Molecular pharmacodynamics, clinical therapeutics, and pharmacokinetics of topiramate

Using oral topiramate for primary generalized and focal-to-bilateral tonic-clonic seizures in patients 2 years of age and older: a review of the literature

INTRODUCTION

Topiramate is a drug belonging to the second generation of antiseizure arsenal, used to treat focal onset seizures without generalization, focal-to-bilateral tonic-clonic seizures, and primary generalized tonic-clonic seizures.

AREAS COVERED

The narrative evaluation of topiramate's clinical research that has been published in this article focuses on the medication's effectiveness and safety when used to treat primary generalized and focal-to-bilateral tonic-clonic seizures. From their founding to the present, the databases MEDLINE, SCOPUS, EBSCO, and GOOGLE SCHOLAR were searched.

EXPERT OPINION

Topiramate treatment has the obvious benefit of being effective in treating tonic-clonic seizures; nevertheless, it may have a drawback in that up to 56% of patients discontinue therapy due to its rather poor tolerability, particularly at doses exceeding 600 mg daily. Patients are most bothered by psychiatric and cognitive side effects, and then by appetite and weight decrease. While the onset of anorexia cannot be prevented by changing the dosage regimen, psychiatric and cognitive side effects can be mitigated by slowly titrating the topiramate dose.

Neuroprotective potential of topiramate, pregabalin and lacosamide combination in a rat model of acute SE and intractable epilepsy: Perspectives from electroencephalographic, neurobehavioral and regional degenerative analysis

The lithium-pilocarpine model is commonly used to recapitulate characteristics of human intractable focal epilepsy. In the current study, we explored the impact of topiramate (TPM) alone and in combination with pregabalin and lacosamide administration for 6 weeks on the evolution of spontaneous recurrent seizures (SRS) and disease-modifying potential on associated neuropsychiatric comorbidities. In addition, redox impairments and neurodegeneration in hippocampus regions vulnerable to temporal lobe epilepsy (TLE) were assessed by cresyl violet staining. Results revealed that acute electrophysiological (EEG) profiling of the ASD cocktail markedly halted sharp ictogenic spikes as well as altered dynamics of brain wave oscillations thus validating the need for polytherapy vs. monotherapy. In TLE animals, pharmacological intervention for 6 weeks with topiramate 10 mg/kg in combination with PREG and LAC at the dose of 20 mg/kg exhibited marked protection from SRS incidence, improved body weight, offensive aggression, anxiety-like behavior, cognitive impairments, and depressive-like behavior (p < 0.05). Moreover, combination therapy impeded redox impairments as evidenced by decreased MDA and AchE levels and increased activity of antioxidant SOD, GSH enzymes. Furthermore, polytherapy rescued animals from SE-induced neurodegeneration with increased neuronal density in CA1, CA3c, CA3ab, hilus, and granular cell layer (GCL) of the dentate gyrus. In conclusion, early polytherapy with topiramate in combination with pregabalin and lacosamide prompted synergy and prevented epileptogenesis with associated psychological and neuropathologic alterations.

Topiramate's effects on normal and fatty liver

Topiramate (TPM), a carbonic anhydrase (CA) inhibitor, is known for its anti-obesity effect. Even though, nonalcoholic fatty liver disease (NAFLD) is present in 80% of obese patients, TPM's effects on oxidant-antioxidant parameters and CA activity on fatty liver is not known. 24 Wistar albino rats were divided into four groups: control, TPM, diet, and diet + TPM. Diet groups fed with high-fat diet while control and TPM groups received standard chow for six weeks. Than 100 mg/kg/day TPM (po) was added to TPM groups for 21 days. Rats' weight and blood glucose levels were monitored weekly, and at the end of the study liver removed for biochemical and histological analysis. TPM eliminated the increases in weight and blood glucose levels caused by high-fat diet. TPM decreased CA activity in all groups. MDA levels increased significantly in TPM and DT groups (p = 0.004; p = 0.008). GSH levels were decreased in the TPM, D and DT groups (p = 0.004; p = 0.015; p = 0.003). Similarly, GPx activity levels were significantly decreased in all groups. Histological evaluation revealed notable infiltration, eosinophilia and cytoplasmic vacuolization in the TPM group. Steatosis and NAFLD activity score (NAS) were higher in the diet group. Ballooning, infiltration and NAS were higher in the diet + TPM group compared to control. CA activity negatively correlated with MDA (p < 0.001), and positively correlated with GSH (p < 0.001). TPM caused oxidant stress and liver damage, which are exacerbated in NAFLD induced rats. Therefore, use of TPM in patients with liver disease should be considered very carefully.

Three Patients of the Early Onset Epileptic Spasms without Hypsarrhythmia

Epileptic spasms without hypsarrhythmia occur when patients do not display hypsarrhythmia on electroencephalogram (EEG) at the onset and throughout the clinical course. We report three patients of epileptic spasms in patients with early onset, all of whom experienced other types of seizures.We detail three patients (two boys and one girl) of epileptic spasms without hypsarrhythmia, occurring between 1 and 3 months of age, with no abnormalities detected on neurometabolic analysis and brain magnetic resonance imaging. Long-term video-EEG monitoring revealed epileptic spasms with focal onset seizures in two patients, and epileptic spasms followed by generalized tonic-clonic seizures in one patient. Hypsarrhythmia was never observed in repeated EEG examinations. Two patients achieved seizure freedom and improved development through treatment with topiramate alone or in combination with valproate, without requiring hormonal therapies or vigabatrin. The remaining patient achieved seizure freedom following administration of antiseizure medications, including topiramate, after a trial of adrenocorticotropic hormone therapy.We report the cases of three patients with early onset epileptic spasms without hypsarrhythmia. All patients achieved seizure freedom after topiramate treatment. Topiramate may be considered as a relatively effective antiseizure medication for early onset epileptic spasms without hypsarrhythmia.

Research Status, Synthesis and Clinical Application of Antiepileptic Drugs

According to the 2017 ILAE's official definition, epilepsy is a slow brain disease state characterized by recurrent episodes. Due to information released by ILAE in 2017, it can be divided into four types, including focal epilepsy, generalized epilepsy, combined generalized, and focal epilepsy, and unknown epilepsy. Since 1989, 24 new antiepileptic drugs have been approved to treat different types of epilepsy. Besides, there are a variety of antiepileptic medications under clinical monitoring. These novel antiepileptic drugs have plenty of advantages. Over the past 33 years, there have been many antiepileptic drugs on the mearket, but no one has been found that can completely cure epilepsy. In this paper, the mentioned drugs were classified according to their targets, and the essential information, and clinical studies of each drug were described. The structure-activity relationship of different chemical structures was summarized. This paper provides help for the follow-up research on epilepsy drugs.

Population Pharmacokinetics of Topiramate in Patients with Epilepsy Using Nonparametric Modeling

BACKGROUND

Topiramate (TPM) is used for the treatment of various epileptic seizures and the prevention of migraine. This study aimed to develop a population pharmacokinetic model and identify covariates that influence TPM behavior in patients with epilepsy in Kuwait.

