Structural insights into the allosteric effects of the antiepileptic drug topiramate on the CaV2.3 channel.

The R-type voltage-gated calcium channel CaV2.3 is predominantly located in the presynapse and is implicated in distinct types of epileptic seizures. It has consequently emerged as a molecular target in seizure treatment. Here, we determined the cryo-EM structure of the CaV2.3-α2δ1-ß1 complex in the topiramate-bound state at a 3.0 Å resolution. We provide a snapshot of the binding site of topiramate, a widely prescribed antiepileptic drug, on a voltage-gated ion channel. The binding site is located at an intracellular juxtamembrane hydrophilic cavity. Further structural analysis revealed that topiramate may allosterically facilitate channel inactivation. These findings provide fundamental insights into the mechanism underlying the inhibitory effect of topiramate on CaV and NaV channels, elucidating a previously unseen modulator binding site and thus pointing toward a route for the development of new drugs.

Exposure to topiramate and acetazolamide causes endocrine disrupting effects in female rats during estrus.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a disease characterized by elevated intracranial pressure (ICP) and is a disease of young females. The first line pharmacological treatments include acetazolamide and topiramate and given the nature of IIH patients and the dosing regimen of these drugs, their effect on the endocrine system is important to evaluate. We aimed to assess the effects of acetazolamide and topiramate on steroid profiles in relevant endocrine tissues. METHODS: Female Sprague Dawley rats received chronic clinically equivalent doses of acetazolamide or topiramate by oral gavage and were sacrificed in estrus. Tissue specific steroid profiles of lateral ventricle CP, 4th ventricle CP, CSF, serum, uterine horn and fundus, ovaries, adrenal glands and pituitary glands were assessed by quantitative targeted LC-MS/MS. We determined luteinizing hormone (LH) and follicle stimulating hormones (FSH) levels in paired serum by ELISA. RESULTS: Topiramate increased the concentration of estradiol and decreased the concentration of DHEA in lateral choroid plexus. Moreover, it decreased the concentration of androstenediol in the pituitary gland. Topiramate increased serum LH. Acetazolamide decreased progesterone levels in serum and uterine fundus and increased corticosteroid levels in the adrenal glands. CONCLUSION: These results demonstrate that both acetazolamide and topiramate have endocrine disrupting effects in rats. Topiramate primarily targeted the choroid plexus and the pituitary gland while acetazolamide had broader systemic effects. Furthermore, topiramate predominantly targeted sex hormones, whereas acetazolamide widely affected all classes of hormones. A similar effect in humans has not yet been documented but these concerning findings warrants further investigations.

Mechanisms of neurodevelopmental toxicity of topiramate.

Prescriptions for antiseizure medications (ASMs) have been rapidly growing over the last several decades due, in part, to an expanding list of clinical indications for which they are now prescribed. This trend has raised concern for potential adverse neurodevelopmental outcomes in ASM-exposed pregnancies. Recent large scale population studies have suggested that the use of topiramate (TOPAMAX, Janssen-Cilag), when prescribed for seizure control, migraines, and/or weight management, is associated with an increased risk for autism spectrum disorder (ASD), intellectual disability, and attention-deficit/hyperactivity disorder (ADHD) in exposed offspring. Here, we critically review epidemiologic evidence demonstrating the neurobehavioral teratogenicity of topiramate and speculate on the neuromolecular mechanisms by which prenatal exposure may perturb neurocognitive development. Specifically, we explore the potential role of topiramate's pharmacological interactions with ligand- and voltage-gated ion channels, especially GABAergic signaling, its effects on DNA methylation and histone acetylation, whether topiramate induces oxidative stress, and its association with fetal growth restriction as possible mechanisms contributing to neurodevelopmental toxicity. Resolving this biology will be necessary to reduce the risk of adverse pregnancy outcomes caused by topiramate or other ASMs.

Ameliorative Effect of Cannabidiol on Topiramate-Induced Memory Loss: The Role of Hippocampal and Prefrontal Cortical NMDA Receptors and CREB/BDNF Signaling Pathways in Rats.

