Effects of Low- and High-Dose Valproic Acid and Lamotrigine on the Heart in Female Rats.

Epilepsy is a chronic neurological disease that affects more than 50 million people worldwide. Antiepileptic drugs (AEDs) are the mainstay of treatment for most patients with epilepsy. However, AEDs have been reported to be associated with adverse cardiac effects. In this study, it was aimed to investigate the possible cardiac effects of low-dose (LD) and high-dose (HD) treatment of valproic acid (VPA) and lamotrigine (LTG), which are commonly used AEDs, in rats without epilepsy. Rats were randomly grouped as control, LD-VPA, HD-VPA, LD-LTG, and HD-LTG. The cardiac effects of AEDs were evaluated using immunohistological, biochemical, and hemodynamic parameters. A dose-dependent increase in the intensity of caspase-3 staining was detected in the VPA and LTG groups. The intensity of connexin-43 and troponin-T staining in the VPA groups and desmin staining in the LTG groups was significantly reduced. Biochemically, HD-VPA and HD-LTG administrations caused a significant increase in MDA level in myocardial tissue. In addition, as a result of hemodynamic evaluations, cardiac functions were found to be affected and blood pressure increased in HD-LTG group. The results of present study support that VPA and LTG treatment can increase cardiac risk markers.

Antiepileptic drugs lamotrigine and valproate differentially affect neuronal maturation in the developing chick embryo, yet with PAX6 as a potential common mediator.

Exposing the immature nervous system to specific antiepileptic drugs (AEDs) during pregnancy is linked to neurodevelopmental disorders such as autism spectrum disorder (ASD). Newer AEDs like lamotrigine (LTG) are hailed as safer, but recent epidemiological data suggest that even LTG carries a risk, although much lower than that associated with valproic acid (VPA), an older AED, which is also known to cause morphological alterations in the developing brain. Increasing evidence highlights cerebellar abnormalities as important in ASD pathophysiology. Transcription factor PAX6 is a key activity-dependent mediator and regulates crucial processes during cerebellar development. The chicken cerebellum recapitulates important characteristics of human cerebellar development, and may thus be suitable for the assessment of interventions aiming to modify maturation and cerebellar development. In the present study, exposure of chicken on embryonic day 16 (E16) to LTG or VPA resulted in decreased cerebellar mass and level of proliferating nuclear cell antigen (PCNA) for clinically relevant concentrations of VPA. However, both AEDs reduced cerebellar protein levels of PAX6 and MMP-9 at E17. Furthermore, PAX6 immunohistochemical staining of coronal sections of chicken cerebellum showed a significant reduction in PAX6-positive cell density and changes in cerebellar cortex thickness, mostly caused by the change in IGL-layer thickness. In conclusion, prenatal exposure to LTG or VPA provoked differential maturational changes in the developing cerebellum that may reflect some of the underlying molecular mechanisms for the observed human ASD pathology after AEDs exposure during pregnancy.

Lamotrigine effects on immune gene expression in larval zebrafish.

PURPOSE: Despite growing evidence that neuroinflammation and pro-inflammatory cytokines are involved in the pathogenesis of seizures and epilepsy, this knowledge has not been incorporated in the proposed mechanism of action of any of the current antiseizure medications (ASMs). Here, we tested the hypothesis by assessing inflammation markers in larval zebrafish (Danio rerio) exposed to lamotrigine (LTG). METHODS: In order to establish the most appropriate LTG concentrations for the transcriptome analysis (RNAseq), we initially assessed for teratogenic (spinal cord deformation, heart oedema, failed inflation of the swim bladder) and behavioural effects (distance moved, time spent active, and average swimming speed during a light/dark test) in zebrafish larvae exposed to 0, 50, 100, 300, 500, 750, and 1000 µM LTG continuously between 5 and 120 h post fertilisation. Subsequently, we repeated the experiment with 0, 50, 100, or 300 µM LTG for transcriptomic analyses. Two databases (Kyoto Encyclopedia of Genes and Genomes; Gene Ontology) were used to interpret changes in gene expression between groups. RESULTS: Major teratogenic effects were observed at concentrations of ≥ 500 µM LTG, whereas behavioural changes were observed at ≥ 300 µM LTG. Transcriptome analysis revealed a non-linear response to LTG. From the suite of differentially expressed genes (DEG), 85% (n = 80 DEGs) were upregulated following exposure to 50 µM LTG, whereas 58% (n = 12 DEGs) and 91% (n = 210 DEGs) were downregulated in response to 100 and 300 µM LTG. The metabolic pathways affected following exposure to 50 and 300 µM LTG were associated with responses to inflammation and pathogens as well development and regulation of the immune system in both groups. Notable genes within the lists of DEGs included component complement 3 (C3.a), which was significantly upregulated in response to 50 µM LTG, whereas interleukin 1ß (IL-1ß) was significantly downregulated in the 300 µM LTG group. The lowest exposure of 50 µM LTG is regarded as clinically relevant to therapeutic exposure. CONCLUSION: We demonstrated that LTG had an impact on the immune system, with a non-monotonic response curve. This dose-dependent relation could indicate that LTG can affect inflammatory responses and also at clinically relevant concentration. Further studies are needed to establish this method as a tool for screening the effects of ASMs on the immune system.