METHODS

Data were collected retrospectively from 108 patients (2 years old and above) with epilepsy who were treated with oral TPM and 174 TPM blood samples from 3 hospitals in Kuwait from 2009 to 2016. Data were randomly divided into 2 groups for model development and validation. The population pharmacokinetic model was built using the nonparametric modeling algorithm (Pmetrics). The model was evaluated internally through the visual predictive check method and externally using a new data set.

RESULTS

A 1-compartment model with first-order elimination fitted the data well. Covariates showing a significant effect on the elimination rate constant were renal function and coadministration of carbamazepine (CBZ). The mean estimated clearance was 2.11 L/h; this was 50% higher for patients coadministered with CBZ. Age and sex were essential covariates for the volume of distribution (V). The visual predictive check of the final model could predict the measured concentrations. External validation further confirmed the favorable predictive performance of the model with low bias and imprecision for predicting the concentration in a particular population.

CONCLUSIONS

TPM elimination was increased with CBZ coadministration and was affected by renal function. Meanwhile, age and sex were the main predictors for V. The predictive performance of the final model proved to be valid internally and externally.

Protective Effect of Topiramate against Diabetic Retinopathy and Computational Approach Recognizing the Role of NLRP3/IL-1β/TNF-α Signaling

The possible impact of topiramate against diabetic retinopathy (DREN) and its molecular mechanisms in relation to the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome has not been studied before. Thus, in the present study, we aimed to utilize a computational approach to investigate the possible protective effect of topiramate on experimental DREN and explore its impact on NLRP3/interlukin-1β signaling and brain-derived neurotrophic factor (BDNF) expression. Male albino mice were distributed to four experimental groups and assigned the following categorizations: (i) saline, (ii) diabetic, (iii) diabetic + topiramate 10 mg/kg and (iv) diabetic + topiramate 30 mg/kg. We observed shrinkage of total retinal thickness and elevation in retinal glutamate, malondialdehyde, NLRP3 and interlukin-1β but decreased glutathione (GSH) levels in the diabetic mice. Additionally, retinal ultra-structures in the diabetic group showed abnormalities and vacuolations in the pigmented epithelium, the photoreceptor segment, the outer nuclear layer, the inner nuclear layer and the ganglion cell layer (GCL). Mice treated with topiramate 10 or 30 mg/kg showed downregulation in retinal malondialdehyde, NLRP3 and interlukin-1β levels; improvements in the retinal pathologies; enhanced immunostaining for BDNF and improved ultra-structures in different retinal layers. Overall, the current results suggest topiramate as a neuroprotective agent for DREN, and future studies are warranted to further elucidate the mechanism of its protective action.

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.

The Effectiveness of Topiramate in the Treatment of Amphetamine and Methamphetamine Use Disorder: A Randomized Controlled Trial

Objective: Limited studies have yet evaluated the effectiveness of topiramate in the treatment of amphetamine and methamphetamine addiction. Therefore, the aim of this study was to investigate the effectiveness of topiramate in the treatment of patients with this disorder. Methods: In this randomized, double-blind, placebo-controlled clinical trial, 52 patients with amphetamine and methamphetamine use disorder, within the age range of 16-60 years, were randomly divided into an intervention group (n = 26) and a placebo group (n = 26). The intervention group was treated with topiramate tablets with a starting dose of 50 mg, which was gradually increased to the target dose of 200 mg. The control group was treated with placebo. The duration of drug intervention in this clinical trial was 12 weeks, and all participants were evaluated before the intervention and 2, 4, 6, 8, 10, and 12 weeks after beginning the intervention. The Beck Depression Inventory, drug use temptation questionnaire, urine test, and side effects questionnaire were used as outcome measures to assess the patients. The data were analyzed using chi-square, independent t-test, and analysis of variance with repeated measurements. Results: There was no significant difference between the intervention and placebo groups in depression at the beginning of the treatment and at the 4th, 8th, and 12th weeks after the intervention (P > 0.05). The urine test also showed no significant difference between the two groups at any of the evaluation stages (P > 0.05). Although there was no significant difference between the two groups in the drug use temptation results at the beginning and the 2nd, 4th and 6th weeks (P > 0.05), the level of drug temptation in the intervention group was significantly lower than the placebo group in the 8th, 10th, and 12th weeks (P < 0.05). Conclusion: Topiramate can be effective in reducing the desire to use amphetamine and methamphetamine. However, further studies are needed to confirm these results.

Pharmacokinetics and Safety of Coadministered Atogepant and Topiramate in Healthy Participants: A Phase 1, Open-Label, Drug-Drug Interaction Study

Atogepant, an oral calcitonin gene-related peptide receptor antagonist, and topiramate, a commonly used oral antiepileptic, are approved as preventive migraine treatments. Given the distinct mechanisms of action of these treatments, it is possible that they may be coprescribed for migraine. This open-label, single-center, 2-cohort, phase 1 trial evaluated the potential pharmacokinetic (PK) 2-way drug-drug interactions (DDIs), safety, and tolerability of atogepant and topiramate in healthy adults. Participants received atogepant 60 mg once daily and topiramate 100 mg twice daily. Cohort 1 (N = 28) evaluated the effect of topiramate on the PK of atogepant; cohort 2 (N = 25) evaluated the effect of atogepant on the PK of topiramate. Potential DDIs were assessed using geometric mean ratios and 90% confidence intervals calculated for maximum plasma drug concentration at steady state (Cmax,ss ) and area under the plasma concentration-time curve during the dosing interval at steady state (AUC0-tau,ss ). Additional PK parameters were assessed. Atogepant AUC0-tau,ss and Cmax,ss decreased by 25% and 24%, respectively, with topiramate coadministration. Topiramate AUC0-tau,ss and Cmax,ss decreased by 5% and 6%, respectively, with atogepant coadministration. The 25% reduction in atogepant exposure when coadministered with topiramate is not considered to be clinically relevant and would not require dose adjustments.

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.

The effect of topiramate versus flunarizine on the non-headache symptoms of migraine

OBJECTIVES

To investigate the impact of topiramate versus flunarizine on the non-headache symptoms (NHS) of migraine, and to observe the changes of dopamine (DA) and prolactin (PRL) before and after prophylactic treatment.

METHODS

Sixty-six episodic migraine patients were enrolled and randomized 1:1 to receive either flunarizine or topiramate treatment. Clinical characteristics and NHS associated with migraine were investigated before and after prophylactic treatment. The DA and PRL levels were also determined before and after prophylactic treatment.

RESULTS

The NHS of migraine in the two groups were significantly better after treatment than before treatment in premonitory phase (PP), headache phase (HP), and resolution phase (RP). The NHS in the two groups had no significant difference in PP, HP, and RP before and after treatment. In the flunarizine group, the PRL content after treatment was significantly higher than that before treatment (t = -4.097, p < 0.001), but the DA content was decreased slightly compared with that before treatment (t = 1.909, p = 0.066). There was no significant difference in PRL content (t = 1.099, p = 0.280) and DA content (t = 1.556, p = 0.130) in topiramate group before and after treatment.

CONCLUSIONS

The two classical prophylactic drugs of migraine were significantly effective in treating the NHS of migraine, but there was no significant difference between the two drugs. The DA-PRL axis may be involved in the underlying mechanism of the flunarizine treatment for the NHS of migraine.

