Clinical utility of therapeutic drug monitoring of antiepileptic drugs: Systematic review

Implementation and validation of a 24/7 system for the monitoring of antiepileptic drugs

Background

Epilepsy is a common neurological disorder associated with seizures that impact patients' quality of life. Treatment includes antiepileptic drugs (AEDs), each effective only at a specific dose, making continuous therapeutic drug monitoring (TDM) useful in clinical cases under inpatient conditions. Conventional liquid chromatography-tandem mass spectrometry (LC-MS/MS) lacks automation for 24/7 operation, limiting clinical applicability. This study validates a fully automated 24/7 AED monitoring system using the Clinical Laboratory Automated Sample Preparation Module 2030 (CLAM-2030).

Methods

The method was validated according to U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines by evaluating linearity, precision, accuracy, carry over, matrix effects, and calibration stability. Twenty-six AEDs were quantified in plasma using multiple reaction monitoring (MRM) transitions in positive and negative electrospray ionization modes. Sample preparation was fully automated: 20 μL methanol was used to wet the column, followed by 20 μL internal standard and 100 μL acetonitrile for protein precipitation. The supernatant was filtered and injected directly into the LC system. Chromatographic separation was achieved within 4.5 min using a C18 column (2.1 × 50 mm, 2.7 μm) under gradient conditions with a mobile phase of 0.2 mM ammonium formate and 0.002% formic acid.

Results

The method demonstrated excellent linearity over the validated concentration ranges (R 2 > 0.99 for all analytes). Within-run imprecision was <15% at the lower limit of quantitation (LLOQ), while between-run imprecision was <10% for most AEDs. Accuracy was within ±10% of nominal concentrations at all quality control (QC) levels. Matrix effects were within acceptable limits (<30% variation) for 23 of 26 analytes, with compensatory corrections applied for carbamazepine-D10, felbamate-D4, and levetiracetam-D6. Carry over was negligible [<2% for all AEDs except retigabine and N-desmethylselegiline (NDMS), which remained below 6.5%]. Calibration stability was maintained over 5 days with concentration and peak area variation <10%. An interlaboratory comparison (ring test) showed a relative standard deviation <20% for all analytes.

Conclusion

This study establishes a robust, fully automated, high-throughput method for continuous AED monitoring in the clinical setting. The CLAM-2030-LCMS-8060NX system enables reliable 24/7 TDM with minimal technical expertise, ensuring optimized AED therapy and improved patient outcomes.

ABCB1 Polymorphism Is Associated with Higher Carbamazepine Clearance in Children

The aim of our study was to investigate the role of ABCB1 polymorphism in the pharmacokinetics of carbamazepine (CBZ) in children. The study enrolled 47 Serbian pediatric epileptic patients on CBZ treatment. Genotyping for ABCB1 1236C Collapse

Key Words

• ABCB1
• carbamazepine
• children
• genetic polymorphism
• population pharmacokinetics

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Grants

• 175007 and 175056 the Ministry of Science and Technology of the Republic of Serbia
• 07/11 Faculty of Medical Sciences, University of Kragujevac, Serbia

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Affiliation(s)

Natasa Djordjevic Department of Pharmacology and Toxicology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia; (J.R.M.); (S.J.); (D.M.)
Jelena Cukic Public Health Institute, Nikole Pasica 1, 34 000 Kragujevac, Serbia; (J.C.); (D.B.)
Dragana Dragas Milovanovic College of Professional Health Studies, Cara Dusana 254, 11 080 Belgrade, Serbia;
Marija Radovanovic Department of Pediatrics, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia; (M.R.); (S.O.)
Ivan Radosavljevic Department of Surgery, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia;
Jelena Vuckovic Filipovic Department of Internal Medicine, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia;
Slobodan Obradovic Department of Pediatrics, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia; (M.R.); (S.O.)
Dejan Baskic Public Health Institute, Nikole Pasica 1, 34 000 Kragujevac, Serbia; (J.C.); (D.B.) Department of Microbiology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia
Jasmina R. Milovanovic Department of Pharmacology and Toxicology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia; (J.R.M.); (S.J.); (D.M.)
Slobodan Jankovic Department of Pharmacology and Toxicology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia; (J.R.M.); (S.J.); (D.M.)
Dragan Milovanovic Department of Pharmacology and Toxicology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac, Serbia; (J.R.M.); (S.J.); (D.M.)