Reverse translational analysis of clinically reported, lamotrigine-induced cardiovascular adverse events using the halothane-anesthetized dogs.

Lamotrigine has been used for patients with epilepsy and/or bipolar disorder, overdose of which induced the hypotension, elevation of the atrial pacing threshold, cardiac conduction delay, wide complex tachycardia, cardiac arrest and Brugada-like electrocardiographic pattern. To clarify how lamotrigine induces those cardiovascular adverse events, we simultaneously assessed its cardiohemodynamic and electrophysiological effects using the halothane-anesthetized dogs (n = 4). Lamotrigine was intravenously administered in doses of 0.1, 1 and 10 mg/kg/10 min under the monitoring of cardiovascular variables, possibly providing subtherapeutic to supratherapeutic plasma concentrations. The low or middle dose of lamotrigine did not alter any of the variables. The high dose significantly delayed the intra-atrial and intra-ventricular conductions in addition to the prolongation of ventricular effective refractory period, whereas no significant change was detected in the other variables. Lamotrigine by itself has relatively wide safety margin for cardiohemodynamics, indicating that clinically reported hypotension may not be induced through its direct action on the resistance arterioles or capacitance venules. The electrophysiological effects suggested that lamotrigine can inhibit Na+ channel in the in situ hearts. This finding may partly explain the onset mechanism of lamotrigine-associated cardiac adverse events in the clinical cases. In addition, elevation of J wave was induced in half of the animals, suggesting that lamotrigine may have some potential to unmask Brugada electrocardiographic genotype in susceptible patients.

Encefalopatía secundaria a intoxicación por lamotrigina / Encephalopathy secondary to lamotrigine toxicity

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Protective Effect of Flax Seed on Brain Teratogenicity Induced by Lamotrigine in Rat Fetuses.

The objective of this study was to assess the effects of the hydroalcoholic extract of flax seed on the teratogenic activity of lamotrigine in the brain of fetuses of rats who had received the drug. In this experimental study, 40 female rats were assigned randomly into four groups and after mating and confirming the vaginal plug, the control animals (group 1) were kept with no intervention, and the other three experimental groups were intraperitoneally injected with respective lamotrigine (75 mg/kg), and 100 and 200 mg/kg of flax seed hydroalcoholic extract. The drug was administered during the organogenesis period. Rats were sacrificed at the 20th day of gestation (one day before term) and fetuses were macroscopically examined, weighed and crown-rump length measured. Fetal brain specimens were processed for H&E and for histological study, using the ImageJ software. Results showed that fetuses of the experimental groups that received lamotrigine had reduced body weight, prefrontal cortical and hippocampal thickness, and pyramidal neurons in the hip-pocampus; Nevertheless, these factors were improved by high-dose administration of flax seed in the experimental group 3 and 4. Our research concludes that lamotrigine negatively influences the development of brain in rats and flax seed has a protective impact on these complications.

Misdiagnosis of lamotrigine toxicity as posterior circulation transient ischemic attack or stroke.