Cannabidiol (CBD) is a promising neurological agent with potential beneficial effects on memory and cognitive function. The combination of CBD and topiramate in the treatment of some neurological diseases has been of great interest. Since Topiramate-induced memory loss is a major drawback of its clinical application and the overall effect of the combination of CBD and topiramate on memory is still unclear, here we investigated the effect of CBD on topiramate-induced memory loss and the underlying molecular mechanisms. A one trial step-through inhibitory test was used to evaluate memory consolidation in rats. Moreover, the role of N-methyl-D-aspartate receptors (NMDARs) in the combination of CBD and topiramate in memory consolidation was evaluated through the intra-CA1 administration of MK-801 and NMDA. Western blot analysis was used to evaluate variations in brain-derived neurotrophic factor (BDNF) and phosphorylated cyclic AMP response element-binding protein (pCREB)/CREB ratio in the prefrontal cortex (PFC) and hippocampus (HPC). While the intraperitoneal (i.p.) administration of topiramate (50, 75, and 100 mg/kg) significantly reduced inhibitory time latency, the i.p. administration of CBD (20 and 40 mg/kg) could effectively reverse these effects. Similarly, the sub-effective doses of NMDA plus CBD (10 mg/kg) could improve the topiramate-induced memory loss along with an enhancement in BDNF and pCREB expression in the PFC and HPC. Contrarily, the administration of sub-effective doses of the NMDAR antagonist (MK-801) diminished the protective effects of CBD (20 mg/kg) on topiramate-induced memory loss associated with decreased BDNF and pCREB levels in the PFC and HPC. These findings suggest that CBD can improve topiramate-induced memory impairment, partially by the NMDARs of the PFC and HPC, possibly regulated by the CREB/BDNF signaling pathway.

Topiramate use in a pediatric patient with comorbid bipolar disorder and trichotillomania: A 3-year follow-up.

Trichotillomania (TTM) is an intractable and chronic mental disorder that causes significant distress or functional impairments in various life domains. Most individuals with trichotillomania have other comorbid diagnoses. Bipolar disorder (BD) is one of the most common comorbid conditions. Up to date, no FDA-approved drugs for TTM are available, not to mention children and adolescent patients with TTM and BD. Here, we present a case of an 8-year-old child with a long history of episodic TTM and bipolar disorder who was effectively treated with topiramate in a 3-year follow-up.

Acupuncture plus topiramate placebo versus topiramate plus sham acupuncture for the preventive treatment of chronic migraine: A single-blind, double-dummy, randomized controlled trial.

BACKGROUND: Acupuncture has been used for the treatment of chronic migraine, but high-quality evidence is scarce. We aimed to evaluate acupuncture's efficacy and safety compared to topiramate for chronic migraine. METHODS: This double-dummy randomized controlled trial included participants aged 18-65 years diagnosed with chronic migraine. They were randomly assigned (1:1) to receive acupuncture (three sessions/week) plus topiramate placebo (acupuncture group) or topiramate (50-100 mg/day) plus sham acupuncture (topiramate group) over 12 weeks, with the primary outcome being the mean change in monthly migraine days during weeks 1-12. RESULTS: Of 123 screened patients, 60 (mean age 45.8, 81.7% female) were randomly assigned to acupuncture or topiramate groups. Acupuncture demonstrated significantly greater reductions in monthly migraine days than topiramate (weeks 1-12: -2.79 [95% CI: -4.65 to -0.94, p = 0.004]; weeks 13-24: -3.25 [95% CI: -5.57 to -0.92, p = 0.007]). No severe adverse events were reported. CONCLUSIONS: Acupuncture may be safe and effective for treating chronic migraine. The efficacy of 12 weeks of acupuncture was sustained for 24 weeks and superior to that of topiramate. Acupuncture can be used as an optional preventive therapy for chronic migraine. TRIAL REGISTRATION: ISRCTN.org Identifier 13563102.

Anticonvulsants in the Treatment of Behavioral and Psychological Symptoms in Dementia: A Systematic Review.

