Low Lacosamide Plasma Protein Binding in Lacosamide-Naive Patients (P01.077)

Development and validation of an innovative UPLC method to quantify lacosamide, oxcarbazepine, and lamotrigine in the serum of children with epilepsy in China

This study has developed and validated a novel UPLC method to quantify lacosamide (LCM), oxcarbazepine (OXC), and lamotrigine (LTG) in children with epilepsy in Xinjiang, China. Phenytoin sodium was used as the internal standard. The mobile phase contained ammonium dihydrogen phosphate solution (10 mmol/L, pH = 4.0) and methanol (55:45, v/v). The flow rate, injection volume, column temperature, and detection wavelength were 0.2 mL/min, 2 μL, 30°C, and 240 nm, respectively. The method was linear within 0.5-40, 2.5-80, and 2.5-40 μg/mL for LCM, 10-hydroxycarbazepine (MHD), and LTG, respectively (r²  ≥ 0.998). The intra- and inter-day precision as measured by the relative standard deviation values was between 1.36 and 4.50, 0.54 and 1.91, and 0.58 and 1.56%. Recovery ranged from 96.58 to 106.22%. All serum samples could be maintained for up to 3 h at ambient temperature, 24 h at 4°C, 30 days at -30°C, and after successive freeze-thaw cycles (24 h per cycle) in the absence of significant degradation.

Assessment of the correlations of lacosamide concentrations in saliva and serum in patients with epilepsy

Therapeutic drug monitoring of antiepileptic drugs is based on patient serum samples. In this study, we evaluated the correlation between lacosamide (LCM) steady state concentrations in serum and saliva samples. Additionally, we investigated the relation with daily dose, and assessed the feasibility of saliva collection. This was an open-label, single center study including data from 25 patients at the Bethel Epilepsy Center treated with LCM (50-650 mg/d). Samples were collected in the morning (fasting values) and in selected cases at 50 minutes to 5 hours after the morning dose. Nonsignificant differences in the mean LCM morning (trough) concentration in serum and saliva were observed. Serum and saliva concentrations across all samples were highly correlated, (r = .874), with a slightly lower correlation when only fasting values were analyzed (r = .860). Higher correlation with daily dosages was observed in serum samples (r = .773) than in saliva samples (r = .604). Serum and saliva concentrations increased significantly after intake of the LCM morning dose (P < .001). The median absolute and percentage increase of LCM in serum were moderately lower than in saliva samples, with a few outliers in saliva samples. Consequently, saliva could offer great clinical potential to monitor drug concentrations and guide LCM treatment in epileptic patients.

Safety and tolerability of lacosamide as adjunctive therapy for adults with partial-onset seizures: Analysis of data pooled from three randomized, double-blind, placebo-controlled clinical trials

OBJECTIVE

The objective of this study was to describe a priori protocol-defined analyses to evaluate the safety and tolerability of adjunctive oral lacosamide (200-600 mg/day) in adults (ages 16-70 years) with partial-onset seizures (POS) using data pooled from three similarly designed randomized, double-blind, placebo-controlled trials (SP667, SP754 [NCT00136019], SP755 [NCT00220415]).

METHODS

Patients with POS (≥2 years' duration, ≥2 previous antiepileptic drugs [AEDs]) uncontrolled by a stable dosing regimen of 1-3 concomitant AEDs were randomized to treatment with lacosamide at doses of 200 mg/day, 400 mg/day, or 600 mg/day, or placebo. Studies comprised a 4- to 6-week titration phase to target dose followed by a 12-week maintenance phase. Safety outcomes included treatment-emergent adverse events (TEAEs) of particular relevance to patients with POS, overall TEAEs, and discontinuations due to TEAEs. Post hoc analyses included evaluation of TEAEs potentially related to cognition and TEAEs leading to discontinuation analyzed by concomitant AEDs.

