The importance of drug interactions in epilepsy therapy

Optimising the oral midazolam dose for premedication in people with intellectual disabilities and/or autism spectrum disorder

BACKGROUND

In people with intellectual disabilities and/or autism spectrum disorder, oral midazolam (OM) is very effective as premedication for facilitating medical treatment. In this retrospective study, we investigated the optimal dosage of OM for premedication.

METHODS

Patients with intellectual disability and/or autism spectrum disorder who were given OM as a premedication were selected from anaesthesia records. The primary outcome variable was the dose of OM (mg/kg) required to produce an adequate sedation.

RESULTS

The mean OM dose required was 0.32 ± 0.10 mg/kg. The required OM dose decreased significantly as age and weight increased, and age and weight were also shown to be significantly associated with the dose of OM in the multivariate linear regression analysis.

CONCLUSION

The dosage of OM to achieve adequate sedation should decrease as the patient ages. Furthermore, adequate sedation can be achieved with even lower doses of OM in obese people.

Intravenous Lacosamide Therapy for Pediatric Patients With Cluster Seizures

BACKGROUND

Few studies have investigated intravenous lacosamide use to treat cluster seizures in pediatric patients. Therefore, we aimed to investigate the efficacy and safety of intravenous lacosamide therapy in pediatric patients with cluster seizures.

METHODS

We retrospectively evaluated the efficacy and safety of intravenous lacosamide therapy in 25 pediatric patients with cluster seizures at Saitama Children's Medical Center between March 2019 and June 2023. Cluster seizures were defined as a single seizure of less than five minutes duration, repeated three or more times within 12 hours, with recovery of consciousness between seizures. Response was defined as seizure freedom for at least 12 hours after lacosamide infusion.

RESULTS

The median age at onset of epilepsy was 1.5 (0.0 to 9.8) years. The median seizure frequency was 5 (3 to 20) times per 12 hours. The etiologies were remote (n = 17), acute (n = 4), and progressive (n = 4). The median age at which intravenous lacosamide therapy was administered was 4.2 (0.0 to 11.3) years. The median lacosamide dose was 2.6 (1.3 to 5.2) mg/kg. In total, 12 of 25 patients (48.0%) responded. Among patients treated with intravenous lacosamide as first-line therapy, nine of 17 (52.9%) had complete seizure remission. The frequency of complete seizure remission in patients with remote etiologies was 58.8% (10 of 17); among them, seven of 12 (58.3%) patients with structural abnormalities showed complete seizure remission. No adverse events were observed.

CONCLUSIONS

Intravenous lacosamide therapy is a potentially useful treatment option for cluster seizures in pediatric patients.

Interactions between antiepileptic drugs and direct oral anticoagulants for primary and secondary stroke prevention

INTRODUCTION

Direct oral anticoagulants (DOAC) are the guideline-recommended therapy for prevention of stroke in atrial fibrillation (AF) and venous thromboembolism. Since approximately 10% of patients using antiepileptic drugs (AED) also receive DOAC, aim of this review is to summarize data about drug-drug interactions (DDI) of DOAC with AED by using data from PubMed until December 2023.

AREAS COVERED

Of 49 AED, only 16 have been investigated regarding DDI with DOAC by case reports or observational studies. No increased risk for stroke was reported only for topiramate, zonisamide, pregabalin, and gabapentin, whereas for the remaining 12 AED conflicting results regarding the risk for stroke and bleeding were found. Further 16 AED have the potential for pharmacodynamic or pharmacokinetic DDI, but no data regarding DOAC are available. For the remaining 17 AED it is unknown if they have DDI with DOAC.

EXPERT OPINION

Knowledge about pharmacokinetic and pharmacodynamic DDI of AED and DOAC is limited and frequently restricted to in vitro and in vivo findings. Since no data about DDI with DOAC are available for 67% of AED and an increasing number of patients have a combined medication of DOAC and AED, there is an urgent need for research on this topic.

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

Nonconvulsive Status Epilepticus: A Review for Emergency Clinicians

BACKGROUND

Status epilepticus is associated with significant morbidity and mortality and is divided into convulsive status epilepticus and nonconvulsive status epilepticus (NCSE).

OBJECTIVE

This review provides a focused evaluation of NCSE for emergency clinicians.

DISCUSSION

NCSE is a form of status epilepticus presenting with prolonged seizure activity. This disease is underdiagnosed, as it presents with nonspecific signs and symptoms, most commonly change in mental status without overt convulsive motor activity. Causes include epilepsy, cerebral pathology or injury, any systemic insult such as infection, and drugs or toxins. Mortality is primarily related to the underlying condition. Patients most commonly present with altered mental status, but other signs and symptoms include abnormal ocular movements and automatisms such as lip smacking or subtle motor twitches in the face or extremities. The diagnosis is divided into electrographic and electroclinical, and although electroencephalogram (EEG) is recommended for definitive diagnosis, emergency clinicians should consider this disease in patients with prolonged postictal state after a seizure with no improvement in mental status, altered mental status with acute cerebral pathology (e.g., stroke, hypoxic brain injury), and unexplained altered mental status. Assessment includes laboratory evaluation and neuroimaging with EEG. Management includes treating life-threatening conditions, including compromise of the airway, hypoglycemia, hyponatremia, and hypo- or hyperthermia, followed by rapid cessation of the seizure activity with benzodiazepines and other antiseizure medications.

CONCLUSIONS

An understanding of the presentation and management of NCSE can assist emergency clinicians in the care of these patients.

In-situ immobilization of covalent organic frameworks as stationary phase for capillary electrochromatography

A new kind of covalent organic framework (COF) was first utilized as an stationary phase for open-tubular electrochromatography (OT-CEC) by in situ synthesis immobilized method at room temperature. On the basis of our previous work, 4,4',4″-(1,3,5-Triazine-2,4,6-triyl)trianiline (TZ) and 2,5-bis(2-propyn-1-yloxy)-1,4-benzenedicarboxaldehyde (BPTA) were employed as building blocks for the synthesis of COF TZ-BPTA. The coated capillary and COF TZ-BPTA were characterized by scanning electron microscopy (SEM). Then, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were also applied to characterize COF TZ-BPTA and the modified column. In SEM, it can be seen that COF TZ-BPTA was the spherical shape and the modified capillary was covered with globular particles equably. The COF TZ-BPTA coated column exhibited good separation resolution and efficiency towards two antiepileptic drugs and other kinds of small organic molecules involving alkylbenzene, sulfonamides, polycyclic aromatic hydrocarbon (PAH), parabens, amino acids and herbicides. The maximum column efficiency was over 2.8 × 105 plates·m-1. In addition, the precisions (RSDs) of the retention times for the alkylbenzenes of intra-day runs (n = 3), inter-day runs (n = 3) and column-to-column runs (n = 3) were all less than 1.70% and separation performance was without obvious change within 100 times run. In addition, the real sample was tested on COF TZ-BPTA coated column. Hence, COF TZ-BPTA showed great potential in the separation domain.

Drug-drug interactions between antiseizure medications and antipsychotic medications: a narrative review and expert opinion

INTRODUCTION

Antiseizure medications (ASMs) and antipsychotic drugs are frequently coadministered with the potential for drug-drug interactions. Interactions may either be pharmacokinetic or pharmacodynamic, resulting in a decrease or increase in efficacy and/or an increase or decrease in adverse effects.

AREAS COVERED

The clinical evidence for pharmacokinetic and pharmacodynamic interactions between ASMs and antipsychotics is reviewed based on the results of a literature search in MEDLINE conducted in April 2023.

