Pharmacogenetics of adverse reactions to antiepileptic drugs

CYP2C19 genotype-phenotype correlation: current insights and unanswered questions

The CYP2C19 enzyme is implicated in the metabolism of several clinically used drugs. Its phenotype is usually predicted by genotyping and indicates the expected enzymatic activity for each patient. However, with a few exceptions, CYP2C19 genotyping has not resulted in a reliable prediction of the metabolizer status, since most of the evidence currently available for this prediction comes from research into populations of predominantly European ancestry. Therefore, this review discusses the main factors that may alter the expected phenotype, as well as the urgent need to include ethnically diverse populations in further studies, so that, in the long term, it is possible to establish guidelines appropriate to these groups.

Causes and Management of Cutaneous Adverse Drug Reactions: A Comprehensive Review

Cutaneous adverse drug reactions (CADRs) are one of the most broadly studied and rigorously researched conditions in recent dermatological advancements. Also termed as "toxidermia," they are heavily involved and are of utmost importance to be understood and studied in the modern healthcare industry. In simple terms, they are dermatological manifestations which result from systemic drug administration to patients. Since allopathy is influenced by the medicines and drugs provided to the patients, cutaneous skin eruptions are a common occurrence in recent times. It is a need of the hour to understand the causative factors for such skin eruptions and the correct management and handling of such disorders to provide better healthcare to patients. The withdrawal of the causative drug which induces the reaction plays a key role in treatment. The risk factors are to be thoroughly studied, and dosages must be in accordance with the patient's situation. They are some of the common public health problems. The age group which is affected is highly variable as people from all age groups can be affected. Those who are affected comprise approximately 10% of all hospitalized patients, and it is also observed in about 1-4% of people who are on multiple medications.

The standardized extract of Centella asiatica L. Urb attenuates the convulsant effect induced by lithium/pilocarpine without affecting biochemical and haematological parameters in rats

BACKGROUND

Status epilepticus (SE) is a type of epileptic activity characterized by a failure of the inhibitory mechanisms that limit seizures, which are mainly regulated by the GABAergic system. This imbalance increases glutamatergic neurotransmission and consequently produces epileptic activity. It is also associated with oxidative stress due to an imbalance between reactive oxygen species (ROS) and antioxidant defences. Unfortunately, long-term treatment with anti-epileptic drugs (AEDs) may produce hepatotoxicity, nephrotoxicity, and haematological alterations. In this way, some secondary metabolites of plants have been used to ameliorate the deterioration of nervous system disorders through their antioxidant properties, in addition to their anticonvulsant effects. An example is Centella asiatica, a plant noted to have a reputed neuroprotective effect related to its antioxidant activity. However, similar to conventional drugs, natural molecules may produce side effects when consumed in high doses, which could occur with Centella asiatica. Therefore, we aimed to evaluate the effect of a standardized extract of Centella asiatica L. Urb with tested anticonvulsant activity on biochemical and haematological parameters in rats subjected to lithium/pilocarpine-induced seizures.

METHODS

Twenty-eight adult male Wistar rats were randomly divided into four groups (n = 7 each): vehicle (purified water), Centella asiatica (200 and 400 mg/kg), and carbamazepine (CBZ) (300 mg/kg) as a pharmacological control of anticonvulsant activity. Treatments were administered orally every 24 h for 35 consecutive days. On Day 36, SE was induced using the lithium/pilocarpine model (3 mEq/kg, i.p. and 30 mg/kg s.c., respectively), and the behavioural and biochemical effects were evaluated.

RESULTS

Centella asiatica 400 mg/kg increased the latency to the first generalized seizure and SE onset and significantly reduced the time to the first generalized seizure compared to values in the vehicle group. Biochemical parameters, i.e., haematic cytometry, blood chemistry, and liver function tests, showed no significant differences among the different treatments.

CONCLUSION

The dose of Centella asiatica that produces anticonvulsant activity in the lithium/pilocarpine model devoid of hepatotoxicity, nephrotoxicity, and alterations in haematological parameters suggests that the standardized extract of this plant could be of utility in the development of new safe therapies for the treatment of convulsions associated with epilepsy.

