Antiepileptic — Sodium Channel Slow Inactivation Enhancer Pregnancy: There are no adequate data from use in pregnant women; animal studies showed no teratogenic effects in rats or rabbits but embryotoxicity at maternally toxic doses, and the potential risk for humans is unknown. Lacosamide should not be used during pregnancy unless clearly necessary (if the benefit to the mother clearly outweighs the potential risk to the foetus). For all antiepileptic medicinal products, the prevalence of malformations in offspring of treated women is two to three times greater than the approximately 3% rate in the general population, but effective antiepileptic therapy must not be interrupted since aggravation of the illness is detrimental to mother and foetus. Physicians should discuss family planning and contraception with women of childbearing potential, and re-evaluate treatment carefully if a woman decides to become pregnant. Lacosamide is excreted in human breast milk and a risk to newborns/infants cannot be excluded — breast-feeding should be discontinued during treatment.

Lacosamide

Brand names: Vimpat

Lacosamide is an antiepileptic used for focal (partial-onset) seizures, as monotherapy or add-on therapy. An intravenous formulation is available for when oral treatment is temporarily not feasible.

Adult dose

Dose: Adults and adolescents/children weighing 50 kg or more — ADJUNCTIVE THERAPY: starting dose 50 mg twice a day (100 mg/day), increased to an initial therapeutic dose of 100 mg twice a day (200 mg/day) after one week, then increased at weekly intervals by 50 mg twice a day (100 mg/day) as needed. MONOTHERAPY: starting dose 50 mg twice a day (100 mg/day) increased to 100 mg twice a day (200 mg/day) after one week, or lacosamide may be initiated directly at 100 mg twice a day (200 mg/day), then increased at weekly intervals by 50 mg twice a day (100 mg/day).

Route: Oral — the physician should prescribe the most appropriate formulation and strength according to weight and dose. This SPC is for lacosamide 10 mg/ml syrup; may be taken with or without food. Shake the bottle well before use and measure with the supplied 12.5 ml oral syringe (doses of 10 mg/1 ml up to 100 mg/10 ml) or 30 ml measuring cup (doses above 200 mg/20 ml), rounding to the nearest graduated increment.

Frequency: Twice a day, approximately 12 hours apart

Max: Monotherapy: up to 300 mg twice a day (600 mg/day). Adjunctive therapy: up to 200 mg twice a day (400 mg/day).

INDICATIONS: monotherapy is for partial-onset seizures; adjunctive therapy is for partial-onset seizures or for primary generalised tonic-clonic seizures. In patients on monotherapy who have reached a dose greater than 200 mg twice a day (400 mg/day) and who need an additional antiepileptic medicinal product, the adjunctive-therapy posology should be followed. LOADING DOSE (alternate initial dosage, adults and patients 50 kg or more): a single 200 mg loading dose followed approximately 12 hours later by a 100 mg twice a day (200 mg/day) maintenance regimen; a loading dose may be used when the physician determines that rapid attainment of steady-state plasma concentration and therapeutic effect is warranted, and must be given under medical supervision because of the potential for increased serious cardiac arrhythmia and CNS adverse reactions. Administration of a loading dose has NOT been studied in acute conditions such as status epilepticus, has not been studied in children, and is not recommended in adolescents and children weighing less than 50 kg. MISSED DOSE: take the missed dose immediately and then take the next dose at the regularly scheduled time; if the missed dose is noticed within 6 hours of the next one, wait and take the next dose at the regularly scheduled time. Patients should not take a double dose. DISCONTINUATION: reduce gradually in weekly decrements of 200 mg/day (patients 50 kg or more) or 4 mg/kg/day (patients under 50 kg) for those who have reached 300 mg/day or 6 mg/kg/day respectively; a slower taper of 100 mg/day or 2 mg/kg/day weekly can be considered if medically necessary. If serious cardiac arrhythmia develops, perform a clinical benefit/risk assessment and discontinue if needed. ELDERLY (over 65 years): no dose reduction is necessary, but age-associated decreased renal clearance with increased AUC should be considered; clinical data in elderly patients with epilepsy are limited, particularly above 400 mg/day. HEPATIC IMPAIRMENT: maximum 300 mg/day for adults and paediatric patients weighing 50 kg or more with mild to moderate hepatic impairment, titrating with caution and considering co-existing renal impairment; a 200 mg loading dose may be considered in adolescents and adults 50 kg or more but titration above 200 mg daily should be cautious; in paediatric patients under 50 kg with mild to moderate hepatic impairment apply a 25% reduction of the maximum dose; pharmacokinetics have not been evaluated in severe hepatic impairment — use only when expected benefits outweigh the risks. CARDIAC MONITORING: dose-related PR interval prolongation has been observed; consider an ECG before increasing above 400 mg/day and after titration to steady state in patients with proarrhythmic conditions, on medicinal products affecting cardiac conduction, or elderly. INTRAVENOUS ROUTE: not covered by this oral-syrup SPC — the IV solution for infusion is a separate SPC that was NOT fetched in this bundle, and its posology has not been reproduced here.

