Zonisamide for Migraine Prophylaxis in Patients Refractory to Topiramate

Exploring the symptoms and sleep disorders associated with migraines in women of Syria: A cross-sectional observational study

Background and Aim

Migraine is a prevalent neurological disorder characterized by recurring episodes of debilitating headache accompanied by associated symptoms and sleep disorders. This study aims to investigate migraine-associated symptoms in female migraineurs within the Syrian population and the relation between migraines and sleep issues.

Methods

A questionnaire-based cross-sectional observational study was conducted among the Syrian population. A total of 1009 women were enrolled in this study, including women without a history of migraine (Control group) and migraineurs (Case group) who had received a diagnosis of migraine from a hospital or private clinic. Data about migraine-related symptoms, including tingling, visual disturbances, Nausea/Vomiting, and epileptic seizures as well as sleep-related symptoms such as interrupted sleep, frequent awakenings, insomnia, snoring, and narcolepsy were gathered. Chi-square test was used to examine the relation between migraines and sleep issues.

Results

A total of 1009 women were enrolled in this study including 531 migraineurs and 478 healthy women. The study revealed that the most commonly experienced symptoms during migraine attacks were nausea/vomiting and visual disturbances, followed by tingling. Total Unduplicated Reach and Frequency analysis showed that visual disturbances and nausea/vomiting were the two most frequent symptoms that co-occurred during migraine attacks. The study also demonstrated a significant relationship between snoring, insomnia, and narcolepsy with migraine (p = 0.038), with these sleep disorders being more prevalent among migraineurs.

Conclusion

The findings indicate a significant association between migraines and sleep disorders, with migraineurs being at a significantly higher risk of experiencing poor sleep quality compared to healthy women. Addressing sleep disorders is crucial in managing patients with migraines. This study is the first of its kind in the Syrian population, providing valuable insights into the symptoms and sleep disorders associated with migraines in this population.

Astrocytes as critical players of the fine balance between inhibition and excitation in the brain: spreading depolarization as a mechanism to curb epileptic activity

Spreading depolarizations (SD) are slow waves of complete depolarization of brain tissue followed by neuronal silencing that may play a role in seizure termination. Even though SD was first discovered in the context of epilepsy research, the link between SD and epileptic activity remains understudied. Both seizures and SD share fundamental pathophysiological features, and recent evidence highlights the frequent occurrence of SD in experimental seizure models. Human data on co-occurring seizures and SD are limited but suggestive. This mini-review addresses possible roles of SD during epileptiform activity, shedding light on SD as a potential mechanism for terminating epileptiform activity. A common denominator for many forms of epilepsy is reactive astrogliosis, a process characterized by morphological and functional changes to astrocytes. Data suggest that SD mechanisms are potentially perturbed in reactive astrogliosis and we propose that this may affect seizure pathophysiology.

Antiseizure Medications for the Prophylaxis of Migraine during the Anti- CGRP Drugs Era

Migraine and epilepsy are fundamentally distinct disorders that can frequently coexist in the same patient. These two conditions significantly differ in diagnosis and therapy but share some widely- used preventive treatments. Antiseizure medications (ASMs) are the mainstay of therapy for epilepsy, and about thirty different ASMs are available to date. ASMs are widely prescribed for other neurological and non-neurological conditions, including migraine. However, only topiramate and valproic acid/valproate currently have an indication for migraine prophylaxis supported by high-quality evidence. Although without specifically approved indications and with a low level of evidence or recommendation, several other ASMs are used for migraine prophylaxis. Understanding ASM antimigraine mechanisms, including their ability to affect the pro-migraine calcitonin gene-related peptide (CGRP) signaling pathway and other pathways, may be instrumental in identifying the specific targets of their antimigraine efficacy and may increase awareness of the neurobiological differences between epilepsy and migraine. Several new ASMs are under clinical testing or have been approved for epilepsy in recent years, providing novel potential drugs for migraine prevention to enrich the treatment armamentarium and drugs that inhibit the CGRP pathway.

An Investigation of the Effects of Chronic Zonisamide, Sultiam, Lacosamide, Clobazam, and Rufinamide Antiseizure Drugs on Foliculogenesis in Ovarian Tissue in Prepubertal Non-Epileptic Rats

