Topiramate monotherapy in the treatment of newly or recently diagnosed epilepsy

Treatment with topiramate in rats during childhood causes testicular structural impairment at adulthood

Topiramate (TOP) is a psychotropic drug prescribed for the treatment of epilepsy in children older than 2 years of age and for migraine prophylaxis in adolescents. There is evidence that TOP promotes negative effects on the reproductive system of male rats. This study aimed to evaluate the immediate and late treatment effects of TOP during childhood and adolescence on the male rat reproductive system. Two experimental groups received 41 mg/kg of TOP daily, by gavage, from postnatal day (PND) 16 to 28 (TOPc group) or from PND 28 to 50 (TOPa group). Control groups (CTRc group or CTRa group) received water daily. Half of the anim-als were evaluated 24 h after the end of treatment (PND 29 and PND 51, respectively) and the remainder were evaluated in adulthood (PND120). The following parameters were determined: anogenital distance, sperm evaluation, testis' histomorphometry and plasma testosterone concentration. At PND 120, the volume (CTRc:62.58 ± 2.13; TOPc: 54.54 ± 2.10*%, p = 0.018) and total length (CTRc: 25.48 ± 1.61; TOPc: 18.94 ± 2.41*, p = 0.035) of seminiferous tubules were decreased and the volume of interstitial tissue (CTRc:37.41 ± 2.13; TOPc: 45.45 ± 2.09*%, p = 0.018) and number of Leydig cells/testis (CTRc: 277.00 ± 36.70; TOPc: 400.20 ± 13.23*, p = 0.013) were increased in the TOPc group. The other parameters remained similar between the groups. Therefore, the present study contributes to our understanding that childhood treatment with TOP has an impact on the rat reproductive system in adulthood, suggesting that this period is more sensitive to TOP exposure than adolescence.

Topiramate treatment in Wistar rats during childhood induces sex-specific vascular dysfunction in adulthood

The present study determined whether treatment during childhood with topiramate (TPM), a new generation antiepileptic drug, results in altered aortic reactivity in adult male and female rats. We also sought to understand the role of endothelium-derived contractile factors in TPM-induced vascular dysfunction. Male and female Wistar rats were treated with TPM (41 mg/kg/day) or water (TPM vehicle) by gavage during childhood (postnatal day, 16-28). In adulthood, thoracic aorta reactivity to phenylephrine (phenyl), as well as aortic thickness and expression of cyclooxygenases (COX-1 and COX-2), NOX2, and p47^phox were evaluated. The aortic response to phenyl was increased in male and female rats from the TPM group when compared with the control group. In TPM male rats, the hyperreactivity to phenyl was abrogated by the inhibition of NADPH oxidase and COX-2, while in female rats, responses were restored only by inhibition of COX-2. In addition, TPM male rats presented aortic hypertrophy and increased expression of NOX-2 and p47phox, while TPM female rats showed increased COX-2 aortic expression. Taken together, for the first-time, the present study provides evidence that treatment with TPM during childhood causes vascular dysfunction in adulthood, and that the mechanism underlying the vascular effects of TPM is sex-specific.

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.

Topiramate protects apoE-deficient mice from kidney damage without affecting plasma lipids

Topiramate is an anticonvulsant drug also prescribed for migraine prophylaxis that acts through several mechanisms of action. Several studies indicate that topiramate induces weight loss and a moderate reduction of plasma lipids and glucose. Based on these favourable metabolic effects, aim of this study was to evaluate if topiramate could modulate atherosclerosis development and protect target organs of dysmetabolic conditions. Thirty apoE-deficient mice were divided into three groups and fed for 12 weeks a high fat diet (Control) or the same diet containing topiramate at 0.125% and 0.250%. Body weight, water and food intake were monitored throughout the study. Plasma lipids and glucose levels were measured and a glucose tolerance test was performed. Atherosclerosis development was evaluated in the whole aorta and at the aortic sinus. Histological analysis of liver, kidney and adipose tissue was performed. Topiramate did not affect weight gain and food intake. Glucose tolerance and plasma lipids were not changed and, in turn, atherosclerosis development was not different among groups. Topiramate did not modify liver and adipose tissue histology. Conversely, in the kidneys, the treatment reduced the occurrence of glomerular lipidosis by decreasing foam cells accumulation and reducing the expression of inflammatory markers. Blood urea nitrogen levels were also reduced by treatment. Our results indicate that topiramate does not affect atherosclerosis development, but preserves kidney structure and function. The study suggests that topiramate could be investigated in drug repurposing studies for the treatment of glomerular lipidosis.