OBJECTIVES: Behavioral and psychological symptoms of dementia (BPSD) are common and impart a significant burden to patients, caregivers, and the health system. However, there are few pharmacological options for treating BPSD. We conducted a systematic review of clinical trials examining the efficacy of anticonvulsants in BPSD. METHODS: We searched five electronic databases through January 2023, for randomized controlled trials and systematic reviews evaluating the efficacy of non-benzodiazepine anticonvulsants for the treatment of BPSD. We used the Cochrane risk of bias tool to ascertain the risk of bias in included trials. Because statistical pooling of results using meta-analysis was not feasible, we synthesized findings using the Cochrane Synthesis Without Meta-analysis reporting guidelines. RESULTS: We identified 12 studies, including randomized controlled trials (RCTs) and 1 systematic review. Five RCTs evaluating valproic acid were synthesized by a recent Cochrane review which concluded that this drug is likely ineffective for BPSD. We extracted data from 6 trials involving 248 individuals comparing non-benzodiazepine anticonvulsants to either placebo or risperidone. Four trials (n = 97 participants) evaluated carbamazepine, only one of which demonstrated an improvement in the Brief Psychiatric Rating Scale measuring agitation, hostility, psychosis, and withdrawal/depression (effect size: 1.13; 95% confidence interval [CI]: 0.54-1.73) relative to placebo. Adverse effects were more common in patients receiving carbamazepine (20/27; 74%) relative to placebo (5/24; 21%). There is low quality evidence that oxcarbazepine is likely ineffective and that topiramate may be comparable to risperidone. CONCLUSION: Anticonvulsants are unlikely to be effective in BPSD, although the quality of existing evidence is low.

Efficacy of topiramate in reducing second-generation antipsychotic-associated weight gain among children: A systematic review and meta-analysis.

AIMS: To conduct a systematic review and meta-analysis with the aim of synthesizing existing data on the efficacy and safety of topiramate as an adjunctive treatment for reducing second-generation antipsychotic (SGA)-associated weight gain in children aged 4-18 years. METHODS: We conducted a comprehensive search of PubMed, Embase, PsychNet and Web of Science from time of their inception up to 12 February 2024, including randomized controlled trials that compared SGA treatment with and without topiramate co-administration in children. The primary outcomes were changes in body weight and body mass index (BMI). Heterogeneity was assessed using I2 statistics. RESULTS: This systematic review included five randomized trials, totalling 139 participants (43.9% female; mean [SD] age 11.9 [3.5] years). Four of these trials were included in the meta-analysis, comprising 116 subjects. We found that topiramate was significantly effective both in reducing SGA-associated weight gain, with a mean difference of -2.80 kg (95% confidence interval [CI] -5.28 to -0.31; p = 0.037, I2 = 86.7%) and a standardized mean difference (SMD) of -1.33 (95% CI -2.14 to -0.51; p = 0.014, I2 = 31.7%), and in reducing BMI change compared to placebo (SMD -1.90, 95% CI -3.09 to -0.70; p = 0.02, I2 = 0%). Sedation risk was lower with topiramate than with placebo (odds ratio 0.19, 95% CI 0.11-0.32; p < 0.01, I2 = 0%). No significant differences were found in dropouts, any other side effects, and metabolic parameters, such as triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein, and glucose. None of the included studies reported assessments on cognitive side effects. CONCLUSION: This meta-analysis suggests that topiramate is an effective and safe option for mitigating SGA-associated weight gain in children.

Comparison of neuroprotective effects of a topiramate-loaded biocomposite based on mesoporous silica nanoparticles with pure topiramate against methylphenidate-induced neurodegeneration.