We aimed to determine the morphological and histological effects of zonisamide, sultiam, lacosamide, clobazam, and rufinamide on ovarian folliculogenesis in rats. Sixty female Wistar rats were equally divided into 6 experimental groups, including control group, zonisamide, sultiam, lacosamide, clobazam, and rufinamide were administered by gavage for 90 days. According to the daily vaginal smears of the rats in the proestrus and diester phases of the estrus cycle, their ovaries were removed and placed in the fixation solution. Immunohistochemical and apoptosis staining protocols were applied. The number of healthy follicles in the control group was found to be statistically significantly higher when compared to the antiseizure drug groups (p<0.001). The number of corpus luteum was found to be statistically significantly lower in the control group when compared with the anti-seizure drug groups (p<0.001). There was a significant difference in the number of TUNEL positive apoptotic follicles between the control and drug groups (p<0.001). There was a significant difference in the number of TUNEL positive apoptotic follicles between the control and drug groups (p<0.001). HSCORE, immunohistochemical EGF, IGF-1 and GDF-9 staining, a very strong immunoreaction was observed in the ovarian multilaminar primary follicle granulosa cells and oocytes in the control group (p<0.001), and an immunoreaction ranging from weak to medium was observed in the antiseizure drug groups. Long-term anti-seizure drug therapy with zonisamide, sultiam, lacosamide, clobazam, and rufinamide from prepubertal to adulthood causes apoptosis and disruption of folliculogenesis in the ovarian follicles of nonepileptic rats.

Interictal plasma glutamate levels are elevated in individuals with episodic and chronic migraine

Glutamate is implicated in migraine pathogenesis including central sensitization and pain transmission. Altered plasma glutamate levels has been noted in migraine. Chronic migraine (CM) presented a higher degree of central sensitization and pain transmission than episodic migraine (EM). However, no study has evaluated plasma glutamate levels separately in EM and CM. This study aimed to assess plasma glutamate levels in EM and CM compared to controls. An enzyme-linked immunosorbent assay was used to assess plasma glutamate levels in females with EM (n = 98) and CM (n = 92) as well as controls (n = 50). Plasma glutamate levels in participants with EM (median and interquartile range, 49.73 [40.82–66.12] μmol/L, p < 0.001) and CM (58.70 [44.64–72.46] μmol/L, p < 0.001) were significantly higher than those in controls (38.79 [29.50–53.60] μmol/L). Glutamate levels were not significantly different between participants with EM and CM (p = 0.075). There was no significant association of plasma glutamate levels with headache frequency (exponential and 95% confidence interval, 1.285 [0.941–1.755]) and intensity (mild, 59.95 [59.95–59.95] μmol/L vs. moderate, 52.76 [40.83–106.89] μmol/L vs. severe, 55.16 [42.34–68.03] μmol/L, p = 0.472). The plasma glutamate level is a potential indicator for EM and CM.

Reactive metabolites of the anticonvulsant drugs and approaches to minimize the adverse drug reaction

Several generations of antiepileptic drugs (AEDs) are available in the market for the treatment of seizures, but these are amalgamated with acute to chronic side effects. The most common side effects of AEDs are dose-related, but some are idiosyncratic adverse drug reactions (ADRs) that transpire due to the formation of reactive metabolite (RM) after the bioactivation process. Because of the adverse reactions patients usually discontinue the medication in between the treatment. The AEDs such as valproic acid, lamotrigine, phenytoin etc., can be categorized under such types because they form the RM which may prevail with life-threatening adverse effects or immune-mediated reactions. Hepatotoxicity, teratogenicity, cutaneous hypersensitivity, dizziness, addiction, serum sickness reaction, renal calculi, metabolic acidosis are associated with the metabolites of drugs such as arene oxide, N-desmethyldiazepam, 2-(1-hydroxyethyl)-2-methylsuccinimide, 2-(sulphamoy1acetyl)-phenol, E-2-en-VPA and 4-en-VPA and carbamazepine-10,11-epoxide, etc. The major toxicities are associated with the moieties that are either capable of forming RM or the functional groups may itself be too reactive prior to the metabolism. These functional groups or fragment structures are typically known as structural alerts or toxicophores. Therefore, minimizing the bioactivation potential of lead structures in the early phases of drug discovery by a modification to low-risk drug molecules is a priority for the pharmaceutical companies. Additionally, excellent potency and pharmacokinetic (PK) behaviour help in ensuring that appropriate (low dose) candidate drugs progress into the development phase. The current review discusses about RMs in the anticonvulsant drugs along with their mechanism vis-a-vis research efforts that have been taken to minimize the toxic effects of AEDs therapy.

Zonisamide in Parkinson's disease: a current update

Parkinson's disease (PD) is a progressive neurodegenerative disease due to the depletion of the neurotransmitter dopamine in basal ganglia. There is a scarcity of available therapies for motor and non-motor symptoms of PD. Zonisamide (ZNS) may be one such potential candidate to alleviate PD symptoms. It was serendipitously found to be useful for PD in a patient with both epilepsy and PD. Since then, there have been many clinical trials, case series, observational studies, and case reports published supporting the efficacy of ZNS in PD. This review focuses on the efficacy and usefulness of ZNS in various motor and non-motor symptoms of PD. A predefined inclusion and exclusion criteria were used for the search protocol and databases searched were PubMed, Cochrane Library, Ovid, and clinicaltrials.gov. Most of the randomized clinical trials used UPDRS III as the primary efficacy point and showed positive results favouring ZNS. This review shows that there is evidence of the efficacy of ZNS in motor symptoms as an adjunctive therapy to levodopa, but for non-motor symptoms, the evidence is lacking and needs further investigation.