Predictors of adverse effects to antiseizure drugs in adult patients with epilepsy from Colombia: A case-control study

INTRODUCTION

Adverse drug reactions (ADRs) to antiseizure therapy can worsen the quality of life, reduce adherence, and potentially lead to treatment discontinuation and uncontrolled seizures.

OBJECTIVES

The aim of the study was to develop a prognostic model for ADRs to antiseizure therapy in adult patients with epilepsy from Colombia.

METHODS

This case-control study included adult patients with epilepsy, who were separated into two groups: one group with ADRs to antiseizure therapy (cases), as determined by a complete evaluation conducted by an epileptologist, and another group without ADRs (controls). Variables were analyzed to identify statistical differences between the two groups and were then selected to construct a prognostic model using logistic regression. The Bonferroni method was applied for multiple comparisons.

RESULTS

Three hundred fifty-four patients with epilepsy were studied. One hundred and fifty (42%) patients had ADRs and 204 (57%) patients did not have ADs. A total of 362 ADRs were reported, with a third of them being general symptoms and most frequently occurring with older-generation antiseizure drugs (58%). Female sex, drug-resistant epilepsy, LEV, and CZP were risk factors, whereras the presence of tumoral etiology, absence of seizure triggers, and VPA were identified as protective factors. A prognostic model was constructed using previously reported risk factors for ADRs to antiseizure therapy and other variables available in this population study. In the multivariable analysis, the number of previously used antiseizure drugs (1, 2, or ≥3), TPM, CZP, LEV, PHT, and female sex were predictors of ADRs. The corrected p-values were estimated by the Bonferroni method; however, not all the variables achieved statistical significance with this adjustment.

CONCLUSIONS

In adult patients with epilepsy from Colombia, we found that the number of previously used antiseizure drugs, TPM, CZP, LEV, PHT, and female sex were predictive factors for ADRs to antiseizure therapy.

SCN1A Polymorphisms and Haplotypes Are Associated With Valproic Acid Treatment Outcomes in Chinese Children With Epilepsy

BACKGROUND

Sodium channel genes, especially SCN1A, were reported to play an important role in the treatment outcomes of antiseizure medications. The aim of this study was to explore the association of SCN1A polymorphisms with efficacy and adverse drug reactions (ADRs) related to valproic acid (VPA) among Chinese children with epilepsy.

METHODS

A total of 126 children with epilepsy treated with VPA for at least 12 months were enrolled in this study. Three single nucleotide polymorphisms (SNPs) of SCN1A including rs2298771, rs10167228, and rs3812718 were genotyped using Sequenom MassArray system. Bioinformatics tools were used to explore the potential targets and pathways of SCN1A in VPA-related ADRs.

RESULTS

The three SNPs in this study were found to be closely associated with treatment outcomes for VPA. Carriers of SCN1A rs3812718 TT genotype tended to be seizure-free with VPA treatment (P = 0.007). AA genotype of rs10167228 and TT genotype of rs2298771 might be protective factors for weight gain induced by VPA, whereas TA genotype of rs10167228 and CT genotype of rs2298771 increased the risk. TAT haplotype carriers were found to respond better to VPA treatment (P = 0.017), whereas CTC haplotype might be a risk factor for VPA-induced weight gain (P = 0.035). Bioinformatics analysis suggested that SCN1A might play a role in VPA-induced weight gain by regulating gated channel activity and GABAergic synapse pathway.

CONCLUSION

This study revealed that SCN1A rs2298771, rs10167228, and rs3812718 polymorphisms and haplotypes might affect the treatment outcomes of VPA in Chinese children with epilepsy.

Low-intensity exercise combined with sodium valproate attenuates kainic acid-induced seizures and associated co-morbidities by inhibiting NF-κB signaling in mice