TOPIRAMATE-INDUCED BILATERAL ANGLE-CLOSURE GLAUCOMA. A CASE REPORT

INTRODUCTION

Topamax (topiramate) is a drug used in the treatment of epilepsy or migraine. Its use may rarely be associated with the occurrence of secondary angle-closure glaucoma due to supraciliary effusion. Although the ocular finding resembles primary angle-closure glaucoma, bilateral infliction should always raise the suspicion that it is drug-induced glaucoma.

CASE REPORT

The authors present a case of a 51-year-old patient on Topamax therapy with sudden vertigo, headache and blurred vision. Ophthalmic examination revealed bilateral angle-closure glaucoma, which was initially treated in the classical manner by administration of local antiglaucoma drugs and pilocarpine, followed by administration of osmotically active substances and laser iridotomy. Only the subsequent discontinuation of Topamax and the use of local cycloplegics and corticosteroids led to the release of the anterior segment angle closure and normalization of intraocular pressure.

CONCLUSION

The indicating physician and ophthalmologist must be aware of the possible side effects of Topamax therapy to determine the correct diagnosis and to administer treatment appropriately.

The immunomodulatory effects of topiramate on azoxymethane-induced colon carcinogenesis in rats: The role of the inflammatory cascade, vascular endothelial growth factor, AKT/mTOR/MAP kinase signaling and the apoptotic markers

BACKGROUND

Colon cancer is a malignant condition that affects the lower gastrointestinal tract and has unfavorable prognosis. Its mechanisms range from enhanced production of reactive oxygen species, inflammatory changes in the colon microenvironment and affection of the apoptotic pathways. Due to the high incidence of resistance of colon cancer to the traditional chemotherapeutic agents, a need for finding safe/effective agents that can attenuate the malignant changes had emerged.

OBJECTIVE

To investigate the possible immunomodulatory and antitumor effects of topiramate on azoxymethane-induced colon cancer in rats.

METHODOLOGY

Fifty male Wistar rats were randomized into five equal groups as follows: Control; azoxymethane-induced colon cancer; azoxymethane + methyl cellulose; azoxymethane + topiramate small dose; and azoxymethane + topiramate large dose. The body weight gain, serum carcinoembryonic antigen (CEA), tissue antioxidant status, proinflammatory cytokines, vascular endothelial growth factor (VEGF), Nrf2/HO-1 content, p-AKT, mTOR, p38 MAP kinase, caspase 9, nerve growth factor beta and beclin-1 were measured. Also, parts of the colon had undergone histopathological and immunohistochemical evaluation.

KEY FINDINGS

Topiramate improved the body weight gain, decreased serum CEA, augmented the antioxidant defenses in the colonic tissues with significant amelioration of the inflammatory changes, decline in tissue VEGF and p-AKT/mTOR/MAP kinase signaling and increased Nrf2/HO-1 content in a dose-dependent manner when compared to rats treated with azoxymethane alone. In addition, topiramate, in a dose-dependent manner, significantly enhanced apoptosis and improved the histopathological picture in comparison to animals treated with azoxymethane alone.

CONCLUSION

Taking these findings together, topiramate might serve as a new effective adjuvant line of treatment of colon cancer.

Human Aquaporins: Functional Diversity and Potential Roles in Infectious and Non-infectious Diseases

Aquaporins (AQPs) are integral membrane proteins and found in all living organisms from bacteria to human. AQPs mainly involved in the transmembrane diffusion of water as well as various small solutes in a bidirectional manner are widely distributed in various human tissues. Human contains 13 AQPs (AQP0-AQP12) which are divided into three sub-classes namely orthodox aquaporin (AQP0, 1, 2, 4, 5, 6, and 8), aquaglyceroporin (AQP3, 7, 9, and 10) and super or unorthodox aquaporin (AQP11 and 12) based on their pore selectivity. Human AQPs are functionally diverse, which are involved in wide variety of non-infectious diseases including cancer, renal dysfunction, neurological disorder, epilepsy, skin disease, metabolic syndrome, and even cardiac diseases. However, the association of AQPs with infectious diseases has not been fully evaluated. Several studies have unveiled that AQPs can be regulated by microbial and parasitic infections that suggest their involvement in microbial pathogenesis, inflammation-associated responses and AQP-mediated cell water homeostasis. This review mainly aims to shed light on the involvement of AQPs in infectious and non-infectious diseases and potential AQPs-target modulators. Furthermore, AQP structures, tissue-specific distributions and their physiological relevance, functional diversity and regulations have been discussed. Altogether, this review would be useful for further investigation of AQPs as a potential therapeutic target for treatment of infectious as well as non-infectious diseases.

Monitoring topiramate concentrations at delivery and during lactation

OBJECTIVE

To determine transplacental passage of topiramate and its transport to colostrum, mature maternal milk and breastfed infants, we examined data from 27 women treated with topiramate from 2004 to 2020.

METHODS

In this cohort study, maternal serum, umbilical cord serum, milk and infant serum levels were measured by gas chromatography in the delivery subgroup, the colostrum subgroup (3-4 days postpartum) and the mature milk subgroup (7-30 days postpartum). Paired umbilical cord serum, maternal serum, breastfed infant serum, and milk levels were used to assess the ratios of umbilical cord/maternal serum, milk/maternal serum and infant/maternal serum levels.

RESULTS

Topiramate levels varied from 1.0 to 7.1 mg/L in maternal serum and from 0.8 to 6.2 mg/L in umbilical cord serum, and the mean umbilical cord/maternal serum ratio was 0.93 ± 0.11. At 3-4 days after delivery, topiramate concentrations were 1.4-8.4 mg/L in maternal serum, 1.5-8.6 mg/L in milk and 0.3-4.4 mg/L in infant serum. The mean milk/maternal serum ratio was 0.99 ± 0.45, and the mean infant/maternal serum ratio was 0.25 ± 0.15. At 7-30 days after delivery, maternal serum levels varied from 1.9 to 9.7 mg/L, milk levels ranged from 2.3 to 10.6 mg/L and infant serum levels ranged from 0.3 to 6.5 mg/L. The mean milk/maternal serum ratio was 1.07 ± 0.31, and the mean infant/maternal serum ratio was 0.51 ± 0.27.

CONCLUSIONS

We extended information about free transplacental passage of topiramate and its extensive transport to maternal milk with lower serum concentrations in breastfed infants in the largest group of patients ever reported to our knowledge.

DATA AVAILABILITY STATEMENT

Authors declare that take full responsibility for the data, the analyses and interpretation, and the conduct of the research; that they have full access to all of the data; and that they have the right to publish all data. Authors were not participations in industry-sponsored research and corporate activities for evaluation of a manuscript.

