Topiramate in the treatment of partial and generalized epilepsy

Narrative Review of Topiramate: Clinical Uses and Pharmacological Considerations

Due to the diverse mechanisms of action of antiseizure drugs, there has been a rise in prescriptions of these drugs for non-epileptic pathologies. One drug that is now being used for a variety of conditions is topiramate. This is a narrative review that used PubMed, Google Scholar, MEDLINE, and ScienceDirect to review literature on the clinical and pharmacologic properties of topiramate. Topiramate is a commonly prescribed second-generation antiseizure drug. The drug works through multiple pathways to prevent seizures. In this regard, topiramate blocks sodium and calcium voltage-gated channels, inhibits glutamate receptors, enhances gamma-aminobutyric acid (GABA) receptors, and inhibits carbonic anhydrase. Topiramate is approved by the Food and Drug Administration (FDA) for epilepsy treatment and migraine prophylaxis. Topiramate in combination with phentermine is also FDA-approved for weight loss in patients with a body mass index (BMI) > 30. The current target dosing for topiramate monotherapy is 400 mg/day and 100 mg/day to treat epilepsy and migraines, respectively. Commonly reported side effects include paresthesia, confusion, fatigue, dizziness, and change in taste. More uncommon and serious adverse effects can include acute glaucoma, metabolic acidosis, nephrolithiasis, hepatotoxicity, and teratogenicity. Related to a broad side effect profile, physicians prescribing this drug should routinely monitor for side effects and/or toxicity. The present investigation reviews various anti-seizure medications before summarizing indications of topiramate, off-label uses, pharmacodynamics, pharmacokinetics, adverse effects, and drug-drug interactions.

Topiramate (Topamax): Evolving Role in Weight Reduction Management: A Narrative Review

Obesity has emerged as a widespread disease with epidemic proportions, necessitating effective management to enhance the overall health outcomes of patients. Medical intervention for weight loss becomes necessary when diet and exercise prove ineffective, and topiramate emerges as a potential treatment option for this global problem. Currently approved as an anti-epileptic and migraine prophylaxis medication, topiramate is frequently utilized as adjunctive therapy for patients with mood and eating disorders, as well as for alcohol use disorders. Its multifaceted mechanisms of action contribute to reducing neuronal excitation and enhancing neuronal inhibition. Given its variety of mechanisms, topiramate shows several off-label outcomes, including weight loss, for patients prescribed this medication. Although the specific mechanism of action concerning weight loss remains uncertain, various hypotheses have been reported. Notably, topiramate may contribute to weight loss by reducing calorie intake, decreasing fat gain, and lowering triglyceride and cholesterol levels. Additionally, its impact on reward pathways associated with food could play a role. Multiple clinical studies have supported the use of topiramate as a weight-loss medication. Notably, the medication demonstrates effectiveness in reducing body weight across different dosages and sustaining weight loss over time, outperforming alternative weight loss methods. Moreover, it was generally well-tolerated in clinical studies, with few side effects observed. In conclusion, topiramate offers promising potential as a weight loss solution and can be a valuable addition to the range of treatment options for combating obesity.

Thalidomide Attenuates Epileptogenesis and Seizures by Decreasing Brain Inflammation in Lithium Pilocarpine Rat Model

Thalidomide (TAL) has shown potential therapeutic effects in neurological diseases like epilepsy. Both clinical and preclinical studies show that TAL may act as an antiepileptic drug and as a possible treatment against disease development. However, the evidence for these effects is limited. Therefore, the antiepileptogenic and anti-inflammatory effects of TAL were evaluated herein. Sprague Dawley male rats were randomly allocated to one of five groups (n = 18 per group): control (C); status epilepticus (SE); SE-TAL (25 mg/kg); SE-TAL (50 mg/kg); and SE-topiramate (TOP; 60mg/kg). The lithium-pilocarpine model was used, and one day after SE induction the rats received pharmacological treatment for one week. The brain was obtained, and the hippocampus was micro-dissected 8, 18, and 28 days after SE. TNF-α, IL-6, and IL-1β concentrations were quantified. TOP and TAL (50 mg/kg) increased the latency to the first of many spontaneous recurrent seizures (SRS) and decreased SRS frequency, as well as decreasing TNF-α and IL-1β concentrations in the hippocampus. In conclusion, the results showed that both TAL (50 mg/kg) and TOP have anti-ictogenic and antiepileptogenic effects, possibly by decreasing neuroinflammation.