Topiramate for Treatment in Patients With Migraine and Epilepsy

BACKGROUND

Antiepileptic drugs (AED) are often considered first line for monotherapy in treatment of patients with migraines, and also those with comorbid migraine and epilepsy. Topiramate, a newer generation AED, has broad mechanism of action and evidence of benefit in patients with either episodic or chronic migraine along with epilepsy, both generalized and focal.

METHODS

Our goal is to review the relevant mechanisms of action along with any supportive evidence published to date on the use of topiramate (TPM) in patients with both migraine headache and epilepsy.

CONCLUSIONS

There has been very little published to date on the use of TPM in patients diagnosed with both disorders. Despite this, TPM has been adopted as first line therapy in this patient population. Future studies investigating the effectiveness of this treatment strategy are warranted in order to determine the most effective use of this medication in patients diagnosed with migraine headaches and epilepsy.

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.

Metabolic disturbances and renal stone promotion on treatment with topiramate: a systematic review

AIMS

The use of topiramate, which is prescribed for the management of epilepsy, for migraine headache prophylaxis and as a weight-loss agent, has been associated with the development of metabolic acidosis, hypokalaemia and renal stone disease. We systematically reviewed all the literature.

METHODS

The systematic review of the literature was realized using the principles underlying the UK Economic and Social Research Council guidance on the conduct of narrative synthesis and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

RESULTS

Fourty-seven reports published between 1996 and 2013 were retained for the final analysis. Five case-control studies and six longitudinal studies addressed the effect of topiramate on acid-base and potassium balance. A significant tendency towards mild-to-moderate hyperchloraemic metabolic acidosis (with bicarbonate ≤21.0 mmol l(-1) in approximately every third case) and mild hypokalaemia (with potassium ≤3.5 mmol l(-1) in 10% of the cases) was noted on treatment with topiramate, which was similar in children and adults. A single study observed that topiramate causes mild hyperuricaemia in male adults. A tendency towards hypocitraturia, a recognized promoter of renal stone formation, was noted in all patients on topiramate.

CONCLUSIONS

Increasing evidence supports the use of topiramate. Topiramate is generally well tolerated, and serious adverse events are rare. Nonetheless, the present systematic review of the literature indicates that its use is linked with the development of acidosis, hypokalaemia, hyperuricaemia and hypocitraturia.

Zonisamide, topiramate, and levetiracetam: efficacy and neuropsychological effects in alcohol use disorders

The anticonvulsant topiramate not only decreases ethanol consumption in alcohol dependence (AD) but also may produce several adverse events including cognitive impairment. Zonisamide is a structurally related anticonvulsant that is a promising agent for the treatment of AD and may have greater tolerability than topiramate. This study evaluated the effects of zonisamide (400 mg/d) on alcohol consumption and its neurotoxic effects in subjects with AD. A double-blind placebo-controlled clinical trial was conducted using 2 comparator anticonvulsant drugs, topiramate (300 mg/d) and levetiracetam (2000 mg/d), which does not impair cognition. Study medications were administered for 14 weeks, including a 2-week taper period. Medication adherence was facilitated using Brief Behavioral Compliance Enhancement Treatment. The neurotoxicity of the study drugs was assessed using neuropsychological tests and the AB-Neurotoxicity Scale. Compared with placebo, both zonisamide and topiramate produced significant reductions in the drinks consumed per day, percent days drinking, and percent days heavy drinking. Only the percent days heavy drinking was significantly decreased in the levetiracetam group. The topiramate cell was the only group that had a significant increase on the mental slowing subscale of the Neurotoxicity Scale compared with placebo at study weeks 11 and 12. Topiramate and zonisamide both produced modest reductions in verbal fluency and working memory. These findings indicate that zonisamide may have efficacy in the treatment of AD, with effect sizes similar to topiramate. Both of these drugs produced similar patterns of cognitive impairment, although only the topiramate group reported significant increases in mental slowing.