RESULTS

One thousand three hundred eight patients were randomized to and received treatment; 944 to lacosamide and 364 to placebo. Most patients (84.4%) were taking 2 or 3 concomitant AEDs. The most common drug-associated TEAEs (reported by ≥5% of patients in any lacosamide dose group and with an incidence at least twice that reported for placebo during the treatment phase) were dizziness (30.6% for lacosamide vs 8.2% for placebo), nausea (11.4% vs 4.4%), and diplopia (10.5% vs 1.9%). Common drug-associated TEAEs generally appeared to be dose-related, and the incidence of each was lower during the 12-week maintenance phase than during the titration phase. Most TEAEs were either mild or moderate in intensity; severe TEAEs were predominantly observed with lacosamide 600 mg/day. No individual serious TEAE occurred in ≥1% of all lacosamide-treated patients. Treatment-emergent adverse events led to discontinuation in 8.1%, 17.2%, and 28.6% of the lacosamide 200-, 400-, and 600-mg/day groups, respectively (vs 4.9% of placebo). Few TEAEs were related to rash, weight loss/gain, changes in clinical chemistry parameters, or psychiatric disturbances, or were seizure-related. The odds of reporting any potential cognition-related TEAE vs placebo increased with dose and were similar between lacosamide doses of 200 and 400mg/day and placebo (odds ratio 1.3, 95% confidence interval 0.7-2.4). Discontinuations due to TEAEs based on most commonly used AEDs taken in combination with lacosamide (all doses combined) were carbamazepine (15.3% [51/334] vs 3.9% [5/129] placebo), lamotrigine (19.2% [56/291] vs 4.3% [5/117]), and levetiracetam (10.1% [28/278] vs 3.9% [4/103]).

CONCLUSIONS

The safety and tolerability profile of adjunctive lacosamide in this detailed evaluation was similar to that observed in the individual double-blind trials. Adjunctive lacosamide was associated with TEAEs related to the nervous system and gastrointestinal tract, predominantly during titration.

Cardiac safety of lacosamide: the non-clinical perspective

OBJECTIVES

Lacosamide is indicated for the adjunctive treatment of partial-onset seizures in adult patients. Unlike other sodium channel-blocking antiepileptic drugs, lacosamide selectively enhances sodium channel slow inactivation. Potential effects of lacosamide on cardiac sodium channels and their cardiovascular consequences were comprehensively assessed. This manuscript presents the non-clinical cardiac safety profile of lacosamide.

METHODS

Lacosamide was tested in vitro on sodium and L-type calcium currents from isolated human atrial myocytes and on hERG-mediated potassium currents from stably transfected HEK293 cells. Cardiac action potentials were recorded in guinea pig ventricular myocytes. In vivo, hemodynamic and ECG parameters were evaluated in anesthetized dogs and monkeys receiving acute cumulative intravenous doses of lacosamide.

RESULTS

Following intravenous dosing with lacosamide, dose-dependent PR and QRS prolongation and ECG abnormalities (loss of P waves, atrioventricular and intraventricular blocks, junctional premature contractions) were observed in anesthetized dogs and monkeys. In vitro, lacosamide reduced human cardiac sodium currents in a concentration-, voltage- and state-dependent manner. Lacosamide reductions in Vmax in guinea pig myocytes were similar to lamotrigine and carbamazepine. Lacosamide showed no relevant inhibitory effects on hERG and L-type calcium channels and did not prolong QTc in vivo.

CONCLUSIONS

ECG findings in anesthetized animals correlate well with in vitro sodium channel-related effects and are also consistent with those (PR prolongation, first-degree atrioventricular block) reported in healthy volunteers and patients with epilepsy. Both in vivo and in vitro effects were detected from exposure levels 1.5- to 2-fold above those achieved with the maximum-recommended human lacosamide dose (400 mg/day).