Sodium valproate (VPA) is a broad-spectrum anticonvulsant that is effective both in adults and children suffering from epilepsy, but it causes psychiatric and behavioral side effects in patients with epilepsy. In addition, 30% of patients with epilepsy develop resistance to VPA. At present, regular physical exercise has shown many benefits and has become an effective complementary therapy for various brain diseases, including epilepsy. Therefore, we wondered whether VPA combined with exercise would be more effective in the treatment of seizures and associated co-morbidities. Here, we used a mouse model with kainic acid (KA)-induced epilepsy to compare the seizure status and the levels of related co-morbidities, such as cognition, depression, anxiety, and movement disorders, in each group using animal behavioral experiment and local field potential recordings. Subsequently, we investigated the mechanism behind this phenomenon by immunological means. Our results showed that low-intensity exercise combined with VPA reduced seizures and associated co-morbidities. This phenomenon seems to be related to the Toll-like receptor 4, activation of the nuclear factor kappa B (NF-κB), and release of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and IL-6. In brief, low-intensity exercise combined with VPA enhanced the downregulation of NF-κB-related inflammatory response, thereby alleviating the seizures, and associated co-morbidities.

Anticonvulsant Effect of Turmeric and Resveratrol in Lithium/Pilocarpine-Induced Status Epilepticus in Wistar Rats

Epilepsy is a chronic neurological disorder that lacks a cure. The use of plant-derived antioxidant molecules such as those contained in turmeric powder and resveratrol may produce short-term anticonvulsant effects. A total of 42 three-month-old male Wistar rats were divided into six groups (n = 7 in each group): Vehicle (purified water), turmeric (150 and 300 mg/kg, respectively), and resveratrol (30 and 60 mg/kg, respectively), administered per os (p.o.) every 24 h for 35 days. Carbamazepine (300 mg/kg/5 days) was used as a pharmacological control for anticonvulsant activity. At the end of the treatment, status epilepticus was induced using the lithium-pilocarpine model [3 mEq/kg, intraperitoneally (i.p.) and 30 mg/kg subcutaneously (s.c.), respectively]. Seizures were evaluated using the Racine scale. The 300 mg/kg of turmeric and 60 mg/kg of resveratrol groups had an increased latency to the first generalized seizure. The groups treated with 150 and 300 mg/kg of turmeric and 60 mg/kg of resveratrol also had an increased latency to status epilepticus and a decreased number of generalized seizures compared to the vehicle group. The chronic administration of turmeric and resveratrol exerts anticonvulsant effects without producing kidney or liver damage. This suggests that both of these natural products of plant origin could work as adjuvants in the treatment of epilepsy.

AS3MT Polymorphism: A Risk Factor for Epilepsy Susceptibility and Adverse Drug Reactions to Valproic Acid and Oxcarbazepine Treatment in Children From South China

Epilepsy is a common neurologic disorder characterized by intractable seizures, involving genetic factors. There is a need to develop reliable genetic markers to predict the risk of epilepsy and design effective therapies. Arsenite methyltransferase (AS3MT) catalyzes the biomethylation of arsenic and hence regulates arsenic metabolism. AS3MT variation has been linked to the progression of various diseases including schizophrenia and attention deficit or hyperactivity disorder. Whether genetic polymorphism of AS3MT contributes to epilepsy remains unclear. In this study, we investigated the association of AS3MT gene polymorphism with susceptibility to epilepsy in children from south China. We also explored the effect of AS3MT variation on the safety of antiepileptic drugs. Genotypic analysis for AS3MT rs7085104 was performed using samples from a Chinese cohort of 200 epileptic children and 244 healthy individuals. The results revealed a genetic association of AS3MT rs7085104 with susceptibility to pediatric epilepsy. Mutant homozygous GG genotype exhibited a lower susceptibility to childhood epilepsy than AA genotype. Carriers of AS3MT rs7085104 AA genotype exhibited a higher risk of digestive adverse drug reactions (dADRs) in children when treated with valproic acid (VPA) or oxcarbazepine (OXC). Additionally, bioinformatics analysis identified eight AS3MT target genes related to epilepsy and three AS3MT-associated genes in VPA-related dADRs. The effects of AS3MT on epilepsy might involve multiple targets including CNNM2, CACNB2, TRIM26, MTHFR, GSTM1, CYP17A1, NT5C2, and YBX3. This study reveals that AS3MT may be a new gene contributing to epileptogenesis. Hence, analysis of AS3MT polymorphisms will help to evaluate susceptibility to pediatric epilepsy and drug safety.