What Is the Effect of Topiramate Use on Growth in Children With Epilepsy?

Objective

The literature related to weight loss as a side effect of using topiramate (TPM) in pediatric patients is inconsistent. The aim of this study was to assess the effect of TPM on the growth of pediatric epileptic patients.

Methods

The electronic medical files of 50 pediatric epileptic patients who were prescribed TPM over 5 years were retrospectively reviewed. Cases treated with other antiepileptic drugs were the control group (n=60).

Results

Height growth was similar in both groups. At the 6-12-month follow-up, there was a decrease in the average BMI in the TPM group of -0.81 kg/m2 (p=0.019) and an increase in the control group of +0.46 kg/m2 (p=0.023). Weight loss was noted in 21/50 (42%) of the TPM group as compared with 13/60 (22%) in the control group (p=0.02). More weight loss was observed in the overweight TPM group in 7/16 (44%) compared to none in the nine cases in the control group (p=0.03). After the one-year follow-up, the average change in weight was +1.73 kg (p=0.0001) and +3.53 kg (p=0.0001) in the TPM and control groups, respectively. In patients with normal initial BMI, the weight increased by +1.3 kg on average, compared to the group with a high initial BMI, which decreased by -2.55 kg.

Conclusion

Topiramate use has no negative effect on height growth in pediatric patients with epilepsy. While mild weight loss occurs frequently in the first year of treatment, weight gain resumes after the first year except in patients with a high initial BMI

Breathing Abnormalities During Sleep and Wakefulness in Rett Syndrome: Clinical Relevance and Paradoxical Relationship With Circulating Pro-oxidant Markers

Background

Breathing abnormalities are common in Rett syndrome (RTT), a pervasive neurodevelopmental disorder almost exclusively affecting females. RTT is linked to mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Our aim was to assess the clinical relevance of apneas during sleep-wakefulness cycle in a population with RTT and the possible impact of apneas on circulating oxidative stress markers.

Methods

Female patients with a clinical diagnosis of typical RTT (n = 66), MECP2 gene mutation, and apneas were enrolled (mean age: 12.5 years). Baseline clinical severity, arterial blood gas analysis, and red blood cell count were assessed. Breathing was monitored during the wakefulness and sleep states (average recording time: 13 ± 0.5 h) with a portable polygraphic screening device. According to prevalence of breath holdings, the population was categorized into the wakefulness apnea (WA) and sleep apnea (SA) groups, and apnea-hypopnea index (AHI) was calculated. The impact of respiratory events on oxidative stress was assessed by plasma and intra-erythrocyte non-protein-bound iron (P-NPBI and IE-NPBI, respectively), and plasma F2-isoprostane (F2-IsoP) assays.

Results

Significant prevalence of obstructive apneas with values of AHI > 15 was present in 69.7% of the population with RTT. The group with SA showed significantly increased AHI values > 15 (p = 0.0032), total breath holding episodes (p = 0.007), and average SpO2 (p = 0.0001) as well as lower nadir SpO2 (p = 0.0004) compared with the patients with WAs. The subgroups of patients with WA and SA showed no significant differences in arterial blood gas analysis variables (p > 0.089). Decreased mean cell hemoglobin (MCH) (p = 0.038) was observed in the group with WAs. P-NPBI levels were significantly higher in the group with WA than in that with SAs (p = 0.0001). Stepwise multiple linear regression models showed WA being related to nadir SpO2, average SpO2, and P-NPBI (adjusted R2 = 0.613, multiple correlation coefficient = 0.795 p < 0.0001), and P-NPBI being related to average SpO2, blood PaCO2, red blood cell mean corpuscular volume (MCV), age, and topiramate treatment (adjusted R2 = 0.551, multiple correlation coefficient = 0.765, p < 0.0001).