Paediatric dose

Dose: 1 mg/kg

Route: Oral — the SPC recommends initiating treatment with the syrup and switching to tablets if desired; when prescribing the syrup the dose should be expressed in volume (ml) rather than weight (mg), calculated on the exact body weight and rounded to the nearest graduated increment (round up if equidistant between two increments)

Frequency: 1 mg/kg twice a day (2 mg/kg/day) as the starting dose, increased to an initial therapeutic dose of 2 mg/kg twice a day (4 mg/kg/day) after one week, then increased by 1 mg/kg twice a day (2 mg/kg/day) at weekly intervals as needed; doses are given approximately 12 hours apart

Max: Weight-banded per-kg maxima (children from 2 years and adolescents under 50 kg). Monotherapy: up to 6 mg/kg twice a day (12 mg/kg/day) in patients 10 kg to under 40 kg; up to 5 mg/kg twice a day (10 mg/kg/day) in patients 40 kg to under 50 kg. Adjunctive therapy: up to 6 mg/kg twice a day (12 mg/kg/day) in patients 10 kg to under 20 kg; up to 5 mg/kg twice a day (10 mg/kg/day) in patients 20 kg to under 30 kg; up to 4 mg/kg twice a day (8 mg/kg/day) in patients 30 kg to under 50 kg.

Applies to children from 2 years of age and adolescents weighing LESS THAN 50 kg; adolescents and children weighing 50 kg or more use the adult dosing. The dose should be gradually increased until the optimum response is obtained and the lowest effective dose used. In the adjunctive 30 kg to under 50 kg band the SPC notes that a dose up to 6 mg/kg twice a day (12 mg/kg/day) has been used by a small number of children in open-label studies, although 4 mg/kg twice a day is the recommended maximum. AGE LIMITS: lacosamide is not recommended below 4 years of age for primary generalised tonic-clonic seizures and below 2 years of age for partial-onset seizures, as safety and efficacy data are limited. A LOADING DOSE IS NOT RECOMMENDED in adolescents and children weighing less than 50 kg and has not been studied in children. RENAL: no dose adjustment in mild or moderate renal impairment (creatinine clearance above 30 ml/min); in paediatric patients under 50 kg with severe renal impairment (creatinine clearance 30 ml/min or less) or end-stage renal disease, reduce the maximum dose by 25%; for all patients on haemodialysis a supplement of up to 50% of the divided daily dose is recommended directly after dialysis. HEPATIC: in paediatric patients under 50 kg with mild to moderate hepatic impairment apply a 25% reduction of the maximum dose. DISCONTINUATION: taper in weekly decrements of 4 mg/kg/day (or 2 mg/kg/day if a slower taper is medically necessary). Verify all paediatric dosing against a children's formulary and specialist paediatric neurology advice before prescribing.

