VIMPAT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VIMPAT (VIMPAT).
Selective enhancement of slow inactivation of voltage-gated sodium channels, resulting in stabilization of hyperexcitable neuronal membranes and inhibition of repetitive neuronal firing.
| Metabolism | Primarily via glucuronidation by UGT2B7, UGT1A8, UGT1A9, and UGT1A1; minor oxidation via CYP2C19 to O-desmethyl metabolite. |
| Excretion | Renal: ~95% (40% as parent drug, 39% as O-desmethyl metabolite, and ~15% as other minor metabolites); minimal biliary/fecal elimination (less than 1%). |
| Half-life | Terminal half-life: 13-16 hours (mean ~13 h at steady state); prolonged with renal impairment (CrCl <30 mL/min: ~22 h) and in patients with hepatic impairment (Child-Pugh B: ~17 h; Child-Pugh C: ~22 h). |
| Protein binding | <15% bound to serum proteins; binding is to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.45 L/kg (mean); distributes into total body water; higher Vd in children (0.6-0.7 L/kg). |
| Bioavailability | Oral immediate-release: ~100% (nearly complete absorption). Intravenous: 100% (bioequivalent to oral). Oral extended-release: ~100% (slightly lower Cmax but bioequivalent in AUC). |
| Onset of Action | Oral: Peak plasma concentration (Tmax) 1-4 hours; initial clinical effect may be seen within a week of starting titration. Intravenous: similar to oral, with Tmax at the end of infusion (30-60 min). |
| Duration of Action | Steady state achieved within 3-4 days; dosing interval is 12 hours for immediate-release; extended-release (XR) formulation allows once-daily dosing. Duration of antiepileptic effect requires consistent dosing; immediate effects for breakthrough seizures are not applicable. |
| Molecular Weight | 250.29 |
Adults: 200 mg oral or IV as a loading dose, followed by 100 mg twice daily (200 mg/day) starting the day after loading. May increase by 50 mg twice daily every week up to 200 mg twice daily (400 mg/day).
| Dosage form | SOLUTION |
| Renal impairment | CrCl ≥50 mL/min: usual dose. CrCl 30-49 mL/min: maximum 250 mg/day. CrCl 15-29 mL/min: maximum 200 mg/day. CrCl <15 mL/min: not recommended. Hemodialysis: maximum 250 mg/day; consider supplement after dialysis. |
| Liver impairment | Child-Pugh A: maximum 300 mg/day. Child-Pugh B: maximum 200 mg/day. Child-Pugh C: not recommended. |
| Pediatric use | 1 month to <17 years: loading dose optional 3.5 mg/kg IV, then 1 mg/kg twice daily (2 mg/kg/day); may increase by 0.5 mg/kg twice daily every week to maintenance 3 mg/kg twice daily (6 mg/kg/day, max 200 mg twice daily). |
| Geriatric use | Consider dose adjustment based on renal function; start at lower dose (e.g., 100 mg/day) if CrCl <50 mL/min. Monitor for adverse effects. |
| 1st trimester | Data from pregnancy registries indicate an increased risk of major congenital malformations, particularly neural tube defects, with first-trimester exposure. Use only if benefit outweighs risk. |
| 2nd trimester | Consider therapeutic drug monitoring and dose adjustments due to pharmacokinetic changes. Risk of adverse fetal outcomes remains elevated. |
| 3rd trimester | Late pregnancy exposure may lead to neonatal adverse effects (e.g., sedation, withdrawal). Monitor neonate for symptoms. Use only if clearly needed. |
Clinical note
Comprehensive clinical and safety monograph for VIMPAT (VIMPAT).
| Placental transfer | Lacosamide crosses the placenta. In ex vivo human placental perfusion studies, transfer rate was approximately 50% of maternal concentrations. Clinical relevance is significant; fetal concentrations may approach maternal levels. |
| Breastfeeding | Lacosamide is excreted into breast milk in low concentrations. Limited data suggest minimal risk to the breastfed infant, but caution is advised. Monitor infant for sedation, poor feeding, or poor weight gain. The American Academy of Pediatrics considers it compatible with breastfeeding, but individual risk-benefit assessment is recommended. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to lacosamide or any excipientsSecond- or third-degree atrioventricular (AV) block (unless patient has a functioning pacemaker)Severe hepatic impairment (Child-Pugh Class C) — not recommended
| Precautions | Suicidal behavior and ideation, Dizziness and ataxia, Syncope and hypotension, Cardiac conduction abnormalities (PR prolongation, atrial fibrillation, atrial flutter), Withdrawal seizures |
| Food/Dietary | VIMPAT can be taken with or without food. No specific food interactions have been reported. Alcohol may increase central nervous system side effects (e.g., dizziness, drowsiness); avoid excessive alcohol consumption. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | VIMPAT (lacosamide) is classified as Pregnancy Category C. Animal studies have shown fetal harm at doses comparable to human therapeutic levels. In first trimester, there is a potential risk of major congenital malformations, though human data are limited. During second and third trimesters, there is risk of adverse neurodevelopmental outcomes and growth restriction. Use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor lacosamide serum concentrations during pregnancy and postpartum. Perform fetal ultrasound for structural anomalies. Assess fetal growth and amniotic fluid volume in third trimester. Monitor for maternal adverse effects including dizziness, ataxia, and ECG changes (PR prolongation). |
| Fertility Effects | In animal studies, lacosamide did not impair fertility. No human data on fertility effects. Theoretical risk of hormonal contraceptive interaction not reported; no enzyme induction. |
| Clinical Pearls |
| VIMPAT (lacosamide) is a third-generation antiepileptic drug that enhances slow inactivation of voltage-gated sodium channels. Dose reduction required in severe renal impairment (CrCl <30 mL/min) and hepatic impairment (Child-Pugh B or C). Anaphylaxis and angioedema reported; discontinue if occurs. May cause PR interval prolongation; caution with other drugs that prolong PR interval (e.g., beta-blockers, calcium channel blockers). Withdrawal should be gradual to avoid increased seizure frequency. IV formulation is bioequivalent to oral; can be used for loading in status epilepticus (200-400 mg IV over 15 min). |
| Patient Advice | Take exactly as prescribed; do not stop suddenly as this may increase seizures. · Common side effects: dizziness, headache, nausea, double vision (diplopia), and coordination problems. These may improve with continued use. · Avoid driving or operating heavy machinery until you know how VIMPAT affects you, as it may cause dizziness or blurred vision. · Inform your doctor if you have kidney or liver disease, heart problems (especially heart block), or if you are pregnant or breastfeeding. · VIMPAT may increase the risk of suicidal thoughts or behavior; monitor mood changes and contact doctor immediately. · Swallow tablets whole; do not crush or chew. Oral solution should be measured with the provided dosing device. |