Conclusion

Our findings indicate that the impact of apneas in RTT is uneven according to the sleep-wakefulness cycle, and that plasma redox active iron represents a potential novel therapeutic target.

A Review on Medicinal Plants Used in the Management of Headache in Africa

The use of medicinal plants in the management of diverse ailments is entrenched in the culture of indigenous people in African communities. This review provides a critical appraisal of the ethnobotanical uses of medicinal plants for the management of headache in Africa. Research articles published from 2010 (Jan) to 2021 (July) with keywords such as Africa, ethnobotany, headache, medicinal plant and traditional medicine were assessed for eligibility based on sets of pre-defined criteria. A total of 117 plants, representing 56 families, were documented from the 87 eligible studies. Asteraceae (10%), Fabaceae (10%), Lamiaceae (9%) and Mimosaceae (5%) were the most represented plant families. The most popular plant species used in the management of headache were Ocimum gratissimum L. (n = 7), Allium sativum L. (n = 3), Ricinus communis L. (n = 3) and Artemisia afra Jack. ex. Wild (n = 2). The leaves (49%), roots (20%) and bark (12%) were the most common plant parts used. Decoction (40%) and infusion (16%) were the preferred methods of preparation, whereas the oral route (52%) was the most preferred route of administration. The data revealed that medicinal plants continue to play vital roles in the management of headache in African communities. In an attempt to fully explore the benefits from the therapeutic potential of indigenous flora for common ailments, further studies are essential to generate empirical evidence on their efficacies, using appropriate test systems/models. This approach may assist with the ongoing drive towards the integration of African traditional medicine within mainstream healthcare systems.

Expanding the Treatment Landscape for Lennox-Gastaut Syndrome: Current and Future Strategies

Lennox-Gastaut syndrome (LGS), a childhood-onset severe developmental and epileptic encephalopathy (DEE), is an entity that encompasses a heterogenous group of aetiologies, with no single genetic cause. It is characterised by multiple seizure types, an abnormal EEG with generalised slow spike and wave discharges and cognitive impairment, associated with high morbidity and profound effects on the quality of life of patients and their families. Drug-refractory seizures are a hallmark and treatment is further complicated by its multiple morbidities, which evolve over the patient's lifetime. This review provides a comprehensive overview of the current and future options for the treatment of seizures associated with LGS. Six treatments are specifically indicated as adjunct therapies for the treatment of seizures associated with LGS in the US: lamotrigine, clobazam, rufinamide, topiramate, felbamate and most recently cannabidiol. These therapies have demonstrated reductions in drop seizures in 15%-68% of patients across trials, with responder rates (≥ 50% reduction in drop seizures) of 37%-78%. Valproate is still the preferred first-line treatment, generally in combination with lamotrigine or clobazam. Other treatments frequently used off-label include the broad spectrum anti-epileptic drugs (AED) levetiracetam, zonisamide and perampanel, while recent evidence from observational studies has indicated that a newer AED, the levetiracetam analogue brivaracetam, may be effective and well tolerated in LGS patients. Other treatments in clinical development include fenfluramine in late phase III, perampanel, soticlestat-OV953/TAK-953, carisbamate and ganaxolone. Non-pharmacologic interventions include the ketogenic diet, vagus nerve stimulation and surgical interventions; these are also expanding, with the potential for less invasive techniques for corpus callosotomy that have promise for reducing complications. However, despite these advancements, patients continue to experience a significant burden. Because LGS is not a single entity, tailoring of treatment is needed as opposed to a 'one size fits all' approach. Further research is needed into the underlying aetiologies and pathophysiology of LGS, together with advancements in treatments that encompass the spectrum of seizures associated with this complex syndrome.