Synchronous neuronal interactions in rat hypothalamic culture: a novel model for the study of network dynamics in metabolic disorders

Synchronous neural activity is a feature of normal brain function, and altered synchronization is observed in several neurological diseases. Dysfunction in hypothalamic pathways leads to obesity, suggesting that hypothalamic neural synchrony is critical for energy homeostasis. The lateral hypothalamic orexin neurons are extensively interconnected with other brain structures and are important for energy balance. Earlier studies show that rats with higher orexin sensitivity are obesity resistant. Similarly, topiramate, an anti-epileptic drug, has been shown to reduce weight in humans. Since orexin enhances neuronal excitation, we hypothesized that obesity-resistant rats with higher orexin sensitivity may exhibit enhanced hypothalamic synchronization. We further hypothesized that anti-obesity agents such as orexin and topiramate will enhance hypothalamic synchronization. To test this, we examined neural synchronicity in primary embryonic hypothalamic cell cultures, obtained from embryonic day 18 (E18) obesity-susceptible Sprague-Dawley (SD) and obesity-resistant rats. Hypothalamic tissue was cultured in multielectrode array (MEA), and recordings were performed twice weekly, from 4th to 32nd day in vitro (DIV). Next, we tested the effects of orexin and topiramate application on neural synchronicity of hypothalamic cultures obtained from SD rat embryos. Signals were analyzed for synchronization using cross correlation. Our results showed that (1) obesity-resistant hypothalamus exhibits significantly higher synchronization compared to obesity-sensitive hypothalamus; and (2) orexin and topiramate enhance hypothalamic synchronization. These results support that enhanced orexin sensitivity is associated with greater neural synchronization, and that anti-obesity treatments enhance network synchronization, thus constrain variability in hypothalamic output signals, to extrahypothalamic structures involved in energy homeostasis.

Topiramate inhibits offensive aggression through targeting ventrolateral periaqueductal gray

Topiramate is an approved antiepileptic drug clinically used to treat epilepsy and prevent migraines. Currently, topiramate has been found to be effective in treating aggressive symptoms in neuropsychiatric patients. In preclinical studies, however, the effects and mechanisms of topiramate on offensive aggression are still largely uninvestigated. Our previous studies indicated that glutamatergic transmission in the ventrolateral periaqueductal gray (vlPAG) plays a crucial role in regulating elements of offensive aggressive behaviors. In the present work, we investigated the actions of topiramate on vlPAG glutamatergic transmission and aggressive behaviors in group-housed (GH) and socially isolated (SI) rats. The results suggested that a single injection of topiramate systemically and dose-dependently inhibited elements of offensive aggressive behaviors of both GH and SI rats in the resident-intruder test (RIT), with long-lasting effective time profiles in SI rats. Moreover, systemic single administration of topiramate reduced the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs) in the vlPAG. Bath perfusion of topiramate directly decreased the frequency and amplitude of mEPSCs and shortened the amplitude of evoked excitatory postsynaptic currents (EPSCs) in the vlPAG. Furthermore, intra-vlPAG single microinjection of topiramate dose-dependently inhibited offensive aggressive behaviors in GH and SI rats in a time-dependent manner. Additionally, both systemic and local topiramate inhibited offensive aggressive behaviors in a (2R,6R)-hydroxynorketamine (HNK)-dependent rat model. In conclusion, the present results suggest that topiramate exerts anti-aggressive roles through its inhibitory actions on glutamatergic activities in the vlPAG. These preclinical results support topiramate as a candidate drug to treat patients with heightened offensive aggression.

The effects of Topiramate on isolation-induced aggression: a behavioral and immunohistochemical study in mice

Topiramate, an antiepileptic drug, has been found to be useful for the treatment of aggression in clinical populations. Most preclinical studies related to Topiramate have been focused exclusively on the quantitative aspects of the aggressive behavior between mice. However, there is still limited knowledge regarding the effects of Topiramate on neuronal mechanisms occurring in aggressive mice. The present work aims to understand further the effects of the antiepileptic drug Topiramate on aggressive behaviors, and on the neural correlates underlying such behaviors. To achieve this, we combined the resident-intruder model of isolation-induced aggression in mice with two drug regimens of Topiramate administration (30.0 mg/kg; acute and sub-chronic treatments). Our data showed that both acute and subchronic treatments decreased the intensity of agonistic encounters and reinforced social behavior. By using C-fos immunoreactivity, we investigated the neuronal activation of several brain regions involved in aggressive behavior following subchronic treatment. We found that Topiramate produced activation in several cortical areas and in the lateral septum of resident brain mice compared with their controls. However, Topiramate induced inhibition in the medial nucleus of the amygdala, the dorsomedial nucleus of the periaqueductal gray, and especially in the anterior hypothalamic nucleus. Finally, we performed microinfusion of Topiramate (0.1 and 0.3 mM) into the lateral septum and anterior hypothalamus on offensive behaviors in isolation-induced-aggression paradigm. Interestingly, the microinfusion of Topiramate into the lateral septum has the capacity to alleviate aggressive behavior, without affecting social behavior. However, the microinfusion of Topiramate into the anterior hypothalamus decreased aggressive behavior and slightly reinforced social behavior. Our observations supported that the dose of 0.1 mM of Topiramate appeared more efficacy to treat aggression in adult mice. These pharmacological characteristics may account for Topiramate efficacy on aggressive symptoms in psychiatric patients.

Topiramate Pharmacotherapy for Alcohol Use Disorder and Other Addictions: A Narrative Review

: Topiramate is a non-benzodiazepine anticonvulsant medication with multi-faceted pharmacologic action. It has emerged as an efficacious pharmacotherapeutic option for the treatment of addiction, especially alcohol use disorder (AUD). We present a broad narrative review of the putative mechanism of action and clinical utility of topiramate with regard to AUD and other substance use disorders. Collective evidence suggests topiramate is an effective treatment option in AUD, with notable efficacy in reducing harmful drinking patterns in AUD. Though not currently approved by the United States Food and Drug Administration for the indication of AUD, topiramate should be considered as a pharmacological treatment option with high utility among AUD patients. Early pharmacogenetic studies raise the intriguing possibility of identifying patients likely to respond to topiramate using genetic testing, and initial studies show that topiramate may also be useful in treating cocaine use disorder, smoking cessation and behavioral addictions. However, further research is needed in all these areas.

Topiramate prevents oxaliplatin-related axonal hyperexcitability and oxaliplatin induced peripheral neurotoxicity

Oxaliplatin (OHP) Induced Peripheral Neurotoxicity (OIPN) is one of the dose-limiting toxicities of the drug and these adverse effects limit cancer therapy with L-OHP, used for colorectal cancer treatment. Acute neurotoxicity consists of symptoms that are the hallmarks of a transient axonal hyperexcitability; chronic neurotoxicity has a clinical picture compatible with a length-dependent sensory neuropathy. Acute OIPN pathogenesis has been linked to sodium voltage-operated channels (Na + VOC) dysfunction and it has been advocated as a possible predisposing factor to chronic neurotoxicity. We tested if topiramate (TPM), a well-known Na + VOC modulator, was able to modify acute as well as chronic OIPN. The project was divided into two parts. In Experiment 1 we tested by means of Nerve Excitability Testing (NET) a cohort of female Wistar rats to assess TPM effects after a single OHP administration (5 mg/kg, iv). In Experiment 2 we assessed TPM effects after chronic OHP treatment (5 mg/kg, 2qw4ws, iv) using NET, nerve conduction studies (NCS), behavioral tests and neuropathology (caudal nerve morphometry and morphology and Intraepidermal Nerve Fiber [IENF] density). In Experiment 1 TPM was able to prevent OHP effects on Na + VOC: OHP treatment induced a highly significant reduction of the sensory nerve's threshold, during the superexcitability period (p-value = 0.008), whereas TPM co-administration prevented this effect. In Experiment 2 we verified that TPM was able to prevent not only acute phenomena, but also to completely prevent chronic OIPN. This latter observation was supported by a multimodal approach: in fact, only OHP group showed altered findings compared to CTRL group at a neurophysiological (proximal caudal nerve sensory nerve action potential [SNAP] amplitude, p-value = 0.001; distal caudal nerve SNAP amplitude, p-value<0.001, distal caudal nerve sensory conduction velocity, p-value = 0.04), behavioral (mechanical threshold, p-value 0.003) and neuropathological levels (caudal nerve fibers density, p-value 0.001; IENF density, p-value <0.001). Our data show that TPM is a promising drug to prevent both acute and chronic OIPN. These findings have a high translational potential, since they were obtained using outcome measures that match clinical practice and TPM is already approved for clinical use being free from detrimental interaction with OHP anticancer properties.