Effects of the Calcium Channel Blocker Otilonium Bromide on Seizure Activity in Rats With Pentylenetetrazole-Induced Convulsions

Millions of people suffer from drug-resistant epilepsy. New therapeutic approaches for removing this life-affecting disease are required. The activation of T-type calcium channels (TTCC) is one of the epileptogenesis mechanisms that cause epilepsy. So, we researched the effects of Otilonium bromide (OB), an antisposmolytic drug that inhibits TTCC, on seizure activity in rats with pentylenetetrazol (PTZ) induced convulsion. Randomly, 48 rats were divided into two groups; for electroencephalography (EEG) recordings and for behavioral assesment. Rats were treated with either intraperitoneal (IP) OB at two separate doses (25 mg/kg and 50 mg/kg) or placebo, and then pentylenetetrazole (IP), a potent seizure-inducing chemical administered to them. In our model we have measured rat seizure activity with EEG, the convulsion scala of Racine (RCS), the time of first myoclonic jerk (FMJ) and MDA levels to assess if OB has antiepileptic properties. The mean EEG spike wave percentage score reduced from 79.5% (placebo) to 59.2% (lower-dose) and 35.2% (higher-dose). FMJ had increased from a mean of 67.2 s (placebo), to 105.2 (lower-dose), 150.6 (higher-dose). RCS reduced from a mean of 5.12 (placebo) to 4.4 (lower-dose), 3.8 (higher-dose). MDA leves reduced from 84.5 nmol/gr to 51.09 nmol/gr (lower-dose), 33.2 nmol/gr (higher-dose). Compared to placebo, OB reduced significantly seizure activity at both doses, probably through blocking T-type calcium channels. All these results were statistically significant with < 0.0001 p-values. Otilonium bromide reduced seizure activity in rats with PTZ-induced convulsion. Therefore, the clinical role of OB and other TTCC inhibitors as potential anti-seizure drugs should be further investigated.

Zonisamide as treatment option in persistent migraine aura

Persistent migraine aura without infarction is a rare but debilitating condition. Treatment options are mostly anecdotal and limited due to inefficacy and side effects. We present a 16-year-old female patient with triple X syndrome, having persistent aura symptoms for over 2 years, consisting of continuous visual and sensory sensations. Previous treatments with seven different migraine preventatives were not successful. The patient successfully responded to zonisamide against refractory prolonged aura and remained symptom-free under the ongoing treatment without any relevant side effects. Zonisamide may be considered a new and safe treatment option for patients with persistent migraine aura.

Prioritizing Pain-Associated Targets with Machine Learning

While hundreds of genes have been associated with pain, much of the molecular mechanisms of pain remain unknown. As a result, current analgesics are limited to few clinically validated targets. Here, we trained a machine learning (ML) ensemble model to predict new targets for 17 categories of pain. The model utilizes features from transcriptomics, proteomics, and gene ontology to prioritize targets for modulating pain. We focused on identifying novel G-protein-coupled receptors (GPCRs), ion channels, and protein kinases because these proteins represent the most successful drug target families. The performance of the model to predict novel pain targets is 0.839 on average based on AUROC, while the predictions for arthritis had the highest accuracy (AUROC = 0.929). The model predicts hundreds of novel targets for pain; for example, GPR132 and GPR109B are highly ranked GPCRs for rheumatoid arthritis. Overall, gene-pain association predictions cluster into three groups that are enriched for cytokine, calcium, and GABA-related cell signaling pathways. These predictions can serve as a foundation for future experimental exploration to advance the development of safer and more effective analgesics.

Pharmacological options for the treatment of chronic migraine pain

Migraine is a debilitating neurological condition with symptoms typically consisting of unilateral and pulsating headache, sensitivity to sensory stimuli, nausea, and vomiting. The World Health Organization (WHO) reports that migraine is the third most prevalent medical disorder and second most disabling neurological condition in the world. There are several options for preventive migraine treatments that include, but are not limited to, anticonvulsants, antidepressants, beta blockers, calcium channel blockers, botulinum toxins, NSAIDs, riboflavin, and magnesium. Patients may also benefit from adjunct nonpharmacological options in the comprehensive prevention of migraines, such as cognitive behavior therapy, relaxation therapies, biofeedback, lifestyle guidance, and education. Preventative therapies are an essential component of the overall approach to the pharmacological treatment of migraine. Comparative studies of newer therapies are needed to help patients receive the best treatment option for chronic migraine pain.