BACKGROUND: Methylphenidate (MPH) abuse has been criticized for its role in neurodegeneration. Also, a high risk of seizure was reported in the first month of MPH treatment. Topiramate, a broad-spectrum Antiepileptic Drug (AED), has been used as a neuroprotective agent in both aforementioned complications. Nanotechnology is introduced to increase desirable neurological treatment with minimum side effects. We aimed to investigate the potential neuroprotective activity of topiramate loaded on nanoparticles. METHODS AND RESULTS: MTT assay was performed to evaluate the cellular cytotoxicity of Mesoporous Silica Nanoparticles (MSN). Male rats were randomly divided into eight groups. Rats received an intraperitoneal (i.p) MPH (10 mg/kg) injection and a daily oral dose of topiramate (TPM, 30 mg/kg), MSN with Zn core (10 and 30 mg/kg), and MSN with Cu core (10 and 30 mg/kg) for three weeks. On day 21, a seizure was induced by a single injection of pentylenetetrazole (PTZ) to evaluate the protective effects of TPM-loaded nanoparticles on seizure latency and duration following MPH-induced neurotoxicity. Moreover, the hippocampal content of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), malondialdehyde (MDA), and the anti-oxidant enzymes (SOD, GPx, and GR) activities were assessed. Also, BAX and Bcl-2 as two main apoptotic markers were evaluated. RESULTS: MPH neurotoxicity was observed as a raised duration and reduced latency in PTZ-induced seizure. However, TPM-loaded MSN with Zn species (NE) treatment reduced the duration and improved the latency time. Also, NE and, somewhat, TPM-loaded MSN with Cu species (NM) administration reduced inflammatory cytokines, MDA, and Bax levels and increased activities in the rat hippocampus. CONCLUSION: TPM-loaded nanoparticles could be used as neuroprotective agents against MPH-induced neurodegeneration by improving seizure parameters and reducing inflammatory, oxidant, and apoptotic factors.

Safety and tolerability of topiramate and N-acetyl cysteine combination in individuals with alcohol use disorder: a 12 week, randomized, double-blind, pilot study.

Topiramate (TPM), a GABA/glutamate modulator, has shown positive results for treating alcohol use disorder (AUD), but causes significant cognitive adverse effects. TPM causes cognitive side effects by reducing glutathione levels in the frontal lobe. N-acetyl cysteine (NAC) increases level of intracellular glutathione. We hypothesized that combining NAC with TPM may mitigate the possible cognitive side effects of TPM, as well as working synergistically in reducing alcohol consumption more efficaciously than using TPM alone. A 12-week, double-blind randomized trial assessing the effects of combining NAC (1200 mg/day) with TPM (200 mg/day) vs TPM alone (i) cognitive side effects caused by TPM, (ii) percentage of heavy drinking days (PHDD) and percentage of days abstinent (PDA) using weekly calendar, and (iii) craving outcomes using the obsessive-compulsive drinking scale. Seventeen participants were randomized into the study (nine received TPM + NAC and eight matching TPM + Placebo). Cognitive adverse events were not significantly different between the treatment arms (P = 0.581). There was no difference in PHDD (P = 0.536) and in PDA over the entire study period (P = 0.892). However, both treatment groups at study end, compared with the baseline, significantly reduced their PHDD and increased their PDA. As for cravings: TPM + NAC group has shown higher level in automaticity of drinking (P = 0.029) and interference due to drinking (P = 0.014) subscales compared with the TPM + Placebo group. No difference was observed between groups in terms of Drinking Obsessions and Alcohol Consumption subscales. This pilot study indicates that combining NAC with TPM is overall safe, but the addition of NAC has no significant benefit over placebo in the incidence of TPM-related cognitive impairment, and alcohol drinking. Furthermore, craving outcomes may become worse with the addition of NAC.

Botulinum neurotoxin as early treatment in acute-onset lesional hemiballism.