PURPOSE: Lamotrigine (LTG) is one of the most used antiseizure medications (ASMs). Titration is indicated for incomplete seizure control, but toxicity with vertigo, ataxia, and diplopia may ensue. Lamotrigine concentration would be the optimal diagnostic test. However, patients often receive a stroke evaluation when presenting to the emergency department (ED), leading to unnecessary cost and delayed management. We investigated the frequency of stroke evaluation for symptoms associated with LTG toxicity and attempted to identify factors leading to this expensive evaluation. METHODS: We identified adult patients treated with LTG who presented to an emergency room with dizziness, ataxia, or diplopia and received a negative stroke evaluation, between 2003 and 2018. They were among 972 patients treated with LTG for epilepsy. We collected age at time of occurrence, symptoms presented, imaging studies performed, LTG dose and serum concentration, and the time the result was available. As a denominator, we also identified patients who developed clinical LTG toxicity during the same time period. RESULTS: Thirteen patients with LTG toxicity had 16 negative stroke evaluations in the emergency room. Their mean age was 62 years (range: 43-79) as compared with 47 years for all patients treated with LTG (p < 0.0005). The mean daily LTG dose was 621 mg (range: 300-900 mg). A LTG serum concentration was requested on the day of evaluation in 7 instances, though the result was never available until at least the next day. In 4 instances, the LTG level was drawn 1-3 days after presentation. Five of the patients in this group were among 71 patients with clinical LTG toxicity and LTG concentration >20. CONCLUSION: Emergency departments will frequently call a stroke alert for patients taking LTG and presenting with symptoms consistent with LTG toxicity, particularly in seniors at greater risk of stroke. This adds not only expense but also radiation and contrast exposure from computed tomography (CT) studies. We recommend that a rapid LTG assay be made available and always ordered in patients receiving LTG, avoiding the considerable expense of an unnecessary stroke evaluation.

Lamotrigine Toxicosis Treated with Intravenous Lipid Emulsion Therapy in a Dog.

A female spayed dachshund/mixed-breed dog was evaluated following ingestion of lamotrigine tablets with subsequent rapid onset of vomiting, diarrhea, and generalized tremoring. On initial examination, the dog was moderately obtunded and nonambulatory with intermittent myoclonus and hyperesthesia. Electrocardiogram revealed sinus tachycardia with prolongation of the QT interval. Intravenous lipid emulsion (ILE) infusion was initiated, with reduction in tremoring and improved patient mentation being noted after ∼20 min of therapy. An elevated cardiac troponin I value measured at 1.02 ng/mL the day after presentation. Serum toxicological assay revealed marked reduction in serum lamotrigine levels following ILE and continued reduction during hospitalization. The dog's clinical signs resolved, corrected QT interval returned to normal, and the patient was discharged 38 hr after presentation. Individual cases of lamotrigine toxicosis have not been fully reported in veterinary literature. This case report documents the rapid onset of clinical signs including neurologic dysfunction, cardiac arrhythmias, and transient corrected QT prolongation. Serial serum concentrations of lamotrigine showed a rapid reduction with ILE therapy and corresponded with clinical recovery, suggesting efficacy of ILE treatment in this case.

Therapeutic Effects of Mesenchymal Stem Cells on a Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis Model.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are the most severe cutaneous drug hypersensitivity reactions, which are unpredictable adverse drug reactions. SJS/TEN is associated with significant mortality and morbidity; however, effective treatment is difficult. Mesenchymal stem cells (MSCs) are well-known for their anti-inflammatory and tissue regeneration properties. The purpose of the present study was to verify whether MSCs could be applied for the treatment of SJS/TEN. We developed an SJS/TEN mouse model using peripheral blood mononuclear cells from a lamotrigine-induced SJS patient. MSCs were injected into the model to verify the treatment effect. In SJS model mice treated with MSCs, ocular damage rarely occurred, and apoptosis rate was significantly lower. We demonstrated a therapeutic effect of MSCs on SJS/TEN, with these cells presenting a potential novel therapy for the management of this disorder.

Delirium Secondary to Lamotrigine Toxicity.

BACKGROUND: Lamotrigine is a phenyltriazine medication that has been approved by the United States Food and Drug Administration as monotherapy and as an adjunctive agent for the treatment of seizure disorder. It was later approved by the FDA for the treatment of bipolar disorder. Lamotrigine is generally well tolerated by patients, but some serious symptoms can occur during treatment. These severe side effects include rashes and multi-organ failure. Lamotrigine has also been associated with the development of mental status changes, frequently when used concurrently with other medications that may impact the metabolism of lamotrigine. OBJECTIVE: To present the case of a 65-year-old man being treated with lamotrigine and valproic acid who developed mental status changes after the addition of sertraline to his medication regimen, and to compare this case to existing cases reported in the literature. DISCUSSION: Our case adds to the existing literature by demonstrating that patients may experience adverse medication effects despite lamotrigine levels that are normally considered to be in the therapeutic range, highlighting the importance of clinical correlation when obtaining medication levels. CONCLUSION: Clinicians should use caution interpreting lamotrigine levels when working up delirium, as normal levels may not rule out the development of lamotrigine toxicity.

Safety evidence on the administration of Fucus vesiculosus L. (bladderwrack) extract and lamotrigine: data from pharmacokinetic studies in the rat.

