Lacosamide

Introduction Overview

Generic Name

lacosamide

Brand Name

Vimpat

Dosage Form

tablet, oral solution, intravenous injection

Drug Class

Miscellaneous anticonvulsants

Pharmacokinetics

Absorption:
Lacosamide is rapidly and nearly completely absorbed after oral administration, achieving peak plasma concentrations within 1 to 4 hours. The absolute bioavailability of oral lacosamide is approximately 100%, indicating excellent systemic availability. Food intake does not significantly affect its absorption, thus lacosamide can be administered with or without food, increasing dosing flexibility. Pharmacokinetic studies show linear and dose-proportional kinetics over the therapeutic dosing range, which supports predictable plasma levels with dose adjustments.

Distribution:
Lacosamide exhibits a moderate volume of distribution, approximately 0.6 L/kg, indicating distribution primarily into total body water. It is about 15% protein-bound, primarily to albumin, which is relatively low compared to many other anticonvulsants, reducing risk of displacement interactions. Lacosamide distributes well to the brain, achieving concentrations adequate to exert its anticonvulsant effect. There is limited data on placental transfer, but lacosamide does cross the placenta and is found in fetal circulation. In addition, lacosamide is excreted in breast milk at low levels.

Metabolism:
Lacosamide undergoes minimal hepatic metabolism, with approximately 40% metabolized mainly by CYP2C19 to an inactive O-desmethyl metabolite. Unlike many older anticonvulsants, lacosamide does not induce or inhibit major CYP enzymes, limiting pharmacokinetic interactions. Metabolism is not highly affected by hepatic impairment, but caution is advised as clinical data is limited. The minor metabolism contributes negligibly to the formation of clinically relevant metabolites, and lacosamide itself is the major active moiety.

Elimination:
Lacosamide exhibits a terminal half-life of approximately 13 hours in healthy adults, supporting twice-daily dosing. Elimination is primarily renal, with about 40% of the dose excreted unchanged in urine. Both renal clearance and total clearance are dose linear and predictable. In patients with renal impairment, dose adjustment may be necessary due to decreased clearance and potential accumulation. Approximately 30% of the dose is recovered as inactive metabolites in the urine. Lacosamide is minimally eliminated via feces, indicating hepatic excretion is minor. The pharmacokinetics are consistent across ages with dosing adjustments recommended in pediatric and neonatal populations based on weight and renal function.

Dosage Forms

Available Dosage Forms:
-Vimpat oral tablet: 50 mg, 100 mg, 150 mg, and 200 mg tablets
-Vimpat oral solution: 10 mg/mL oral solution supplied in bottles
-Vimpat injection: 10 mg/mL solution for intravenous infusion

Dosages for Adults and Adolescents:
-Monotherapy for partial-onset seizures in patients 17 years and older:
Initial dose: 100 mg orally twice daily
Titration: Increase by 100 mg/day (50 mg twice daily) no more frequently than once a week
Maintenance dose: 150-200 mg orally twice daily

-Adjunctive therapy for partial-onset seizures or primary generalized tonic-clonic seizures (≥17 years):
Initial dose: 50 mg orally twice daily
Titrate similarly with increments of 100 mg/day (50 mg twice daily)
Maintenance dose: 100-200 mg orally twice daily

-Loading dose regime (adults):
200 mg oral or IV once, then 100 mg every 12 hours starting 12 hours later for at least one week
Loading dose administration should be done under medical supervision due to increased CNS adverse effects

-Administration considerations:
Oral and IV doses are equivalent; IV infusion preferred over 30-60 minutes but may be given over 15 minutes if necessary; IV use limited to 5 consecutive days.

Specific Patient Populations:
-Pediatric dosing (≥1 month old):
Dose adjusted according to body weight; IV and oral doses equivalent

Weight less than 6 kg (monotherapy only):
Initial: 2 mg/kg/day divided thrice daily (IV 0.66 mg/kg) or twice daily oral 1 mg/kg
Maintenance: 7.5-15 mg/kg/day divided thrice or twice daily

Weight 6 to <11 kg (monotherapy only):
Initial: 1 mg/kg oral/IV twice daily
Maintenance: 3-6 mg/kg oral/IV twice daily

4 to <17 years:
11 to <30 kg:
Initial: 1 mg/kg oral/IV twice daily
Maintenance: 3-6 mg/kg oral/IV twice daily

30 to <50 kg:
Initial: 1 mg/kg oral/IV twice daily
Maintenance: 2-4 mg/kg oral/IV twice daily

≥50 kg:
Initial: 50 mg oral/IV twice daily
Monotherapy maintenance: 150-200 mg oral/IV twice daily
Adjunctive therapy maintenance: 100-200 mg oral/IV twice daily

-Use of loading dose in pediatric patients has not been established.