The Pharmacology and Clinical Efficacy of Antiseizure Medications: From Bromide Salts to Cenobamate and Beyond

Epilepsy is one of the most common and disabling chronic neurological disorders. Antiseizure medications (ASMs), previously referred to as anticonvulsant or antiepileptic drugs, are the mainstay of symptomatic epilepsy treatment. Epilepsy is a multifaceted complex disease and so is its treatment. Currently, about 30 ASMs are available for epilepsy therapy. Furthermore, several ASMs are approved therapies in nonepileptic conditions, including neuropathic pain, migraine, bipolar disorder, and generalized anxiety disorder. Because of this wide spectrum of therapeutic activity, ASMs are among the most often prescribed centrally active agents. Most ASMs act by modulation of voltage-gated ion channels; by enhancement of gamma aminobutyric acid-mediated inhibition; through interactions with elements of the synaptic release machinery; by blockade of ionotropic glutamate receptors; or by combinations of these mechanisms. Because of differences in their mechanisms of action, most ASMs do not suppress all types of seizures, so appropriate treatment choices are important. The goal of epilepsy therapy is the complete elimination of seizures; however, this is not achievable in about one-third of patients. Both in vivo and in vitro models of seizures and epilepsy are used to discover ASMs that are more effective in patients with continued drug-resistant seizures. Furthermore, therapies that are specific to epilepsy etiology are being developed. Currently, ~ 30 new compounds with diverse antiseizure mechanisms are in the preclinical or clinical drug development pipeline. Moreover, therapies with potential antiepileptogenic or disease-modifying effects are in preclinical and clinical development. Overall, the world of epilepsy therapy development is changing and evolving in many exciting and important ways. However, while new epilepsy therapies are developed, knowledge of the pharmacokinetics, antiseizure efficacy and spectrum, and adverse effect profiles of currently used ASMs is an essential component of treating epilepsy successfully and maintaining a high quality of life for every patient, particularly those receiving polypharmacy for drug-resistant seizures.

Effectiveness of dose-escalated topiramate monotherapy and add-on therapy in neurosurgery-related epilepsy: A prospective study

BACKGROUND

Lesional and symptomatic causes of epilepsy are the most common neurological disorders of the brain. Topiramate effectively controls newly diagnosed epilepsy and refractory focal seizures, but high-dose topiramate does not improve seizure control. This study aimed to evaluate the clinical efficacy and safety of dose-escalated topiramate as first-line monotherapy and add-on therapy in patients with neurosurgery-related epilepsy.

MATERIAL AND METHODS

A total of 55 neurosurgical patients with epilepsy were divided into monotherapy and add-on therapy groups and both groups received topiramate via the dose-escalation method. The primary efficacy outcomes were seizure-free rate and seizure response rate. Adverse events and seizure frequency were recorded.

RESULTS

The seizure response rate in the first month of monotherapy was significantly better than that of add-on therapy (89% vs 65%, P < .05), but no significant differences were found in seizure response rates between the 2 groups after 2 months of treatment. Both monotherapy and add-on therapy were effective in controlling seizures, with mean seizure frequency of 0.725 vs 0.536 and seizure-free rate of 88% vs 78.6%. Both treatments showed good improvement of seizure frequency in patients without tumor. The efficacy of monotherapy was better than that of add-on therapy (80% vs 29.2%) in patients with body mass index (BMI) ≤24. However, add-on therapy was better than monotherapy (76.7% vs 21.4%) in patients with BMI > 24. Dizziness (25.5%) and headache (16.4%) were the most common adverse events. No severe adverse event such as cognitive impairment was observed.