Proof-of-concept that network pharmacology is effective to modify development of acquired temporal lobe epilepsy

Epilepsy is a complex network phenomenon that, as yet, cannot be prevented or cured. We recently proposed network-based approaches to prevent epileptogenesis. For proof of concept we combined two drugs (levetiracetam and topiramate) for which in silico analysis of drug-protein interaction networks indicated a synergistic effect on a large functional network of epilepsy-relevant proteins. Using the intrahippocampal kainate mouse model of temporal lobe epilepsy, the drug combination was administered during the latent period before onset of spontaneous recurrent seizures (SRS). When SRS were periodically recorded by video-EEG monitoring after termination of treatment, a significant decrease in incidence and frequency of SRS was determined, indicating antiepileptogenic efficacy. Such efficacy was not observed following single drug treatment. Furthermore, a combination of levetiracetam and phenobarbital, for which in silico analysis of drug-protein interaction networks did not indicate any significant drug-drug interaction, was not effective to modify development of epilepsy. Surprisingly, the promising antiepileptogenic effect of the levetiracetam/topiramate combination was obtained in the absence of any significant neuroprotective or anti-inflammatory effects as indicated by multimodal brain imaging and histopathology. High throughput RNA-sequencing (RNA-seq) of the ipsilateral hippocampus of mice treated with the levetiracetam/topiramate combination showed that several genes that have been linked previously to epileptogenesis, were significantly differentially expressed, providing interesting entry points for future mechanistic studies. Overall, we have discovered a novel combination treatment with promise for prevention of epilepsy.

Preventive Treatment for Episodic Migraine

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

Inhibitors of Mammalian Aquaporin Water Channels

Aquaporins (AQPs) are water channel proteins that are essential to life, being expressed in all kingdoms. In humans, there are 13 AQPs, at least one of which is found in every organ system. The structural biology of the AQP family is well-established and many functions for AQPs have been reported in health and disease. AQP expression is linked to numerous pathologies including tumor metastasis, fluid dysregulation, and traumatic injury. The targeted modulation of AQPs therefore presents an opportunity to develop novel treatments for diverse conditions. Various techniques such as video microscopy, light scattering and fluorescence quenching have been used to test putative AQP inhibitors in both AQP-expressing mammalian cells and heterologous expression systems. The inherent variability within these methods has caused discrepancy and many molecules that are inhibitory in one experimental system (such as tetraethylammonium, acetazolamide, and anti-epileptic drugs) have no activity in others. Some heavy metal ions (that would not be suitable for therapeutic use) and the compound, TGN-020, have been shown to inhibit some AQPs. Clinical trials for neuromyelitis optica treatments using anti-AQP4 IgG are in progress. However, these antibodies have no effect on water transport. More research to standardize high-throughput assays is required to identify AQP modulators for which there is an urgent and unmet clinical need.

Current Status of Antiepileptic Drugs as Preventive Migraine Therapy

BACKGROUND

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

PURPOSE OF THIS REVIEW

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

RECENT FINDINGS

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

Gender-related issues in the pharmacology of new anti-obesity drugs

Four new medicines-liraglutide, lorcaserin, bupropion/naltrexone, and phentermine/topiramate-have been recently added to the pharmacological arsenal for obesity treatment and could represent important tools to manage this epidemic disease. To achieve satisfactory anti-obesity goals, the use of these new medicines should be optimized and tailored to specific patient subpopulations also by applying dose adjustments if needed. In the present review, we posit that gender could be among the factors influencing the activity of the new obesity drugs both because of pharmacokinetic and pharmacodynamic factors. Although evidence from premarketing clinical studies suggested that no dose adjustment by gender is necessary for any of these new medicines, these studies were not specifically designed to identify gender-related differences. This observation, together with the strong theoretical background supporting the hypothesis of a gender-dimorphic response, strongly call upon an urgent need of new real-life data on gender-related difference in the pharmacology of these new obesity drugs.

Anti-Obesity Therapy: from Rainbow Pills to Polyagonists

With their ever-growing prevalence, obesity and diabetes represent major health threats of our society. Based on estimations by the World Health Organization, approximately 300 million people will be obese in 2035. In 2015 alone there were more than 1.6 million fatalities attributable to hyperglycemia and diabetes. In addition, treatment of these diseases places an enormous burden on our health care system. As a result, the development of pharmacotherapies to tackle this life-threatening pandemic is of utmost importance. Since the beginning of the 19th century, a variety of drugs have been evaluated for their ability to decrease body weight and/or to improve deranged glycemic control. The list of evaluated drugs includes, among many others, sheep-derived thyroid extracts, mitochondrial uncouplers, amphetamines, serotonergics, lipase inhibitors, and a variety of hormones produced and secreted by the gastrointestinal tract or adipose tissue. Unfortunately, when used as a single hormone therapy, most of these drugs are underwhelming in their efficacy or safety, and placebo-subtracted weight loss attributed to such therapy is typically not more than 10%. In 2009, the generation of a single molecule with agonism at the receptors for glucagon and the glucagon-like peptide 1 broke new ground in obesity pharmacology. This molecule combined the beneficial anorectic and glycemic effects of glucagon-like peptide 1 with the thermogenic effect of glucagon into a single molecule with enhanced potency and sustained action. Several other unimolecular dual agonists have subsequently been developed, and, based on their preclinical success, these molecules illuminate the path to a new and more fruitful era in obesity pharmacology. In this review, we focus on the historical pharmacological approaches to treat obesity and glucose intolerance and describe how the knowledge obtained by these studies led to the discovery of unimolecular polypharmacology.

Sensitive detection of topiramate degradation products by high-performance liquid chromatography/electrospray ionization mass spectrometry using ion-pairing reagents and polarity switching

RATIONALE

The chromatographic analysis of topiramate and its degradation products is challenging due to the absence of chromophoric moieties in their structures, the wide polarity range of the compounds and their ionization differences. This work proposes two new mass spectrometry approaches for evaluating these analytes.

METHODS

Based on the calculated experimental limit of detection (LOD), a highly sensitive high-performance liquid chromatography (HPLC) paired-ion electrospray ionization mass spectrometry (PIESI-MS) method was developed for the determination of topiramate inorganic degradation products. The influence of different solvent systems on the LODs for topiramate and its main degradation products was determined in both positive/negative ionization modes. In addition, a HPLC method to analyze both organic and inorganic degradation products was proposed by mass spectrometry with positive/negative ion switching electrospray ionization.