Role of Pharmacogenetics in Adverse Drug Reactions: An Update towards Personalized Medicine

Adverse drug reactions (ADRs) are an important and frequent cause of morbidity and mortality. ADR can be related to a variety of drugs, including anticonvulsants, anaesthetics, antibiotics, antiretroviral, anticancer, and antiarrhythmics, and can involve every organ or apparatus. The causes of ADRs are still poorly understood due to their clinical heterogeneity and complexity. In this scenario, genetic predisposition toward ADRs is an emerging issue, not only in anticancer chemotherapy, but also in many other fields of medicine, including hemolytic anemia due to glucose-6-phosphate dehydrogenase (G6PD) deficiency, aplastic anemia, porphyria, malignant hyperthermia, epidermal tissue necrosis (Lyell's Syndrome and Stevens-Johnson Syndrome), epilepsy, thyroid diseases, diabetes, Long QT and Brugada Syndromes. The role of genetic mutations in the ADRs pathogenesis has been shown either for dose-dependent or for dose-independent reactions. In this review, we present an update of the genetic background of ADRs, with phenotypic manifestations involving blood, muscles, heart, thyroid, liver, and skin disorders. This review aims to illustrate the growing usefulness of genetics both to prevent ADRs and to optimize the safe therapeutic use of many common drugs. In this prospective, ADRs could become an untoward "stress test," leading to new diagnosis of genetic-determined diseases. Thus, the wider use of pharmacogenetic testing in the work-up of ADRs will lead to new clinical diagnosis of previously unsuspected diseases and to improved safety and efficacy of therapies. Improving the genotype-phenotype correlation through new lab techniques and implementation of artificial intelligence in the future may lead to personalized medicine, able to predict ADR and consequently to choose the appropriate compound and dosage for each patient.

Evolving Role of Pharmacogenetic Biomarkers to Predict Drug-Induced Hematological Disorders

ABSTRACT

Drug-induced hematological disorders constitute up to 30% of all blood dyscrasias seen in the clinic. Hematologic toxicity from drugs may range from life-threatening marrow aplasia, agranulocytosis, hemolysis, thrombosis to mild leukopenia, and thrombocytopenia. Pathophysiologic mechanisms underlying these disorders vary from an extension of the pharmacological effect of the drug to idiosyncratic and immune-mediated reactions. Predicting these reactions is often difficult, and this makes clinical decision-making challenging. Evidence supporting the role of pharmacogenomics in the management of these disorders in clinical practice is rapidly evolving. Despite the Clinical Pharmacology Implementation Consortium and Pharmacogenomics Knowledge Base recommendations, few tests have been incorporated into routine practice. This review aims to provide a comprehensive summary of the various drugs which are implicated for the hematological adverse events, their underlying mechanisms, and the current evidence and practical recommendations to incorporate pharmacogenomic testing in clinical care for predicting these disorders.

An Insight into Molecular Mechanisms and Novel Therapeutic Approaches in Epileptogenesis

Epilepsy is the second most common neurological disease with abnormal neural activity involving the activation of various intracellular signalling transduction mechanisms. The molecular and system biology mechanisms responsible for epileptogenesis are not well defined or understood. Neuroinflammation, neurodegeneration and Epigenetic modification elicit epileptogenesis. The excessive neuronal activities in the brain are associated with neurochemical changes underlying the deleterious consequences of excitotoxicity. The prolonged repetitive excessive neuronal activities extended to brain tissue injury by the activation of microglia regulating abnormal neuroglia remodelling and monocyte infiltration in response to brain lesions inducing axonal sprouting contributing to neurodegeneration. The alteration of various downstream transduction pathways resulted in intracellular stress responses associating endoplasmic reticulum, mitochondrial and lysosomal dysfunction, activation of nucleases, proteases mediated neuronal death. The recently novel pharmacological agents modulate various receptors like mTOR, COX-2, TRK, JAK-STAT, epigenetic modulators and neurosteroids are used for attenuation of epileptogenesis. Whereas the various molecular changes like the mutation of the cell surface, nuclear receptor and ion channels focusing on repetitive episodic seizures have been explored by preclinical and clinical studies. Despite effective pharmacotherapy for epilepsy, the inadequate understanding of precise mechanisms, drug resistance and therapeutic failure are the current fundamental problems in epilepsy. Therefore, the novel pharmacological approaches evaluated for efficacy on experimental models of epilepsy need to be identified and validated. In addition, we need to understand the downstream signalling pathways of new targets for the treatment of epilepsy. This review emphasizes on the current state of novel molecular targets as therapeutic approaches and future directions for the management of epileptogenesis. Novel pharmacological approaches and clinical exploration are essential to make new frontiers in curing epilepsy.