EXPERT OPINION

There is now extensive published evidence for the clinical importance of interactions between ASMs and antipsychotics. Enzyme-inducing ASMs can decrease blood concentrations of many of the antipsychotics. There is also evidence that enzyme-inhibiting ASMs can increase antipsychotic blood concentrations. Similarly, there is limited evidence showing that antipsychotic drugs may affect the blood concentrations of ASMs through pharmacokinetic interactions. There is less available evidence for pharmacodynamic interactions, but these can also be important, as can displacement from protein binding. The lack of published evidence for an interaction should not be interpreted as meaning that the given interaction does not occur; the evidence is building continually. There is no substitute for careful patient monitoring and sound clinical judgment.

Application of the Population Pharmacokinetics Model-Based Approach to the Prediction of Drug-Drug Interaction between Rivaroxaban and Carbamazepine in Humans

Rivaroxaban (RIV) is one of the direct oral anticoagulants used to prevent and treat venous and arterial thromboembolic events. Considering the therapeutic indications, RIV is likely to be concomitantly administered with various other drugs. Among these is carbamazepine (CBZ), one of the recommended first-line options to control seizures and epilepsy. RIV is a strong substrate of cytochrome P450 (CYP) enzymes and Pgp/BCRP efflux transporters. Meanwhile, CBZ is well known as a strong inducer of these enzymes and transporters. Therefore, drug-drug interaction (DDI) between CBZ and RIV is expected. This study aimed to predict the DDI profile of CBZ and RIV in humans by using a population pharmacokinetics (PK) model-based approach. We previously investigated the population PK parameters of RIV administered alone or with CBZ in rats. In this study, those parameters were extrapolated from rats to humans by using simple allometry and liver blood flow scaling, and then applied to back-simulate the PK profiles of RIV in humans (20 mg RIV per day) used alone or with CBZ (900 mg CBZ per day). Results showed that CBZ significantly reduced RIV exposure. The AUC_inf and C_max of RIV decreased by 52.3% and 41.0%, respectively, following the first RIV dose, and by 68.5% and 49.8% at the steady state. Therefore, the co-administration of CBZ and RIV warrants caution. Further studies investigating the extent of DDIs between these drugs should be conducted in humans to fully understand their safety and effects.

Understanding Contexts and Challenges of Information Management for Epilepsy Care

Epilepsy is a common chronic neurological disease. People with epilepsy (PWE) and their caregivers face several challenges related to their epilepsy management, including quality of care, care coordination, side effects, and stigma management. The sociotechnical issues of the information management contexts and challenges for epilepsy care may be mitigated through effective information management. We conducted 4 focus groups with 5 PWE and 7 caregivers to explore how they manage epilepsy-related information and the challenges they encountered. Primary issues include challenges of finding the right information, complexities of tracking and monitoring data, and limited information sharing. We provide a framework that encompasses three attributes - individual epilepsy symptoms and health conditions, information complexity, and circumstantial constraints. We suggest future design implications to mitigate these challenges and improve epilepsy information management and care coordination.

Magnitude of uncontrolled seizures and associated factors among people with epilepsy. Data from a major teaching hospital in Southwest Ethiopia

BACKGROUND

Epilepsy is a major public health problem affecting 70 million people worldwide. 90% of global people with epilepsy were living in developing regions like Ethiopia. Due to the lack of clear guidelines for treatment selection and the difficulty of individualizing care in resource-poor settings, achieving seizure control can be challenging. Seizure control status among epileptic patients is affected by different factors. Accordingly, this study aimed to assess the magnitude of uncontrolled seizures and associated factors among people with epilepsy attending the outpatient clinic of Jimma Medical Center, Southwest Ethiopia.

METHODS

A hospital-based retrospective chart review and a respective patient interview conducted among people with epilepsy from October 2020 to June 2021. Sociodemographic, behavioral-related factors, medication adherence, and medication belief were obtained through patient interviews. Seizure control status in the last two years before the study period was retrospectively evaluated and recorded from the charts. Data were entered into Epi Data manager version 4.6 and then exported to SPSS version 23.0 for analysis. A backward logistic regression analysis was done to identify factors associated with uncontrolled seizures.

RESULTS

From a total of 314 medical charts reviewed, 149(47.5 %) of patients were with uncontrolled seizures. 28.7 %,12.8 %, and 6 % of the patients experienced 1-5,6-10, and >10 seizure episodes during the last two years respectively. Comorbidity [adjusted odds ratio [(AOR): 2.13, 95 % confidence interval (CI):1.26-3.58], nonadherence [AOR: 2.41, 95 %CI: 1.46-3.9], possible adverse drug reaction (ADR) [AOR:1.79, 95 %CI: 1.107-3.01], and drug interaction [AOR: 3.06, 95 %CI: 1.24-7.57] were associated with an uncontrolled seizure.

CONCLUSION AND RECOMMENDATION

Our study showed that a substantial proportion of the patients were with uncontrolled seizures. Epileptic patients with comorbidities, nonadherence, adverse drug reactions, and drug interactions were more prone to have uncontrolled seizures. Hence, to overcome these problems, strategies like community-based education, treatment intensification, and routine assessment of adverse drug reactions and drug interaction may help to improve seizure control status.

Seizures in patients with kidney diseases: a neglected problem?

Nephrologists may encounter many systemic problems in their patients, including involvement of the neurological system and the development of seizures. Seizures are defined as abnormal neurological functions that cause overstimulation of neurons in the cerebral cortex or limbic system. Seizures may be focal or generalized depending on their origin and may have tonic, clonic, tonic-clonic or myoclonic character depending on the level of involvement of the motor movements. Patients with kidney disease may develop seizures due to etiologies seen in the general population (such as intracranial bleeding, cerebrovascular events, tumors, infections and intoxications) or due to kidney-related etiologies (such as uremic encephalopathy, dialysis disequilibrium syndrome and hyponatremia). Management of seizures in kidney patients is challenging for proper determination of the type and dosage of antiepileptic drugs due to varying renal clearances. This review covers the major causes of new-onset seizures in patients with acute kidney injury, electrolyte imbalances, chronic kidney disease, dialysis, renal transplantation or hypertension, and the available management approaches.

Pharmacokinetic Interactions Between Antiseizure and Psychiatric Medications

Antiseizure medications and drugs for psychiatric diseases are frequently used in combination. In this context, pharmacokinetic interactions between these drugs may occur. The vast majority of these interactions are primarily observed at a metabolic level and result from changes in the activity of the cytochrome P450 (CYP). Carbamazepine, phenytoin, and barbiturates induce the oxidative biotransformation and can consequently reduce the plasma concentrations of tricyclic antidepressants, many typical and atypical antipsychotics and some benzodiazepines. Newer antiseizure medications show a lower potential for clinically relevant interactions with drugs for psychiatric disease. The pharmacokinetics of many antiseizure medications is not influenced by antipsychotics and anxiolytics, while some newer antidepressants, namely fluoxetine, fluvoxamine and viloxazine, may inhibit CYP enzymes leading to increased serum concentrations of some antiseizure medications, including phenytoin and carbamazepine. Clinically relevant pharmacokinetic interactions may be anticipated by knowledge of CYP enzymes involved in the biotransformation of individual medications and of the influence of the specific comedication on the activity of these CYP enzymes. As a general rule, these interactions can be managed by careful evaluation of clinical response and, when indicated, individualized dosage adjustments guided by measurement of drugs serum concentrations, especially if pharmacokinetic interactions may cause any change in seizure control or signs of toxicity. Further studies are required to improve predictions of pharmacokinetic interactions between antiseizure medications and drugs for psychiatric diseases providing practical helps for clinicians in the clinical setting.