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Therapeutic drug monitoring of free perampanel concentrations in practice: A practical analytical technique based on centrifugal ultrafiltration sample separation

Objectives

The centrifugal ultrafiltration-high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established to determine the free perampanel (PER) concentration in children with epilepsy.

Methods

Free PER concentration was obtained using centrifugal ultrafiltration devices. The internal standard was PER-D5. The method was investigated for selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, matrix effects, recovery, and stability. The Spearman's correlation coefficient was used to evaluate the correlation between the free and total PER concentrations. A nonparametric test was used to estimate the effects of PER along with other antiepileptic drugs on the total and free PER concentrations.

Results

The free PER concentration was positively correlated with the total PER concentration in the 57 plasma samples (r = 0.793 > 0, P < 0.001). Additionally, the free PER concentrations were significantly (P < 0.05) increased in valproic acid (VPA) co-therapy (9.87 ± 5.83) compared with non-VPA co-therapy (5.03 ± 4.57).

Conclusions

The proposed method is efficient, sensitive, and suitable for detecting free PER concentrations in children with epilepsy. Simultaneously, the free PER concentration response to clinical outcomes in children with epilepsy was more clinically significant, particularly when combined with VPA.

Innovative LC-MS/MS method for therapeutic drug monitoring of fenfluramine and cannabidiol in the plasma of pediatric patients with epilepsy

We present a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying fenfluramine (FFA), its active metabolite norfenfluramine (norFFA), and Epidyolex®, a pure cannabidiol (CBD) oral solution in plasma. Recently approved by the EMA for the adjunctive treatment of refractory seizures in patients with Dravet and Lennox-Gastaut syndromes aged above 2 years, FFA and CBD still do not have established therapeutic blood ranges, and thus need careful drug monitoring to manage potential pharmacokinetic and pharmacodynamic interactions. Our method, validated by ICH guidelines M10, utilizes a rapid extraction protocol from 100 µL of human plasma and a reversed-phase C-18 HPLC column, with deuterated internal standards. The Thermofisher Quantiva triple-quadrupole MS coupled with an Ultimate 3000 UHPLC allowed multiple reaction monitoring detection, ensuring precise analyte quantification. The assay exhibited linear responses across a broad spectrum of concentrations: ranging from 1.64 to 1000 ng/mL for both FFA and CBD, and from 0.82 to 500 ng/mL for norFFA. The method proves accurate and reproducible, free from matrix effect. Additionally, FFA stability in plasma at 4 °C and -20 °C for up to 7 days bolsters its clinical applicability. Plasma concentrations detected in patients samples, expressed as mean ± standard deviation, were 0.36 ± 0.09 ng/mL for FFA, 19.67 ± 1.22 ng/mL for norFFA. This method stands as a robust tool for therapeutic drug monitoring (TDM) of FFA and CBD, offering significant utility in assessing drug-drug interactions in co-treated patients, thus contributing to optimized patient care in complex therapeutic scenarios.

Dose Monitoring of Lamotrigine Monotherapy in Pregnancy: Are Pregnant Women with Epilepsy Currently Optimally Managed? A Systematic Review

BACKGROUND

Lamotrigine monotherapy is the first-line treatment for epilepsy in pregnant women. However, altered pharmacokinetics during pregnancy can lead to suboptimal drug levels and increased seizure risk. This systematic review aimed to evaluate current therapeutic drug monitoring (TDM) strategies for lamotrigine monotherapy in pregnant women with epilepsy and provide guidance for monitoring and dose adjustments.

METHODS

A systematic search was performed using the Ovid-MEDLINE, Ovid-EMBASE, and Ovid-Cochrane Central Register of Controlled Trials databases. Studies were included if data on lamotrigine dosing, concentration, TDM strategies, efficacy, or safety were available.

RESULTS

Eleven studies were analyzed, revealing heterogeneity in outcomes with selective reporting of TDM strategies; however, clear similarities were observed. Blood samples were collected every 1-3 months during pregnancy to maintain prepregnancy baseline drug levels. Lamotrigine's apparent and relative clearance increased across trimesters, particularly in the second and third trimesters, coinciding with a period of increased seizure frequency and required dose adjustments. Details on dose adjustments were limited. Some studies have proposed using the threshold of the ratio to the target concentration to predict increased seizure risk. No distinct association was observed between adverse newborn outcomes and lamotrigine dose or serum concentration. Few maternal adverse effects have been reported after delivery, confirming the necessity of empirical postpartum tapering.