The art and science of drug titration

A “one-size-fits-all” approach has been the standard for drug dosing, in particular for agents with a wide therapeutic index. The scientific principles of drug titration, most commonly used for medications with a narrow therapeutic index, are to give the patient adequate and effective treatment, at the lowest dose possible, with the aim of minimizing unnecessary medication use and side effects. The art of drug titration involves the interplay of scientific drug titration principles with the clinical expertise of the healthcare provider, and an individualized, patient-centered partnership between the provider and the patient to review the delicate balance of perceived benefits and risks from both perspectives. Drug titration may occur as up-, down-, or cross-titration depending on whether the goal is to reach or maintain a therapeutic outcome, decrease the risk of adverse effects, or prevent withdrawal/discontinuation syndromes or recurrence of disease. Drug titration introduces additional complexities surrounding the conduct of clinical trials and real-world studies, confounding our understanding of the true effect of medications. In clinical practice, wide variations in titration schedules may exist due to a lack of evidence and consensus on titration approaches that achieve an optimal benefit-harm profile. Further, drug titration may be challenging for patients to follow, resulting in suboptimal adherence and may require increased healthcare-related visits and coordination of care amongst providers. Despite the challenges associated with drug titration, it is a personalized approach to drug dosing that blends science with art, and with supportive real-world outcomes-based evidence, can be effective for optimizing pharmacotherapeutic outcomes and improving drug safety.

Cost-utility model of brivaracetam in the adjunctive treatment of patients with epilepsy in Spain

OBJECTIVE

This study aims to assess the cost utility of Brivaracetam compared with the third-generation anti-epileptic drugs used as standard care.

METHODS

A cost utility analysis of Brivaracetam was carried out with other third-generation comparators. The treatment pathway of a hypothetical cohort over a period of 2 years was simulated using the Markov model. Data for effectiveness and the QALYs of each health status for epilepsy, as well as for the disutilities of adverse events of treatments, were analyzed through a studies review. The cost of the anti-epileptics and the use of medical resources linked to the different health statuses were taken into consideration. A probabilistic sensitivity analysis was performed using a Monte Carlo simulation.

RESULTS

Brivaracetam was shown to be the dominant alternative, with Incremental Cost Utility Ratio (ICUR) values from -11,318 for Lacosamide to -128,482 for Zonisamide. The probabilistic sensitivity analysis validates these results. The ICUR sensitivity is greater for increases in the price of Brivaracetam than for decreases, and for Eslicarbizapine over the other adjunctives considered in the analysis.

CONCLUSIONS

Treatment with Brivaracetam resulted in cost effective and incremental quality adjusted life years come at an acceptable cost.

Adverse Skin Reactions with Antiepileptic Drugs Using Korea Adverse Event Reporting System Database, 2008-2017

BACKGROUND

Severe and life-threatening drug eruptions include drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). One class of medications that has been highly associated with such drug eruptions is antiepileptic drugs (AEDs). We attempt to investigate drug eruptions associated with AEDs as a class, as well as with individual AEDs, in Korea.

METHODS

We used the Korea Institute of Drug Safety and Risk Management - Korea Adverse Event Reporting System (KIDS-KAERS) database, a nationwide database of adverse events reports, between January 2008 and December 2017 to investigate the reporting count of all drug eruptions and calculated the ratio of DRESS/SJS/TEN reports for each AED.