Migraine Care in the Era of COVID-19: Clinical Pearls and Plea to Insurers

Objective

To outline strategies for the treatment of migraine which do not require in‐person visits to clinic or the emergency department, and to describe ways that health insurance companies can remove barriers to quality care for migraine.

Background

COVID‐19 is a global pandemic causing widespread infections and death. To control the spread of infection we are called to observe “social distancing” and we have been asked to postpone any procedures which are not essential. Since procedural therapies are a mainstay of headache care, the inability to do procedures could negatively affect our patients with migraine. In this manuscript we review alternative therapies, with particular attention to those which may be contra‐indicated in the setting of COVID‐19 infection.

Design/Results

The manuscript reviews the use of telemedicine visits and acute, bridge, and preventive therapies for migraine. We focus on evidence‐based treatment where possible, but also describe “real world” strategies which may be tried. In each section we call out areas where changes to rules from commercial health insurance companies would facilitate better migraine care.

Conclusions

Our common goal as health care providers is to maximize the health and safety of our patients. Successful management of migraine with avoidance of in‐person clinic and emergency department visits further benefits the current urgent societal goal of maintaining social distance to contain the COVID‐19 pandemic.

Characterization of Carbonic Anhydrase In Vivo Using Magnetic Resonance Spectroscopy

Carbonic anhydrase is a ubiquitous metalloenzyme that catalyzes the reversible interconversion of CO2/HCO3-. Equilibrium of these species is maintained by the action of carbonic anhydrase. Recent advances in magnetic resonance spectroscopy have allowed, for the first time, in vivo characterization of carbonic anhydrase in the human brain. In this article, we review the theories and techniques of in vivo 13C magnetization (saturation) transfer magnetic resonance spectroscopy as they are applied to measuring the rate of exchange between CO2 and HCO3- catalyzed by carbonic anhydrase. Inhibitors of carbonic anhydrase have a wide range of therapeutic applications. Role of carbonic anhydrases and their inhibitors in many diseases are also reviewed to illustrate future applications of in vivo carbonic anhydrase assessment by magnetic resonance spectroscopy.

Preventive Treatment for Episodic Migraine

Episodic migraine is a debilitating condition. Preventive therapy is used to reduce frequency, duration, or severity of attacks. This review discusses principles of preventive treatment with a focus on preventive treatment options for people with episodic migraine. Specifically discussed is evidence and use of new migraine-specific treatment options for episodic migraine, such as calcitonin gene-related peptide monoclonal antibodies, a noninvasive transcutaneous electrical nerve stimulation device, and a single-pulse transcranial magnetic stimulator device. Also discussed are evidence-based updates from the 2012 American Academy of Neurology and the American Headache Society guidelines regarding major medication classes recommended for preventive episodic migraine treatment.

Consensus of the Brazilian Headache Society on the treatment of chronic migraine

Chronic migraine poses a significant personal, social and economic burden and is characterized by headache present on 15 or more days per month for at least three months, with at least eight days of migrainous headache per month. It is frequently associated with analgesic or acute migraine medication overuse and this should not be overlooked. The present consensus was elaborated upon by a group of members of the Brazilian Headache Society in order to describe current evidence and to provide recommendations related to chronic migraine pharmacological and nonpharmacological treatment. Withdrawal strategies in medication overuse headache are also described, as well as treatment risks during pregnancy and breastfeeding. Oral topiramate and onabotulinum toxin A injections are the only treatments granted Class A recommendation, while valproate, gabapentin, and tizanidine received Class B recommendation, along with acupuncture, biofeedback, and mindfulness. The anti-CGRP or anti-CGRPr monoclonal antibodies, still unavailable in Brazil, are promising new drugs already approved elsewhere for migraine prophylactic treatment, the efficacy of which in chronic migraine is still to be definitively proven.

Zonisamide for Cluster Headache Prophylaxis: A Case Series

OBJECTIVE

There is very little literature surrounding the prophylactic use of zonisamide in cluster headaches. The study aims to evaluate the effectiveness of zonisamide for prophylaxis of cluster headache in patients with chronic or episodic cluster headache.

BACKGROUND

Both chronic and episodic cluster headaches are debilitating disorders which are often refractory to multiple prophylactic medication regimens. There is a scarcity of research in this area, and current prophylactic options for patients are fairly limited, which is troublesome for affected patients. Zonisamide is an established antiepileptic with a multifactorial mechanism of action which has shown to be useful in other headache disorders such as migraine.