CONCLUSIONS

Further studies are required to establish evidence-based standardized protocols encompassing all aspects of TDM. Early interventions, such as empirical dose increases during pregnancy and postpartum tapering, and routine monitoring from preconception to the postpartum period may enhance seizure control, reducing the risk of breakthrough seizures for the mother and unborn child.

Therapeutic drug monitoring, liquid biopsies or pharmacogenomics for prediction of human drug metabolism and response

Pharmacokinetics plays a central role in understanding the significant interindividual differences that exist in drug metabolism and response. Effectively addressing these differences requires a multi-faceted approach that encompasses a variety of tools and methods. In this review, we examine three key strategies to achieve this goal, namely pharmacogenomics, therapeutic drug monitoring (TDM) and liquid biopsy-based monitoring of hepatic ADME gene expression and highlight their advantages and limitations. We note that larger cohort studies are needed to validate the utility of liquid biopsy-based assessment of hepatic ADME gene expression, which includes prediction of drug metabolism in the clinical setting. Modern mass spectrometers have improved traditional TDM methods, offering versatility and sensitivity. In addition, the identification of endogenous or dietary markers for CYP metabolic traits offers simpler and more cost-effective alternatives to determine the phenotype. We believe that future pharmacogenomic applications in clinical practice should prioritize the identification of missing heritable factors, using larger, well-characterized patient studies and controlling for confounding factors such as diet, concomitant medication and physical health. The intricate regulation of ADME gene expression implies that large-scale studies combining long-read next-generation sequencing (NGS) of complete genomes with phenotyping of patients taking different medications are essential to identify these missing heritabilities. The continuous integration of such data into AI-driven analytical systems could provide a comprehensive and useful framework. This could lead to the development of highly effective algorithms to improve genetics-based precision treatment by predicting drug metabolism and response, significantly improving clinical outcomes.

A 5-Year Study of Antiseizure Medications (ASMs) Monitoring in Patients with Neuropsychiatric Disorders in an Italian Clinical Center

Despite receiving appropriate antiseizure medications (ASMs), a relevant percentage of neuropsychiatric patients do not benefit from this approach, and one reason is subtherapeutic ASMs plasma concentration (C(p)) due to improper drug adherence, interindividual pharmacokinetic differences, or metabolic interactions among different drugs. For these reasons, therapeutic drug monitoring (TDM) by measuring ASMs C(p) is an effective tool that improves pharmacological therapies in clinical practice. Based on these premises, in the present real-world study, we analyzed the C(p) of the most used ASMs in diverse medical conditions, which were assayed during the years 2018-2022 at the University Hospital of Pisa, including about 24,000 samples. This population was largely heterogeneous, and our database did not contain clinical information about the patients. The most used ASMs were Valproate (VPA: 54.5%) and Levetiracetam (LEV: 18.6%), followed by Oxcarbazepine (OxCBZ: 8.3%) and Carbamazepine (CBZ: 7.2%), whereas the associations LEV/VPA, Ethosuximide (ESM)/VPA, and CBZ/VPA were the most frequently proposed. In about 2/3 of assays, ASMs C(p) was in range, except for VPA, which was underdosed in almost half of the samples. Importantly, toxic levels of ASMs C(p) were found very rarely. For VPA, there was a decrease of mean C(p) across ages, from adolescents to older patients, while the C(p) of LEV, CBZ, OxCBZ, and Topiramate (TPM) showed a slight tendency to increase. When we compared females and males, we found that for VPA, the average age was higher for females, whereas women taking Lamotrigine (LTG) and OxCBZ were younger than men. Then, comparing ASMs used in neurologic and psychiatric disorders, based on the request form, it emerged that the mean C(p) of CBZ, OxCBZ, and LTG on samples collected in the Psychiatric Unit was lower compared to the Neurology and Child Neuropsychiatry Units. Finally, the ASMs subjected to multiple dosing starting from an initial subtherapeutic C(p) increased their level at different time points within a year, reaching the reference range for some of them. In conclusion, the present study suggests that TDM is widely applied to monitor ASMs C(p), finding many of them within the reference range, as a demonstration of its utility in clinical practice.

