Minimizing pharmacodynamic interactions of high doses of lacosamide

Pharmacology of lacosamide: From its molecular mechanisms and pharmacokinetics to future therapeutic applications

Epilepsy is one of the most common brain disorders, affecting more than 50 million people worldwide. Although its treatment is currently symptomatic, the last generation of anti-seizure drugs is characterized by better pharmacokinetic profiles, efficacy, tolerability and safety. Lacosamide is a third-generation anti-seizure drug that stands out due to its good efficacy and safety profile. It is used with effectiveness in the treatment of partial-onset seizures with or without secondary generalization, primary generalized tonic-clonic seizures and off-label in status epilepticus. Despite scarcely performed until today, therapeutic drug monitoring of lacosamide is proving to be advantageous by allowing the control of inter and intra-individual variability and promoting a successful personalized therapy, particularly in special populations. Herein, the pharmacology, pharmacokinetics, and clinical data of lacosamide were reviewed, giving special emphasis to the latest molecular investigations underlying its mechanism of action and therapeutic applications in pathologies besides epilepsy. In addition, the pharmacokinetic characteristics of lacosamide were updated, as well as current literature concerning the high pharmacokinetic variability observed in special patient populations and that must be considered during treatment individualization.

Switching from traditional sodium channel blockers to lacosamide in patients with epilepsy

PURPOSE

Lacosamide (LCM) is a recently developed sodium channel blocker (SCB), which acts mainly on the slow activation state in sodium channels. Although LCM shares a range of dose-dependent adverse effects with traditional SCBs, it has several advantages in that it does not induce hepatic drug metabolizing enzymes and has less risk of drug interactions and idiosyncratic adverse effects.

METHODS

We retrospectively analyzed the efficacy and tolerability of switching from traditional SCBs to LCM. The reason for the switch was classified as insufficient efficacy, adverse effects, or concern about metabolic derangement, resulting in conditions such as atherosclerosis and osteoporosis, with long-term use of traditional SCBs.

RESULTS

Seventy-five patients were switched to LCM from traditional SCBs. The overall rate of successful switching was high (81.3%, 61/75 patients). However, the success rate was strongly dependent on the reason for the switch; patients with insufficient efficacy on SCBs had less chance of a successful switch (71.8%, 28/39 patients) than those with adverse effects (89.5%, 17/19) or concerns about metabolic derangement (94.1%, 16/17, p =  0.038). Patients with insufficient efficacy were significantly younger (p =  0.004) and had a higher chance of drug-resistant epilepsy (p =  0.004) than those in the other two groups.

CONCLUSIONS

Our study shows that switching from traditional SCBs to LCM is usually successful and the likelihood of a successful switch is higher in patients when the reason for the switch is adverse effects or concerns about metabolic derangement on traditional SCBs.

Influence of titration schedule and maintenance dose on the tolerability of adjunctive eslicarbazepine acetate: An integrated analysis of three randomized placebo-controlled trials

OBJECTIVE

To examine the influence of titration schedule and maintenance dose on the incidence and type of treatment-emergent adverse events (TEAEs) associated with adjunctive eslicarbazepine acetate (ESL).

METHODS

Data from three randomized, double-blind, placebo-controlled trials were analyzed. Patients with refractory partial-onset seizures were randomized to maintenance doses of ESL 400, 800, or 1200mg QD (dosing was initiated at 400 or 800mg QD) or placebo. The incidence of TEAEs was analyzed during the double-blind period (2-week titration phase; 12-week maintenance phase), according to the randomized maintenance dose and the titration schedule.

RESULTS

1447 patients were included in the analysis. During the first week of treatment, 62% of patients taking ESL 800mg QD had ≥1 TEAE, vs 35% of those taking 400mg QD and 32% of the placebo group; dizziness, somnolence, nausea, and headache were numerically more frequent in patients taking ESL 800mg than those taking ESL 400mg QD. During the double-blind period, the incidences of common TEAEs were lower in patients who initiated ESL at 400mg vs 800mg QD. For the 800 and 1200mg QD maintenance doses, rates of TEAEs leading to discontinuation were lower in patients who began treatment with 400mg than in those who began taking ESL 800mg QD.

CONCLUSIONS

Initiation of ESL at 800mg QD is feasible. However, initiating treatment with ESL 400mg QD for 1 or 2 weeks is recommended, being associated with a lower incidence of TEAEs, and related discontinuations. For some patients, treatment may be initiated at 800mg QD, if the need for more immediate seizure reduction outweighs concerns about increased risk of adverse reactions during initiation.

Comparing Safety and Efficacy of "Third-Generation" Antiepileptic Drugs: Long-Term Extension and Post-marketing Treatment

Four "third-generation" antiepileptic drugs (AEDs) were approved for adjunctive treatment of refractory focal onset seizures during the past 10 years. Long-term efficacy and safety of the drugs were demonstrated in large extension studies and in reports of subgroups of patients not studied in pivotal trials. Reviewing extension study and post-marketing outcome series for the four newer AEDs-lacosamide, perampanel, eslicarbazepine acetate and brivaracetam-can guide clinicians in treating and monitoring patients. AED extension studies evaluate treatment retention, drug tolerability, and drug safety during individualized treatment with flexible dosing and thus provide information not available in rigid pivotal trials. Patient retention in the studies ranged from 75 to 80% at 1 year and from 36 to 68% at 2-year treatment intervals. Safety findings were generally similar to those of pivotal trials, with no major safety risks identified and with several specific adverse drug effects, such as hyponatremia, reported. The third-generation AEDs, some through new mechanisms and others with improved tolerability compared to related AEDs, provide new options in efficacy and tolerability.