-Renally impaired and hepatic impairment require cautious dosing and monitoring.

Special Instructions:
-Oral tablets should be swallowed whole without crushing or chewing.
-Oral solution dosage should be measured precisely using a dosing syringe or appropriate device.
-Oral solution should not be frozen and discarded 7 weeks after opening.

Mechanism Of Action

Lacosamide, the active agent in Vimpat, exerts its antiepileptic effects primarily through selective enhancement of slow inactivation of voltage-gated sodium channels. Unlike traditional sodium channel blockers which primarily affect the fast inactivation phase, lacosamide selectively enhances slow inactivation, stabilizing hyperexcitable neuronal membranes and reducing repetitive firing of neurons. This novel mechanism allows for suppression of pathological neuronal discharges without significantly affecting normal physiological activity, contributing to its favorable tolerability profile.

At a molecular level, lacosamide binds to specific sites on sodium channels that regulate the transition to and recovery from the slow inactivated state. This leads to prolonged closure of sodium channels during sustained depolarization events, decreasing the ability of neurons to generate and propagate high-frequency action potentials associated with seizure activity. This unique targeting of slow inactivation gates distinguishes lacosamide from other sodium channel blockers such as phenytoin and carbamazepine, which primarily enhance fast inactivation.

Beyond its action on sodium channels, lacosamide has been shown to interact with collapsin response mediator protein-2 (CRMP-2), a cytosolic protein involved in neuronal differentiation and axonal outgrowth. Although the clinical relevance of CRMP-2 interaction remains under investigation, it may contribute to neuroprotective effects and modulation of neuronal plasticity, potentially influencing long-term outcomes in epilepsy treatment.

Clinical studies demonstrate that lacosamide's selective enhancement of slow inactivation leads to a reduction in seizure frequency in patients with partial-onset and primary generalized tonic-clonic seizures. Comparative studies indicate that lacosamide provides effective seizure control with fewer cognitive and motor side effects compared to older sodium channel blockers. Current research continues to explore its potential utility in other neurological disorders characterized by neuronal hyperexcitability.

Pharmacological Actions

Selective enhancement of slow inactivation of voltage-gated sodium channels leading to stabilization of hyperexcitable neuronal membranes.
Reduction of repetitive neuronal firing by prolonging sodium channel closure during sustained depolarization.
Interaction with collapsin response mediator protein-2 (CRMP-2) potentially affecting neuronal differentiation and plasticity.
Anticonvulsant activity effective in partial-onset and primary generalized tonic-clonic seizures.
Minimal effect on fast inactivation of sodium channels, distinguishing it from other sodium channel blockers.
Exhibits neuroprotective properties in preclinical models possibly through CRMP-2 modulation.
Low protein binding reduces potential for drug-drug displacement interactions.
Does not induce or inhibit cytochrome P450 enzymes, decreasing risk of metabolic interactions.
Provides seizure control with a lower incidence of cognitive and psychomotor impairment compared to traditional anticonvulsants.
IV and oral formulations allow flexible administration routes in clinical practice.
Does not demonstrate significant action on GABAergic or glutamatergic neurotransmission directly.
Does not act as a significant enzyme inducer or inhibitor, preserving the pharmacokinetics of co-administered drugs.
Exerts a dose-proportional pharmacokinetic profile enabling predictable dose adjustments.