Antiseizure medications (antiepileptic drugs) in adults: starting, monitoring and stopping

Up to 10% of people living to 80 years of age have one or more seizures; and many will not require anti-seizure medication (ASMs). In 85% of patients, the diagnosis comes from the history of the index event. One-third of patients with an apparent "first seizure" have previous events, changing their diagnosis to epilepsy. Targeted investigations are important for classification and risk prediction. Patients with a low risk of seizure recurrence are not usually offered ASM treatment. High-risk patients have multiple seizures, neurological deficits, intellectual disability and/or relevant abnormal investigations; and are offered ASMs. Individual factors modulate this decision-making. Future integrated technologies offer the game-changing potential for seizure monitoring and prediction, but are not yet robust, convenient or affordable. Therapeutic drug monitoring in patients taking ASMs may confirm ASM toxicity, or when non-adherence, malabsorption, or rapid metabolism are suspected causes of breakthrough seizures. They are less useful when these factors are intermittent or irregular. Current evidence does not favour routine monitoring of serum levels, as it neither reliably predicts control, relapse, or adverse effects. The decision to discontinue ASM should follow a full discussion with the patient of risks and benefits. Along with population risk factors for seizure recurrence, the patient's lifestyle and preferences must be considered. ASM are usually discontinued in a slow step-wise fashion, one at a time, after at least two years of remission. Seizure recurrence risk plateaus only after 2 years following ASM discontinuation, and patients need access to specialist follow-up over that period.

Integrative genomics reveals pathogenic mediator of valproate-induced neurodevelopmental disability

Prenatal exposure to the anti-seizure medication sodium valproate (VPA) is associated with an increased risk of adverse postnatal neurodevelopmental outcomes, including lowered intellectual ability, autism spectrum disorder and attention-deficit hyperactivity disorder. In this study, we aimed to clarify the molecular mechanisms underpinning the neurodevelopmental consequences of gestational VPA exposure using integrative genomics. We assessed the effect of gestational VPA on foetal brain gene expression using a validated rat model of valproate teratogenicity that mimics the human scenario of chronic oral valproate treatment during pregnancy at doses that are therapeutically relevant to the treatment of epilepsy. Two different rat strains were studied-inbred Genetic Absence Epilepsy Rats from Strasbourg, a model of genetic generalized epilepsy, and inbred non-epileptic control rats. Female rats were fed standard chow or VPA mixed in standard chow for 2 weeks prior to conception and then mated with same-strain males. In the VPA-exposed rats maternal oral treatment was continued throughout pregnancy. Foetuses were extracted via C-section on gestational Day 21 (1 day prior to birth) and foetal brains were snap-frozen and genome-wide gene expression data generated. We found that gestational VPA exposure via chronic maternal oral dosing was associated with substantial drug-induced differential gene expression in the pup brains, including dysregulated splicing, and observed that this occurred in the absence of evidence for significant neuronal gain or loss. The functional consequences of VPA-induced gene expression were explored using pathway analysis and integration with genetic risk data for psychiatric disease and behavioural traits. The set of genes downregulated by VPA in the pup brains were significantly enriched for pathways related to neurodevelopment and synaptic function and significantly enriched for heritability to human intelligence, schizophrenia and bipolar disorder. Our results provide a mechanistic link between chronic foetal VPA exposure and neurodevelopmental disability mediated by VPA-induced transcriptional dysregulation.

Development and evaluation of a simple and easy HPLC-UV system simultaneously suitable for determination of 24 anti-epileptic drugs in plasma

This paper aims to establish a simple and easy HPLC system coupled with UV detector suitable for simultaneous determination of 24 antiepileptic drugs in human plasma. Optimized chromatographic separation was performed on a ZORBAX Eclipse Plus-C18 (4.6 mm×150 mm, 3.5 μm) column with acetonitrile and 5 mM potassium dihydrogen phosphate water solution as mobile phase. 24 antiepileptic drugs were divided into three groups and eluted with different gradient procedures, respectively. The column temperature was maintained at 35 °C and the detection wavelength was set at 210 nm. Plasma was processed with ethyl acetate or acetonitrile. The calibration curves of 24 antiepileptic drugs demonstrated good linearity within the test range (r > 0.996). The intra- and inter-batch precision and accuracy were all less than 15%, while extraction recoveries were in the range of 74.57%∼90.89% with the RSD values less than 15%. The validated methods have been successfully applied to determination of some antiepileptic drugs in rat or patient plasma. Those results indicated that the developed methods were simple and easy, and could be suitable for the determination of 24 antiepileptic drugs in plasma just by changing the gradient elution procedures of mobile phase. This article is protected by copyright. All rights reserved.