Application of physiologically-based pharmacokinetic model approach to predict pharmacokinetics and drug-drug interaction of rivaroxaban: A case study of rivaroxaban and carbamazepine

Rivaroxaban (RIV; Xarelto; Janssen Pharmaceuticals, Beerse, Belgium) is one of the direct oral anticoagulants. The drug is a strong substrate of cytochrome P450 (CYP) enzymes and efflux transporters. This study aimed to develop a physiologically-based pharmacokinetic (PBPK) model for RIV. It contained three hepatic metabolizing enzyme reactions (CYP3A4, CYP2J2, and CYP-independent) and two active transporter-mediated transfers (P-gp and BCRP transporters). To illustrate the performance of the developed RIV PBPK model on the prediction of drug-drug interactions (DDIs), carbamazepine (CBZ) was selected as a case study due to the high DDI potential. Our study results showed that CBZ significantly reduces the exposure of RIV. The area under the concentration-time curve from zero to infinity (AUC_inf ) of RIV was reduced by 35.2% (from 2221.3 to 1438.7 ng*h/ml) and by 25.5% (from 2467.3 to 1838.4 ng*h/ml) after the first dose and at the steady-state, respectively, whereas the maximum plasma concentration (C_max ) of RIV was reduced by 37.7% (from 266.3 to 166.1 ng/ml) and 36.4% (from 282.3 to 179.5 ng/ml), respectively. The developed PBPK model of RIV could be paired with PBPK models of other interested perpetrators to predict DDI profiles. Further studies investigating the extent of DDI between CBZ and RIV should be conducted in humans to gain a full understanding of their safety and effects.

The Perioperative Anesthetic Management of the Pediatric Patient with Special Needs: An Overview of Literature

The perioperative management of pediatric patients with psycho-physical disorders with related relational and cognitive problems must be carefully planned, in order to make the entire hospitalization process as comfortable and as less traumatic as possible. This article reports an overview of the anesthetic management of non-cooperative patients between 6 and 14 years old. The pathologies most frequently responsible for psycho-physical disorders can be summarized into three groups: (1) collaboration difficulties (autism spectrum disorders, intellectual impairment, phobia); (2) motor dysfunction (cerebral palsy, epilepsy, other brain pathologies, neuromuscular disorders), and (3) craniofacial anomalies (Down syndrome, other genetic syndromes). Anesthesia can be performed safely and successfully due to careful management of all specific problems of these patients, such as a difficult preoperative evaluation (medical history, physical examination, blood sampling, evaluation of vital parameters and predictive indices of difficult airway) and the inapplicability of a "standard" perioperative path (timing and length of the hospitalization, anesthetic premedication, postoperative management). It is necessary to ensure a dedicated perioperative process that is safe, comfortable, tailored to specific needs, and as less traumatic as possible. At the same time, all necessary precautions must be taken to minimize possible complications.

Cytochrome P450-mediated antiseizure medication interactions influence apoptosis, modulate the brain BAX/Bcl-XL ratio and aggravate mitochondrial stressors in human pharmacoresistant epilepsy

Polytherapy with antiseizure medications (ASMs) is often used to control seizures in patients suffering from epilepsy, where about 30% of patients are pharmacoresistant. While drug combinations are intended to be beneficial, the consequence of CYP-dependent drug interactions on apoptotic protein levels and mitochondrial function in the epileptic brain remains unclear. We examined the interactions of ASMs given prior to surgery in surgically resected brain tissues and of three ASMs (lacosamide, LCM; oxcarbazepine, OXC; levetiracetam LEV) in isolated brain cells from patients with drug-resistant epilepsy (n = 23). We divided the patients into groups-those who took combinations of NON-CYP + CYP substrate ASMs, NON-CYP + CYP inducer ASMs, CYP substrate + CYP substrate or CYP substrate + CYP inducer ASMs-to study the 1) pro- and anti-apoptotic protein levels and other apoptotic signaling proteins and levels of reactive oxygen species (reduced glutathione and lipid peroxidation) in brain tissues; 2) cytotoxicity at blood-brain barrier epileptic endothelial cells (EPI-ECs) and subsequent changes in mitochondrial membrane potential in normal neuronal cells, following treatment with LCM + OXC (CYP substrate + CYP inducer) or LCM + LEV (CYP substrate + NON-CYP-substrate) after blood-brain barrier penetration, and 3) apoptotic and mitochondrial protein targets in the cells, pre-and post-CYP3A4 inhibition by ketoconazole and drug treatments. We found an increased BAX (pro-apoptotic)/Bcl-XL (anti-apoptotic) protein ratio in epileptic brain tissue after treatment with CYP substrate + CYP substrate or inducer compared to NON-CYP + CYP substrate or inducer, and subsequently decreased glutathione and elevated lipid peroxidation levels. Further, increased cytotoxicity and Mito-ID levels, indicative of compromised mitochondrial membrane potential, were observed after treatment of LCM + OXC in combination compared to LCM + LEV or these ASMs alone in EPI-ECs, which was attenuated by pre-treatment of CYP inhibitor, ketoconazole. A combination of two CYP-mediated ASMs on EPI-ECs resulted in elevated caspase-3 and cytochrome c with decreased SIRT3 levels and activity, which was rescued by CYP inhibition. Together, the study highlights for the first time that pro- and anti-apoptotic proteins levels are dependent on ASM combinations in epilepsy, modulated via a CYP-mediated mechanism that controls free radicals, cytotoxicity and mitochondrial activity. These findings lead to a better understanding of future drug selection choices offsetting pharmacodynamic CYP-mediated interactions.

Carbamazepine and carbamazepine-epoxide concentrations in mothers, colostrum, and breastfed newborns: Comparison with concentrations determined during delivery and in the mature milk period

OBJECTIVE

To obtain information on the transport of carbamazepine and its active metabolite carbamazepine-epoxide from mother to colostrum and breastfed newborns.

METHODS

In this cohort study, carbamazepine and carbamazepine-epoxide concentrations in maternal serum (162 women), milk (i.e., colostrum) and breastfed newborn serum were analysed between the 1st and 5th days after delivery from November 1990 to February 2021. The measured concentrations were compared with the delivery and mature milk periods. The effect of the combination with both enzyme-inducing antiseizure medication and valproic acid was also evaluated.

RESULTS

Carbamazepine concentrations varied from 1.0 to 11.2 mg/L (epoxide 0.3-4.4 mg/L) in maternal serum, from 0.5 to 6.8 mg/L (epoxide 0.3-2.4 mg/L) in milk and from 0.5 to 4.7 mg/L (epoxide 0.3-1.7 mg/L) in newborn serum. The median milk/maternal serum concentration ratio of carbamazepine was 0.45 (epoxide 0.71), the median newborn/maternal serum concentration ratio of carbamazepine was 0.20 (epoxide 0.41), and the median newborn serum/milk concentration ratio of carbamazepine was 0.38 (epoxide 0.50). A highly significant correlation was found between the milk and maternal serum concentrations of both carbamazepine and carbamazepine-epoxide and between the milk and newborn serum concentrations of carbamazepine.

CONCLUSIONS

In the serum of breastfed newborns, only one concentration of carbamazepine reached the reference range used for the general epileptic population, and more than half was below the lower limit of quantification. Routine monitoring of serum carbamazepine concentrations is not required in breastfed newborns. However, observation of newborns is desirable, and if signs of potential adverse reactions are noted, the serum concentrations in newborns should be measured.