BACKGROUND: Hemiballism (HB) and hemichorea (HC) are the most frequent secondary movement disorders, usually caused by cerebrovascular diseases. In only a minority of cases, these involuntary movements are not self-limited, and they may severely compromise patients' quality of life, so that symptomatic treatments are required. Typical and atypical neuroleptics as well as tetrabenazine are considered therapies of choice. However, anecdotal reports of antiseizures medications and botulinum neurotoxin injection effectiveness have been described. METHODS: We described a case of severely disabling acute-onset lesional HB/HC, where high dosage of first- and second-line therapies was contraindicated due to patient's comorbidities. RESULTS: After botulin neurotoxin (BoNT) injections in his left upper limb muscles (biceps brachii, triceps brachii, teres major, and deltoid), the patient experienced gradual reduction of hyperkinetic movements. The gradual discontinuation of topiramate (TPM) did not worsen the clinical picture. DISCUSSION: The reduction of hyperkinetic movements led to rhabdomyolysis resolution as well as cutaneous injuries healing with renal function improvement, so that the patient was able to be eligible for rehabilitation, which was prevented by HB/HC itself. The clinical improvement was consistent with BoNT pharmacokinetic. The administration of BoNT early after the onset of lesional HB/HC remarkably modified the clinical management and drove toward comorbidities resolution and rehabilitation. CONCLUSION: The present case highlights the effectiveness of unconventional therapeutic options in disabling acute onset lesional HB/HC when first-line therapies are contraindicated. Particularly, this report may encourage BoNT application in the early stage of movement disorder emergencies.

Caffeine Decreases Topiramate Levels in Zebrafish Larvae in a Pentylenetetrazol-Induced Seizure Model.

Epilepsy ranks as the second-most prevalent neurological disease, and is characterized by seizures resulting in neurobiological and behavioral impairment. Naturally occurring in coffee beans or tea leaves, the alkaloid caffeine (CAF) is the most prevalent global stimulant. Caffeine has been observed to influence epileptic seizures and the efficacy of antiepileptic medications, with a notable impact on topiramate (TPM). This study aimed to explore the influence of CAF on TPM's anticonvulsant effects in zebrafish larvae within a PTZ-induced seizure model, concurrently determining TPM concentrations through a sophisticated analytical approach based on ultrahigh-performance liquid chromatography and subsequent mass spectrometric detection. Zebrafish larvae four days post-fertilization were incubated for 18 h with varying doses of TPM or combinations of CAF + TPM, and locomotor activity was then assessed. Seizures were induced by introducing a PTZ solution to achieve a final concentration of 20 mM. Utilizing liquid chromatography-mass spectrometry (LC-MS/MS), TPM levels in the larvae were quantified. CAF co-administration (especially in higher doses) with TPM caused a decrease in the average locomotor activity in the larvae compared to TPM alone. Moreover, CAF decreased TPM levels in the larvae at all investigated doses. In conclusion, these findings offer a novel perspective on the interplay between CAF and TPM, shedding light on previously unexplored facets. The potential impact of CAF consumption in assisting with epileptic seizure control, unless proven otherwise, suggests a noteworthy consideration for future research and clinical practices.

Is erenumab an efficient alternative for the prevention of episodic and chronic migraine in Spain? Results of a cost-effectiveness analysis.

BACKGROUND: The reimbursement of erenumab in Spain and other European countries is currently restricted because of the cost of this novel therapy to patients with migraine who have experienced previous failures to traditional preventive treatments. However, this reimbursement policy should be preferably based on cost-effectiveness studies, among other criteria. This study performed a cost-effectiveness analysis of erenumab versus topiramate for the prophylactic treatment of episodic migraine (EM) and versus placebo for chronic migraine (CM). METHODS: A Markov model with a 10-year time horizon, from the perspective of the Spanish National Healthcare System, was constructed based on data from responder and non-responder patients. A responder was defined as having a minimum 50% reduction in the number of monthly migraine days (MMD). A hypothetical cohort of patients with EM with one or more prior preventive treatment failures and patients with CM with more than two treatment failures was considered. The effectiveness score was measured as an incremental cost per quality-adjusted life year (QALY) gained and cost per migraine day (MD) avoided. Data from clinical outcomes and patient characteristics were obtained from erenumab clinical trials (NCT02066415, STRIVE, ARISE, LIBERTY and HER-MES). Deterministic and probabilistic sensitivity analyses were performed to validate the robustness of the model. RESULTS: After a 10-year follow-up, the estimated QALYs were 5.88 and 6.11 for patients with EM treated with topiramate and erenumab, respectively. Erenumab showed an incremental cost per patient of €4,420 vs topiramate. For CM patients, erenumab resulted in 0.756 QALYs gained vs placebo; and an incremental cost of €1,814. Patients treated with erenumab achieved reductions in MD for both EM and CM (172 and 568 MDs, respectively). The incremental cost per QALY gained with erenumab was below the Spanish threshold of €30,000/QALY for both health and societal perspectives (EM €19,122/QALY and CM €2,398/QALY). CONCLUSIONS: Erenumab is cost-effective versus topiramate as a preventive treatment for EM and versus placebo for patients with CM from the perspective of the Spanish National Health System.

