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# Lennox-Gastaut Syndrome (LGS)
## Overview
LGS is a severe form of childhood-onset epilepsy characterized by multiple seizure types (atonic, tonic, atypical absence), slow spike-wave complexes on EEG, and intellectual impairment. Treatment is often refractory, requiring polypharmacy.
## Primary Indications
Adjunctive therapy for seizures associated with LGS in patients ≥1 year of age.
## Adult Dosing
* **Rufinamide:** Start 400–800 mg/day in two divided doses; increase by 400–800 mg/day every 2 days to max 3200 mg/day.
* **Clobazam:** Start 5–10 mg/day; titrate to 20 mg/day (divided dose) over 2 weeks.
* **Cannabidiol (CBD):** Start 2.5 mg/kg BID (5 mg/kg/day); after 1 week, increase to 5 mg/kg BID (10 mg/kg/day). Max 20 mg/kg/day.
* **Fenfluramine:** 0.1 mg/kg BID (max 17 mg/day).
## Pediatric Dosing
* **Rufinamide (≥1 year):** 10 mg/kg/day divided BID; titrate by 10 mg/kg/day every other day to target 45 mg/kg/day (not to exceed 3200 mg/day).
* **Clobazam (≥2 years):** Weight-based: <30 kg: Start 5 mg/day, max 20 mg/day; ≥30 kg: Start 10 mg/day, max 40 mg/day.
* **Cannabidiol (≥1 year):** Same as adult dosing (titrated by weight: 5 mg/kg/day → 10 mg/kg/day).
* **Topiramate (Off-label/Adjunctive):** 5-9 mg/kg/day divided BID.
* **Lamotrigine:** 0.15 mg/kg/day (dose must be titrated slowly to avoid rash).
## Dose Adjustments
* **Hepatic Impairment:** Reduce starting/maintenance doses by 50% for CBD and fenfluramine. Rufinamide is contraindicated in severe hepatic impairment.
* **Renal Impairment:** No specific adjustment for most, but monitor closely.
## Contraindications
* **Rufinamide:** Short QT syndrome.
* **Fenfluramine:** History of valvular heart disease or pulmonary hypertension.
* **General:** Known hypersensitivity to the specific drug class.
## Adverse Effects
* **Common:** Somnolence, fatigue, dizziness, decreased appetite, diarrhea, and weight loss.
* **Serious:** Suicidal ideation (all AEDs), DRESS syndrome (lamotrigine), QTc shortening (rufinamide), QTc prolongation (potential with others), and hepatic enzyme elevation.
## Key Drug Interactions
* **Valproate:** Significantly increases serum concentrations of rufinamide and clobazam; dose reduction of these agents is frequently required.
* **CYP450 Inducers (e.g., Carbamazepine, Phenytoin):** May decrease levels of cannabidiol, clobazam, and topiramate.
* **CNS Depressants:** Additive sedation with clobazam and other benzodiazepines.
## Monitoring
* **Cardiac:** Baseline/periodic ECG for rufinamide (QT shortening) and fenfluramine (echocardiogram screening per REMS).
* **Hepatic:** Baseline and periodic LFTs (especially with CBD, valproate, or topiramate).
* **Clinical:** Seizure frequency and duration diaries; screening for mood changes/suicidality.
## Clinical Pearls
* **Valproate Synergy:** Valproate is often the anchor therapy for LGS given its broad efficacy for myoclonic/atonic seizures, but it drastically alters the PK of many co-administered AEDs.
* **Avoidance:** Avoid medications that may exacerbate seizures (e.g., tiagabine, vigabatrin) unless under strict specialist supervision.
* **Titration:** Slow titration is mandatory for lamotrigine to mitigate the risk of severe dermatological reactions (SJS/TEN).
* **REMS:** Always verify if the specific agent (e.g., Fenfluramine) requires enrollment in a restricted distribution program.
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*Disclaimer: This information is for educational purposes for healthcare professionals. Dosing and clinical practices vary by institution. Always verify current prescribing information, package inserts, and local protocols before prescribing.*