Effect of topiramate on interleukin 6 expression in the hippocampus of amygdala-kindled epileptic rats

The objective of this study was to analyze the changes in expression and the possible functions of interleukin-6 (IL-6) in electrical kindling of the basolateral amygdala (BLA) in epileptic rats. Bipolar electrodes were implanted into the BLA of Sprague-Dawley rats, and the rats were then subjected to chronic electrical stimulation through the electrodes to induce kindling. The seizure characteristics and behavioral changes of the rats were observed, and electroencephalograms were recorded during and following kindling. The IL-6 mRNA expression in the hippocampi of the rats was analyzed using semi-quantitative reverse transcription-polymerase chain reaction, and control and topiramate (TPM)-treated groups were compared. The mean time-period required for kindling was 13.50±3.99 days, and the afterdischarge duration (ADD) measured between 21,450 and 119,720 msec. The expression of IL-6 mRNA was significantly upregulated in the kindled rats. TPM was able to depress the seizures and decrease the IL-6 level in the kindled rats. In conclusion, IL-6 mRNA was upregulated in the hippocampi of epileptic rats, and IL-6 may have participated in the process of kindling.

The effects of topiramate and valproate therapy on insulin, c-peptide, leptin, neuropeptide Y, adiponectin, visfatin, and resistin levels in children with epilepsy

PURPOSE

Antiepileptic drugs may affect the endocrine system. We investigated the effects of valproic acid and topiramate on the levels of insulin, c-peptide and adipocytokines in pre-pubertal patients with idiopathic partial and generalized epilepsy.

METHODS

Forty-one children with epilepsy were included. The patients were divided into two groups (valproic acid; n = 21, topiramate; n = 20). The weight, height, body mass index and homeostasis model assessment of insulin resistance (HOMA-IR) were recorded and insulin, c-peptide, leptin, neuropeptide Y, adiponectin, visfatin and resistin levels were determined at 0, 6 and 12 months of therapy.

RESULTS

In the valproate group, weight and height increased significantly. Seven of 21 patients were overweight at the end of one year. Leptin was higher in the overweight subgroup. Although insulin and HOMA-IR increased (p < 0.05), none of the patients showed hyperinsulinism or IR. Resistin had decreased at the 6th and 12th months (p < 0.05). In the topiramate group, some statistically nonsignificant changes were demonstrated.

CONCLUSION

The mechanisms behind valproate and topiramate-related weight control are still unclear, especially in children. Valproate and topiramate affect the weight, BMI, and insulin, leptin and adipocytokine levels in prepubertal children. We suggest that further studies including more patients with a long follow-up period are necessary to draw a firm conclusion regarding an association between the treatment with these drugs and the levels of leptin, insulin and adipocytokines.

Propylisopropylacetic acid (PIA), a constitutional isomer of valproic acid, uncompetitively inhibits arachidonic acid acylation by rat acyl-CoA synthetase 4: a potential drug for bipolar disorder

BACKGROUND

Mood stabilizers used for treating bipolar disorder (BD) selectively downregulate arachidonic acid (AA) turnover (deacylation-reacylation) in brain phospholipids, when given chronically to rats. In vitro studies suggest that one of these, valproic acid (VPA), which is teratogenic, reduces AA turnover by inhibiting the brain long-chain acyl-CoA synthetase (Acsl)4 mediated acylation of AA to AA-CoA. We tested whether non-teratogenic VPA analogues might also inhibit Acsl4 catalyzed acylation, and thus have a potential anti-BD action.

METHODS

Rat Acsl4-flag protein was expressed in Escherichia coli, and the ability of three VPA analogues, propylisopropylacetic acid (PIA), propylisopropylacetamide (PID) and N-methyl-2,2,3,3-tetramethylcyclopropanecarboxamide (MTMCD), and of sodium butyrate, to inhibit conversion of AA to AA-CoA by Acsl4 was quantified using Michaelis-Menten kinetics.

