Pharmacokinetic interaction study between eslicarbazepine acetate and lamotrigine in healthy subjects

Overnight switch from carbamazepine to eslicarbazepine in a real-life clinical scenario: a retrospective study

BACKGROUND

Carbamazepine (CBZ) is a first-choice anti-seizure medication (ASM) whose efficacy is often invalidated by adverse effects (AEs). Eslicarbazepine (ESL) is a structural derivative of CBZ with better pharmacokinetic/tolerability profiles. We describe our experience of the overnight CBZ to ESL switch in people with epilepsy (PwE) to improve seizure control, AEs, and ASMs adherence.

METHODS

We retrospectively included 19 PwE (12 females, 53 ± 21 years old) who underwent CBZ to ESL overnight switch due to single/multiple issues: poor efficacy (pEff, N = 8, 42%), tolerability (pToll, N = 11, 58%), adherence (pAdh, N = 2, 10%). 9/19 (47%) had psychiatric comorbidities. Clinical variables, seizure frequency, and AEs were recorded at switch time (T0) after 3.5 ± 3 (T1) and 6.5 ± 1.5 months (T2).

RESULTS

At T1, in pEff group, 1/8 (13%) was seizure free, 2/8 (25%) were responders (> 50% seizure reduction), 2/8 (25%) had no seizure changes, 3/8 (37%) had seizure worsening; the latter were those with the most severe epilepsy and encephalopathy. In pToll group, all PwE experienced AEs disappearance/amelioration. In pAdh group, all PwE reported adherence amelioration. Four dropouts. At T2, no changes were recorded within groups, while in the whole sample, 6/15 (40%) were responders, and 4/15 (27%) were seizure-free. No one complained of Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation psychiatric worsening, while 6/19 (32%) experienced mood/behavior benefits.

CONCLUSIONS

CBZ to ESL overnight switch offers an opportunity to improve efficacy, tolerability, adherence, and psychiatric symptoms.

Predictors of seizure freedom, response and retention after 12 months of treatment with eslicarbazepine acetate: A post-hoc analysis of the Euro-Esli study

Eslicarbazepine acetate (ESL) is a once-daily antiseizure medication (ASM) that is approved in Europe and the USA for the treatment of focal-onset seizures. The Euro-Esli study, which included over 2000 patients, investigated the real-world effectiveness, safety and tolerability of ESL when used in everyday clinical practice in Europe. This post-hoc analysis of Euro-Esli employed univariate and multivariate binary logistic regression analyses to investigate the relationship between demographic and baseline characteristics (including epilepsy- and treatment-related factors) and the likelihood of seizure freedom, response and retention in adult patients with focal seizures after 12 months of ESL treatment in the real-world setting. Multivariate analysis revealed that the factors associated with seizure freedom and response at 12 months (N = 1054) were generally those characterising patients who were relatively early in their disease course and/or less refractory to treatment, such as older age at onset of epilepsy, absence of seizures at baseline and lower number of concomitant ASMs at baseline. Although it was not possible to construct a multivariate model to predict retention on ESL treatment at 12 months, when the univariate regression model was adjusted for age and epilepsy duration, the factors found to be significantly associated with retention at 12 months (N = 1559) comprised shorter duration of epilepsy, absence of any seizures at baseline, lower baseline seizure frequency (<5 vs. ≥ 5 seizures/month), lower number of previous ASMs, lower number of concomitant ASMs, and the absence of concomitant use of lamotrigine at baseline. These findings therefore identify baseline characteristics that are predictive of the effectiveness of ESL treatment in clinical practice, which may help clinicians choose appropriate ASM therapy for patients.

Exposure-safety and efficacy response relationships and population pharmacokinetics of eslicarbazepine acetate

Objectives

Eslicarbazepine acetate (ESL) is a once‐daily (QD) oral antiepileptic drug (AED) for focal‐onset seizures (FOS). Pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to assess dose selection, identify significant AED drug interactions, and quantitate relationships between exposure and safety and efficacy outcomes from Phase 3 trials of adjunctive ESL.

Methods

Eslicarbazepine (the primary active metabolite of ESL) population PK was evaluated using data from 1351 subjects enrolled in 14 studies (11 Phase 1 and three Phase 3 studies) after multiple oral doses ranging from 400 to 1200 mg. Population PK and PD models related individual eslicarbazepine exposures to safety outcomes and efficacy responses.