Treatment outcomes in drug resistant juvenile myoclonic epilepsy: Valproate resistance may not be the end of the road

OBJECTIVE

To determine treatment responses to various antiseizure medicines (ASMs) in patients with drug resistant juvenile myoclonic epilepsy (DRJME) METHODS: We reviewed records of all JME patients attending epilepsy clinics at 5 centers during a 5-year period. We used International Consensus Criteria to diagnose JME and International League Against Epilepsy Criteria to define drug resistance and sustained seizure freedom. We only used broad spectrum medicines which included valproate, lamotrigine, topiramate, levetiracetam, clobazam, phenobarbitone, clonazepam, and zonisamide. We considered an ASM successful if patient achieved seizure freedom within 3 months of attaining maintenance dose.

RESULTS

We studied 116 patients (61 males) with DRJME. At terminal followup, 82 (70.7%) patients had achieved sustained seizure freedom with a mean followup of 3.2 ± 1.3 years after last dose change. In patients where valproate failed as first- or second-line ASM (n=70; 60.3%), 49(70%) became seizure-free. In this group, 33(67%) patients became seizure-free after addition of lamotrigine. Success rate of lamotrigine and valproate combination was 69% as compared to 9% with all other combinations (p = 0.001). In patients who were not exposed to valproate as initial therapy (n=46), 33 (71.7%) became seizure-free, 30 (91%) after adding valproate. At last follow-up, 75 (90%) seizure-free patients were receiving valproate including 45 (55%) patients with a combination of valproate and lamotrigine. Only one of 24 patients became seizure-free after failing valproate and lamotrigine combination.

CONCLUSION

Seizure freedom can be achieved in two-thirds of patients with DRJME. A combination of valproate and lamotrigine is the most effective duotherapy.

Past, present and future perspectives of therapeutic drug monitoring in India

Therapeutic drug monitoring (TDM) is the clinical practice of performing drug assays and interpreting results to maintain constant therapeutic concentrations in patients' bloodstream. Conventional TDM was started way back in the 1960s and served to optimise pharmacotherapy by maximising therapeutic efficacy by evaluating efficacy failure and monitoring drug compliance, while minimising adverse events, in drugs with a narrow therapeutic range. Currently, the scope of TDM has been extended to additional indications which are of importance to India. Apart from the conventional indications, TDM can also help combat drug resistance amongst patients treated with antimicrobials, including anti-tubercular drugs and critically ill patients with compromised pharmacokinetics. TDM is also indicated for patients on antiretroviral drugs under specific clinical scenarios and is of high importance to India. Target concentration intervention (TCI) and apriori TDM (by merging TDM with pharmacogenomics) are emerging fields explored in developed nations. The authors sought to assess the evolution of TDM in India and evaluate the potential impact of newer indications in rationalising pharmacotherapy. In the mid-1980s, TDM was presented to India. Despite showing some initial progress, its use is limited to conventional indications. Its utility is also challenged by cost and higher reliance on conventional prescribing practices. However, the newer indications such as antimicrobial resistance, tuberculosis and HIV, with their high prevalence in developing nations, present an opportunity for the growth of TDM in these countries. Indian clinician's awareness and buoyant demands alongside expert contributions from clinical pharmacologists could widen its scope.

Redefining the age-specific therapeutic ranges of lamotrigine for patients with epilepsy: A step towards optimizing treatment and increasing cost-effectiveness

OBJECTIVE

The pharmacokinetics of lamotrigine exhibits age-related characteristics. Nevertheless, current evidence regarding the therapeutic range of lamotrigine has been derived almost exclusively from studies in adult patients, and the applicability of this therapeutic range to the pediatric population remains unclear. The purpose of this study was to establish the appropriate age-specific therapeutic ranges of lamotrigine corresponding to adequate clinical responses for patients with epilepsy.