Therapeutic Or Clinical Uses

Monotherapy for partial-onset seizures in adults (≥17 years) and pediatric patients (≥1 month old).
Adjunctive therapy for partial-onset seizures in adults and pediatric patients.
Adjunctive treatment of primary generalized tonic-clonic seizures in patients aged 4 years and older.
Alternative treatment option for patients inadequately controlled on conventional antiepileptic drugs.
Useful in patients requiring intravenous anticonvulsant therapy due to inability to take oral medication.
Treatment of epilepsy syndromes where sodium channel blockade is beneficial.
Management of seizures in patients with comorbidities limited by enzyme inducing AEDs due to low interaction potential.
Potential off-label uses under investigation for neuropathic pain and other neuronal hyperexcitability disorders.
Treatment option in epileptic patients intolerant to older anticonvulsants due to improved side effect profile.
Rapid titration possible with loading dose under medical supervision for urgent seizure control.
Use in pediatric populations with weight-based dosing protocols to provide seizure control from neonatal age.
Applicable in polytherapy regimens alongside other antiepileptic medications without significant interactions.
Maintains seizure control with convenient twice-daily dosing, improving patient adherence.
Suitable for long-term epilepsy management given its tolerability and safety profile.
May be used in hospital settings via IV infusion during acute seizure management or perioperative periods.

Side Or Adverse Effects

Common side effects include headache, dizziness, and drowsiness.
Visual disturbances such as double vision (diplopia) may occur.
Nausea and gastrointestinal discomfort are reported in some patients.
Possible cardiac conduction abnormalities including PR interval prolongation on ECG.
Some patients may experience tachycardia or palpitations during treatment.
At higher doses or during loading, central nervous system adverse reactions such as ataxia, diplopia, or dizziness increase in frequency.
Rare but serious hypersensitivity reactions including rash, fever, and lymphadenopathy.
Mood and behavioral changes including depression, anxiety, irritability, agitation, and suicidal ideation have been reported.
Risk of addiction or dependence with misuse, though relatively low compared to other CNS agents.
Potential for dizziness and lightheadedness leading to falls in susceptible individuals.
Rarely, severe hypersensitivity or multi-organ reactions may occur, requiring immediate discontinuation.
Withdrawal symptoms including increased seizure frequency may occur if drug is stopped abruptly.
Fatigue and somnolence reported, which may impact daily activities and alertness.
Very slow or very fast heart rates may occur, necessitating cardiac monitoring in at-risk patients.
Dark urine or signs of liver dysfunction are rare but may warrant medical evaluation.

Precautions

Do not discontinue therapy abruptly to avoid increased seizure frequency and status epilepticus.
Use cautiously in patients with pre-existing cardiac conduction problems, including AV block or bundle branch block.
Monitor patients for central nervous system effects such as dizziness, somnolence, and impaired coordination.
Assess psychiatric history, as lacosamide may exacerbate depression or suicidal thoughts.
Caution advised in patients with renal impairment; dose adjustment and monitoring recommended.
Not established as safe in children under 1 month for seizures and under 4 years for generalized seizures.
Avoid activities requiring mental alertness until response to medication is known due to possible dizziness or blurred vision.
Phenylalanine content in oral solution may affect patients with phenylketonuria (PKU).
Pregnant patients should not start or discontinue therapy without medical advice due to seizure risks to mother and fetus.
Breastfeeding during lacosamide therapy requires risk-benefit assessment due to low milk concentrations.
Monitor liver function tests during therapy in patients with underlying hepatic disease.
Regular psychiatric evaluation recommended to detect mood changes early.
Ensure secure storage to prevent misuse, addiction, or accidental ingestion, especially in children.
Injection formulation should be used only by healthcare professionals with infusion monitoring.
Patients should wear medical identification indicating epilepsy and use of Vimpat.

Warnings

Risk of increased seizure frequency or severity if Vimpat is stopped suddenly.
Possible development of suicidal ideation or behavior; monitor patients carefully.
Reports of fainting or syncope warrant urgent evaluation, especially in patients with cardiac history.
Loading dose administration requires medical supervision due to higher incidence of CNS adverse reactions.
Avoid abrupt withdrawal during pregnancy to prevent seizure-related maternal and fetal complications.
Use with caution in patients with cardiac conduction abnormalities or structural heart disease.
Risk of serious skin reactions or hypersensitivity syndrome, although rare, necessitates prompt discontinuation if symptoms develop.
Patients should be advised against driving or operating machinery until effects on alertness are known.
Potential for serious drug interactions with heart or blood pressure medications requiring careful evaluation.
Careful monitoring required during drug titration phases to minimize adverse reactions.
Extended use beyond recommended duration without medical supervision is not advised.
Risk of overdose necessitates keeping medication out of reach of children and others.
Increased adverse effects observed with doses exceeding 200 mg twice daily, without added efficacy.
IV use is limited to short-term administration (up to 5 consecutive days); long-term IV use safety unknown.
Observe for psychiatric or behavioral changes during treatment and upon dose changes.