Results

Eslicarbazepine PK was described by a one‐compartment model with linear absorption and elimination. The probability of a treatment‐emergent adverse event (TEAE; dizziness, headache, or somnolence) was higher with an initial dose of ESL 800 mg than with an initial dose of ESL 400 mg QD. Body weight, sex, region, and baseline use of carbamazepine (CBZ) or lamotrigine were also found to influence the probability of TEAEs. Eslicarbazepine exposure influenced serum sodium concentration, standardized seizure frequency, and probability of response; better efficacy outcomes were predicted in patients not from Western Europe (WE; vs WE patients) and those not taking CBZ (vs taking CBZ) at baseline.

Conclusions

Pharmacokinetic and PK/PD modeling were implemented during the development of ESL for adjunctive treatment of FOS in adults. This quantitative approach supported decision‐making during the development of ESL, and contributed to dosing recommendations and labeling information related to drug interactions.

Update on the role of eslicarbazepine acetate in the treatment of partial-onset epilepsy

Eslicarbazepine acetate (ESL) is a once daily new third generation antiepileptic drug that shares the basic chemical structure of carbamazepine and oxcarbazepine - a dibenzazepine nucleus with the 5-carboxamide substituent, but is structurally different at the 10,11-position. ESL is a pro-drug metabolized to its major active metabolite eslicarbazepine. Despite the fact that the exact mechanism of action has not been fully elucidated, it is thought to involve inhibition of voltage-gated sodium channels (VGSC). ESL inhibits sodium currents in a voltage-dependent way by an interaction predominantly with the inactivated state of the VGSC, thus selectively reducing the activity of rapidly firing (epileptic) neurons. ESL reduces VGSC availability through enhancement of slow inactivation. In Phase III studies, adjunctive therapy with ESL 800 or 1,200 mg/day leads to a significant decrease in the seizure frequency in adults with refractory partial onset epilepsy. Based on these results, ESL has been approved in Europe (by the European Medicines Agency) and in the United States (by the US Food and Drug Administration) as add-on therapy. Data on efficacy and safety have been confirmed by 1-year extension and real life observational studies. Recently, based on results from two randomized, double-blind, historical control Phase III trials, ESL received US Food and Drug Administration approval also as a monotherapy for patients with partial onset epilepsy. In the pediatric setting, encouraging results have been obtained suggesting its potential role in the management of epileptic children. Overall ESL was generally well tolerated. The most common adverse events were dizziness, somnolence, headache, nausea, diplopia, and vomiting. Adverse events can be minimized by appropriate titration. In conclusion, ESL seems to overcome some drawbacks of the previous antiepileptic drugs, suggesting a major role of ESL in the management of focal onset epilepsy for both new onset and refractory cases, either as monotherapy or as adjunctive treatment.

Eslicarbazepine acetate: a review of its use as adjunctive therapy in refractory partial-onset seizures

Eslicarbazepine acetate (Aptiom(®), Zebinix(®)) is approved for the adjunctive treatment of partial-onset seizures in adults aged ≥18 years. Adjunctive therapy with oral eslicarbazepine acetate 800 or 1,200 mg once daily was associated with a significantly lower standardized seizure frequency (primary endpoint) than placebo in patients aged ≥18 years with refractory partial-onset seizures in three, randomized, double-blind, multinational, phase III trials. In a fourth randomized, double-blind, multinational, phase III trial in patients aged ≥16 years with refractory partial-onset seizures, adjunctive eslicarbazepine acetate 1,200 mg once daily, but not 800 mg once daily, was associated with a significantly lower standardized seizure frequency (primary endpoint). Responder rates were significantly higher with eslicarbazepine acetate 1,200 mg once daily than with placebo in these four trials, and with eslicarbazepine acetate 800 mg once daily than with placebo in two trials. The efficacy of eslicarbazepine acetate was maintained in the longer term, according to the results of 1-year extension studies. Adjunctive therapy with oral eslicarbazepine acetate was generally well tolerated in patients with refractory partial-onset seizures, with most adverse events being of mild to moderate severity. In conclusion, eslicarbazepine acetate is a useful option for the adjunctive treatment of patients with refractory partial-onset seizures.