RESULTS

Among a total of 2,942 reports, most were of rash/urticaria (2,702, 91.8%), followed by those of DRESS (109, 3.7%), SJS (106, 3.6%), and TEN (25, 0.85%). The common causative AEDs were lamotrigine (699, 23.8%), valproic acid (677, 23%), carbamazepine (512, 17.4%), oxcarbazepine (320, 10.9%), levetiracetam (181, 6.2%), and phenytoin (158, 5.4%). In limited to severe drug eruptions (DRESS, SJS, and TEN; total 241 reports), the causative AEDs were carbamazepine (117, 48.8%), lamotrigine (57, 23.8%), valproic acid (20, 8.3%), phenytoin (15, 6.3%), and oxcarbazepine (10, 4.2%). When comparing aromatic AED with non-aromatic AED, aromatic AEDs were more likely to be associated with severe drug eruption (aromatic AEDs: 204/1,793 versus non-aromatic AEDs: 37/1,149; OR, 3.86; 95% CI, 2.7-5.5). Death was reported in 7 cases; DRESS was the most commonly reported adverse event (n = 5), and lamotrigine was the most common causative AED (n = 5).

CONCLUSION

Although most cutaneous drug eruptions in this study were rash or urticaria, approximately 8% of reports were of severe or life-threatening adverse drug reactions, such as SJS, TEN, or DRESS. When hypersensitivity skin reactions occurred, aromatic AEDs were associated with 4 fold the risk of SJS/TEN/DRESS compared with non-aromatic AEDs. Our findings further emphasize that high risk AEDs should be prescribed under careful monitoring, and early detection and prompt interventions are needed to prevent severe complications.

Study of the allelic variants CYP2C9*2 and CYP2C9*3 in samples of the Peruvian mestizo population

Introducción.

El citocromo CYP2C9 metaboliza, aproximadamente, el 15 % de los fármacos prescritos. Su gen presenta alelos cuyas frecuencias difieren entre grupos étnicos y poblaciones. Los alelos CYP2C9*2 y CYP2C9*3 dan cuenta de una enzima con actividad disminuida cuya frecuencia no ha sido determinada en la población mestiza peruana.

Objetivo.

Caracterizar la frecuencia de las variantes *2 (rs1799853) y *3 (rs1057910) del gen CYP2C9 en muestras de población mestiza peruana provenientes de Lima, Tacna y Junín.

Materiales y métodos.

Se hizo un estudio descriptivo, observacional y prospectivo, con muestreo no probabilístico, por conveniencia e incidental. Se incluyeron 218 sujetos según los criterios de inclusión y exclusión; todos los participantes otorgaron su consentimiento informado. El ADN genómico se obtuvo mediante hisopado de mucosa oral, y la detección de los genotipos para los alelos CYP2C9*2 y CYP2C9*3 se hizo mediante reacción en cadena de la polimerasa (PCR) en tiempo real, utilizando sondas TaqMan™.

Resultados.

Las variantes de CYP2C9*2 y CYP2C9*3 están presentes en la población mestiza peruana con frecuencias de 0,046 y 0,062, respectivamente. El análisis de las frecuencias genotípicas observadas permitió predecir que la frecuencia de fenotipos metabolismo intermedio sería del 15,13 % (CYP2C9*1/*2: 5,96 %; CYP2C9*1/*3: 9,17 %), y la de fenotipos de metabolismo lento, del 3,22 % (CYP2C9*2/*2: 1,38 %; CYP2C9*3/*3: 1,38 %; CYP2C9*2/*3: 0,46 %).

Conclusiones.

Se lograron determinar las frecuencias genotípicas y alélicas para las variantes *2 y *3 del gen CYP2C9 en una muestra no probabilística de población mestiza peruana. Las frecuencias obtenidas (0,046 y 0,062, respectivamente) están entre las esperadas para una población mestiza sudamericana con ascendencia amerindia, europea, africana y asiática.

Adverse drug reactions associated with six commonly used antiepileptic drugs in southern China from 2003 to 2015

BACKGROUND

This active, open observational study aimed to investigate adverse drug reactions (ADRs) associated with six commonly used antiepileptic drugs (AEDs) in southern Chinese outpatients with epilepsy from 2003 to 2015.