RESULTS

A sensitive HPLC/PIESI-MS method was achieved for the efficient separation of topiramate inorganic degradation products. Both sulfate and sulfamate were detected in the positive selected ion monitoring (SIM) mode with an increased sensitivity compared with the negative SIM mode. The HPLC/ESI-MS analysis with positive/negative ion switching allowed the simultaneous separation and detection of the major degradation products of topiramate in a 10-min run using a single column and a single detector.

CONCLUSIONS

Two new alternative MS approaches for analyzing the main degradation products of topiramate were developed. The proposed methods are considered advantageous over the existing methods and can be applied to quality control studies of topiramate.

Real-world assessment of treatment with extended-release topiramate (Trokendi XR®) and comparison with previous immediate-release topiramate treatment

AIM

Examine clinical profile of extended-release topiramate (Trokendi XR^®) and compare treatment-emergent adverse events (TEAEs) associated with Trokendi XR versus previous immediate-release topiramate (TPM-IR) treatment.

PATIENTS & METHODS

Pilot retrospective study analyzing data extracted from medical charts of patients ≥6 years of age prescribed Trokendi XR.

RESULTS

Trokendi XR was the most commonly used to prevent migraine. The most common TEAEs recorded during topiramate treatment were cognitive symptoms (word-finding difficulty, attention/concentration difficulty, slowed thinking), paresthesia, gastrointestinal problems and decreased appetite/weight loss. TEAE incidence was significantly (p < 0.001) lower during Trokendi XR versus previous TPM-IR treatment.

CONCLUSION

Trokendi XR use and outcomes in clinical practice were consistent with established profile of topiramate. Results supported the potential for better tolerability of Trokendi XR versus TPM-IR.

Chronic and intermittent administration of systemic nitroglycerin in the rat induces an increase in the gene expression of CGRP in central areas: potential contribution to pain processing

Background

Calcitonin gene related peptide (CGRP) is a key neuropeptide involved in the activation of the trigeminovascular system and it is likely related to migraine chronification. Here, we investigated the role of CGRP in an animal model that mimics the chronic migraine condition via repeated and intermittent nitroglycerin (NTG) administration. We also evaluated the modulatory effect of topiramate on this experimental paradigm. Male Sprague-Dawley rats were injected with NTG (5 mg/kg, i.p.) or vehicle, every 2 days over a 9-day period (5 total injections). A group of animals was injected with topiramate (30 mg/kg, i.p.) or saline every day for 9 days. Twenty-four hours after the last administration of NTG or vehicle, animals underwent tail flick test and orofacial Von Frey test. Rats were subsequently sacrificed to evaluate c-Fos and CGRP gene expression in medulla-pons region, cervical spinal cord and trigeminal ganglia.

Results

NTG administration induced spinal hyperalgesia and orofacial allodynia, together with a significant increase in the expression of CGRP and c-Fos genes in trigeminal ganglia and central areas. Topiramate treatment prevented NTG-induced changes by reversing NTG-induced hyperalgesia and allodynia, and inhibiting CGRP and c-Fos gene expression in all areas evaluated.

Conclusions

These findings point to the role of CGRP in the processes underlying migraine chronification and suggest a possible interaction with gamma-aminobutyrate (GABA) and glutamate transmission to induce/maintain central sensitization and to contribute to the dysregulation of descending pain system involved in chronic migraine.

Topiramate exhibits anti-tumorigenic and metastatic effects in ovarian cancer cells

Ovarian cancer is one of the leading causes of cancer related deaths among women worldwide, with an overall 5-year survival of only 30-40%. Carbonic anhydrases are up-regulated in many types of cancer and play an important role in tumor progression and metastasis. Carbonic anhydrase 9 has been implicated as a potential anti-tumorigenic target. Topiramate (TPM) is a potent inhibitor of carbonic anhydrase isozymes, including carbonic anhydrase 9, and has been shown to have anti-tumorigenic activity in several cancer types. Our goal was to evaluate the effect of TPM on cell proliferation and to identify possible mechanisms by which TPM inhibits cell growth in ovarian cancer. TPM significantly inhibited ovarian cancer cell proliferation and induced cell cycle G1 arrest, cellular stress and apoptosis through the AKT/mTOR and MAPK pathways. TPM also exerted anti-metastatic effects by decreasing the adhesion and invasion of ovarian cancer cells and affecting the expression of critical regulators of the epithelial-mesenchymal transition (EMT). Our findings demonstrate that TPM has anti-tumorigenic effects in ovarian cancer and is worthy of further exploration in clinical trials.

Pharmacological characterization of nicotine-induced tremor: Responses to anti-tremor and anti-epileptic agents

We previously showed that nicotine evoked kinetic tremor by activating the inferior olive, which is implicated in the pathogenesis of essential tremor, via α7 nicotinic acetylcholine receptors. Here, we evaluated the effects of various anti-tremor and anti-epileptic agents on nicotine-induced tremor in mice to clarify the pharmacological characteristics of nicotine tremor. Drugs effective for essential tremor, propranolol, diazepam and phenobarbital, all significantly inhibited kinetic tremor induced by an intraperitoneal (i.p.) injection of nicotine (1 mg/kg). In contrast, none of the medications for Parkinson's disease, l-DOPA, bromocriptine or trihexyphenidyl, affected the nicotine tremor. Among the anti-epileptic agents examined, valproate, carbamazepine and ethosuximide, significantly inhibited nicotine-induced tremor. In addition, a selective T-type Ca²⁺ channel blocker, TTA-A2, also suppressed the nicotine tremor. However, neither gabapentin, topiramate, zonisamide nor levetiracetam significantly affected nicotine-induced tremor. The present results show that nicotine-induced tremor resembles essential tremor not only on the neural basis, but also in terms of the pharmacological responses to anti-tremor agents, implying that nicotine-induced tremor can serve as a model for essential tremor. In addition, it is suggested that anti-epileptic agents, which have stimulant actions on the GABAergic system or blocking actions on voltage-gated Na⁺ channels and T-type Ca²⁺ channels, can alleviate essential tremor.

Molecular bases of anorexia nervosa, bulimia nervosa and binge eating disorder: shedding light on the darkness

Eating-disorders (EDs) consequences to human health are devastating, involving social, mental, emotional, physical and life-threatening aspects, concluding on impairment and death in cases of extreme anorexia nervosa. It also implies that people suffering an ED need to find psychiatric and psychological help as soon as possible to achieve a fully physical and emotional recovery. Unfortunately, to date, there is a crucial lack of efficient clinical treatment to these disorders. In this review, we present an overview concerning the actual pharmacological and psychological treatments, the knowledge of cells, circuits, neuropeptides, neuromodulators and hormones in the human brain- and other organs- underlying these disorders, the studies in animal models and, finally, the genetic approaches devoted to face this challenge. We will also discuss the need for new perspectives, avenues and strategies to be developed in order to pave the way to novel and more efficient therapeutics.

Levetiracetam and topiramate poisoning: Two overdoses on those drugs with no lasting effects

Levetiracetam and topiramate are newer anticonvulsants, which is why international data on overdoses of these drugs are lacking. Only a few mild adverse reactions have been noted. These anticonvulsants have been the drug of choice for neurologists. Despite their wide usage, there is a dearth of literature on symptoms and signs of their toxicity. Presented here is the case of a 21-year-old female who overdosed twice on levetiracetam and topiramate. The woman was admitted and discharged after the first overdose. Ten days later, she took multiple tablets of both drugs and was seen again. Amazingly, the woman went home after the incident with no complications at all.