CONCLUSIONS

Dose-escalated topiramate monotherapy and add-on therapy demonstrate good efficacy and safety, with fewer adverse events in seizure control in neurosurgical patients.

Study of the More Suitable Drugs and Dosage Forms for Administration to Newborn Infants via Feeding Tube Using the Collection Rate as an Indicator

The dosages of drugs in newborn infants are small. Small dose necessitate consideration of the loss of drug when administered via feeding tube. In this study, we conducted a tube administration test for seven kinds of antiepileptic drugs and two kinds of potassium supplements using a neonatal feeding tube and investigated the drug loss using the collection rate. We also studied the differences in collection rates among different dosage forms and drugs to determine the more suitable dosage forms and drugs. We investigated three dosage forms: powder, fine granules or dry syrup (powdery form) drugs, powdery form drugs that have been pulverized (pulverized powdery forms), and pulverized tablets. Additionally, we investigated two potassium supplements to determine which was more suitable: potassium L-aspartate and potassium gluconate. For topiramate, only the powdery form caused tube obstructions; the collection rates of the pulverized powdery form and pulverized tablets were > 90%. All antiepileptic drugs other than topiramate that were tested had collection rates of about > 90%. Considering stability and pharmacokinetics, the more suitable dosage form for topiramate is pulverized tablets, whereas the more suitable dosage form for other antiepileptic drugs is powdery form. Collection rate of potassium gluconate was higher than that of potassium L-aspartate. The current study, which indicates that potassium gluconate powdery form is the more suitable drug, presents the more suitable dosage form and drug for administration via feeding tube to newborn infants. These results show that it is essential to evaluate passage through the tube using the collection rate.

Repurposed molecules for antiepileptogenesis: Missing an opportunity to prevent epilepsy?

Prevention of epilepsy is a great unmet need. Acute central nervous system (CNS) insults such as traumatic brain injury (TBI), cerebrovascular accidents (CVA), and CNS infections account for 15%-20% of all epilepsy. Following TBI and CVA, there is a latency of days to years before epilepsy develops. This allows treatment to prevent or modify postinjury epilepsy. No such treatment exists. In animal models of acquired epilepsy, a number of medications in clinical use for diverse indications have been shown to have antiepileptogenic or disease-modifying effects, including medications with excellent side effect profiles. These include atorvastatin, ceftriaxone, losartan, isoflurane, N-acetylcysteine, and the antiseizure medications levetiracetam, brivaracetam, topiramate, gabapentin, pregabalin, vigabatrin, and eslicarbazepine acetate. In addition, there are preclinical antiepileptogenic data for anakinra, rapamycin, fingolimod, and erythropoietin, although these medications have potential for more serious side effects. However, except for vigabatrin, there have been almost no translation studies to prevent or modify epilepsy using these potentially "repurposable" medications. We may be missing an opportunity to develop preventive treatment for epilepsy by not evaluating these medications clinically. One reason for the lack of translation studies is that the preclinical data for most of these medications are disparate in terms of types of injury, models within different injury type, dosing, injury-treatment initiation latencies, treatment duration, and epilepsy outcome evaluation mode and duration. This makes it difficult to compare the relative strength of antiepileptogenic evidence across the molecules, and difficult to determine which drug(s) would be the best to evaluate clinically. Furthermore, most preclinical antiepileptogenic studies lack information needed for translation, such as dose-blood level relationship, brain target engagement, and dose-response, and many use treatment parameters that cannot be applied clinically, for example, treatment initiation before or at the time of injury and dosing higher than tolerated human equivalent dosing. Here, we review animal and human antiepileptogenic evidence for these medications. We highlight the gaps in our knowledge for each molecule that need to be filled in order to consider clinical translation, and we suggest a platform of preclinical antiepileptogenesis evaluation of potentially repurposable molecules or their combinations going forward.