RESULTS

Acsl4-mediated conversion of AA to AA-CoA in vitro was inhibited uncompetitively by PIA, with a Ki of 11.4mM compared to a published Ki of 25mM for VPA, while PID, MTMCD and sodium butyrate had no inhibitory effect.

CONCLUSIONS

PIA's ability to inhibit conversion of AA to AA-CoA by Acsl4 in vitro suggests that, like VPA, PIA may reduce AA turnover in brain phospholipids in unanesthetized rats, and if so, may be effective as a non-teratogenic mood stabilizer in BD patients.

Outcomes of sustained-release formulation of valproate and topiramate monotherapy in patients with epilepsy: a multi-centre, cohort study

BACKGROUND

New-generation antiepileptic drugs (AEDs) tend to replace traditional AEDs as the first-line choice for epilepsy. However, whether this change results in better outcome, especially in China, remains unknown.

METHODOLOGY/PRINCIPAL FINDINGS

Two broad spectrum AEDs, the traditional drug of sustained-release formulation of valproate (SRVPA) and the new-generation drug of topiramate, were compared in patients with epilepsy as monotherapy in this multi-centre, observational cohort study from 2000 to 2011. The primary outcome was time to treatment failure. The secondary outcomes included time to first seizure, time to 12-month remission, and time to 24-month remission. Drug tolerability was assessed. Cox proportional hazard models (95% confidence interval [CI]) were used to analyse the relative risks expressed as hazard ratios (HR). Of the 1008 recruited patients, 519 received SRVPA and 489 received topiramate. SRVPA was better than topiramate (28.3% vs. 41.5%; HR = 0.62, [95% CI 0.49-0.77]; p<0.0001) in primary outcome, and in time to first seizure (56.1% vs. 69.3%; HR = 0.73, [95% CI 0.62-0.86]; p = 0.0002). No significant difference was observed between two groups in time to 12-month remission (52.6% vs. 42.5%; HR = 1.01, [95% CI 0.84-1.23]; p = 0.88) and time to 24-month remission (34.7% vs. 25.2%; HR = 1.11, [95% CI 0.88-1.42]; p = 0.38). 36 patients (6.9%) in SRVPA group and 37 patients (7.6%) in topiramate group presented treatment failure associated with intolerable adverse events, there was no significant difference between the two groups (p = 0.70).

CONCLUSIONS

The SRVPA is more suitable than topiramate for Chinese epileptic patients, and our results support the viewpoint that traditional AEDs should be the first-line choice for epilepsy rather than new-generation AEDs.

Short term outcomes of topiramate monotherapy as a first-line treatment in newly diagnosed West syndrome

Purpose

To investigate the efficacy of topiramate monotherapy in West syndrome prospectively.

Methods

The study population included 28 patients (15 male and 13 female children aged 2 to 18 months) diagnosed with West syndrome. After a 2-week baseline period for documentation of the frequency of spasms, topiramate was initiated at 2 mg/kg/day. The dose was increased by 2 mg/kg every week to a maximum of 12 mg/kg/day. Clinical assessment was based on the parents' report and a neurological examination every 2 weeks for the first 2 months of treatment. The baseline electroencephalograms (EEGs) were compared with the post-treatment EEGs at 2 weeks and 1 month.

Results

West syndrome was considered to be cryptogenic in 7 of the 28 patients and symptomatic in 21 patients. After treatment, 11 patients (39%) became spasm-free, 6 (21%) had more than 50% spasmsreduction, 3 (11%) showed less than 50% reduction, and 8 (29%) did not respond. The effective daily dose for achieving more than 50% reduction in spasm frequency, including becoming spasm-free, was found to be 5.8±1.1 mg/kg/day. Nine patients (32%) showed complete disappearance of spasms and hypsarrhythmia, and 11 (39%) showed improved EEG results. Despite adverse events (4 instances of irritability, 3 of drowsiness, and 1 of decreased feeding), no patients discontinued the medication.

Conclusion

Topiramate monotherapy seems to be effective and well tolerated as a first line therapy for West syndrome and is not associated with serious adverse effects.

Pharmacotherapy for children and adolescents with epilepsy

INTRODUCTION

Childhood epilepsies are the most frequent neurological problems that occur in children. Despite the introduction of new antiepileptic drugs (AEDs) 25-30% of children with epilepsy remain refractory to medical therapy.

