be additive. None of these AED combinations were associated with motor and long-term memory impairment. Furthermore, whilst brain AED concentrations were unaffected by ZNS, PHT significantly increased and PB reduced brain ZNS concentrations. Thus, the resultant interactions between ZNS and PHT and between ZNZ and PB were consequent to both pharmacodynamic and pharmacokinetic components. Finally, one can conclude that because of the synergistic pharmacodynamic interaction between ZNS and VPA, this combination might be useful in clinical practice.

Novel anticonvulsant drugs

Principles of complex mechanisms of action of anticonvulsants including latest reports concerning new antiepileptic drugs (AED) are considered. Different aspects of new anticonvulsant drugs (2nd generation) from preclinical and clinical testing, pharmacokinetics, and mono or combination therapy in children and adults are summarized. In the following condensed synopsis pharmacological and clinical characteristics of gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), pregabalin (PGB) and tiagabine (TGB) as well as topiramate (TPM) and zonisamide (ZNS) are discussed. In addition to the mechanisms of action, pharmacokinetics, interactions, indications and dosages as well as side effects are considered. Important data concerning the effect and tolerability of anticonvulsant drugs can be obtained from controlled studies. In comparison to drugs of the first generation (phenobarbital [PB], primidon [PRD], phenytoin [PHT], carbamazepine [CBZ] and valproic acid [VPA]) the potential for interactions and side effects due to enzyme induction or inhibition is reduced by most of the anticonvulsant drugs of the second generation. New anticonvulsant drugs increase the spectrum of treatment and represent further steps with regard to the optimization of an individual therapy of the epilepsies.

Zonisamide - a review of experience and use in partial seizures

Zonisamide is a modern antiepileptic drug (AED) that is distinguished from other AEDs by its unique structure and broad mechanistic profile. Preclinical studies have reported a range of potential mechanisms of action for zonisamide, such as blocking voltage-gated sodium channels, reduction of T-type calcium channel currents, and enhancement of gamma-aminobutyric acid (GABA)-mediated inhibition, which are indicative of its broad antiseizure effects. Zonisamide has a favorable linear pharmacokinetic profile, a long half-life, and a low incidence of protein-binding interactions with other AEDs. Hepatically metabolized through the cytochrome P450 pathway, zonisamide does not induce its own metabolism or liver enzymes. For more than 2 decades, zonisamide has been extensively used as monotherapy and adjunctive therapy for the treatment of partial and generalized seizures in pediatric and adult patients in Japan. Zonisamide was approved in the USA in 2000 as adjunctive therapy for partial seizures in adults. With over 2 million patient-years of exposure internationally, zonisamide has demonstrated safety and efficacy against a multitude of epilepsy and seizure types, including both partial and generalized seizures. This review focuses on the experience and use of zonisamide in partial seizures, as well as possible new uses for zonisamide.

Zonisamide prophylaxis in refractory pediatric headache

INTRODUCTION

Currently, no medications are approved for pediatric headache prophylaxis in the United States. Zonisamide is an antiepileptic drug with preliminary studies suggesting some efficacy in the adult headache population.

METHODS

A retrospective chart review was conducted on refractory headache patients in our multidisciplinary Headache Clinic who were treated with zonisamide, an antiepileptic drug, for headache prophylaxis. Records were reviewed for pertinent data including patient history, diagnosis, prior treatment regimens, and zonisamide response, along with headache frequency.

RESULTS

Twelve patients were identified (8 girls); mean age was 13.5 years. Eight of the 12 patients had a positive response to zonisamide with greater than 50% reduction in headaches from pretreatment values.

CONCLUSION

Zonisamide had some efficacy in headache reduction. It was well tolerated with only minor side effects. Further prospective studies with zonisamide are warranted in refractory pediatric headache patients.

Investigational therapies in the treatment of obesity

Obesity is a major public health concern and environmental factors are involved in its development. The hypothalamus is a primary site for the integration of signals for the regulation of energy homeostasis. Dysregulation of these pathways can lead to weight loss or gain. Some drugs in development can have favourable effects on body weight, acting on some of these pathways and leading to responses resulting in weight loss. Strategies for the management of weight reduction include exercise, diet, behavioural therapy, drug therapy and surgery. Investigational antiobesity medications can modulate energy homeostasis by stimulating catabolic or inhibiting anabolic pathways. Investigational drugs stimulating catabolic pathways consist of leptin, agonists of melanocortin receptor-4, 5-HT and dopamine; bupropion, growth hormone fragments, cholecystokinin subtype 1 receptor agonist, peptide YY3-36, oxyntomodulin, ciliary neurotrophic factor analogue, beta3-adrenergic receptor agonists, adiponectin derivatives and glucagon-like peptide-1. On the other hand, investigational drugs inhibiting anabolic pathways consist of the ghrelin receptor, neuropeptide Y receptor and melanin-concentrating hormone-1 antagonists; somatostatin analogues, peroxisome proliferator-activated receptor-gamma and -beta/delta antagonists, gastric emptying retardation agents, pancreatic lipase inhibitors, topiramate and cannabinoid-1 receptor antagonists. These differing approaches are reviewed and commented on in this article.

Efficacy and safety of zonisamide monotherapy in a cohort of children with epilepsy

The aim of this study was to evaluate the efficacy and safety of zonisamide monotherapy in a cohort of children and adolescents with various types of epilepsy. Retrospective review of charts of our institution from 2001 through 2004 identified 69 children (19 males and 50 females, mean age 13.2 years) with epilepsy on zonisamide monotherapy. Seizure count and side effect profile were maintained during therapy. Sixty-one percent had idiopathic generalized epilepsy, 4% symptomatic generalized epilepsy, and 35% partial-onset epilepsy. Zonisamide was the first-line and second-line monotherapy for 32% and 68% of patients, respectively. The mean duration of follow-up on treatment was 22 months (range 3-48 months). The overall efficacy of zonisamide was 75.4% (> or = 50% seizure frequency reduction: good responders). Sixty-seven percent of good responders became seizure-free. Seventy-nine percent of patients with partial epilepsy and 71% with generalized epilepsy were good responders, of whom 79% and 63% were free of seizure, respectively. Eighteen (26%) patients developed side effects: weight loss (9), cognitive impairment (3), sleepiness (3), dizziness (2), and decreased appetite (1). In seven patients (10%), zonisamide had to be discontinued: four due to side effects and three because of poor seizure control. Zonisamide was demonstrated to be effective as monotherapy in children with epilepsy.