Contraindication

Known hypersensitivity or allergy to lacosamide or any component of the formulation.
Patients with history of cardiac conduction abnormalities without appropriate monitoring.
Should not be used in children younger than 1 month for seizures or younger than 4 years for generalized seizures.
Contraindicated in patients with phenylketonuria when using oral solution containing phenylalanine, unless benefit outweighs risk.
Patients with history of severe hypersensitivity reactions to lacosamide should not be retreated.
Not recommended in individuals unable to swallow tablets and who cannot receive injection or oral solution due to specific contraindications.
Use contraindicated without medical supervision in nursing mothers if risk to infant outweighs benefit.
Any previous severe psychiatric adverse reaction to lacosamide discourages re-administration.
Contraindicated in patients with history of drug abuse without appropriate safeguards, due to addiction risk.
Cannot be used as monotherapy in children less than 4 years old for generalized tonic-clonic seizures.
Patients with advanced hepatic failure should avoid use unless benefits outweigh risks and monitoring is possible.
Contraindicated during situations where rapid discontinuation is necessary without medical support due to seizure risk.
Known intolerance to excipients in the formulation such as any fillers, dyes, or preservatives.
Contraindicated where IV infusion is not feasible but oral administration is contraindicated.
Not suitable for use in patients with unstable epilepsy requiring immediate alternative treatment.

Drug Interactions

Lacosamide does not induce or inhibit major CYP450 enzymes, resulting in minimal pharmacokinetic interactions.
Potential additive CNS depressant effects when co-administered with other antiepileptic drugs, benzodiazepines, opioids, or alcohol.
Possible increased risk of cardiac conduction slowing when combined with other drugs that prolong PR interval or cause AV block.
Concomitant use with heart or blood pressure medications requires cautious monitoring for bradycardia or arrhythmias.
No significant interaction with oral contraceptives has been reported, making it a safer option for women of childbearing age.
Drugs that affect renal excretion may alter lacosamide clearance, necessitating dose adjustments in renal impairment.
Co-administration with other sodium channel blockers may increase risk of CNS side effects or cardiac conduction abnormalities.
Minimal drug interaction potential facilitates use in polytherapy antiepileptic regimens.
Lacosamide metabolism via CYP2C19 is limited; inhibitors or inducers of this enzyme may slightly affect levels but are not clinically significant.
Avoid concomitant use with drugs known to prolong PR interval such as beta blockers or certain antiarrhythmics without cardiac monitoring.
No significant interaction documented with common antidepressants or antipsychotics, but monitoring is advised due to overlapping CNS effects.
No known interaction with herbal supplements or vitamins that alter enzyme activity have been observed.
No clinically relevant interaction with warfarin or other anticoagulants documented, but patient monitoring remains prudent.
Potential additive sedative effects when combined with alcohol or CNS depressants requires patient education.
Food does not significantly affect lacosamide pharmacokinetics, so no interaction with meals is expected or observed.

Preparations Of The Drug

Oral tablets available in strengths of 50 mg, 100 mg, 150 mg, and 200 mg for flexible dosing adjustments.
Oral solution formulation at concentration of 10 mg/mL for accurate dosing in pediatric and adult patients unable to swallow tablets.
Intravenous injection solution at 10 mg/mL concentration to be administered by IV infusion over 30 to 60 minutes.
Injection formulation intended for short-term use (up to 5 consecutive days) in hospital settings.
Tablets are film-coated to allow ease of swallowing and to prevent degradation.
Oral solution contains phenylalanine; caution advised in patients with phenylketonuria.
All preparations are formulated to ensure high bioavailability and consistent plasma levels.
Parenteral formulation intended as alternative to oral administration when patients are NPO or unable to take medications orally.
Packaging includes dosing syringes for oral solution to enhance administration accuracy.
Available in unit dose packaging for tablets to improve dosing compliance and reduce medication errors.
Storage requirements: tablets and oral solution stored at room temperature away from moisture and heat; oral solution should not be frozen and discarded 7 weeks after opening.
Labeling includes detailed instructions on administration, storage, and monitoring for adverse reactions.
Tablets to be swallowed whole, and not to be crushed, chewed, or broken to maintain controlled release properties.
Oral solution is colorless to slightly yellow and free from particulates to assure quality and safety.
IV preparation requires dilution and administration by trained healthcare professionals with appropriate monitoring.