Advances in epilepsy treatment: lacosamide pharmacokinetic profile

Lacosamide (LCM) is a functionalized amino acid specifically developed for use as an antiepileptic drug (AED) and is currently indicated as adjunctive treatment for partial-onset seizures in adults with focal epilepsy (maximum approved dose 400 mg/day). Characterization of the pharmacokinetic profile is an important aspect in the development of LCM. Studies in healthy subjects and in patients with focal epilepsy have established that LCM has several favorable pharmacokinetic characteristics, including rapid absorption and high oral bioavailability not affected by food, linear and dose-proportional pharmacokinetics, low inter- and intraindividual variability, low plasma protein binding, renal elimination, and a low potential for clinically relevant pharmacokinetic drug-drug interactions both with AEDs and other common medications. Studies have demonstrated bioequivalence among the three LCM formulations (oral tablets, oral solution, and solution for intravenous (IV) infusion), allowing direct conversion to or from oral and IV administration without titration. Thus, the favorable and predictable pharmacokinetic profile and bioequivalence of LCM formulations, coupled with the low potential for clinically relevant pharmacokinetic drug-drug interactions, make LCM an easy-to-use adjunctive treatment for the management of patients with focal epilepsy.

Lacosamide: a review of its use as adjunctive therapy in the management of partial-onset seizures

Lacosamide (Vimpat(®)) is a functionalized amino acid available orally (as a syrup or tablet) and as an intravenous infusion. It is believed to exert its antiepileptic effect by selectively enhancing the slow inactivation of voltage-gated sodium channels. Lacosamide is approved in several countries worldwide as an adjunctive therapy for the treatment of partial-onset seizures; however, prescribing regulations differ between countries. This article reviews the use of lacosamide as indicated in adults and adolescents (aged 16-18 years) in the EU, where it is approved in this patient population as an adjunctive therapy to other AEDs in the treatment of partial-onset seizures, with or without secondary generalization. In three randomized, double-blind, placebo-controlled, multicentre studies in adults and adolescents (aged 16-18 years) with partial-onset seizures, adjunctive therapy with oral lacosamide (administered for an initial titration period followed by 12 weeks' maintenance therapy) generally reduced the frequency of seizures to a significantly greater extent than placebo, with antiepileptic efficacy sustained following longer-term treatment (up to 8 years) in this patient population. Oral and intravenous lacosamide were generally well tolerated in clinical studies, with the majority of adverse events being mild or moderate in severity. Very common adverse reactions following adjunctive therapy with oral lacosamide included diplopia, dizziness, headache and nausea; the tolerability profile of intravenous lacosamide appeared consistent with that of oral lacosamide, although intravenous administration was associated with local adverse events, such as injection site discomfort or pain, irritation and erythema. Thus, oral and intravenous lacosamide as an adjunctive therapy to other AEDs provides a useful option in the treatment of patients with partial-onset seizures.

Pharmacodynamic and pharmacokinetic evaluation of coadministration of lacosamide and an oral contraceptive (levonorgestrel plus ethinylestradiol) in healthy female volunteers

PURPOSE

To determine whether the antiepileptic drug lacosamide affects the pharmacokinetics or pharmacodynamics of a combined oral contraceptive (OC; ethinylestradiol 0.03 mg plus levonorgestrel 0.15 mg).

METHODS

This was an open-label trial in healthy female volunteers. Eligible women entered cycle 1 of the trial on the first day of menstruation. Cycle 1 was a medication-free, run-in phase of approximately 28 days to confirm that normal ovulation occurred. Volunteers with confirmed ovulation entered the subsequent cycle and started taking OCs. After establishing ovulation suppression (defined as progesterone serum concentration <5.1 nm on day 21 of the menstrual cycle) in volunteers taking the OCs in cycle 2, lacosamide 400 mg/day was administered concomitantly in the subsequent cycle (cycle 3). The pharmacokinetic parameters of area under the concentration-time curve (AUC), maximum steady-state plasma drug concentration (Cmax ), and time to maximum concentration (tmax ) were measured for the OC components and lacosamide.