METHODS

Twenty cluster headache patients, both episodic (n = 12; ICHD 3.1.1) and chronic (n = 8; ICHD 3.1.2), who had been or currently were treated with zonisamide, were retrospectively evaluated. Effectiveness of the medication was assessed and identified as headache remission or a reduction in severity or frequency of cluster headache of greater than 50%. Responder status, side effects, and dosage were recorded.

RESULTS

Fourteen (70%) patients responded to zonisamide treatment, while 6 (30%) did not. Recorded effective plasma zonisamide levels ranged from 10.2 to 31.9 μg/mL. Of the 6 non-responders, 2 stopped the medication due to ineffectiveness, while 4 discontinued the medication secondary to intolerable side effects ranging from gastrointestinal upset to malaise. No more serious adverse events occurred. Eight patients total experienced weight loss/anorexia which many perceived as a positive effect; they lost an average of 10.5% of their body weight in the first 6 months of therapy.

CONCLUSIONS

Zonisamide appears to be an effective prophylactic treatment for patients with chronic and episodic cluster headache disorders. Further research in this area is clearly warranted.

Current Status of Antiepileptic Drugs as Preventive Migraine Therapy

BACKGROUND

Antiepileptic drugs (AEDs) are an important class of agents used in the treatment of migraine, a neurological disorder that imparts significant socioeconomic burden. It is important for neurologists to understand the rationale for AEDs in migraine-preventive treatment, as well as each agent's efficacy and tolerability profile, in order to best determine clinical care.

PURPOSE OF THIS REVIEW

This article specifically provides the following: (1) a review of the mechanism of action, efficacy, and tolerability of topiramate and divalproex sodium/sodium valproate, the most widely used AEDs for migraine prevention, (2) a discussion on emerging evidence regarding the efficacy of zonisamide and levetiracetam, and (3) comments on gabapentin, pregabalin, carbamazepine, oxcarbazepine, and lamotrigine, AEDs which have insufficient evidence for use in migraine prevention.

RECENT FINDINGS

The potential role for new extended-release formulations of topiramate in migraine prevention is discussed. There is substantial evidence supporting the use of AEDs in migraine prevention. Specific agents should be chosen based on their efficacy and tolerability profiles. Further studies are needed to determine the efficacy of the newer AEDs, zonisamide and levetiracetam, in migraine prevention and to clarify the role of gabapentinoids in headache management.

Comparing Zonisamide With Sodium Valproate in the Management of Migraine Headaches: Double-Blind Randomized Clinical Trial of Efficacy and Safety

Background

Migraine is one of the most debilitating medical conditions and has a high socioeconomic burden. As conventional therapeutic methods do not entirely alleviate the symptoms, new alternatives are being considered.

Objectives

This study evaluates the efficacy and safety of zonisamide compared with sodium valproate in the management of migraine headaches.

Patients and Methods

In the current double-blind, parallel, randomized, controlled trial, 96 patients with a migraine diagnosis based on the international headache society (HIS) criteria were selected. They were divided randomly into two groups; the case group was given zonisamide, and sodium valproate was given to a control group. In addition to the side effects of the drugs, the severity, duration, and frequency of migraine attacks were evaluated at baseline and at three months.

Results

The 96 selected patients were divided randomly into two treatment groups (zonisamide n = 48, sodium valproate n = 48). Seven patients were excluded from analysis because of early dropout, leaving 89 (n = 45; n = 44) patients for analysis. While using zonisamide, six (13%) patients complained of fatigue, and two (4%) patients encountered noticeable appetite and weight loss. In the control group, five (11%) patients reported dizziness, and four (9%) patients faced obvious appetite and weight gain. Both drugs were considerably efficient in reducing further attacks. There was no statistically significant correlation between frequency or severity of migraine attacks and the drug used for treatment in three months of follow-up.

Conclusions

Both medications are effective in reducing migraine attacks. It will be important to consider the drugs’ adverse effects and availability and patients’ medical and socioeconomic condition to select the appropriate treatment.

The Use of Antiepileptics in Migraine Prophylaxis

BACKGROUND

Migraine is a chronic debilitating disorder. Selected antiepileptic drugs (AEDs) are proposed as preventives for migraine. Clinical efficacy and side effects of these AEDs are discussed.