METHODS

The Wenzhou Epilepsy Follow-Up Registry Database (WEFURD) was established by a single epilepsy center in China in January 2003 to record AED efficacy and the associated ADRs by registered outpatients diagnosed with epilepsy. We reviewed the data of outpatients who had only taken one or more of six commonly used AEDs, namely, carbamazepine (CBZ), valproate (VPA), lamotrigine (LTG), oxcarbazepine (OXC), topiramate (TPM) and levetiracetam (LEV), and were registered in the WEFURD between 2003 and 2015. We evaluated the ADRs caused by the single or combined use of the above six specific AEDs based on the WHO-UMC scale. The data of the ADRs were categorized by age, sex, number of AEDs related to ADRs, medications, seriousness of ADRs, causality levels of the WHO-UMC scale and system organ class (SOC). The unit of analysis was one ADR.

RESULTS

A total of 3069 epilepsy outpatients (1807 outpatients with 5049 eligible ADRs and 1262 outpatients without ADRs) were included. The overall ADR rate was 58.88% (1807/3069). An average of 2.79 ADRs (5049/1807) occurred per patient with an ADR; 53.8% of the 5049 ADRs were recorded in females, and 50.4% were caused by monotherapy. Of the ADRs, 10.6% (537/5049) were severe adverse reactions (SARs), including 34 serious adverse effects (SAEs). The SAR rates caused by one, two and three or more AEDs were 9.9, 10.0 and 19.6%, respectively (p <  0.001). Eighteen SOC categories were identified, and the top three were psychiatric disorders (1633/5049, 32.3%), neurological disorders (1222/5049, 24.2%) and gastrointestinal disorders (564/5049, 11.2%). Of the 537 SARs, skin and appendage disorders accounted for 24.4% (131/537). Among the 34 SAEs, serious allergies, fetal malformations, renal calculus and pancreatitis accounted for the majority.

CONCLUSIONS

Our findings suggest that clinicians should pay attention to psychiatric ADRs and be alert for SARs, especially when three or more AEDs are used together. Moreover, active surveillance might provide another method of pharmacovigilance in China.

Lamotrigine-Valproic Acid Interaction Leading to Stevens-Johnson Syndrome

Lamotrigine (LTG) is currently indicated as adjunctive therapy for focal and generalized tonic-clonic seizures and for treatment of bipolar disorder and neuropathic pain. A common concern with LTG in children is the frequency of appearance of skin rash. The intensity of this adverse effect can vary from transient mild rash to Stevens–Johnson syndrome (SJS), which can be fatal mainly when LTG is coadministered with valproic acid (VPA). Hereby, we present the case of an 8-year-old boy who suffered from SJS and other complications two weeks after LTG was added to his VPA treatment in order to control his seizures. VPA is known to decrease LTG clearance via reduced glucuronidation. In this case, the minor elimination pathway of LTG would play a more important role, and the formation of an arene oxide metabolite would be enhanced. As this reactive metabolite is detoxified mainly by enzymatic reactions, involving microsomal epoxide hydrolase and/or GSH-S-transferases and these enzymes are polymorphically expressed in humans, arene oxide toxicity is increased when epoxide hydrolase or GSH-S-transferases is either defective or inhibited or a depletion of intracellular glutathione levels is taking place. VPA can cause inhibition of epoxide hydrolase enzymes and/or depletion of glutathione levels leading to adverse cutaneous reactions.

Carbamazepine adverse drug reactions

INTRODUCTION

Carbamazepine (CBZ) is used for the treatment of epilepsy and other neurological and psychiatric disorders. The occurrence of adverse reactions (ADRs) to CBZ can negatively impact the quality of life of patients, as well as increase health-care costs. Thus, knowledge of CBZ-induced ADRs is important to achieve safer treatment outcomes. Areas covered: This review describes the clinical features, known mechanisms, and clinical management of the main CBZ-induced ADRs. In addition, pharmacogenetic studies focused on ADRs induced by CBZ are cited. Expert commentary: CBZ-induced ADRs are well known in the literature. The metabolite CBZ-10,11-epoxide plays an important role in the mechanism that underlies the ADRs induced by CBZ. Several factors should be considered for a safer use of CBZ, such as monotherapy prescription when possible, an adequate dose titration, knowledge of previous ADRs in the patient, and routine monitoring of CBZ plasma concentrations in symptomatic patients. Pharmacogenetics is a potential tool for CBZ therapy improvement, and the design of multicenter studies focused on the identification of biomarkers for CBZ-induced ADRs could provide useful information for a safer CBZ therapy.