Caffeinated drinks, fruit juices, and epilepsy: A systematic review

The aim of this systematic review was to provide the required information regarding different aspects of the relationship between epilepsy/antiseizure medications and non-alcoholic drinks. The recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were followed. MEDLINE and Scopus from the inception until 7 August 2021 were systematically searched. These key words were used: "epilepsy" OR "seizure" OR "antiepileptic" OR "antiseizure" OR "anticonvulsant" AND "coffee" OR "tea" OR "soda" OR "juice" OR "drink" OR "cola" OR "diet" (35 key word combinations). The primary search yielded 21 458 publications (PubMed, n = 4778; Scopus, n = 16 680). Only 50 studies met all the inclusion criteria and were included in the current systematic review. In total, 17 articles investigated various non-alcoholic drinks in human studies, 11 studies were case reports/series, and 22 articles were animal/in vitro studies. None of the studies provided a class 1 of evidence. There is limited evidence suggesting that certain drinks (eg, caffeinated energy drinks) might trigger seizures. Patients with epilepsy should avoid excessive consumption of certain fruit juices (eg, grapefruit, lime, pomegranate, kinnow, and star fruit) and caffeinated drinks. However, daily coffee and tea intake can be part of a healthy balanced diet, and their consumption does not need to be stopped in patients with epilepsy. Coffee/tea consumption is not harmful if consumed at levels of 200 mg (caffeine) in one sitting (about 2½ cups of coffee) or 400 mg daily (about five cups of coffee).

The effect of erythromycin and clarithromycin versus azithromycin on serum valproate concentration

Introduction

Unlike azithromycin, erythromycin and clarithromycin strongly inhibit CYP450, which metabolizes valproic acid. The aim of this study was to evaluate the impact of macrolide administration on serum valproate trough levels.

Methods

This retrospective cohort study included hospitalized adult patients who concomitantly received valproate with a macrolide. Patients who received a carbapenem, those who do not have a baseline and/or post-levels, and those who received different doses of valproate were excluded. The change in serum valproate trough level from baseline to after the occurrence of co-administration (post-level) was compared in patients who received either erythromycin or clarithromycin versus those who received azithromycin.

Results

A total of thirteen patients were included in the comparison. The mean ± SD for change in serum valproate trough levels was significantly higher in the erythromycin/clarithromycin group than the azithromycin group (209.1 ± 105.9 µmol/L [equivalent to 30.1 ± 15.2 mg/L] vs. 12.7 ± 52.1 µmol/L [equivalent to 1.8 ± 7.5 mg/L]; P = 0.002).

Conclusion

This study found a significantly higher increase in serum trough levels of valproate after co-administration of erythromycin/clarithromycin versus azithromycin. Clinicians should consider avoiding co-administration of erythromycin and clarithromycin with valproate if possible or close monitoring of valproate levels with dose reduction.

Delayed awakening time from general anesthesia for dental treatment of patients with disabilities

Background

Patients with disabilities often require general anesthesia for dental treatment because of their cooperative or physical problems. Since most patients with disabilities take central nervous system drugs, the management of recovery status is important because of drug interactions with anesthetics.

Methods

The anesthesia records of patients under general anesthesia for dental treatment were reviewed, and data were collected. Healthy patients under general anesthesia for dental phobia or severe gagging reflex were designated as the control group. Patients with disabilities were divided into two groups: those not taking any medication and those taking antiepileptic medications. The awakening time was evaluated in 354 patients who underwent dental treatment under general anesthesia (92 healthy patients, 183 patients with disabilities, and 79 patients with disabilities taking an antiepileptic drug). Based on the data recorded in anesthesia records, the awakening time was calculated, and statistical processes were used to determine the factors affecting awakening time.

Results

Significant differences in awakening time were found among the three groups. The awakening time from anesthesia in patients with disabilities (13.09 ± 5.83 min) (P < 0.0001) and patients taking antiepileptic drugs (18.18 ± 7.81 min) (P < 0.0001) were significantly longer than in healthy patients (10.29 ± 4.87 min).

Conclusion

The awakening time from general anesthesia is affected by the disability status and use of antiepileptic drugs.

Effect of Chronic Administration of 5-(3-chlorophenyl)-4-Hexyl-2,4 -Dihydro-3H-1,2,4-Triazole-3-Thione (TP-315)-A New Anticonvulsant Drug Candidate-On Living Organisms

About 70 million people suffer from epilepsy—a chronic neurodegenerative disease. In most cases, the cause of the disease is unknown, but epilepsy can also develop as the result of a stroke, trauma to the brain, or the use of psychotropic substances. The treatment of epilepsy is mainly based on the administration of anticonvulsants, which the patient must most often use throughout their life. Despite significant progress in research on antiepileptic drugs, about 30% of patients still have drug-resistant epilepsy, which is insensitive to pharmacotherapy used so far. In our recent studies, we have shown that 4-alkyl-5-aryl-1,2,4-triazole-3-thiones act on the voltage-gated sodium channels and exhibit anticonvulsant activity in an MES (maximal electroshock-induced seizure) and 6Hz test in mice. Previous studies have shown their beneficial toxic and pharmacological profile, but their effect on a living organism during chronic use is still unknown. In the presented study, on the basis of the previously conducted tests and the PAMPA (parallel artificial membrane permeability assay) BBB (blood–brain barrier) test, we selected one 1,2,4-triazole-3-thione derivative—TP-315—for further studies aimed at assessing the impact of its chronic use on a living organism. After long-term administration of TP-315 to Albino Swiss mice, its effect on the functional parameters of internal organs was assessed by performing biochemical, morphological, and histopathological examinations. It was also determined whether the tested compound inhibits selected isoforms of the CYP450 enzyme system. On the basis of the conducted tests, it was found that TP-315 does not show nephrotoxic nor hepatotoxic effects and does not cause changes in hematological parameters. In vitro tests showed that TP-315 did not inhibit CYP2B6, CYP2D6, CYP3A4, or CYP3A5 enzymes at the concentration found in the serum of mice subjected to long-term exposure to this compound.

Effect of Panax ginseng on Carbamazepine Pharmacokinetics in Rabbits

Objectives

Carbamazepine (CBZ) is a well-known drug prescribed to treat epilepsy and the preferred drug for trigeminal neuralgia. This study was conducted to investigate the effect of Panax ginseng extract (PGE) on the disposition of CBZ, a CYP3A4 substrate, in rabbits.

Materials and Methods

An in vivo randomized parallel design was used to examine herb-drug interactions in 12 male rabbits distributed into 2 groups. In the 1^st group (control group), 6 rabbits (control group) were administered orally with CBZ suspension (30 mg/kg/day) as a single daily dose for 10 days. In the 2^nd group (test group), 6 rabbits was treated concomitantly with CBZ and a dose of PGE (2.5 mg/kg/day) at the same time as in the 1^st group. Blood samples were withdrawn from the marginal ear vein of the rabbits at intervals of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 6.0, 12.0, and 24.0 h.

Results

CBZ had no significantly different pharmacokinetic (PK) parameters, namely, C_max, t_max, AUC_0-24, AUC_0-∞, t_½, and K_e, when it was given alone or concurrently with PGE (p≥0.05).

Conclusion

PGE may unlikely interfere with the PK of CBZ when it is co-administered with CBZ. Therefore, PGE can be used safely without precautions or dose monitoring.