Impact of maternal topiramate ingestion on ossification of skull and appendicular bones in rat fetuses.

The skull and appendicular bones are derived from different embryological sources during their development. The impact of prenatal exposure of topiramate on ossification of these bones is not adequately studied. The goal of this study was to assess the ossification patterns of the craniofacial bones and bones of the forelimbs and hindlimbs in 20-day-old rat fetuses after maternal exposure to topiramate at doses equivalent to human therapeutic doses. Three groups of Sprague-Dawley pregnant rats were used: control, topiramate 50mg/kg/day (T50) and topiramate 100mg/kg/day (T100). Topiramate was given by oral gavage from day 6 to day19 of gestation. Ossification was evaluated in the bones of 20 days fetuses after staining with Alizarin red. Results showed a significant reduction in complete ossified centers of the metacarpal, metatarsal and craniofacial bones in topiramate-exposed fetuses at both doses when compared to the control group. Also, a significant decrease in the length of ossified part of the long bones of the forelimbs and hindlimbs in topiramate-exposed fetuses at both doses was noted when compared to the control group. Crown-rump length and fetal weight were significantly decreased in topiramate treated groups compared to the control group. In all examined groups, there was a positive correlation between the crown-rump length and the lengths of humerus and femur. No abnormalities in the ossified bones and no significant changes in their ossification pattern were observed between the treated groups. In conclusion, prenatal administration of topiramate in doses equivalent to human therapeutic doses delayed ossification and development of craniofacial and appendicular bones in rat fetuses and their effects are not dose dependent at doses investigated. The implications of these findings in women who require topiramate therapy in pregnancy merit further evaluation.

Genome-wide DNA methylation analysis in an antimigraine-treated preclinical model of cortical spreading depolarization.

BACKGROUND: Cortical spreading depolarization, the cause of migraine aura, is a short-lasting depolarization wave that moves across the brain cortex, transiently suppressing neuronal activity. Prophylactic treatments for migraine, such as topiramate or valproate, reduce the number of cortical spreading depression events in rodents. OBJECTIVE: To investigate whether cortical spreading depolarization with and without chronic treatment with topiramate or valproate affect the DNA methylation of the cortex. METHODS: Sprague-Dawley rats were intraperitoneally injected with saline, topiramate or valproate for four weeks when cortical spreading depolarization were induced and genome-wide DNA methylation was performed in the cortex of six rats per group. RESULTS: The DNA methylation profile of the cortex was significantly modified after cortical spreading depolarization, with and without topiramate or valproate. Interestingly, topiramate reduced by almost 50% the number of differentially methylated regions, whereas valproate increased them by 17%, when comparing to the non-treated group after cortical spreading depolarization induction. The majority of the differentially methylated regions lay within intragenic regions, and the analyses of functional group over-representation retrieved several enriched functions, including functions related to protein processing in the cortical spreading depolarization without treatment group; functions related to metabolic processes in the cortical spreading depolarization with topiramate group; and functions related to synapse and ErbB, MAPK or retrograde endocannabinoid signaling in the cortical spreading depolarization with valproate group. CONCLUSIONS: Our results may provide insights into the underlying physiological mechanisms of migraine with aura and emphasize the role of epigenetics in migraine susceptibility.

Impact on Cardiovascular Health of Using Phentermine/Topiramate in Combination With Laparoscopic Sleeve Gastrectomy in Super Obesity.