Advances in anti-epileptic drug testing

In the past twenty-one years, 17 new antiepileptic drugs have been approved for use in the United States and/or Europe. These drugs are clobazam, ezogabine (retigabine), eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, perampanel, pregabalin, rufinamide, stiripentol, tiagabine, topiramate, vigabatrin and zonisamide. Therapeutic drug monitoring is often used in the clinical dosing of the newer anti-epileptic drugs. The drugs with the best justifications for drug monitoring are lamotrigine, levetiracetam, oxcarbazepine, stiripentol, and zonisamide. Perampanel, stiripentol and tiagabine are strongly bound to serum proteins and are candidates for monitoring of the free drug fractions. Alternative specimens for therapeutic drug monitoring are saliva and dried blood spots. Therapeutic drug monitoring of the new antiepileptic drugs is discussed here for managing patients with epilepsy.

Pharmacotherapy of the third-generation AEDs: lacosamide, retigabine and eslicarbazepine acetate

INTRODUCTION

The search for new, more effective antiepileptic drugs (AEDs) continues. The three most recently approved drugs, the so-called third-generation AEDs, include lacosamide, retigabine and eslicarbazepine acetate and are licensed as adjunctive treatment of partial epilepsy in adults.

AREAS COVERED

For the above three AEDs, their mechanisms of action, pharmacokinetic characteristics, drug-drug interactions, pharmacotherapeutics, dose and administration and therapeutic drug monitoring are reviewed in this paper.

EXPERT OPINION

Lacosamide and retigabine act through novel mechanisms, while eslicarbazepine acetate, a pro-drug for eslicarbazepine, acts in a similar manner to several other AEDs. All three AEDs are associated with linear pharmacokinetic and rapid absorption and undergo metabolism. Their drug-drug interaction profile is low (lacosamide and retigabine) to modest (eslicarbazepine) in propensity. At the highest approved doses for the three AEDs, responder rates were similar. The most commonly observed adverse effects compared with placebo were dizziness, headache, diplopia and nausea for lacosamide; dizziness, somnolence and fatigue for retigabine and dizziness and somnolence for eslicarbazepine acetate. The precise role that these new AEDs will have in the treatment of epilepsy and whether they will make a significant impact on the prognosis of intractable epilepsy is not yet known and will have to await further clinical experience.

Pharmacokinetics, drug interactions and exposure-response relationship of eslicarbazepine acetate in adult patients with partial-onset seizures: population pharmacokinetic and pharmacokinetic/pharmacodynamic analyses

BACKGROUND

Eslicarbazepine acetate (Zebenix®) is a voltage-gated sodium channel blocker approved in 2009 by the European Medicines Agency as adjunctive therapy in adults with partial-onset seizures, with or without secondary generalization.

OBJECTIVES

The objectives of the current population pharmacokinetic (PK) and PK/pharmacodynamic analyses were to characterize the population PK of eslicarbazepine (the main active metabolite of eslicarbazepine acetate), to evaluate the influence of patient factors and concomitant antiepileptic drugs (AEDs) on the PK variability of eslicarbazepine, to assess the effect of eslicarbazepine acetate on the PK of concomitant AEDs and to investigate the relationship between eslicarbazepine systemic exposure and eslicarbazepine acetate antiepileptic activity in patients with partial-onset seizures uncontrolled with one to three AEDs.

METHODS

Sparse plasma concentrations of eslicarbazepine and concomitant AEDs, along with efficacy data, were obtained from 641 patients enrolled in eslicarbazepine acetate phase III studies. Data were analysed using nonlinear mixed-effect modelling methods. Most analyses used a model using log-transformed data from trough concentration (minimum steady-state plasma concentration during a dosage interval [C(min,ss)]). The model estimated the apparent total body clearance from plasma (CL/F), which is sufficient to predict average plasma concentrations at steady state (C(av,ss)). After the final model was validated, individual concentrations at steady state were predicted, and exposure parameters (area under the plasma concentration-time curve over 24 hours, C(min,ss) and C(av,ss)) for a one-compartmental model with first-order elimination were calculated.