A Review of the Metabolism and Potential Drug-drug Interactions With Addictive Drugs

People who use drugs (PWUD) are at increased risk for drug-related harms such as overdose. Additionally, they are also at increased risk of secondary harms from bacterial and other infections such as hepatitis B, hepatitis C, and Human Immunodeficiency Virus. These secondary harms, along with other medical conditions, typically require treatment with prescription medications. When considering treatment options, drug-drug interactions (DDIs) must be considered, unfortunately these interactions are often overlooked with addictive drugs. Although DDIs in PWUD have been reviewed for certain drug classes and specific drugs of abuse, no comprehensive list could be found. The objective of this article is to compile a list of potential DDIs between prescription drugs and addictive drugs to create a list allowing prescribers to make more informed decisions when prescribing a medication to PWUD.

A Gluten Free Diet in the Management of Epilepsy in People with Coeliac Disease or Gluten Sensitivity

The aim of this review was to assess the effects of a gluten free diet (GFD) in the management of epilepsy in people with coeliac disease (CD) or gluten sensitivity (GS). A systematic approach was used to undertake a literature review. Five electronic databases (PubMed; Scopus; Google Scholar; Cochrane Epilepsy Group specialised register; Cochrane Register of Controlled Trails (CENTRAL) via the Cochrane Register of Online Trials) were searched using predetermined relevant search terms. In total, 668 articles were identified. Duplicates were removed and predefined inclusion and exclusion criteria were applied, and a PRISMA flow chart was produced. Data was extracted using Covidence software. Twelve studies on Epilepsy and CD involving a total of 70 participants were selected for analysis; narrative synthesis was used owing to the small sample sizes in the selected studies. None of the 12 studies meeting inclusion criteria investigated gluten sensitivity and epilepsy. All the included studies support a link between epilepsy and CD. GFD was effective in 44 out of 70 participants across the studies in terms of a reduction of seizures, reduction of antiepileptic drugs (AEDs) or normalisation of EEG pattern. A total of 44 participants showed a reduction in seizures (across eight studies) and complete cessation of seizures was reported in 22 participants. In general, the earlier the GFD is implemented after the onset of seizures, the better the likelihood of the GFD being successful in supporting control of seizures. Mechanisms linking gluten with epilepsy are not fully understood; possible hypotheses include gluten mediated toxicity, immune-induced cortical damage and malabsorption. Evidence suggests the effectiveness of a GFD in supporting the management of epilepsy in patients with CD, although the quality of evidence is low. There appears to be a growing number of neurologists who are prepared to advocate the use of a GFD. A multidisciplinary approaches and further research are recommended. It could be argued that when balancing potential treatments such as AEDs or surgery, a GFD has a low likelihood of harm.

Pharmacological Augmentation in Unipolar Depression: A Guide to the Guidelines

BACKGROUND

Pharmacological augmentation is a recommended strategy for patients with treatment-resistant depression. A range of guidelines provide advice on treatment selection, prescription, monitoring and discontinuation, but variation in the content and quality of guidelines may limit the provision of objective, evidence-based care. This is of importance given the side effect burden and poorer long-term outcomes associated with polypharmacy and treatment-resistant depression. This review provides a definitive overview of pharmacological augmentation recommendations by assessing the quality of guidelines for depression and comparing the recommendations made.

METHODS

A systematic literature search identified current treatment guidelines for depression published in English. Guidelines were quality assessed using the Appraisal of Guidelines for Research and Evaluation II tool. Data relating to the prescription of pharmacological augmenters were extracted from those developed with sufficient rigor, and the included recommendations compared.

RESULTS

Total of 1696 records were identified, 19 guidelines were assessed for quality, and 10 were included. Guidelines differed in their quality, the stage at which augmentation was recommended, the agents included, and the evidence base cited. Lithium and atypical antipsychotics were recommended by all 10, though the specific advice was not consistent. Of the 15 augmenters identified, no others were universally recommended.

CONCLUSIONS

This review provides a comprehensive overview of current pharmacological augmentation recommendations for major depression and will support clinicians in selecting appropriate treatment guidance. Although some variation can be accounted for by date of guideline publication, and limited evidence from clinical trials, there is a clear need for greater consistency across guidelines to ensure patients receive consistent evidence-based care.

Utilization of Physiologically Based Pharmacokinetic Modeling in Clinical Pharmacology and Therapeutics: an Overview

The purpose of this review was to assess the advancement of applications for physiologically based pharmacokinetic (PBPK) modeling in various therapeutic areas. We conducted a PubMed search, and 166 articles published between 2012 and 2018 on FDA-approved drug products were selected for further review. Qualifying publications were summarized according to therapeutic area, medication(s) studied, pharmacokinetic model type utilized, simulator program used, and the applications of that modeling. The results showed a 13-fold increase in the number of papers published from 2012 to 2018, with the largest proportion of articles dedicated to the areas of infectious diseases, oncology, and neurology, and application extensions including prediction of drug-drug interactions due to metabolism and/or transporter-mediated effects and understanding drug kinetics in special populations. In addition, we profiled several high-impact studies whose results were used to guide package insert information and formulate dose recommendations. These results show that while utilization of PBPK modeling has drastically increased over the past several years, regulatory support, lack of easy-to-use systems for clinicians, and challenges with model validation remain major challenges for the widespread adoption of this practice in institutional and ambulatory settings. However, PBPK modeling will continue to be a useful tool in the future to assess therapeutic drug monitoring and the growing field of personalized medicine.

Reduction in N-Desmethylclozapine Level Is Determined by Daily Dose But Not Serum Concentration of Valproic Acid-Indications of a Presystemic Interaction Mechanism

BACKGROUND

Valproic acid (VPA) is frequently used together with clozapine (CLZ) as mood-stabilizer or for the prevention of seizures in patients with psychotic disorders. VPA is known to reduce levels of the pharmacologically active CLZ-metabolite N-desmethylclozapine (N-DMC), but factors determining the degree of this interaction are unknown. Here, we investigated the relationship between VPA dose and serum concentration on N-DMC levels in a large patient population adjusting for sex, age, and smoking habits as covariates.

METHODS

A total of 763 patients with steady-state serum concentrations of CLZ and N-DMC concurrently using VPA (cases, n = 76) or no interacting drugs (controls, n = 687) were retrospectively included from a therapeutic drug monitoring service at Diakonhjemmet Hospital, Oslo, between March 2005 and December 2016. In addition to information about prescribed doses, age, sex, smoking habits, and use of other interacting drugs were obtained. The effects of VPA dose and serum concentration on dose-adjusted N-DMC levels were evaluated by univariate correlation and multivariate linear mixed-model analyses adjusting for covariates.

RESULTS

The dose-adjusted N-DMC levels were approximately 38% lower in VPA users (cases) versus nonusers (controls) (P < 0.001). Within the VPA cases, a negatively correlation between VPA dose and dose-adjusted N-DMC levels was observed with an estimated reduction of 1.42% per 100-mg VPA dose (P = 0.033) after adjusting for sex, age, and smoking. By contrast, there was no correlation between VPA serum concentration and dose-adjusted N-DMC levels (P = 0.873).

CONCLUSIONS

The study shows that VPA dose, not concentration, is of relevance for the degree of reduction in N-DMC level in clozapine-treated patients. Presystemic induction of UGT enzymes or efflux transporters might underlie the reduction in N-DMC level during concurrent use of VPA. Our findings indicate that a VPA daily dose of 1500 mg or higher provides a further 21% reduction in N-DMC concentration. This is likely a relevant change in the exposure of this active metabolite where low levels are associated with implications of CLZ therapy.