SUMMARY OF REVIEW

The American Academy of Neurology and the American Society of Headache classify topiramate (TPM) and divalproex sodium (DVPX) as Level-A medications and recommend offering them to patients for migraine prophylaxis. Their mechanism(s) of actions remains not entirely known. Their recognized action as sodium channel blockers may affect the neural component of migraine pain. TPM or DVPX can be considered an obvious choice for those patients with a concomitant seizure disorder. Care must be taken to plan their treatment with their psychiatrist if a mood disorder is present. DVPX tends not to be prescribed as first/second choice due to its potential for weight gain and hepatotoxicity. TPM is generally first choice, but bears severe contraindications. Both medications require education on teratogenesis in childbearing women. Consideration of gabapentin, acetazolamide, leviteracetam, zonisamide, and carbamazipine may be given later as empiric options and in selected patients. Patients must be made aware that there is insufficient scientific support for their use in migraine.

CONCLUSIONS

Available AEDs to prophylactically treat migraine are few but of robust clinical efficacy. Special care needs to be exerted with respect to their side effects. Future research is needed for a better understanding of their mechanisms of action in migraine. Such research has the potential of providing some insight into the pathophysiology of migraine.

Protective effect of melatonin against zonisamide-induced reproductive disorders in male rats

INTRODUCTION

Zonisamide (ZNS) is a modern antiepileptic drug (AED) that is distinguished from other AEDs by its unique structure and broad mechanistic profile. The pineal hormone melatonin is involved in the regulation of reproductive function, including the timing of the luteinizing hormone (LH) surge. The aim of the present work was to study the protective effect of melatonin against the potential suppression impact of ZNS on reproductive activity.

MATERIAL AND METHODS

Ninety adult albino male rats were allocated to several groups treated with melatonin (10 mg/kg BW), ZNS (10, 20 and 50 mg/kg BW) and 10 mg/kg of melatonin plus ZNS (10, 20 or 50 mg/kg BW, respectively). Reproductive hormones (testosterone, LH and follicle-stimulating hormone (FSH)) levels were measured in animal serum. Sperm abnormalities and DNA fragmentation in testis tissues as well as expression alteration of several reproductive-related genes were analyzed.

RESULTS

The results revealed that ZNS decreased the levels of serum free testosterone, LH, and FSH and expression of their encoding genes in male rats. In addition, ZNS treatment increased the sperm abnormalities and DNA fragmentation and inducible nitric oxide synthase (iNOS) in testis tissues as well as GABA level in liver tissues. However, melatonin supplementation inhibited the negative symptoms of ZNS in which it increased the levels of reproductive hormones and expression of their encoding genes in the ZNS-treated rats. Moreover, melatonin decreased the sperm abnormalities, DNA fragmentation, iNOS activity and GABA level in ZNS-treated rats.

CONCLUSIONS

The data obtained in this study suggest that melatonin administration confers protection against toxicity inflicted by ZNS, and support the contention that melatonin protection is achieved by its ability as a scavenger for free radicals generated by ZNS.

Efficacy of zonisamide in migraineurs with nonresponse to topiramate

This study investigated another type of carbonic anhydrase inhibitor and antiepileptic drug, zonisamide, in order to evaluate its potential effectiveness for migraine prophylaxis refractory to topiramate, and to assess intolerability to adverse events, paresthesia in particular. This is an open-labeled retrospective single center study. We included headache patients who met the requirement of migraine without aura and were refractory to topiramate. Patients were treated only with zonisamide 100 mg/day, directly switching from topiramate. Patients were monitored every month for three months. A positive response to treatment (responders) was defined as a 50% or greater reduction in headache days at three months after study commencement, compared with baseline. One hundred and twenty migraineurs who were refractory to topiramate were recruited. Compared with baseline, headache days with zonisamide showed a decrease, compared with baseline (P < 0.01). Two patients complained of adverse effects, such as paresthesia. These results suggest that zonisamide is effective for migraine prophylaxis refractory to topiramate, or intolerable patients due to topiramate-induced paresthesia.

Tackling chronic migraine: current perspectives

In the last decade, several diagnostic criteria and definitions have been proposed for chronic migraine (CM). The third edition of the International Classification of Headache Disorders–3 beta, published in 2013, has revised CM diagnostic criteria. CM is defined as “headache occurring on 15 or more days per month for more than 3 months, which has the features of migraine headache on at least 8 days per month.” Patients who meet the criteria for CM and for medication-overuse headache should be given both diagnoses. Worldwide, CM prevalence ranges 1%–3%, and its incidence has been estimated to be 2.5% per year. CM is associated with disability and poor quality of life. Modifiable risk factors include (among others): migraine progression (defined as an increase in frequency and severity of migraine attacks); medication and caffeine overuse; obesity; stressful life events; and snoring. CM patients have a significantly higher frequency of some comorbid conditions, including chronic pain, psychiatric disorders, respiratory illness, and some vascular risk factors. Management includes identification and control of comorbidities and risk factors that predispose to CM; treatment and prevention for medication overuse; early treatment for migraine attacks; and an adequate preventive therapy for CM. Several randomized controlled clinical trials have shown the efficacy of topiramate, amitriptyline, onabotulinumtoxinA, and cognitive-behavioral therapy in CM.