RESULTS

Eslicarbazepine CL/F was affected by bodyweight, dose of carbamazepine (D(CAR)) and co-administration of barbiturates or phenytoin (AED(PB)), as predicted by the equation CL/F = (2.36 + 0.00149 • D(CAR) + 1.41 • AED(PB)) • (weight/70)0.75, which means that CL/F is 2.36 L/h for a subject with a bodyweight of 70 kg and without concomitant carbamazepine and barbiturates/phenytoin. Concomitant use of lamotrigine, valproic acid, topiramate, gabapentin, clobazam and levetiracetam showed no effect on the exposure to eslicarbazepine. Inter-individual variability of eslicarbazepine CL/F was 44% and the residual error (intra-subject variability) was proportional to the log of concentrations, with a coefficient of variation of 6%. Age, ethnicity, sex and creatinine clearance did not affect eslicarbazepine CL/F. Eslicarbazepine acetate did not affect the CL/F of clobazam, gabapentin, phenytoin, phenobarbital, levetiracetam and valproic acid. Eslicarbazepine acetate slightly increased the CL/F of carbamazepine (up to 14%), lamotrigine (up to 12%) and topiramate (up to 16%). The antiepileptic effect of eslicarbazepine acetate, as assessed by a decrease in seizure frequency, increased with the increase of eslicarbazepine acetate dose and eslicarbazepine concentrations. The concomitant administration of other AEDs did not affect the eslicarbazepine acetate exposure-response relationship.

CONCLUSIONS

The magnitude of the effect of eslicarbazepine acetate on the CL/F of the concomitant AEDs assessed appears to be not clinically relevant and does not justify the need for dose adjustment in most patients. A continuous dose-response relationship was observed between eslicarbazepine concentrations and seizure frequency reduction, which was not affected by concomitant AEDs.

A review of eslicarbazepine acetate for the adjunctive treatment of partial-onset epilepsy

Eslicarbazepine acetate (ESL) is a novel antiepileptic drug indicated for the treatment of partial-onset seizures. Structurally, it belongs to the dibenzazepine family and is closely related to carbamazepine and oxcarbazepine. Its main mechanism of action is by blocking the voltage-gated sodium channel. ESL is a pro-drug that is rapidly metabolized almost exclusively into S-licarbazepine, the biologically active drug. It has a favorable pharmacokinetic and drug-drug interaction profile. However, it may induce the metabolism of oral contraceptives and should be used with caution in females of child-bearing age. In the pre-marketing placebo-controlled clinical trials ESL has proven effective as adjunctive therapy in adult patients with refractory of partial-onset seizures. Best results were observed on a single daily dose between 800 and 1200 mg. In general, ESL was well tolerated, with most common dose-related side effects including dizziness, somnolence, headache, nausea and vomiting. Hyponatremia has been observed (0.6%–1.3%), but the incidence appears to be lower than with the use of oxcarbazepine. There is very limited information on the use of ESL in children or as monotherapy.

Hepatic UDP-glucuronosyltransferase is responsible for eslicarbazepine glucuronidation

Eslicarbazepine acetate (ESL) is a once-daily novel antiepileptic drug approved in Europe for use as adjunctive therapy for refractory partial-onset seizures with or without secondary generalization. Metabolism of ESL consists primarily of hydrolysis to eslicarbazepine, which is then subject to glucuronidation followed by renal excretion. In this study, we have identified that human liver microsomes (HLM) enriched with uridine 5'-diphosphoglucuronic acid give origin to a single Escherichia coli β-glucuronidase-sensitive eslicarbazepine glucuronide (most likely the O-glucuronide). The kinetics of eslicarbazepine glucuronidation in HLM was investigated in the presence and absence of bovine serum albumin (BSA). The apparent K(m) were 412.2 ± 63.8 and 349.7 ± 74.3 μM in the presence and absence of BSA, respectively. Incubations with recombinant human UDP glucuronosyltransferases (UGTs) indicated that UGT1A4, UGT1A9, UGT2B4, UGT2B7, and UGT2B17 appear to be involved in eslicarbazepine conjugation. The UGT with the highest affinity for conjugation was UGT2B4 (K(m) = 157.0 ± 31.2 and 28.7 ± 10.1 μM, in the absence and presence of BSA, respectively). There was a significant correlation between eslicarbazepine glucuronidation and trifluoperazine glucuronidation, a typical UGT1A4 substrate; however, no correlation was found with typical substrates for UGT1A1 and UGT1A9. Diclofenac inhibited eslicarbazepine glucuronidation in HLM with an IC(50) value of 17 μM. In conclusion, glucuronidation of eslicarbazepine results from the contribution of UGT1A4, UGT1A9, UGT2B4, UGT2B7, and UGT2B17, but the high-affinity component of the UGT2B4 isozyme may play a major role at therapeutic plasma concentrations of unbound eslicarbazepine.