Effects of enzyme-inducing antiseizure medication on vitamin D dosing in adult veterans with epilepsy

BACKGROUND

The association of antiseizure medication (ASM) and bone density abnormalities has long been recognized; however, there remains a lack of consensus on efficacy and optimal vitamin D dosing in patients receiving enzyme inducing and non-inducing ASMs. The objective was to explore the relationship between ASMs and vitamin D supplementation requirements in a population of adult patients with epilepsy.

METHODS

Patients with a diagnosis of epilepsy receiving supplemental vitamin D were included in this retrospective chart review. All instances of 25-hydroxyvitamin D₃ (25-OHD) measured among those patients were compared between patients taking an enzyme inducing antiseizure medication (EIASM) to patients receiving ASM regimens only containing non-enzyme inducing antiseizure medications (NIASM). ASM use, prescription and over the counter (OTC) vitamin D use, 25-OHD plasma concentration, presence of chronic kidney disease (CKD), age, gender, and ethnicity were collected. Multiple linear regression was used to adjust for potentially confounding variables; the model included a cluster by participant term to account for repeated patients in the dataset.

RESULTS

There were 542 vitamin D levels evaluated from 172 unique patients. There was an 11.5 % higher absolute percent increase in patients who achieved a 25-OHD level over 30 ng/mL in the NIASM (p = 0.012). Patients on EIASMs were supplemented with an additional 508 units of vitamin D daily (95 %CI 136-878, p = 0.007). When adjusted for CKD, OTC vitamin D use, OTC multivitamin use, age, gender, and ethnicity, patients on EIASMs were supplemented with an additional 445 units of vitamin D (95 %CI -69 to 960, p = 0.089) compared to NIASM use.

CONCLUSIONS

Patients taking EIASMs had an increase in vitamin D deficiency and vitamin D supplementation suggesting that EIASMs impact vitamin D metabolism. Closer monitoring of vitamin D status in patients with epilepsy, especially those on EIASMs, is warranted. This evaluation suggests that for patients taking ASM, use of a lower dose OTC requires closer monitoring of vitamin D status in patients with epilepsy, especially those on EIASMs, is warranted. vitamin D agent may not be adequate.

Multi-drug therapy for epilepsy influenced bispectral index after a bolus propofol administration without affecting propofol's pharmacokinetics: a prospective cohort study

Some previous studies have indicated that valproate (VPA) might change the pharmacokinetics and enhance the effects of propofol. We evaluated whether clinical VPA therapy affected the propofol blood level, the protein-unbound free propofol level, and/or the anesthetic effects of propofol in the clinical setting. The subjects were divided into the control group (not medicated with antiepileptics), the mono-VPA group (medicated with VPA alone), and the poly-VPA group (medicated with VPA, other antiepileptics, and/or psychoactive drugs). General anesthesia was induced via the administration of a single bolus of propofol and a remifentanil infusion, and when the bispectral index (BIS) exceeded 60 sevoflurane was started. There were no significant differences in the total blood propofol level at 5, 10, 15, and 20 min or the protein-unbound free propofol level at 5 min after the intravenous administration of propofol between the 3 groups. However, the minimum BIS was significantly lower and the time until the BIS exceeded 60 was significantly longer in the poly-VPA group. In the multivariate regression analysis, belonging to the poly-VPA group was found to be independently associated with the minimum BIS value and the time until the BIS exceeded 60. Clinical VPA therapy did not influence the pharmacokinetics of propofol. However, multi-drug therapy involving VPA might enhance the anesthetic effects of propofol.

Personalized medicine: Vinpocetine to reverse effects of GABRB3 mutation

Objective

To screen a library of potential therapeutic compounds for a woman with Lennox‐Gastaut syndrome due to a Y302C GABRB3 (c.905A>G) mutation.

Methods

We compared the electrophysiological properties of cells with wild‐type or the pathogenic GABRB3 mutation.

Results

Among 1320 compounds, multiple candidates enhanced GABRB3 channel conductance in cell models. Vinpocetine, an alkaloid derived from the periwinkle plant with anti‐inflammatory properties and the ability to modulate sodium and channel channels, was the lead candidate based on efficacy and safety profile. Vinpocetine was administered as a dietary supplement over 6 months, reaching a dosage of 20 mg three times per day, and resulted in a sustained, dose‐dependent reduction in spike‐wave discharge frequency on electroencephalograms. Improved language and behavior were reported by family, and improvements in global impression of change surveys were observed by therapists blinded to intervention.

Significance

Vinpocetine has potential efficacy in treating patients with this mutation and possibly other GABRB3 mutations or other forms of epilepsy. Additional studies on pharmacokinetics, potential drug interactions, and safety are needed.

The number and kind of antiepileptics affect propofol dose requirement for anesthesia: observational study

The propofol dose requirement and the emergence time are affected by antiepileptic use. The effects on anesthesia of the number and kind of antiepileptic agents have not been reported. We investigated the relationship between the kind and number of antiepileptic agents and the propofol dose requirement for anesthesia and emergence time in intravenous general anesthesia for dental treatment for patients with neurological disorders. We studied 247 patients with neurological disorders who underwent dental treatment under intravenous general anesthesia. Patients were categorized according to the number of antiepileptics (none, single agent, two kinds, and three or more kinds of antiepileptics) and the kind of antiepileptic (carbamazepine, valproate, phenobarbital, phenytoin, zonisamide, clobazam, or topiramate) being received. The propofol dose requirement for anesthesia, emergence time, and predicted blood propofol concentration at emergence were evaluated. Patients on three or more kinds of antiepileptics had significantly lower propofol dose requirement (reduction in 25%, compare with no use) and predicted blood propofol concentration at emergence (reduction in 41%) and significantly longer emergence time (extension in 50%) (P < 0.05). Valproate and clobazam reduced the propofol dose (valproate 9% and clobazam 19%) and predicted blood propofol concentration at emergence (valproate 18% and clobazam 33%), while phenobarbital increased these parameters (30% and 125%) (P < 0.05). The number and kind of antiepileptics effects propofol dose requirement. In particular, valproate and clobazam reduce the propofol dose requirement, while phenobarbital increases this.Clinical trial registration UMIN No. UMIN000014179.

Effects site concentrations of propofol using target-controlled infusion in dental treatment under deep sedation among different intellectual disability types

Background

We aimed to assess the dose needed to achieve the propofol effect-site concentration using target-controlled infusion in intellectually disabled patients and to detail the most effective method for achieving a safe level of consciousness without hemodynamic changes as well as detail any resulting adverse effects.

Methods

We performed a retrospective review of sedation service records of 138 intellectually disabled patients (51, mental retardation; 36, autism; 30, brain lesion, 12 genetic diseases, 9 dementia) aged over 15 years and weighing over 30 kg. These patients had received propofol via target-controlled infusion in the special care dental clinic of Seoul National University Dental Hospital from May 2008 to September 2018 for restorative treatment (112), minor surgery (13), prosthodontics (7), periodontics treatment (5), and implant (1).

Results

For all groups, the duration of dental treatments was 43 ± 18 minutes, total sedation time was 73 ± 23 minutes, and total BIS values was 57 ± 12. The propofol maintenance dosage values for each group were: mental retardation, 3 ± 0.5 (2–4) µg/ml; autism, 3.1 ± 0.7 (2–5) µg/ml; brain lesion, 2.8 ± 0.7 (1.5–5) µg/ml; genetic disease, 2.9 ± 0.9 (1–4) µg/ml; and dementia 2.3 ± 0.7 (1–3.4) µg/ml.