Fucus vesiculosus is often incorporated in weight loss dietary supplements to improve weight loss in overweight adults. Obesity is a common condition in epilepsy patients and is indeed increasing in refractory epilepsy and in patients under polytherapy. Since lamotrigine (LTG) is a first-line antiepileptic drug, used in monotherapy or adjunctive therapy, the main objective of this work was to investigate the potential pharmacokinetic-based interactions between F. vesiculosus and LTG in rats. In a first pharmacokinetic study, a single oral dose of F. vesiculosus extract (575 mg/kg, p.o.) was co-administered with a single-dose of LTG (10 mg/kg, p.o.). In a second study, rats were orally pretreated with F. vesiculosus extract (575 mg/kg/day, p.o.) for 14 days and received LTG (10 mg/kg, p.o.) on the 15th day. In the control groups, rats received water instead of the extract. After LTG administration, blood samples were taken until 96 h post-dose, and LTG concentrations measured in plasma were submitted to a non-compartmental pharmacokinetic analysis. The co-administration of F. vesiculosus extract and LTG caused no significant changes in the drug kinetics. However, the repeated pretreatment with F. vesiculosus extract significantly reduced the peak concentrations of LTG and caused a slightly decrease in the extent of systemic drug exposure. Overall, based on these results, no significant clinical impact is expected from the administration of F. vesiculosus dietary supplements and LTG.

Evaluation of Teratogenic Activity of Antiepileptic Drug Lamotrigine in Mouse Fetuses.

BACKGROUND: Use of antiepileptic drugs during pregnancy can be associated with an increased risk of teratogenicity as well as congenital abnormalities. However, there are numerous discrepancies to determine whether lamotrigine, as an antiepileptic drug, can significantly induce malformation in newborn infants or not. Thus, the purpose of the study was to evaluate the teratogenic effects of lamotrigine on mouse fetuses. MATERIALS AND METHODS: In the present study, 21 pregnant mice were assigned to four groups. Groups 1 and 2 (controls) received mock treatment and ethanol 20%, respectively. Groups 3 and 4 (treatment) were intraperitoneally administered with 25 and 75 mg/kg lamotrigine for three days, respectively. The treatment protocol was performed within the gestational days of 9-18 in all groups. On gestational day 18, 117 fetuses were taken out of the fallopian tube of studied mice and then examined for any anomalies (vertebral, limbs and cranial), followed by a measurement of their height and weight. RESULTS: The results revealed that, in the treated groups, the weight and the height had significantly decreased (p<0.01) and also various anomalies were evident. Moreover, as the dose of lamotrigine increased, the decrease in the weight and the height and rising trend in anomalies were intensified. CONCLUSION: According to the findings, lamotrigine (LTG) could be considered as a risk factor for the development of the anomalies examined.

Strain and interindividual differences in lamotrigine-induced liver injury in mice.

Lamotrigine (LTG) has been widely prescribed as an antipsychotic drug, although it causes idiosyncratic drug-induced liver injury in humans. LTG is mainly metabolized by UDP-glucuronosyltransferase, while LTG undergoes bioactivation by cytochrome P450 to a reactive metabolite; it is subsequently conjugated with glutathione, suggesting that reactive metabolite would be one of the causes for LTG-induced liver injury. However, there is little information regarding the mechanism of LTG-induced liver injury in both humans and rodents. In this study, we established an LTG-induced liver injury mouse model through co-administration with LTG and a glutathione synthesis inhibitor, l-buthionine-(S,R)-sulfoximine. We found an increase in alanine aminotransferase (ALT) levels (>10 000 U/L) in C57BL/6J mice, with apparent interindividual differences. On the other hand, a drastic increase in ALT was not noted in BALB/c mice, suggesting that the initiation mechanism would be different between the two strains. To examine the cause of interindividual differences, C57BL/6J mice that were co-administered LTG and l-buthionine-(S,R)-sulfoximine were categorized into three groups based on ALT values: no-responder (ALT <100 U/L), low-responder (100 U/L < ALT < 1000 U/L) and high-responder (ALT >1000 U/L). In the high-responder group, induction of hepatic oxidative stress, inflammation and damage-associated molecular pattern molecules in mRNA was associated with vacuolation and karyorrhexis in hepatocytes. In conclusion, we demonstrated that LTG showed apparent strain and interindividual differences in liver injuries from the aspects of initiation and exacerbation mechanisms. These results would support interpretation of the mechanism of LTG-induced liver injury observed in humans.