Dose adjustments

Renal

No dose adjustment is necessary in mildly and moderately renally impaired adult and paediatric patients (creatinine clearance above 30 ml/min). In adults and paediatric patients weighing 50 kg or more with mild or moderate renal impairment a 200 mg loading dose may be considered, but further titration above 200 mg daily should be performed with caution. In adults and paediatric patients weighing 50 kg or more with severe renal impairment (creatinine clearance 30 ml/min or less) or end-stage renal disease, a maximum dose of 250 mg/day is recommended with cautious titration; if a loading dose is indicated, use an initial 100 mg dose followed by 50 mg twice daily for the first week. In paediatric patients weighing less than 50 kg with severe renal impairment or end-stage renal disease, reduce the maximum dose by 25%. For all patients requiring haemodialysis, a supplement of up to 50% of the divided daily dose is recommended directly after the end of haemodialysis. Treat end-stage renal disease with caution — clinical experience is limited and a metabolite (with no known pharmacological activity) accumulates.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

US labelling (FDA)

Reference — US labelling, may differ from UK

Adults (17 years and older): Initial dosage for monotherapy for the treatment of partial-onset seizures is 100 mg twice daily (2.1) Initial dosage for adjunctive therapy for the treatment of partial-onset seizures or primary generalized tonic-clonic seizures is 50 mg twice daily (2.1) Maximum recommended dosage for monotherapy and adjunctive therapy is 200 mg twice daily (2.1) Pediatric Patients 4 years to less than 17 years : The recommended dosage is based on body weight and is administered orally twice daily (2.1) Increase dosage based on clinical response and tolerability, no more frequently than once per week (2.1) Injection: for intravenous use only when oral administration is …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-10-16. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Known second- or third-degree atrioventricular (AV) block

Side effects

Dizziness — very common (10% or more); the most common reason for discontinuation, and its incidence may be higher after a loading dose
Headache — very common (10% or more)
Nausea — very common (10% or more)
Diplopia — very common (10% or more); somnolence and ataxia were also frequently reported
Suicidal ideation and behaviour; cardiac rhythm and conduction disorders including AV block, atrial fibrillation or flutter and ventricular tachyarrhythmia (rarely leading to asystole, cardiac arrest and death in patients with proarrhythmic conditions); new onset or worsening of myoclonic seizures; drug hypersensitivity, DRESS and agranulocytosis

Interactions

Medicinal products affecting cardiac conduction — antiarrhythmics and sodium channel blocking antiepileptic medicinal products (SPC section 4.4); the US label adds beta-blockers, calcium channel blockers and potassium channel blockers, including those prolonging the PR interval, because of a risk of AV block, bradycardia or ventricular tachyarrhythmia. Consider an ECG before starting and after titration to steady state, and monitor closely
Strong CYP3A4 or CYP2C9 inhibitors — patients with renal or hepatic impairment taking these may have a significant increase in lacosamide exposure and dose reduction may be necessary (US label section 7.1)
NOTE: the UK SPC section 4.5 was NOT retrieved in this bundle; the entries above draw on UK SPC section 4.4 and the US prescribing information section 7 and must be checked against the UK SPC section 4.5

Clinical monograph

How it works

It selectively enhances the slow inactivation of voltage-gated sodium channels, stabilising hyperexcitable neuronal membranes and reducing repetitive firing.

Prescribing in practice

It can prolong the PR interval — use with caution in known cardiac conduction problems, with other PR-prolonging drugs, or in severe cardiac disease, and obtain a baseline ECG where clinically relevant.
Dizziness, double vision and unsteadiness are common and tend to be dose-related.
Titrate gradually and reduce the dose in significant renal or hepatic impairment; withdraw slowly rather than stopping abruptly.

Monitoring

Assess cardiac conduction risk before starting, with ECG where relevant; review seizure control, dose-related neurological side effects, and mood or suicidal ideation as with all antiepileptics.

Counselling the patient

Dizziness and double vision are common, especially when starting or increasing the dose — take care with driving and tasks needing balance.
Do not stop the medicine suddenly, as this can provoke seizures.
Report palpitations, fainting or a markedly irregular pulse.

Evidence & guidelines

Licensed and guideline-recognised option for focal seizures (NICE NG217).

Reference: NICE NG217; EMA Vimpat SPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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