Conclusions

The dementia group needed a lower dosage to reach a safe, effective propofol effect-site concentration than the other groups. Since there were no complications, deep sedation is a great alternative to general anesthesia for dental treatment of intellectually disabled patients.

Therapeutic Drug Monitoring of Antiepileptic Drugs in Epilepsy: A 2018 Update

BACKGROUND

Antiepileptic drugs (AEDs) are the mainstay of epilepsy treatment. Since 1989, 18 new AEDs have been licensed for clinical use and there are now 27 licensed AEDs in total for the treatment of patients with epilepsy. Furthermore, several AEDs are also used for the management of other medical conditions, for example, pain and bipolar disorder. This has led to an increasingly widespread application of therapeutic drug monitoring (TDM) of AEDs, making AEDs among the most common medications for which TDM is performed. The aim of this review is to provide an overview of the indications for AED TDM, to provide key information for each individual AED in terms of the drug's prescribing indications, key pharmacokinetic characteristics, associated drug-drug pharmacokinetic interactions, and the value and the intricacies of TDM for each AED. The concept of the reference range is discussed as well as practical issues such as choice of sample types (total versus free concentrations in blood versus saliva) and sample collection and processing.

METHODS

The present review is based on published articles and searches in PubMed and Google Scholar, last searched in March 2018, in addition to references from relevant articles.

RESULTS

In total, 171 relevant references were identified and used to prepare this review.

CONCLUSIONS

TDM provides a pragmatic approach to epilepsy care, in that bespoke dose adjustments are undertaken based on drug concentrations so as to optimize clinical outcome. For the older first-generation AEDs (carbamazepine, ethosuximide, phenobarbital, phenytoin, primidone, and valproic acid), much data have accumulated in this regard. However, this is occurring increasingly for the new AEDs (brivaracetam, eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, perampanel, piracetam, pregabalin, rufinamide, stiripentol, sulthiame, tiagabine, topiramate, vigabatrin, and zonisamide).

In vitro metabolism of magnolol and honokiol in rat liver microsomes and their interactions with seven cytochrome P substrates

RATIONALE

Magnolol and honokiol are the main active components of Magnolia officinalis Rehd. et Wils. The study of their interactions with liver microsomes is very important for the clinical safety of M. officinalis Rehd. et Wils.

METHODS

The main metabolites of magnolol and honokiol in rat liver microsomes were investigated using ultrahigh-performance liquid chromatography/mass spectrometry and their possible structures were identified. In addition, cytochrome P450 (CYP450) isoenzymes of the major rat metabolites of magnolol and honokiol were identified using a specific inhibitor.

RESULTS

This study suggests that the CYP2E1 subtype is responsible for the oxidation of magnolol and honokiol terminal double bonds to epoxy metabolites. CYP3A4 appears to be the major subtype responsible for further hydrolytic metabolism, while CYP1A2 may promote decarboxylation of the metabolites. CYP2A6 may be the main subtype responsible for the hydrogenation of magnolol (p < 0.05).

CONCLUSIONS

This study demonstrated that different CYP450 enzyme isoforms showed different activities in the in vitro metabolism of magnolol and honokiol in rat liver microsomes. It has certain practical applications in that we should pay attention to drug-drug interactions in clinical medications and also to drug-enzyme interactions.

Pharmacokinetic Interactions of Clinical Interest Between Direct Oral Anticoagulants and Antiepileptic Drugs

Direct oral anticoagulants (DOACs), namely apixaban, dabigatran, edoxaban, and rivaroxaban are being increasingly prescribed among the general population, as they are considered to be associated to lower bleeding risk than classical anticoagulants, and do not require coagulation monitoring. Likewise, DOACs are increasingly concomitantly prescribed in patients with epilepsy taking, therefore, antiepileptic drugs (AEDs), above all among the elderly. As a result, potential interactions may cause an increased risk of DOAC-related bleeding or a reduced antithrombotic efficacy. The objective of the present review is to describe the pharmacokinetic interactions between AEDs and DOACs of clinical relevance. We observed that there are only few clinical reports in which such interactions have been described in patients. More data are available on the pharmacokinetics of both drugs classes which allow speculating on their potential interactions. Older AEDs, acting on cytochrome P450 isoenzymes, and especially on CYP3A4, such as phenobarbital, phenytoin, and carbamazepine are more likely to significantly reduce the anticoagulant effect of DOACs (especially rivaroxaban, apixaban, and edoxaban). Newer AEDs not affecting significantly CYP or P-gp, such as lamotrigine, or pregabalin are not likely to affect DOACs efficacy. Zonisamide and lacosamide, which do not affect significantly CYP activity in vitro, might have a quite safe profile, even though their effects on P-gp are not well-known, yet. Levetiracetam exerts only a potential effect on P-gp activity, and thus it might be safe, as well. In conclusion, there are only few case reports and limited evidence on interactions between DOACs and AEDs in patients. However, the overall evidence suggests that the interaction between these drug classes might be of high clinical relevance and therefore further studies in larger patients' cohorts are warranted for the future in order to better clarify their pharmacokinetic and define the most appropriate clinical behavior.

Population pharmacokinetics of valproic acid in epileptic children: Effects of clinical and genetic factors

Valproic acid (VPA) is a first-line anti-epileptic drug that is used in the treatment of generalized and partial seizures. Gene variants had been proved to influence the pharmacokinetics (PK) of VPA and contribute to its inter-individual variability (IIV). The aim of this study was to systematically investigate the effects of candidate gene variants (CYPs, UGTs, ABC transporters, and nuclear receptors) on VPA PK in Chinese children with epilepsy. A total of 1065 VPA serum trough concentrations at steady state were collected from 264 epileptic pediatric patients aged 3 months to 16 years. The population pharmacokinetic (PPK) model was developed using a nonlinear mixed effects modelling (NONMEM) approach. For the final PPK model, the oral clearance (CL/F) of VPA was estimated to be 0.259 L/h with IIV of 13.3%. The estimates generated by NONMEM indicated that the VPA CL/F was significantly influenced by patient body weight (increased by an exponent of 0.662), co-administration with carbamazepine (increased CL/F by 22%), and daily dose of VPA (increased by an exponent of 0.22). CL/F in patients with the LEPR rs1137101 variant (668 AG and GG genotypes) was much lower than in patients with the AA genotype (17.8% and 22.6% lower, respectively). However, none of the CYPs or UGTs gene variants was found to influence the PK of VPA in this study. Evaluation by bootstrap and normalized prediction distribution error (NPDE) showed that the final model was stable. The predictive performance was evaluated by goodness-of-fit (GOF) plots and visual predictive checks (VPC), and the results indicated satisfactory precision. Our model suggests a correlation between VPA CL/F and LEPR rs1137101 variants, which might be beneficial in the context of individual dose optimization.

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.

Effects of the antiepileptic drugs topiramate and lamotrigine on bone metabolism in rats

Long-term treatment with antiepileptic drugs (AED) is associated with an elevated risk of bone fracture due to decreased bone mineral density (BMD). Phenytoin has been shown to affect bone metabolism adversely, whereas newly developed AEDs have not been studied. This study evaluated the effects of topiramate and lamotrigine on bone metabolism in rats. Five-week-old male Sprague-Dawley rats were treated orally with phenytoin (20 mg/kg), topiramate (5 or 20 mg/kg), or lamotrigine (2 or 10 mg/kg) daily for 12 weeks. Phenytoin reduced bone strength, measured by maximum load to failure of the femoral mid-diaphysis, along with reduced femur total BMD. Serum tartrate-resistant acid phosphatase-5b levels significantly increased after phenytoin treatment, while serum osteocalcin levels decreased after topiramate 20 mg/kg treatment. Furthermore, osteoblast surface and bone mineralizing surface were significantly lowered by topiramate. Lamotrigine treatment did not affect bone strength, BMD, or bone turnover. We demonstrated that phenytoin treatment significantly increased bone resorption and lowered BMD and bone strength. Since lamotrigine did not affect bone metabolism, it can be concluded that lamotrigine is safety medicine for bone health. Topiramate was associated with decreased bone formation, which may affect bone strength and BMD with chronic use. Thus, patients taking topiramate should be monitored for changes in BMD to avoid risk of fracture.