A novel LC-MS/MS method for the simultaneous quantification of topiramate and its main metabolites in human plasma

The aim of the present report was to develop and validate simple, sensitive and reliable LC-MS/MS method for quantification of topiramate (TPM) and its main metabolites: 2,3-desisopropylidene TPM, 4,5-desisopropylidene TPM, 10-OH TPM and 9-OH TPM in human plasma samples. The most abundant metabolite 2,3-desisopropylidene TPM was isolated from patients urine, characterized and afterwards used as an authentic standard for method development and validation. Sample preparation method employs 100μL of plasma sample and liquid-liquid extraction with a mixture of ethyl acetate and diethyl ether as extraction solvent. Chromatographic separation was achieved on a 1290 Infinity UHPLC coupled to 6460 Triple Quad Mass Spectrometer operated in negative MRM mode using Kinetex C18 column (50×2.1mm, 2.6μm) by gradient elution using water and methanol as a mobile phase and stable isotope labeled TPM as internal standard. The method showed to be selective, accurate, precise and linear over the concentration ranges of 0.10-20μg/mL for TPM, 0.01-2.0μg/mL for 2,3-desisopropylidene TPM, and 0.001-0.200μg/mL for 4,5-desisopropylidene TPM, 10-OH TPM and 9-OH TPM. The described method is the first fully validated method capable of simultaneous determination of TPM and its main metabolites in plasma over the selected analytical range. The suitability of the method was successfully demonstrated by the quantification of all analytes in plasma samples of patients with epilepsy and can be considered as reliable analytical tool for future investigations of the TPM metabolism.

Comparative pre-emptive analgesic efficacy study of novel antiepileptic agents gabapentin, lamotrigine and topiramate in patients undergoing major surgeries at a tertiary care hospital: a randomized double blind clinical trial

BACKGROUND

Surgical injury leads to postoperative pain hypersensitivity preceded by central nervous sensitization, due to lowered pain threshold in peripheral nociceptors and increased excitability of the spinal neurons. Pre-emptive analgesia is intended to decrease pain perception and overall analgesic need by use of drug regimen seizing central nervous system sensitization before exposure to painful stimuli. Earlier, few studies support pre-emptive analgesic efficacy of novel antiepileptic agent gabapentin. But topiramate and lamotrigine though proven analgesic in animal models of chronic pain and clinical studies of gabapentin resistant neuropathic pain; literature search revealed scarce data on its pre-emptive analgesic efficacy. The present study is designed to study and compare the pre-emptive analgesic efficacy of lamotrigine, topiramate and gabapentin (as control) in postoperative pain control.

METHODS

This randomized clinical trial included 90 patients of either sex, between 18 and 70 years undergoing major surgeries. Patients were randomly allocated into control and test groups and received respective treatment 30 min before induction of anesthesia. Aldrete's score and pain score were recorded using visual analogue scale and facial and behavioral rating scales at awakening and at 1, 2, 4, 6 and 24 h. Postoperative rescue analgesic consumption for 24 h was recorded. Data were analyzed using OpenEpi and SciStatCalc statistical softwares.

RESULTS

Significantly higher pain scores were observed in the topiramate group postoperatively for 2 h on all pain scales (p<0.05). Lamotrigine-treated patients were more comfortable throughout the study with significantly less (p<0.05) postoperative analgesic requirement comparable to gabapentin.

CONCLUSIONS

Study results are strongly suggestive of pre-emptive analgesic efficacy of single oral dose lamotrigine comparable to gabapentin and superior to topiramate in postoperative pain control.

Alteration of Monoamine Receptor Activity and Glucose Metabolism in Pediatric Patients with Anticonvulsant-Induced Cognitive Impairment

A landmark study from the Institute of Medicine reported that the assessment of cognitive difficulties in children with epilepsy is timely and imperative. Anticonvulsant-induced cognitive impairment could influence the quality of life more than seizure itself in patients. Although the monoaminergic system is involved in the regulation of cognitive process, its role in anticonvulsant-induced cognitive impairment remains unclear. Methods: To explore in vivo monoamine receptor binding activity in patients with anticonvulsant-induced cognitive impairment, each patient underwent PET imaging with both monoamine receptor binding agent ¹¹C-N-methylspiperone and glucose metabolic agent ¹⁸F-FDG. Tests of intelligence quotient (IQ), including verbal IQ (VIQ), performance IQ (PIQ), and full-scale IQ (FSIQ), were performed in each patient. Results: Compared with the patients with monotherapy, patients with polytherapy had significantly lower VIQ, PIQ, and FSIQ (P < 0.01 in each comparison), as well as significantly lower monoamine receptor activities detected in the caudate nucleus, prefrontal cortex, dorsal anterior cingulate cortex, and amygdale (P < 0.05 in each comparison). However, regarding the glucose metabolism, there was no significant difference found in patients with monotherapy or polytherapy (P > 0.05). Conclusion: Monoamine receptor PET imaging could be a promising in vivo imaging biomarker for mapping anticonvulsant-induced cognitive impairment.

Topiramate as a neuroprotective agent in a rat model of spinal cord injury

Topiramate (TPM) is a widely used antiepileptic and antimigraine agent which has been shown to exert neuroprotective effects in various experimental traumatic brain injury and stroke models. However, its utility in spinal cord injury has not been studied extensively. Thus, we evaluated effects of TPM on secondary cellular injury mechanisms in an experimental rat model of traumatic spinal cord injury (SCI). After rat models of thoracic contusive SCI were established by free weight-drop method, TPM (40 mg/kg) was given at 12-hour intervals for four times orally. Post TPM treatment, malondialdehyde and protein carbonyl levels were significantly reduced and reduced glutathione levels were increased, while immunoreactivity for endothelial nitric oxide synthase, inducible nitric oxide synthase, and apoptotic peptidase activating factor 1 was diminished in SCI rats. In addition, TPM treatment improved the functional recovery of SCI rats. This study suggests that administration of TPM exerts neuroprotective effects on SCI.

From genetic studies to precision medicine in alcohol dependence

Genetic factors contribute to more than 50% of the variation in the vulnerability to alcohol dependence (AD). Although significant advances have been made in medications for AD, these medications do not work for all people. Precise tailoring of medicinal strategies for individual alcoholic patients is needed to achieve optimal outcomes. This review updates the most promising information on genetic variants in AD, which may be useful for improving diagnostic, therapeutic, and monitoring strategies. We describe genetic candidates of various neurotransmitter and enzyme systems. In addition to biological and allelic associations with AD, genetic effects on AD-related phenotypes and treatment responses have also been described. Gene-gene and gene-environment interactions have been considered. Potential applications of genomewide and epigenetic approaches for identifying genetic biomarkers of AD have been discussed. Overall, the application of genetic findings in precision medicine for AD will likely involve an integrated approach that distinguishes effect sizes of specific genetic predictors with regard to sex, pharmacotherapy, ethnicity, and AD-related aspects and considers gene-gene and gene-environment interactions. Our work may pave the way toward more precise treatment for AD that could ultimately improve clinical management and interventions.