Phenotypic Characterization of Larval Zebrafish (Danio rerio) with Partial Knockdown of the cacna1a Gene

The CACNA1A gene encodes the pore-forming α1 subunit of voltage-gated P/Q type Ca²⁺ channels (Ca_v2.1). Mutations in this gene, among others, have been described in patients and rodents suffering from absence seizures and episodic ataxia type 2 with/without concomitant seizures. In this study, we aimed for the first time to assess phenotypic and behavioral alterations in larval zebrafish with partial cacna1aa knockdown, placing special emphasis on changes in epileptiform-like electrographic discharges in larval brains. Whole-mount in situ hybridization analysis revealed expression of cacna1aa in the optic tectum and medulla oblongata of larval zebrafish at 4 and 5 days post-fertilization. Next, microinjection of two antisense morpholino oligomers (individually or in combination) targeting all splice variants of cacna1aa into fertilized zebrafish eggs resulted in dose-dependent mortality and decreased or absent touch response. Over 90% knockdown of cacna1aa on protein level induced epileptiform-like discharges in the optic tectum of larval zebrafish brains. Incubation of morphants with antiseizure drugs (sodium valproate, ethosuximide, lamotrigine, topiramate) significantly decreased the number and, in some cases, cumulative duration of epileptiform-like discharges. In this context, sodium valproate seemed to be the least effective. Carbamazepine did not affect the number and duration of epileptiform-like discharges. Altogether, our data indicate that cacna1aa loss-of-function zebrafish may be considered a new model of absence epilepsy and may prove useful both for the investigation of Cacna1a-mediated epileptogenesis and for in vivo drug screening.

Perspective: Therapeutic Potential of Flavonoids as Alternative Medicines in Epilepsy

Epilepsy is a chronic neurological disorder that affects many people worldwide. Temporal lobe epilepsy is the most common and most studied type of epilepsy, but the pathological mechanisms underlying this condition are poorly understood. More than 20 antiepileptic drugs (AEDs) have been developed and used for the treatment of epilepsy; however, 30% of patients still experience uncontrolled epilepsy and associated comorbidities, which impair their quality of life. In addition, various side effects have been reported for AEDs, such as drowsiness, unsteadiness, dizziness, blurred or double vision, tremor (shakiness), greater risk of infections, bruising, and bleeding. Thus, critical medical needs remain unmet for patients with uncontrolled epilepsy. Flavonoids belong to a subclass of polyphenols that are widely present in fruits, vegetables, and certain beverages. Recently, many studies have reported that some flavonoids elicit various beneficial effects in patients with epilepsy without causing the side effects associated with conventional medical therapies. Moreover, flavonoids may have a property of regulating microRNA expression associated with inflammation and cell survival. These findings suggest that flavonoids, which are more effective but impose fewer adverse effects than conventional AEDs, could be used in the treatment of epilepsy.

Efficacy, safety, and tolerability of brivaracetam with concomitant lamotrigine or concomitant topiramate in pooled Phase III randomized, double-blind trials: A post-hoc analysis

OBJECTIVE

The objective was to assess the efficacy and safety of adjunctive brivaracetam (BRV) with concomitant use of lamotrigine (LTG) or topiramate (TPM) in patients with uncontrolled focal seizures.

METHODS

Data were pooled from three randomized, placebo-controlled Phase III studies (NCT00490035/N01252, NCT00464269/N01253, NCT01261325/N01358) of adults with focal (partial-onset) seizures. Patients taking concomitant levetiracetam were excluded from the efficacy populations, but included in the safety populations. This post-hoc analysis reports data from patients taking BRV in the approved therapeutic range (50-200mg/day) concomitantly with LTG or TPM.