Lacosamide and sodium channel-blocking antiepileptic drug cross-titration against levetiracetam background therapy

OBJECTIVE

To assess prospectively the effectiveness of lacosamide (LCM) added to levetiracetam (LEV) after down-titration of a concomitant sodium channel blocker (SCB) among patients with focal epilepsy not adequately controlled on LEV and SCB.

METHODS

In this open-label trial, LCM was initiated at 100 mg/day and up-titrated to 200-600 mg/day over 9 weeks; SCB down-titration started when LCM dose reached 200 mg/day. Patients remained on stable LCM/LEV doses for 12 weeks' maintenance (21-week treatment period). The primary outcome was retention rate on LCM.

RESULTS

Due to recruitment challenges, fewer than the planned 300 patients participated in the trial, resulting in the trial being underpowered. Overall, 120 patients (mean age 39.7 years) started and 93 completed the trial. The most frequently used SCBs were lamotrigine (39.2%), carbamazepine (30.8%) and oxcarbazepine (27.5%). Eighty-four patients adhered to protocol and discontinued their SCB after cross-titration, but there was insufficient evidence for 36 patients. Retention rate was 73.3% (88/120) for all patients and 83.3% (70/84) for those with evidence of SCB discontinuation. Seizure freedom for patients completing maintenance was 14.0% (13/93). Discontinuation due to adverse events (6.7%) and lack of efficacy (3.3%) occurred primarily during cross-titration. Most frequently reported adverse events during treatment were dizziness (23.3%), headache (15.0%) and fatigue (8.3%).

CONCLUSIONS

In patients with uncontrolled seizures on LEV/SCB, the LCM/LEV combination appeared to be effective and well tolerated. A cross-titration schedule-flexible LCM up-titration, concomitant SCB down-titration and stable background LEV-could present a feasible and practical approach to initiating LCM while minimizing pharmacodynamic interactions with a SCB.

Lacosamide tolerability in adult patients with partial-onset seizures: Impact of planned reduction and mechanism of action of concomitant antiepileptic drugs

OBJECTIVE

We evaluated the impact of planned dose reduction and mechanism of action of concomitant AEDs on tolerability in adults with partial-onset seizures undergoing lacosamide (LCM) titration.

METHODS

Data were collected at baseline and 3-6 and 12-24 months post-LCM initiation. Subjects were categorized as having planned reduction of concomitant AEDs or not; AEDs were categorized as traditional sodium channel blockers (TSCB) or non-TSCB (NTSCB). Groups with/without planned reduction were compared on the presence and number of treatment-emergent adverse events (TEAEs) using chi-square tests or logistic regression and on time to LCM discontinuation with time-to-event methods controlling for standardized (STD) AED dose, a measure of concomitant AED load. Similar analyses were performed comparing subjects taking TSCB and NTSCB agents and used to identify relationships with ≥50% decreases in seizure frequency.

RESULTS

One hundred six adults (mean age 41.4 ± 13.4; 50% male) underwent LCM titration from June 2009-2011 with complete data. Reduction of concomitant AEDs was planned at the time of LCM initiation in 59 (55.7%) subjects. Fewer subjects with planned reduction had TEAEs (49.2% vs. 68.1%; p=0.05), and these subjects had a lower risk of TEAEs (OR 0.36; p=0.019) after adjusting for STD AED dose. The hazard ratio (95% CI) for LCM discontinuation was 0.46 (0.23, 0.94) in subjects with planned reduction of concomitant AEDs vs. others (p=0.033) and 3.29 (1.01, 10.70) in subjects taking TSCB vs. NTSCB agents (p=0.048). Among all cases, those who ever had TEAEs had significantly higher STD dose at both follow-up visits (p=0.033 and p=0.023, respectively). Seizure outcomes were not significantly different between groups at the last follow-up assessment.

SIGNIFICANCE

Planned reduction of concomitant AEDs during LCM initiation and the use of NTSCB agents only are associated with a reduced risk of TEAEs and LCM discontinuation in adults with partial-onset seizures. This study extends prior observations by considering total AED load in the assessment of tolerability and supports the benefits of early reduction of concomitant AEDs during LCM initiation.

Use of lacosamide in children with refractory epilepsy

OBJECTIVES

Lacosamide was approved by the US Food and Drug Administration in 2008 for adjunctive therapy for focal onset seizures in patients 17 years of age and older. The efficacy of this agent in adults has led clinicians to consider lacosamide for children with refractory seizures.

METHODS

The MEDLINE database (1950-June 2012) was searched for abstracts containing lacosamide as the key term. Additional references were obtained from the manufacturer and the bibliographies of the articles reviewed. All available English-language case reports and clinical trials were included in the evaluation.

RESULTS

Several case series studies have been published which support the use of lacosamide in children with refractory seizures. In the papers published to date, 30% to 50% of children experienced at least a 50% reduction in seizure frequency, similar to results obtained in clinical trials in adults. Children with focal onset seizures were most likely to benefit from treatment, while results in children with generalized seizures or multiple seizure types were mixed. Adverse effects in children were similar to those seen in adults, with dizziness, headache, and nausea occurring most frequently. Lack of efficacy has been the most common cause of discontinuation.

CONCLUSIONS

Lacosamide appears to be a useful adjunct therapy in children with refractory seizures. Clinical trials are under way that may provide more definitive information on the efficacy and safety of lacosamide in children and allow clinicians to determine the appropriate place of this antiseizure drug in pediatric epilepsy management.