A rational approach to the management of chronic migraine

About 2% of the adult population has chronic migraine with only 20% diagnosed with this disorder. Those with medication overuse may improve with withdrawal of overuse medications. The intravenous dihydroergotamine regimen usually produces short-term benefit for those with medically refractory chronic migraine. OnabotulinumtoxinA and topiramate have shown efficacy in large placebo-controlled randomized trials. Sodium valproate, gabapentin, tizanidine, amitriptyline, fluoxetine, zonisamide, and possibly memantine may be alternative or possibly combined treatment options but with lesser levels of evidence supporting their use. Preliminary evidence suggests that nerve blocks might be beneficial. Acupuncture, biofeedback, relaxation therapy, and cognitive behavioral therapy might be of benefit. Surgical treatments including bariatric and deactivation of trigger points are of growing interest but not appropriate for most sufferers. Occipital nerve stimulation is a promising treatment with ongoing studies defining its use.

The adverse event profile of zonisamide: a meta-analysis

The first aim of our study was to analyze the adverse events statistically significantly associated with zonisamide, through a systematic review and meta-analysis of available randomized placebo-controlled trials (RCTs). The second aim was to compare these results with those obtained from an analysis of non-RCTs and observational studies. Randomized controlled trials were identified using Medline (PubMed), EMBASE (Ovid), and Cochrane CENTRAL, from 1990 to September 2012. RevMan version 5.1 and OpenMeta[Analyst] were used for analyses of RCT and non-RCTs, respectively. Six eligible studies with 1184 patients between 12 and 80 years of age were included in RCTs analysis. Fifteen adverse events were investigated. In this first part of the analysis, no adverse events were statistically significantly associated with zonisamide. In the non-RCT analysis, a high incidence of weight loss and headache was found. In RCTs, zonisamide was statistically significantly associated with an increased risk of adverse event-related study withdrawals [RR (99% CI) = 1.81 (1.07-3.08)]. Although our study revealed no statistically significantly associated adverse effects (AEs) with zonisamide, this is very likely a consequence of the small numbers in the RCTs available. The limited data available from the studies appear to reveal no major safety concerns related to zonisamide. However, the high incidence of weight loss and headache in the non-RCTs suggests that these AEs could be of clinical significance.

Preventive agents for migraine: focus on the antiepileptic drugs

Migraine is among the 10 most disabling disorders worldwide. It is characterized by episodes of moderate or severe headaches with various degree of disability, resulting in a considerable health burden upon the sufferers and their family. The objective of this article is to review the use of prophylaxis with antiepileptic drugs. Particular focus is given to their mechanism of action, metabolism, pharmacokinetics, safety profile, efficacy and to provide a summary of the most relevant clinical studies and patient preference.

Nightmare-enacting behavior responding to zonisamide in early Parkinson's disease

Recently, zonisamide (ZNS) has been approved as a new adjunctive therapy for motor complications of Parkinson's disease (PD). More recently, ZNS was reported to be effective for the management of impulse control behavior in PD, suggesting potential effects on non-motor PD symptoms. Dream enactment associated with aggressive, violent behavior can carry a serious risk of injury to patients, as well as to spouses or caretakers. This report describes a patient with PD who had vivid nightmares and dream-enacting behavior that resolved after treatment with ZNS. The present case raises the question whether ZNS might potentially be effective for the management of vivid nightmares or dream-enacting behavior.

Zonisamide versus topiramate in migraine prophylaxis: a double-blind randomized clinical trial

BACKGROUND

Topiramate is an antiepileptic drug that has been approved for migraine prophylaxis. Despite appropriate efficacy for migraine prophylaxis, some patients cannot tolerate its adverse effects. The aim of this study was to compare the efficacy of zonisamide, another antiepileptic drug, with topiramate in decreasing the frequency and severity of migraine attacks to determine whether it could be used as an alternative for noncompliant patients to topiramate.

METHODS

Eighty patients, recruited from referred migraineurs to our neurology clinic, who met the diagnosis and inclusion criteria were allocated randomly to group A (50-mg/d zonisamide, gradually titrated up to 200 mg/d) and group B (25-mg/d topiramate, gradually titrated up to 100 mg/d). Each patient was followed for 12 weeks and was assessed at entrance, in the fourth week and twelfth week for frequency of attacks, headache severity, need for acute medication, migraine disability assessment score, and adverse effects. A P < 0.05 was considered as the level of significant difference in all tests.