Update on treatment of partial onset epilepsy: role of eslicarbazepine

Partial epilepsy comprises simple partial seizures, complex partial seizures, and secondarily generalized seizures, and covers more than 60% of patients with epilepsy. Antiepileptic drugs are generally considered to be the major therapeutic intervention for epilepsy but, despite a broad range of commonly used antiepileptic drugs, approximately 30% of adult patients and approximately 25% of children with epilepsy have inadequate seizure control. Eslicarbazepine acetate (ESL) is a novel voltage-gated sodium channel-blocking agent with presumed good safety and efficacy for adjunctive treatment of patients with drug-resistant partial epilepsy. ESL is a prodrug of eslicarbazepine (the active entity responsible for pharmacologic effects), and is rapidly and extensively hydrolyzed during first pass by liver esterases after oral administration. The half-life of eslicarbazepine at steady-state plasma concentrations is 20-24 hours, compatible with once-daily administration. ESL 800 mg and 1200 mg significantly reduces seizure frequency and shows a favorable safety profile in adult patients with drug-resistant partial-onset seizures, as demonstrated in previous Phase II and III trials. In children, ESL showed a clear dose-dependent decrease in seizure frequency with good tolerability. The most commonly reported adverse events associated with ESL are dizziness, somnolence, nausea, diplopia, headache, vomiting, blurred vision, vertigo, and fatigue. In conclusion, these characteristics suggest that ESL might be a valid and well tolerated treatment option for patients with drug-resistant partial-onset epilepsy. The convenience of once-daily dosing and a short, simple titration regimen would be of special interest for children, although conclusive published data are lacking to date. Hence, there is an urgent need to establish the therapeutic value of ESL in this special population in the near future.

Therapeutic Drug Monitoring of the Newer Anti-Epilepsy Medications

In the past twenty years, 14 new antiepileptic drugs have been approved for use in the United States and/or Europe. These drugs are eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, rufinamide, stiripentol, tiagabine, topiramate, vigabatrin and zonisamide. In general, the clinical utility of therapeutic drug monitoring has not been established in clinical trials for these new anticonvulsants, and clear guidelines for drug monitoring have yet to be defined. The antiepileptic drugs with the strongest justifications for drug monitoring are lamotrigine, oxcarbazepine, stiripentol, and zonisamide. Stiripentol and tiagabine are strongly protein bound and are candidates for free drug monitoring. Therapeutic drug monitoring has lower utility for gabapentin, pregabalin, and vigabatrin. Measurement of salivary drug concentrations has potential utility for therapeutic drug monitoring of lamotrigine, levetiracetam, and topiramate. Therapeutic drug monitoring of the new antiepileptic drugs will be discussed in managing patients with epilepsy.

Therapeutic Drug Monitoring of the Newer Anti-Epilepsy Medications

In the past twenty years, 14 new antiepileptic drugs have been approved for use in the United States and/or Europe. These drugs are eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, rufinamide, stiripentol, tiagabine, topiramate, vigabatrin and zonisamide. In general, the clinical utility of therapeutic drug monitoring has not been established in clinical trials for these new anticonvulsants, and clear guidelines for drug monitoring have yet to be defined. The antiepileptic drugs with the strongest justifications for drug monitoring are lamotrigine, oxcarbazepine, stiripentol, and zonisamide. Stiripentol and tiagabine are strongly protein bound and are candidates for free drug monitoring. Therapeutic drug monitoring has lower utility for gabapentin, pregabalin, and vigabatrin. Measurement of salivary drug concentrations has potential utility for therapeutic drug monitoring of lamotrigine, levetiracetam, and topiramate. Therapeutic drug monitoring of the new antiepileptic drugs will be discussed in managing patients with epilepsy.