AREAS COVERED

This review aims to highlight the main published data on the treatment of childhood epilepsy. The electronic database, PubMed, and abstract proceedings were used to identify studies. The aim of antiepileptic therapy should be to provide complete seizure control, if possible without the burden of any side effect. Since 1993, new agents have been approved for use as an antiepileptic. Although there are few published data (especially in pediatric populations) to establish that the second-generation AEDs are more efficacious than the older AEDs, they appear to have better tolerability.

EXPERT OPINION

Old AEDs are efficacious agents that continue to play a major role in the current treatment of epilepsy. These agents actually remain the first-line treatment for many specific seizure types or epileptic syndromes. The new AEDs were initially approved as adjunct agents and--subsequently--as monotherapy for various seizure types in the adult and children. Despite these improvements, few AEDs are now considered to be a first-choice for the treatment of epilepsy in children.

Chronic impact of topiramate on acid-base balance and potassium in childhood

Topiramate, which is commonly prescribed for seizure disorders and migraine prophylaxis, sometimes causes metabolic acidosis and hypokalemia. Since the effects of topiramate on acid-base balance and potassium levels have not been well explored in children, acid-base balance, anion gap and potassium were assessed in 24 patients (8 females and 16 males) aged between 4.6 and 19 years on topiramate for more than 12 months and in an age-matched control group. Plasma bicarbonate (21.7 versus 23.4 mmol/L; P<0.03), carbon dioxide pressure (39.7 versus 43.2mm Hg; P<0.05), and potassium (3.7 versus 4.0 mmol/L; P<0.03) were on the average lower and chloride (109 versus 107 mmol/L; P<0.03) higher in patients treated with topiramate than in controls. Blood pH, plasma sodium and the anion gap were similar in patients on topiramate and in controls. In patients on topiramate no significant correlation was observed between the dosage of this agent and plasma bicarbonate or potassium as well as between topiramate blood level and the mentioned electrolytes. In conclusion long-term topiramate treatment is associated with a mild, statistically significant tendency towards compensated normal anion gap metabolic acidosis and hypokalemia.

Evidences for pharmacokinetic interaction of riluzole and topiramate with pilocarpine in pilocarpine-induced seizures in rats

In this study we investigated the effectiveness of two antiepileptic drugs: riluzole and topiramate against pilocarpine-induced seizures, which are considered to be a model of intractable epilepsy commonly used to investigate the antiepileptic effect of drugs and mechanisms of epileptogenesis. Seizures and status epilepticus were induced by pilocarpine in adult male Wistar rats. Riluzole (1-4mg/kg) administered intraperitoneally before pilocarpine dose-dependently protected rats against seizures with the anticonvulsant ED(50) value (50% effective anticonvulsant dose) of 1.8 (1.3-2.6)mg/kg. In contrast, riluzole at 8 and 12mg/kg administered after the onset of pilocarpine-induced seizures affected neither status epilepticus nor mortality of rats. Topiramate significantly enhanced convulsive action of pilocarpine, lowering the convulsant CD(50) value (50% effective convulsant dose) of pilocarpine from 350.8 (329.2-373.8) to 246.4 (218.6-278.2)mg/kg. Riluzole (4mg/kg) lowered plasma and brain concentration of pilocarpine administered at a dose of 400mg/kg from 168.0+/-8.6 to 75.3+/-19.9microg/ml and from 193.7+/-6.6 to 97.0+/-26.1microg/g, respectively. Topiramate (200mg/kg) increased plasma and brain concentration of pilocarpine administered at a dose of 300mg/kg from 78.1+/-2.9 to 106.0+/-6.8microg/ml and from 138.4+/-5.0 to 155.2+/-5.1microg/g, respectively. It seems that both anticonvulsant effect exerted by riluzole and proconvulsant effect exerted by topiramate in pilocarpine model of seizures are due to a pharmacokinetic interaction. Therefore, we postulate that the concentration of pilocarpine should be measured routinely whenever the anticonvulsant effect of drugs is determined in the pilocarpine model of seizures.