A pharmacokinetic-pharmacodynamic (efficacy) analysis was performed based on the pooled data from the 3 efficacy trials for partial-onset seizures. Lacosamide exposure is correlated with the reduction in seizure frequency. However, doses above 400 mg/day do not appear to confer additional benefit in group analyses.
Cardiac Electrophysiology
Electrocardiographic effects of lacosamide were determined in a double-blind, randomized clinical pharmacology trial of 247 healthy subjects. Chronic oral doses of 400 and 800 mg/day (equal to and Two times the maximum daily recommended dose, respectively) were compared with placebo and a positive control (400 mg moxifloxacin). Lacosamide did not prolong QTc interval and did not have a dose-related or clinically important effect on QRS duration. Lacosamide produced a small, dose-related increase in mean PR interval. At steady-state, the time of the maximum observed mean PR interval corresponded with tmax. The placebo-subtracted maximum increase in PR interval (at tmax) was 7.3 ms for the 400 mg/day group and 11.9 ms for the 800 mg/day group. For patients who participated in the controlled trials, the placebo-subtracted mean maximum increase in PR interval for a 400 mg/day lacosamide dose was 3.1 ms in patients with partial-onset seizures and 9.4 ms for patients with diabetic neuropathy.
The pharmacokinetics of lacosamide have been studied in healthy adult subjects (age range 18 to 87), adults with partial-onset seizures, adults with diabetic neuropathy, and subjects with renal and hepatic impairment. The pharmacokinetics of lacosamide are similar in healthy subjects, patients with partial-onset seizures, and patients with primary generalized tonic-clonic seizures.
Lacosamide is completely absorbed after oral administration with negligible first-pass effect with a high absolute bioavailability of approximately 100%. The maximum lacosamide plasma concentrations occur approximately 1-to-4-hour post-dose after oral dosing, and elimination half-life is approximately 13 hours. Steady state plasma concentrations are achieved after 3 days of twice daily repeated administration. Pharmacokinetics of lacosamide are dose proportional (100 to 800 mg) and time invariant, with low inter- and intra-subject variability. Compared to lacosamide the major metabolite, O-desmethyl metabolite, has a longer Tmax (0.5 to 12 hours) and elimination half-life (15-23 hours).
Absorption and Bioavailability
Lacosamide is completely absorbed after oral administration. The oral bioavailability of lacosamide tablets is approximately 100%. Food does not affect the rate and extent of absorption.
After intravenous administration, Cmax is reached at the end of infusion. The 30- and 60-minute intravenous infusions are bioequivalent to the oral tablet. For the 15-minute intravenous infusion, bioequivalence was met for AUC(0-tz) but not for Cmax. The point estimate of Cmax was 20% higher than Cmax for oral tablet and the 90% CI for Cmax exceeded the upper boundary of the bioequivalence range.
In a trial comparing the oral tablet with an oral solution containing 10 mg/mL lacosamide, bioequivalence between both formulations was shown.
A single loading dose of 200 mg approximates steady-state concentrations comparable to the 100 mg twice daily oral administration.
Distribution
The volume of distribution is approximately 0.6 L/kg and thus close to the volume of total body water. Lacosamide is less than 15% bound to plasma proteins.
Metabolism and Elimination
Lacosamide is primarily eliminated from the systemic circulation by renal excretion and biotransformation.
After intravenous administration of 100 mg [14C]-lacosamide approximately 95% of radioactivity administered was recovered in the urine and less than 0.5% in the feces. The major compounds excreted were unchanged lacosamide (approximately 40% of the dose), its O-desmethyl metabolite (approximately 30%), and a structurally unknown polar fraction (~20%). The plasma exposure of the major human metabolite, O-desmethyl-lacosamide, is approximately 10% of that of lacosamide. This metabolite has no known pharmacological activity.
The CYP isoforms mainly responsible for the formation of the major metabolite (O-desmethyl) are CYP3A4, CYP2C9, and CYP2C19. The elimination half-life of the unchanged drug is approximately 13 hours and is not altered by different doses, multiple dosing or intravenous administration.
There is no enantiomeric interconversion of lacosamide.
Specific Populations
Renal Impairment
Lacosamide and its major metabolite are eliminated from the systemic circulation primarily by renal excretion.
The AUC of lacosamide was increased approximately 25% in mildly (CLCR 50-80 mL/min) and moderately (CLCR 30-50 mL/min) and 60% in severely (CLCR≤30 mL/min) renally impaired patients compared to subjects with normal renal function (CLCR>80 mL/min), whereas Cmax was unaffected. Lacosamide is effectively removed from plasma by hemodialysis. Following a 4-hour hemodialysis treatment, AUC of lacosamide is reduced by approximately 50% [see Dosage and Administration (2.4)].
Hepatic Impairment
Lacosamide undergoes metabolism. Subjects with moderate hepatic impairment (Child-Pugh B) showed higher plasma concentrations of lacosamide (approximately 50-60% higher AUC compared to healthy subjects). The pharmacokinetics of lacosamide have not been evaluated in severe hepatic impairment [see Dosage and Administration (2.5)].
Pediatric Patients (1 month to less than 17 Years of Age)
A multicenter, double-blind, randomized, placebo-controlled, parallel-group study with a 20-day titration period and 7-day maintenance period using lacosamide (8 mg/kg/day to 12 mg/kg/day) was conducted in 255 (128 were randomized to lacosamide and 127 were randomized to placebo) pediatric patients with epilepsy 1 month to less than 4 years of age with uncontrolled partial-onset seizures. The pediatric pharmacokinetic profile of lacosamide was determined in a population pharmacokinetic analysis using sparse plasma concentration data obtained in six placebo-controlled studies and five open-label studies in 1655 adult and pediatric patients with epilepsy aged 1 month to less than 17 years who received intravenous, formulation.