RESULTS

The number of patients in each of the three BRV dosage groups was small, particularly for the TPM subgroup. Mean percent reduction over placebo in baseline-adjusted focal seizure frequency/28days for BRV 50, 100, and 200mg/day was 8.7, 5.3, and 8.9 in the LTG subgroup (n=220), and 8.4, 21.3, and -4.2 in the TPM subgroup (n=122). The ≥50% responder rate with concomitant LTG or TPM with BRV 50, 100, and 200mg/day or placebo was LTG: 28.1%, 36.1%, 34.1%, and 29.1%; and TPM: 14.3%, 44.4%, 25.0%, and 17.5%. There were numerically ≥50%, ≥75%, ≥90%, and 100% responder rates for patients taking BRV ≥50mg/day compared with placebo in both subgroups. In the LTG and TPM safety populations (n=245 versus n=125), treatment-emergent adverse events (TEAEs) were reported with LTG 68.7% versus 68.4%, and TPM 65.6% versus 57.8% (BRV ≥50mg/day versus placebo). Discontinuations due to TEAEs versus placebo were LTG 7.3% versus 6.3% and TPM 8.2% versus 4.7%. The three most frequently reported TEAEs for both subgroups were somnolence, dizziness, and fatigue. Of these, the incidence of fatigue in the LTG population appeared to increase with dose.

SIGNIFICANCE

In this post-hoc pooled analysis, BRV administered with concomitant LTG or TPM reduced seizure frequency and was generally well tolerated for BRV doses of 50-200mg/day.

Efficacy and Tolerability of Second and Third Generation Anti-epileptic Drugs in Refractory Epilepsy: A Network Meta-Analysis

This study was proposed to compare the relative efficacy and tolerability of the second and third generation AEDs for refractory epilepsy. The 50% responder rate (RR) was selected as the efficacy outcome whereas the incidence of dizziness and somnolence were considered to evaluate the tolerability of AEDs. Odds ratio (OR) and their 95% credible interval (CrI) were obtained using a consistency model and surface under the cumulative ranking curve (SUCRA) value was calculated to rank AEDs. Topiramate appeared to be significantly more effective than placebo, eslicarbazepine acetate, perampanel, pregabalin, zonisamide, gabapentin and lamotrigine with respect to the 50% RR (all OR > 1). Patients who were managed by eslicarbazepine acetate, perampanel, oxcarbazepine, topiramate and pregabalin were more likely to suffer from dizziness compared to those who receive placebo (all OR > 1). Perampanel, topiramate and pregabalin were related to elevated risks of somnolence compared to placebo (all OR > 1). Moreover, topiramate ranked highest with respect to 50% RR (SUCRA = 0.968) whereas levetiracetam appeared to have balanced efficacy and tolerability (SUCRA = 0.769, 0.743, 0.604 and 0.659). In conclusion, topiramate was the most efficacious AED, while levetiracetam was able to provide patients with balanced efficacy and tolerability.

Effect of acute and long term potassium bromide administration on spatial working memory in rat

Potassium bromide (KBr), an old antiepileptic agent, is illegally used in pharmaceutical or food industries to improve the product appearance. KBr has been proven to influence several pathways which are important in memory formation. Therefore, the present study aimed to evaluate the effect of KBr on spatial working memory using object recognition task (ORT). Rats received a single dose of KBr (50, 100 or 150 mg/kg), per oral, in acute treatment. KBr long term effects were also studied in animals receiving 50 mg/kg/day of KBr for 28 consecutive days. At the end of treatments, animals underwent two trials of ORT, five min each. In the first trial (T₁), animals encountered with two identical objects for exploration. After 1 h, the animals were exposed to a familiar and an unfamiliar object (T₂). The exploration times for discrimination (D) and recognition (R) as well as the frequency of exploration for any objects were determined. Acute administration of 150 mg/kg of KBr significantly decreased the discrimination and recognition indices (RI and DI) (P < 0.01) compared to the control. However, lower doses failed to influence the animals’ performance in the test. In addition, long term administration of KBr remarkably diminished the DI and RI and the frequency of exploration (P < 0.05). The results of this study indicate that acute doses of KBr as high as 150 mg/kg are required to hamper memory function in ORT. However, cognitive impairment occured with lower doses of KBr when the duration of treatment is extended.