METHODS

This prospective cohort study of therapeutic drug monitoring included 582 Chinese epilepsy patients receiving lamotrigine monotherapy. Patients were divided into three age-related subgroups: (1) toddler and school-age group (2-12 years old, n = 168), (2) adolescent group (12-18 years old, n = 171), and (3) adult group (>18 years old, n = 243). Patients with a reduction in seizure frequency of 50 % or greater than baseline were defined as responders, and the remaining patients were non-responders. The relationship between lamotrigine serum concentrations and clinical response was assessed using multivariate logistic regression analysis. A receiver operating characteristic curve was generated to determine the representative cut-off values of lamotrigine trough levels, to distinguish responders from non-responders. The upper margin of the therapeutic range of lamotrigine was determined by developing concentration-effect curves for the three age-related subgroups.

RESULTS

The median trough levels of lamotrigine were significantly higher in responders than in non-responders from all three age-related groups (P < 0.0001). Results of logistic regression analysis revealed that higher serum concentrations of lamotrigine predicted a higher probability that seizure frequency would be reduced by more than 50 % compared to baseline (adjusted odds ratio: 1.228, 95 % CI: 1.137-1.327; P < 0.0001), and younger children were less likely to be responders (adjusted odds ratio: 1.027, 95 % CI: 1.012-1.043; P = 0.001). Based on a trade-off between sensitivity and specificity, the optimal cut-off values for lamotrigine trough concentrations corresponding to clinical response were 3.29 mg/L, 2.06 mg/L, and 1.61 mg/L in the toddler and school-age group, adolescent group, and adult group, respectively. By reducing interpatient variability, the results of the concentration-effect curves suggested no additional clinical benefit from a continued increase of doses for lamotrigine concentrations exceeding 9.08 mg/L, 8.43 mg/L, and 10.38 mg/L in the toddler and school-age group, adolescent group, and adult group, respectively. In conclusion, the therapeutic ranges of lamotrigine trough concentrations corresponding to adequate clinical response were 3.29-9.08 mg/L in the toddler and school-age group, 2.06-8.43 mg/L in the adolescent group, and 1.61-10.38 mg/L in the adult group.

CONCLUSIONS

The study determined age-specific therapeutic ranges corresponding to optimal clinical efficacy for lamotrigine. Our findings lay the foundation for catalyzing novel opportunities to optimize treatment and reduce therapeutic costs. Based on the age-specific therapeutic ranges identified in this study, individualized and cost-effective algorithms for lamotrigine treatment of epilepsy patients may be developed and validated in larger cohort studies of therapeutic drug monitoring.

Unanticipated improvement in seizure control in drug-resistant epilepsy- real world observations

OBJECTIVES

To determine the clinical features and anti-seizure medication (ASM) strategies associated with an unanticipated substantial improvement in seizure control in patients with drug-resistant epilepsy (DRE).

METHODS

This retrospective analysis of patients attending a tertiary care epilepsy clinic between 2008 and 2017 identified all patients with active DRE (at least 1 seizure per month for 6 months, despite treatment with 2 different ASMs). All treatment interventions were recorded from when DRE was first identified to the end of the study. The primary end points were seizure freedom or meaningful reduction in seizure frequency (greater than 75 %) sustained for at least 12 months after a treatment intervention.

RESULTS

Three hundred and twenty-two patients were included in the analysis. Overall, 10 % became seizure free following ASM adjustment and an additional 10 % had a greater than 75 % improvement in seizure control (median follow-up, 4 years). An ASM introduction was ten times more likely than an ASM dose increase to improve seizure control. Combined focal and generalized epilepsy, intellectual disability and prior treatment with more than 5 ASMs were more frequently observed in those with continued pharmacoresistance. ASM responders were more likely to have primary generalized epilepsy. Rational polytherapy (combining ASMs with different mechanisms of action) was almost ubiquitous amongst ASMs responders (95 % taking at least 2 drugs with different mechanistic targets). Of the ASM additions that heralded improved seizure control, 85 % were maintained at submaximal doses.

CONCLUSIONS

This retrospective analysis of a large number of 'real-world' patients provides evidence to persist with ASM trials in DRE. Early rotation of ASMs if a clinical response is not observed at a substantial dose and rational ASM polytherapy may yield better clinical outcomes in patients with DRE, although a prospective study would need to be conducted to validate these findings.