A weight based dosing regimen is necessary to achieve lacosamide exposures in pediatric patients 1 month to less than 17 years of age similar to those observed in adults treated at effective doses of lacosamide [see Dosage and Administration (2.1)]. For patients weighing 10 kg, 28.9 kg (the mean population body weight), and 70 kg, the typical plasma half-life (t1/2) is 7.2 hours, 10.6 hours, and 14.8 hours, respectively. Steady state plasma concentrations are achieved after 3 days of twice daily repeated administration.
The pharmacokinetics of lacosamide in pediatric patients are similar when used as monotherapy or as adjunctive therapy for the treatment of partial-onset seizures and as adjunctive therapy for the treatment of primary generalized tonic-clonic seizures.
Geriatric Patients
In the elderly (>65 years), dose and body-weight normalized AUC and Cmax is about 20% increased compared to young subjects (18-64 years). This may be related to body weight and decreased renal function in elderly subjects.
Gender
Lacosamide clinical trials indicate that gender does not have a clinically relevant influence on the pharmacokinetics of lacosamide.
Race
There are no clinically relevant differences in the pharmacokinetics of lacosamide between Asian, Black, and Caucasian subjects.
CYP2C19 Polymorphism
There are no clinically relevant differences in the pharmacokinetics of lacosamide between CYP2C19 poor metabolizers and extensive metabolizers. Results from a trial in poor metabolizers (PM) (N=4) and extensive metabolizers (EM) (N=8) of cytochrome P450 (CYP) 2C19 showed that lacosamide plasma concentrations were similar in PMs and EMs, but plasma concentrations and the amount excreted into urine of the O-desmethyl metabolite were about 70% reduced in PMs compared to EMs.
Drug Interactions
In Vitro Assessment of Drug Interactions
In vitro metabolism studies indicate that lacosamide does not induce the enzyme activity of drug metabolizing cytochrome P450 isoforms CYP1A2, 2B6, 2C9, 2C19 and 3A4. Lacosamide did not inhibit CYP 1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2D6, 2E1, 3A4/5 at plasma concentrations observed in clinical studies.
In vitro data suggest that lacosamide has the potential to inhibit CYP2C19 at therapeutic concentrations. However, an in vivo study with omeprazole did not show an inhibitory effect on omeprazole pharmacokinetics.
Lacosamide was not a substrate or inhibitor for P-glycoprotein.
Lacosamide is a substrate of CYP3A4, CYP2C9, and CYP2C19. Patients with renal or hepatic impairment who are taking strong inhibitors of CYP3A4 and CYP2C9 may have increased exposure to lacosamide.
Since <15% of lacosamide is bound to plasma proteins, a clinically relevant interaction with other drugs through competition for protein binding sites is unlikely.
In Vivo Assessment of Drug Interactions
* Drug interaction studies with AEDs
o Effect of Lacosamide on concomitant AEDs
Lacosamide 400 mg/day had no influence on the pharmacokinetics of 600 mg/day valproic acid and 400 mg/day carbamazepine in healthy subjects.
The placebo-controlled clinical studies in patients with partial-onset seizures showed that steady-state plasma concentrations of levetiracetam, carbamazepine, carbamazepine epoxide, lamotrigine, topiramate, oxcarbazepine monohydroxy derivative (MHD), phenytoin, valproic acid, phenobarbital, gabapentin, clonazepam, and zonisamide were not affected by concomitant intake of lacosamide at any dose.
o Effect of concomitant AEDs on Lacosamide
Drug-drug interaction studies in healthy subjects showed that 600 mg/day valproic acid had no influence on the pharmacokinetics of 400 mg/day lacosamide. Likewise, 400 mg/day carbamazepine had no influence on the pharmacokinetics of lacosamide in a healthy subject study. Population pharmacokinetics results in patients with partial-onset seizures showed small reductions (15% to 20% lower) in lacosamide plasma concentrations when lacosamide was coadministered with carbamazepine, phenobarbital or phenytoin.
* Drug-drug interaction studies with other drugs
o Digoxin
There was no effect of lacosamide (400 mg/day) on the pharmacokinetics of digoxin (0.5 mg once daily) in a study in healthy subjects.
o Metformin
There were no clinically relevant changes in metformin levels following coadministration of lacosamide (400 mg/day).
Metformin (500 mg three times a day) had no effect on the pharmacokinetics of lacosamide (400 mg/day).
o Omeprazole
Omeprazole is a CYP2C19 substrate and inhibitor.
There was no effect of lacosamide (600 mg/day) on the pharmacokinetics of omeprazole (40 mg single dose) in healthy subjects. The data indicated that lacosamide had little in vivo inhibitory or inducing effect on CYP2C19.
Omeprazole at a dose of 40 mg once daily had no effect on the pharmacokinetics of lacosamide (300 mg single dose). However, plasma levels of the O-desmethyl metabolite were reduced about 60% in the presence of omeprazole.
o Midazolam
Midazolam is a 3A4 substrate.
There was no effect of lacosamide (200 mg single dose or repeat doses of 400 mg/day given as 200 mg BID) on the pharmacokinetics of midazolam (single dose, 7.5 mg), indicating no inhibitory or inducing effects on CYP3A4.
o Oral Contraceptives
There was no influence of lacosamide (400 mg/day) on the pharmacodynamics and pharmacokinetics of an oral contraceptive containing 0.03 mg ethinylestradiol and 0.15 mg levonorgestrel in healthy subjects, except that a 20% increase in ethinylestradiol Cmax was observed.
o Warfarin
Co-administration of lacosamide (400 mg/day) with warfarin (25 mg single dose) did not result in a clinically relevant change in the pharmacokinetic and pharmacodynamic effects of warfarin in a study in healthy male subjects.