A muliticenter retrospective study of the actual using patterns and clinical effects of topiramate in patients with neurosurgical disease

BACKGROUND AND PURPOSE

This study is to investigate the actual using patterns and clinical effects of topiramate in patients with neurosurgical disease as antiepileptic drugs (AEDs) in 94 korean multicenters.

METHODS

A total of 7,152 patients who had taken topiramate for at least 3 months between August 2008 and February 2009 were eligible to participate in this study. We evaluated demographic data, disease entities, duration of topiramate administration, initial and subsequent dosage adjustment, concomitant AEDs, the frequency of seizure reduction, and adverse events.

RESULTS

Topiramate was commonly prescribed in stroke (38%) and head trauma group (36%). In the dosage of topiramate, the mean initial dosage was 65 mg/day, and the mean maintenance dosage was adjusted into 105 mg/day. The mean duration of the initial dosage for topiramate administration was 24 days, and the mean duration of the maintenance dosage was 125 days, respectively. Among groups with prophylactic administration, 98% did not develop convulsion and among groups with therapeutic administration, 2% was ineffective to control seizure. After taking topiramate, 2% patients showed adverse events, that sensory aberration was the most common.

CONCLUSIONS

These results suggest that topiramate prescribe widely in diverse neurosurgical disorders, and effective in reduction of seizure frequency, and does not cause serious adverse effects comparable with old AEDs.

Vague effects of chronic topiramate administration on maximal electroshock-induced seizures in mice

BACKGROUND

Almost all experimental studies evaluating interactions between antiepileptic and non-antiepileptic drugs are based on their single administration, whereas epileptic patients require chronic pharmacotherapy. Herein, we attempted to figure out whether single and repeated administration of topiramate leads to the same anticonvulsant and undesired effects.

METHODS

Experiments were conducted in the model of maximal electroshock in mice. Motor coordination was evaluated in the chimney test. Brain concentrations of topiramate were determined by high-performance liquid chromatography and triple quadrupole mass spectrometry.

RESULTS

The anticonvulsant activity of topiramate administered once or twice a day for 7 days did not significantly differ from the respective effect of topiramate given acutely in a single injection. However, calculating of 50% effective doses for topiramate applied in 14-days protocol (once or two times a day) was impossible. The antiepileptic administered at the dose range of 80-150 mg/kg did not offer protection in more than 50% of mice. This phenomenon cannot be attributed to pharmacokinetic events, because there were no significant differences between plasma and brain concentrations of topiramate after its acute and chronic administration. Topiramate (150 mg/kg) did not affect motor performance in mice.

CONCLUSIONS

Maximal electroshock in mice does not seem to be an appropriate seizure model to test anticonvulsant effects of chronic topiramate.

Topiramate: Effects on cognition in patients with epilepsy, migraine headache and obesity

This paper reviews the clinical implications of topiramate (TPM)-induced cognitive deficits in patients with epilepsy, migraine headache, obesity, and in normal populations, followed by reviews of the literature describing the reversal of such deficits upon medication discontinuation. It also discusses animal investigations of TPM's role of neuroprotection in brain injury. TPM's most intolerable adverse effects (AEs) are on verbal fluency and reaction time, resulting in high discontinuation rates in patients taking it for epilepsy and migraine headache. However, because TPM is so effective in the treatment of epilepsy and migraine headache, its use is expected to continue. There appears to be greater tolerance of TPM's cognitive AEs when it is used in the treatment of obesity, perhaps because of the lower doses required. Research attempting to predict the populations most vulnerable to the cognitive effects caused by TPM is ongoing. Studies suggest that one such population may include patients with a past psychiatric history. Slow titration and administration of the lowest possible doses may decrease risk of cognitive deficits.