KEY FINDINGS

A total of 37 volunteers completed cycle 1, and 32 completed cycle 2. In each of the 31 volunteers who completed the trial (through cycle 3), pharmacodynamic assessment showed progesterone serum concentration was <5.1 nm on day 21 of cycle 2, when the OC was administered alone, and on day 21 of cycle 3, when lacosamide was administered concomitantly. The AUC of ethinylestradiol alone versus together with lacosamide was 1,067 ± 404 versus 1,173 ± 330 pg h/ml. Corresponding values of Cmax were 116.9 ± 48.8 versus 135.7 ± 28.6 pg/ml. For levonorgestrel, the AUC alone was 74.2 ± 21.4 versus 80.9 ± 18.5 ng h/ml with lacosamide. Corresponding values of Cmax were 6.7 ± 1.9 versus 7.4 ± 1.5 ng/ml. The AUC and Cmax point estimates and almost all 90% confidence intervals (except for Cmax of ethinylestradiol) for ethinylestradiol and levonorgestrel (with and without lacosamide) were within the conventional bioequivalence range, and no relevant changes in tmax were observed for ethinylestradiol (1.5 ± 0.6 h alone vs. 1.4 ± 0.7 h with lacosamide) or for levonorgestrel (1.5 ± 1.0 h alone vs. 1.1 ± 0.6 h with lacosamide). Lacosamide pharmacokinetics were consistent with those observed in previous studies of lacosamide alone, with values for AUC of 113.5 ± 20.7 μg h/ml, Cmax of 13.8 ± 2.2 μg/ml, and tmax of 1.1 ± 0.4 h.

SIGNIFICANCE

Lacosamide and an OC containing ethinylestradiol and levonorgestrel have low potential for drug-drug interaction; therefore, coadministration of the two drugs is unlikely to result in contraceptive failure or loss of seizure control.

Tolerability, pharmacokinetics, and bioequivalence of the tablet and syrup formulations of lacosamide in plasma, saliva, and urine: saliva as a surrogate of pharmacokinetics in the central compartment

PURPOSE

To test for bioequivalence of 200 mg lacosamide oral tablet and syrup formulations. Additional objectives were to compare the pharmacokinetic profile of lacosamide in saliva and plasma, and to evaluate its tolerability.

METHODS

This open-label, randomized, two-way crossover trial was conducted in 16 healthy Caucasian male participants in Germany. The bioequivalence of 200 mg lacosamide tablet and syrup was evaluated using plasma to determine maximum measured concentration (C(max)) and area under the curve from zero to the last time point (AUC)(0-tz). Plasma and saliva samples for evaluation of pharmacokinetic parameters of lacosamide and the major metabolite O-desmethyl lacosamide (SPM 12809) were taken over 15 time points (0.5-72 h) and used to statistically compare bioavailability of the two. Urine samples were collected predose and over five time points (0-48 h) to evaluate the cumulative amount of unchanged drug and metabolite.

KEY FINDINGS

Lacosamide median time to reach C(max) (t(max)) was 1 h for tablet and 0.5 h for syrup in plasma and saliva. Mean terminal half life (t(½)) for tablet and syrup was 12.5 and 12.4 h in plasma, and 13.1 and 13.3 h in saliva, respectively. Tablet and syrup mean plasma AUC(0-tz) was 84.5 and 83.3 μg/mL*h, respectively. Mean AUC(0-tz) in saliva was 93.2 μg/mL*h for tablet and syrup. Mean C(max) for tablet was 5.26 μg/mL in plasma and 5.63 μg/mL in saliva. Syrup mean C(max) was 5.14 and 8.32 μg/mL in plasma and saliva, respectively. Within 2 h of syrup administration, elevated lacosamide concentration in saliva compared to plasma was observed. The ratio of lacosamide syrup to tablet was 0.98 for C(max) and 0.99 for AUC(0-tz) in plasma, and 1.00 for AUC((0-tz)) in saliva; the 90% confidence intervals (CIs) for these parameters were within the range of 0.80-1.25, which meets accepted bioequivalence criteria. The syrup-to-tablet ratio for C(max) in saliva was 1.48, and the 90% CIs exceeded the accepted upper boundary for bioequivalence (1.32-1.66). Both formulations were well tolerated. Metabolite concentration versus time profiles for saliva were similar to plasma following tablet and syrup administration.

SIGNIFICANCE

The tablet and syrup formulations of lacosamide 200 mg were bioequivalent and well tolerated. Saliva samples were demonstrated to be a suitable surrogate to evaluate lacosamide tablet pharmacokinetics in the central compartment. Due to residual syrup in the buccal cavity, limitations exist when using saliva to evaluate the pharmacokinetics of lacosamide syrup <2 h after administration.