RESULTS

Both drugs caused a significant decrease in frequency, severity, need for acute medication in migraine attacks, and migraine disability assessment score (P < 0.05). Except headache severity that was reduced significantly better by zonisamide (P < 0.008), there were no significant difference between the 2 groups in other items. Except for 2 cases of intolerable paresthesia, both drugs were tolerated well during the study.

CONCLUSION

Our results indicated that zonisamide is as effective as topiramate in migraine prophylaxis and can be considered as an alternative treatment when topiramate is not tolerated well.

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.

Choosing among antiepileptic drugs

Selecting an antiepileptic drug (AED) for treatment of seizures is daunting because there are now 20 from which to choose. Following simple principles allows a systematic approach to drug selection. Efficacy studies provide limited information. For initial monotherapy of partial seizures, high-level evidence exists for the efficacy of lamotrigine, carbamazepine, oxcarbazepine, and topiramate. For initial monotherapy of generalized seizures, high-level evidence is available for valproate, lamotrigine, topiramate, and oxcarbazepine. For initial monotherapy of absence seizures, high-level evidence exists for valproate, lamotrigine, and ethosaximide. All second-generation AEDs have efficacy as adjunctive therapy for partial seizures. AEDs are often useful for comorbid conditions or have properties that should be avoided in some groups. Thus, AEDs should usually be selected on the basis of comorbid conditions, including depression, migraine, chronic pain, obesity, and nephrolithiasis, or patient characteristics, especially for women of childbearing potential and older adults.

Zonisamide in managing impulse control disorders in Parkinson's disease

Impulse control disorders (ICDs) are a set of behaviours that take place in a subgroup of patients with Parkinson's disease (PD). Although reduction or switch of dopamine agonists or decrease of levodopa are the common treatment, this does not always improve the compulsive behaviour. Zonisamide (ZNS) has proved effective for motor symptoms in PD and it may be also useful in the field of ICDs. The aim of our study is to evaluate the safety and efficacy of ZNS in PD patients with ICDs who did not improve following a reduction of either levodopa or dopamine agonists. Fifteen patients were initiated on 25 mg/day ZNS dosage, which was titrated to 200 mg/day, as tolerated. Severity of the behaviours was assessed by means of the Clinical Global Impression and the Barratt Impulsiveness Scale, while motor impairment was assessed by means of the Unified Parkinson's Disease Rating Scale (UPDRS). Demographic data, medication dose, treatment duration and adverse events were also collected and analyzed. There was a marked reduction in the severity of impulsive behaviours and global impulsiveness (mean change from baseline -5.8 to -4.8, respectively). UPDRS changed only marginally. ZNS was generally well tolerated. Our study suggests that ZNS may be effective for ICDs in PD. The lack of studies with other medications to treat these behaviours in PD and the potential beneficial effects of ZNS for motor complications make this drug important in the treatment of the disease.

New drugs for migraine

After the triptans, a calcitonin gene-related peptide blocker (telcagepant) is the first acute medicine that has been developed primarily for treatment of acute migraine. Otherwise, the new drugs have been developed first for other purposes, like anticonvulsants, antihypertensives and antidepressants used for migraine prophylaxis. For acute attacks, a new way to administer a traditional drug like dihydroergotamine is under way, and documentation of efficacy in migraine has been gained for some commonly used painkillers and anti-inflammatory drugs, and for some herbal extracts. Based on insights into the basic pathophysiological mechanisms of the disorder, some drugs have been developed which seem promising in early phase II studies (NOS inhibitors and 5HT1F-receptor agonists). In the future, development and enhancements of existing medicines must be accompanied by increased efforts to develop truly new migraine drugs based on knowledge of the pathophysiology if one wishes to reduce substantially the great burden migraine poses on patients and society.

A review of the use of zonisamide in Parkinson's disease

Although zonisamide was previously only used to treat epilepsy, recently more applications have been forthcoming. Due to a good side effect profile, a lower frequency of interactions and a more comfortable posology, there are several studies regarding its uses in other pathologies such as migraine, neuropathic pain, essential tremor and various psychiatric diseases. A multicentered, randomized, double-blind, placebo-controlled study conducted in Japan suggested that zonisamide, as an add-on treatment, has efficacy in treating motor symptoms in patients with Parkinson's disease. In addition, other studies support the utility of zonisamide in other symptoms of this disease. The therapeutic doses of zonisamide for the treatment of Parkinson's disease are considerably lower than those for the treatment of epilepsy. This antiepileptic drug has been used in Japan for more than 15 years and so it is expected that it will be safe and well tolerated in patients with Parkinson's disease. However, the pharmacological mechanisms of the antiparkinsonian actions of zonisamide remain unclear and more basic investigation is warranted. The aim of this paper is to review the structure, mechanisms of action, pharmacokinetics and antiparkinsonian action of zonisamide.