INTRODUCTION: Management of patients with BMI≥50 kg/m2 is challenging. In previous work, pre and postoperative pharmacotherapy with phentermine/topiramate plus laparoscopic sleeve gastrectomy (PT + SG) promoted greater weight loss than sleeve gastrectomy (SG) alone at 24 mo postoperatively. This current secondary analysis studied the impact of PT + SG on blood pressure (BP), heart rate, and antihypertensive usage. METHODS: Patients with BMI≥50 kg/m2 planning to have SG (n = 13) were recruited from 2014 to 2016, at an academic medical center in Winston-Salem, North Carolina, for this open-label trial. Participants took phentermine/topiramate (PT; 7.5/46-15/92 mg/d) for ≥3 mo preoperatively and 24 mo postoperatively. The control group (n = 40) underwent SG during the same time frame. We used mixed models for BP and heart rate to compare PT + SG versus SG alone over time, adjusted for age, sex, and initial BP. RESULTS: By 24 mo postoperatively the model adjusted changes in systolic blood pressure/diastolic blood pressure (SBP/DBP) (mm Hg) were -24.44 (-34.46,-14.43)/-28.60 (-40.74,-16.46) in the PT + SG group versus -11.81 (-17.58,-6.05)/-13.89 (-21.32,-6.46) in the control group (SBP P = 0.02; DBP P = 0.03). At baseline 8 (61.5%) participants in the PT + SG arm and 22 (55.0%) in the control group used antihypertensives. Excluding patients lost to follow-up (n = 3), by 24 mo postoperatively, none of the PT + SG participants were on antihypertensives compared to 14 (41.2%) in the control group (P = 0.01). CONCLUSIONS: Patients with BMI≥50 kg/m2 treated with PT + SG had greater improvement in BP with no use of antihypertensive medication at 24 mo postoperatively versus SG alone, where 41% continued medication use. Larger trials are required to evaluate this.

An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS)-based candidate reference measurement procedure for the quantification of topiramate in human serum and plasma.

OBJECTIVES: Topiramate is an antiepileptic drug (AED) used for the monotherapy or adjunctive treatment of epilepsy and for the prophylaxis of migraine. It has several pharmacodynamic properties that contribute to both its clinically useful properties and observed adverse effects. Accurate measurement of its concentration is therefore essential for dose adjustment/optimisation of AED therapy. Our aim was to develop and validate a novel reference measurement procedure (RMP) for the quantification of topiramate in human serum and plasma. METHODS: An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method in combination with a protein-precipitation-based sample preparation allows for quantification of topiramate in human serum and plasma. To assure traceability to SI units, quantitative nuclear magnetic resonance (qNMR) was applied to characterize the reference material used as primary calibrator for this RMP. Matrix effects were determined by performing a post-column infusion experiment and comparing standard line slopes. Accuracy and precision was evaluated performing an extensive five day precision experiment and measurement uncertainty was evaluated according Guide to the Expression of Uncertainty in Measurement (GUM). RESULTS: The method enabled topiramate quantification within the range of 1.20-36.0 µg/mL without interference from structurally related compounds and no evidence of a matrix effect. Intermediate precision was ≤3.2 % and repeatability was 1.4-2.5 % across all concentration levels. The relative mean bias was -0.3 to 3.5 %. Expanded measurement uncertainties for target value assignment (n=6) were found to be ≤2.9 % (k=2) independent of the concentration level and the nature of the sample. CONCLUSIONS: In human serum and plasma, the RMP demonstrated high analytical performance for topiramate quantification and fulfilled the requirements on measurement uncertainty. Traceability to SI units was established by qNMR content determination of the topiramate, which was used for direct calibration of the RMP. This RMP is, therefore, fit for purpose for routine assay standardization and clinical sample evaluation.

Intravenous topiramate for seizure emergencies - First in human case report.