Topiramate in Migraine Prevention: A 2016 Perspective

BACKGROUND

In evidence-based guidelines published in 2000, topiramate was a third-tier migraine preventive with no scientific evidence of efficacy; recommendation for its use reflected consensus opinion and clinical experience. Its neurostabilizing activity, coupled with its favorable weight profile, made topiramate an attractive alternative to other migraine preventives that caused weight gain. When guidelines for migraine prevention in episodic migraine were published in 2012, topiramate was included as a first-line option based on double-blind, randomized controlled trials involving nearly 3000 patients. The scientific and clinical interest in topiramate has generated a large body of data from randomized controlled trials, meta-analyses, patient registries, cohort studies, and claims data analyses that have more fully characterized its role as a migraine preventive.

AIM

This article will review the profile of topiramate that has emerged out of the past decade of research and clinical use in migraine prophylaxis. It will also address the rationale for extended-release (XR) formulations in optimizing topiramate therapy in migraine.

SUMMARY

Topiramate has activity at multiple molecular targets, which may account for why it is effective in migraine and most other, more specific, anticonvulsants are not. Based on randomized controlled trials, topiramate reduces migraine frequency and acute medication use, improves quality of life, and reduces disability in patients with episodic migraine and in those with chronic migraine with or without medication overuse headache. Its efficacy in chronic migraine is not improved by the addition of propranolol. Topiramate's ability to prevent progression from high-frequency episodic migraine to chronic migraine remains unclear. Consistent with clinicians' perceptions, migraineurs are more sensitive to topiramate-associated side effects than patients with epilepsy. Paresthesia is a common occurrence early in treatment but is rarely cause for terminating topiramate treatment. Cognitive problems occur much less frequently than paresthesia but are more troublesome in terms of treatment discontinuation. Cognitive complaints can often be managed by slowly increasing the topiramate dose in small increments to allow habituation. As with other carbonic anhydrase inhibitors, topiramate has metabolic effects that favor the development of metabolic acidosis and possibly renal stones. Because migraineurs have an increased risk of renal stones independent of topiramate exposure, clinicians should counsel all migraine patients to maintain hydration. Abrupt onset of blurring, other visual disturbances, and/or ocular pain following topiramate's initiation should be evaluated promptly since this may indicate rare but potentially sight-threatening idiosyncratic events. Postmarketing evidence has shown that first-trimester exposure to topiramate monotherapy is associated with increased occurrence of cleft lip with or without cleft palate (Pregnancy Category D). Even though topiramate's long half-life would seemingly support q.d. dosing, randomized controlled migraine trials used b.i.d. administration of immediate-release (IR) topiramate, which has more favorable plasma concentration-time profile (ie, lower peak concentrations and higher trough concentrations) than q.d. IR dosing. Given the sensitivity of migraineurs to topiramate-related adverse events, particularly cognitive effects, pharmacokinetic profiles should be considered when optimizing migraine outcomes. The extended-release (XR) formulations Qudexy^® XR (Upsher-Smith Laboratories) and Trokendi XR^® (Supernus Pharmaceuticals) were specifically designed to achieve the adherence benefits of q.d. dosing but with more favorable (ie, more constant) steady-state plasma concentrations over the 24-hour dosing interval vs IR topiramate b.i.d. Intriguing results from a study in healthy volunteers showed consistently less impairment in neuropsychometric tests of verbal fluency and mental processing speed with an XR topiramate formulation (Trokendi XR) vs IR topiramate b.i.d. These findings suggest a pharmacodynamic effect associated with significantly reducing plasma concentration fluctuation when topiramate absorption is slowed. Results of retrospective studies in migraineurs treated with XR topiramate appear to support a clinically meaningful benefit of XR topiramate vs IR topiramate in terms of significantly fewer cognitive effects, improved adherence, and overall better outcomes of migraine prophylaxis with topiramate.

Comparative Pre-Emptive Analgesic Efficacy Study of Novel Antiepileptic Agents Lamotrigine and Topiramate in Patients Undergoing Major Surgeries at a Tertiary Care Hospital: A Randomized Double Blind Clinical Trial

BACKGROUND

Central nervous sensitization, following surgical injury, leads to postoperative pain hypersensitivity due to lowered pain threshold in peripheral nociceptors and increased excitability of spinal neurons. Pre-emptive analgesia is intended to decrease pain perception and overall analgesic need by use of drug regimen, seizing CNS sensitization before exposure to painful stimuli. Few studies support pre-emptive analgesic efficacy of novel antiepileptic agent Gabapentin. Though Topiramate and Lamotrigine have been proven analgesic in animal models of chronic pain and clinical studies of Gabapentin-resistant neuropathic pain, literature search revealed scarce data on its pre-emptive analgesic efficacy.

PURPOSE

This study is designed to study and compare the pre-emptive analgesic efficacy of Lamotrigine, Topiramate, and Diclofenac sodium in postoperative pain control.

METHODS

This randomized clinical trial included 90 patients of either sex, between 18 and 70 years undergoing major surgeries. Patients were randomly allocated to control and test groups and received respective treatment 30 min before induction of anesthesia. Aldrete's and pain scores were recorded using the Visual Analog Scale, Facial and Behavioral Rating Scale at awakening and at 1, 2, 4, 6, and 24 h. Postoperative rescue analgesic consumption for 24 h was recorded.

RESULTS

Significantly higher pain scores were observed in the Topiramate group postoperatively for 2 h on all pain scales (p < 0.05), whereas in the control group it was significantly higher at 1 h (p < 0.05). Lamotrigine-treated patients were more comfortable throughout the study with significantly less (p < 0.05) postoperative analgesic requirement.

CONCLUSIONS

Study results strongly suggest the pre-emptive analgesic efficacy of a single oral dose of Lamotrigine over Diclofenac and Topiramate in postoperative pain control.

Mechanisms of Action of Antiseizure Drugs and the Ketogenic Diet

Antiseizure drugs (ASDs), also termed antiepileptic drugs, are the main form of symptomatic treatment for people with epilepsy, but not all patients become free of seizures. The ketogenic diet is one treatment option for drug-resistant patients. Both types of therapy exert their clinical effects through interactions with one or more of a diverse set of molecular targets in the brain. ASDs act by modulation of voltage-gated ion channels, including sodium, calcium, and potassium channels; by enhancement of γ-aminobutyric acid (GABA)-mediated inhibition through effects on GABAA receptors, the GABA transporter 1 (GAT1) GABA uptake transporter, or GABA transaminase; through interactions with elements of the synaptic release machinery, including synaptic vesicle 2A (SV2A) and α2δ; or by blockade of ionotropic glutamate receptors, including α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors. The ketogenic diet leads to increases in circulating ketones, which may contribute to the efficacy in treating pharmacoresistant seizures. Production in the brain of inhibitory mediators, such as adenosine, or ion channel modulators, such as polyunsaturated fatty acids, may also play a role. Metabolic effects, including diversion from glycolysis, are a further postulated mechanism. For some ASDs and the ketogenic diet, effects on multiple targets may contribute to activity. Better understanding of the ketogenic diet will inform the development of improved drug therapies to treat refractory seizures.