Clinical reappraisal of the influence of drug-transporter polymorphisms in epilepsy

INTRODUCTION

Although novel antiepileptic drugs (AEDs) have been recently released, the issue of drug resistance in epileptic patients remains unsolved and largely unpredictable. Areas covered: We aim to assess the clinical impact of genetic variations that may influence the efficacy of medical treatment in epilepsy patients. Indeed, many genes, including genes encoding drug transporters (ABCB1), drug targets (SCN1A), drug-metabolizing enzymes (CYP2C9, CYP2C19), and human leucocyte antigen (HLA) proteins, may regulate the mechanisms of drug resistance in epilepsy. This review specifically focuses on the ABC genes, which encode multidrug resistance-associated proteins (MRPs) and may reduce the blood-brain barrier penetration of anticonvulsant AEDs. Expert opinion: Drug resistance remains a crucial problem in epilepsy patients. Pharmacogenomic studies may improve our understanding of drug responses and drug resistance by exploring the impact of gene variants and predicting drug responses and tolerability.

Interactions of aliskiren, a direct renin inhibitor, with antiepileptic drugs in the test of maximal electroshock in mice

Experimental studies showed that certain angiotensin-converting enzyme inhibitors and angiotensin AT₁ receptor antagonists can decrease seizure severity in rodents. Additionally, some of these blockers of the renin-angiotensin system have been documented to enhance the anticonvulsant activity of antiepileptic drugs against maximal electroshock-induced seizures. The aim of the current study was to investigate the effect of aliskiren, a direct renin inhibitor and a novel antihypertensive drug, on the protective action of numerous antiepileptic drugs (carbamazepine, valproate, clonazepam, phenobarbital, oxcarbazepine, lamotrigine, topiramate and pregabalin) in the test of maximal electroshock in mice. The examined drugs were administered intraperitoneally. Aliskiren up to a dose of 75mg/kg did not affect the threshold for electroconvulsions, however, aliskiren (75mg/kg) enhanced the anticonvulsant action of clonazepam and valproate. Following aliskiren treatment, a higher brain concentration of valproate was noted, suggesting a pharmacokinetic interaction. In the rota-rod test, the concomitant treatment with aliskiren (50 or 75mg/kg) and clonazepam (22.6mg/kg) impaired motor coordination while clonazepam (22.6mg/kg) alone showed strong tendency towards this impairment. The combination of aliskiren (75mg/kg) with phenobarbital (25.5mg/kg) caused long-term memory deficits in the passive avoidance task. This study shows that there are no negative interactions between aliskiren and the examined antiepileptic drugs as concerns their anticonvulsant activity. Aliskiren even potentiated the anticonvulsant action of clonazepam and valproate against maximal electroshock. The impact of aliskiren alone on seizure activity or on the anticonvulsant and adverse activity of antiepileptic drugs needs further evaluation in other animal models of seizures.

Perampanel Serum Concentrations in Adults With Epilepsy: Effect of Dose, Age, Sex, and Concomitant Anti-Epileptic Drugs

BACKGROUND

Perampanel (PMP), a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist, is a novel anti-epileptic drug (AED) licensed for the adjunctive treatment of focal and generalized epilepsy. There is limited information on PMP's pharmacokinetics and drug interaction characteristics with concomitant AEDs. We have investigated the effects of PMP dose, age, sex, and coprescribed AEDs on serum PMP concentrations.

METHODS

We used the database of a therapeutic drug monitoring unit at a tertiary epilepsy referral center to identify patients who had PMP as part of their treatment and extracted clinical information from their medical notes. Sera PMP concentrations were determined using liquid chromatography/mass spectroscopy.

RESULTS

In total, 160 sera from 107 patients (66 females) aged 18-70 years and weighing 40-125 kg were identified. They were prescribed a median PMP dose of 6 mg/d (range 2-12 mg/d) and were coprescribed a variety of AEDs, including enzyme-inducing [carbamazepine (CBZ) and oxcarbazepine (OXC)] and enzyme-inhibiting (valproic acid) AEDs. A linear relationship was observed between PMP dose and serum concentrations (r = 0.714, P < 0.0005). Sex and age were found not to influence PMP serum concentration. Enzyme-inducing AEDs dose-dependently decreased PMP concentrations, with CBZ and OXC decreasing mean values by 69% and 37%, respectively. In contrast, although topiramate and phenytoin also decreased mean PMP concentrations by 18% and 13%, respectively, these changes did not achieve statistical significance.

CONCLUSIONS

PMP exhibits a linear dose-concentration relationship, with serum PMP concentrations being age and sex independent. CBZ and OXC can significantly decrease PMP concentrations, probably through an induction of CYP3A4-mediated metabolism.

Co-morbidity and clinically significant interactions between antiepileptic drugs and other drugs in elderly patients with newly diagnosed epilepsy

PURPOSE

A study was conducted to investigate the frequency of potential pharmacokinetic drug-to-drug interactions in elderly patients with newly diagnosed epilepsy. We also investigated co-morbid conditions associated with epilepsy.

METHOD

From the register of Kuopio University Hospital (KUH) we identified community-dwelling patients aged 65 or above with newly diagnosed epilepsy and in whom use of the first individual antiepileptic drug (AED) began in 2000-2013 (n=529). Furthermore, register data of the Social Insurance Institution of Finland were used for assessing potential interactions in a nationwide cohort of elderly subjects with newly diagnosed epilepsy. We extracted all patients aged 65 or above who had received special reimbursement for the cost of AEDs prescribed on account of epilepsy in 2012 where their first AED was recorded in 2011-2012 as monotherapy (n=1081). Clinically relevant drug interactions (of class C or D) at the time of starting of the first AED, as assessed via the SFINX-PHARAO database, were analysed.

RESULTS

Hypertension (67%), dyslipidemia (45%), and ischaemic stroke (32%) were the most common co-morbid conditions in the hospital cohort of patients. In these patients, excessive polypharmacy (more than 10 concomitant drugs) was identified in 27% of cases. Of the patients started on carbamazepine, 52 subjects (32%) had one class-C or class-D drug interaction and 51 (31%) had two or more C- or D-class interactions. Only 2% of the subjects started on valproate exhibited a class-C interaction. None of the subjects using oxcarbazepine displayed class-C or class-D interactions. Patients with 3-5 (OR 4.22; p=0.05) or over six (OR 8.86; p=0.003) other drugs were more likely to have C- or D-class interaction. The most common drugs with potential interactions with carbamazepine were dihydropyridine calcium-blockers, statins, warfarin, and psychotropic drugs.

CONCLUSIONS

Elderly patients with newly diagnosed epilepsy are at high risk of clinically relevant pharmacokinetic interactions with other drugs, especially if exposed to carbamazepine, but these interactions can be controlled via rational drug choices and with prediction of the possible drug-to-drug interactions. Patients on dihydropyridine calcium-channel blockers, statins, warfarin, and risperidone face the highest risk of interactions.