Topiramate (TPM) is widely used in focal and generalized epilepsies. It is commercially available as tablets and sprinkles capsules for oral treatment. Previous studies comparing intravenous (IV) to oral TPM in healthy adults showed more rapid pharmacodynamic effects in cases of IV administration. Despite promising findings, no clinical application in humans followed. We present a case of a pregnant woman with idiopathic generalized epilepsy who experienced a generalized tonic-clonic seizure in the third trimenon due to low TPM levels attributed to pregnancy followed by repeated prolonged absences. We applied a new meglumine-based solution (1%) of TPM (10 mg/ml) in two IV infusions of 200 mg each under EEG monitoring over a total duration of 1 hour. The infusion was well tolerated and led to a rapid increase in plasma TPM levels. A clinical as well as electroencephalographic improvement was documented within the first hours. To the best available knowledge, this is the first reported case where IV TPM was used therapeutically for seizure treatment in humans. It is also the first time that the new meglumine-based solution was used in a human with epilepsy. The advantages of IV route delivery and the solution's quick preparation, high tolerability, and low toxicity make it ideal for use in many clinical settings and high-care patients. IV TPM seems to be a reasonable adjunctive option for adults with seizures, previously stabilized on oral TPM, who need rapid plasma concentration boosting. Although our experience was successful in using injectable TPM in seizure emergencies, randomized controlled clinical trials are required to make recommendations for the use of IV TPM on patients with epilepsy. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022 in Salzburg, Austria.

Changes over 24 years in a pregnancy register - Teratogenicity and epileptic seizure control.

OBJECTIVES: To trace (i) changes in Australian Pregnancy Register (APR) records concerning antiseizure medications (ASMs) prescribed for women with epilepsy (WWE) over the course of 24 years and correlate the changes with (ii) rates of occurrence of pregnancies involving foetal malformations, (iii) the body organs involved in the malformations, and (iv) freedom from epileptic seizures. RESULTS: Use of valproate and carbamazepine decreased progressively, use of lamotrigine remained relatively static, and the use of levetiracetam increased progressively, whereas the use of topiramate first increased and then fell again, associated with a temporary increase in malformation-associated pregnancy rate. More serious malformations, such as spina bifida, became less frequent, whereas more trivial ones tended to increase, whereas epileptic seizure freedom rates improved. CONCLUSIONS: The increasing use of newer ASMs in pregnant women has been associated with overall advantages in relation to the frequency and severity of foetal malformation and with advantages in relation to freedom from epileptic seizures.

Population pharmacokinetics of topiramate in Chinese children with epilepsy.

OBJECTIVE: Topiramate, a broad-spectrum antiepileptic drug, exhibits substantial inter-individual variability in both its pharmacokinetics and therapeutic response. The aim of this study was to investigate the influence of patient characteristics and genetic variants on topiramate clearance using population pharmacokinetic (PPK) models in a cohort of Chinese pediatric patients with epilepsy. METHOD: The PPK model was constructed using a nonlinear mixed-effects modeling approach, utilizing a dataset comprising 236 plasma concentrations of topiramate obtained from 181 pediatric patients with epilepsy. A one-compartment model combined with a proportional residual model was employed to characterize the pharmacokinetics of topiramate. Covariate analysis was performed using forward addition and backward elimination to assess the influence of covariates on the model parameters. The model was thoroughly evaluated through goodness-of-fit analysis, bootstrap, visual predictive checks, and normalized prediction distribution errors. Monte Carlo simulations were utilized to devise topiramate dosing strategies. RESULT: In the final PPK models of topiramate, body weight, co-administration with oxcarbazepine, and a combined genotype of GKIR1-UGT (GRIK1 rs2832407, UGT2B7 rs7439366, and UGT1A1 rs4148324) were identified as significant covariates affecting the clearance (CL). The clearance was estimated using the formulas CL (L/h) = 0.44 × (BW/11.7)0.82 × eOXC for the model without genetic variants and CL (L/h) = 0.49 × (BW/11.7)0.81 × eOXC × eGRIK1-UGT for the model incorporating genetic variants. The volume of distribution (Vd) was estimated using the formulas Vd (L) = 6.6 × (BW/11.7). The precision of all estimated parameters was acceptable. Furthermore, the model demonstrated good predictability, exhibiting stability and effectiveness in describing the pharmacokinetics of topiramate. CONCLUSION: The clearance of topiramate in pediatric patients with epilepsy may be subject to the influence of factors such as body weight, co-administration with oxcarbazepine, and genetic polymorphism. In this study, PPK models were developed to better understand and account for these factors, thereby improving the precision and individualization of topiramate therapy in children with epilepsy.