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# Lennox-Gastaut Syndrome (LGS)
## Overview
Lennox-Gastaut Syndrome is a severe form of childhood-onset epilepsy characterized by multiple seizure types (tonic, atonic, absence), slow spike-and-wave EEG patterns, and cognitive impairment. Pharmacotherapy focuses on polytherapy to manage refractory seizures.
## Primary Indications
Adjunctive therapy for seizures associated with LGS. Commonly used agents include clobazam, rufinamide, topiramate, lamotrigine, and cannabidiol.
## Adult Dosing
* **Clobazam:** Start 5–10 mg/day, titrate to 20 mg/day. Max: 40 mg/day.
* **Rufinamide:** Start 400–800 mg/day in two divided doses. Titrate upward by 400–800 mg increments every 2 days. Max: 3200 mg/day.
* **Topiramate:** Start 25 mg/day; titrate weekly by 25–50 mg increments. Target: 200–400 mg/day.
* **Cannabidiol:** 10 mg/kg/day, increasing to 20 mg/kg/day over 2 weeks.
## Pediatric Dosing
* **Clobazam (≥2 yrs):** Weight-based. <30 kg: 5 mg/day, increase to 20 mg/day. ≥30 kg: 10 mg/day, increase to 40 mg/day.
* **Rufinamide (≥1 yr):** 10 mg/kg/day in two doses. Titrate by 10 mg/kg/day every other day. Max: 45 mg/kg/day or 3200 mg/day (whichever is less).
* **Topiramate (≥2 yrs):** 5–9 mg/kg/day in two divided doses.
* **Cannabidiol (≥1 yr):** 5 mg/kg/day BID; increase to 10 mg/kg/day BID after 1 week.
* **Felbamate:** Start 15 mg/kg/day, increase to 45 mg/kg/day. Reserved for severe refractory cases due to safety profile.
## Dose Adjustments
* **Renal:** Consider dose reduction for topiramate and rufinamide (consult prescribing information for creatinine clearance thresholds).
* **Hepatic:** Reduce doses for clobazam and cannabidiol in moderate-to-severe hepatic impairment.
* **General:** Titration must be individualized; rapid titration increases the risk of adverse neurological effects (e.g., ataxia, somnolence).
## Contraindications
* **Felbamate:** Known hypersensitivity, history of aplastic anemia, or hepatic impairment.
* **Rufinamide:** Familial Short QT syndrome.
* **General:** Hypersensitivity to active ingredients or excipients.
## Adverse Effects
* **Common:** Somnolence, fatigue, dizziness, ataxia, decreased appetite, and irritability.
* **Serious:**
* *Felbamate:* Aplastic anemia, acute liver failure.
* *Topiramate:* Metabolic acidosis, nephrolithiasis, glaucoma (secondary angle-closure).
* *Cannabidiol:* Transaminase elevations (monitor LFTs).
* *General:* Suicidal ideation (common to all antiepileptic drugs).
## Key Drug Interactions
* **Valproate:** Significantly increases serum levels of clobazam and rufinamide (dose reduction often required).
* **CNS Depressants:** Additive sedation with clobazam.
* **CYP450 Inducers/Inhibitors:** Many AEDs (especially topiramate and rufinamide) are affected by potent enzyme inducers; monitor for therapeutic failure.
## Monitoring
* **Safety:** CBC and LFTs at baseline and periodically for felbamate and cannabidiol.
* **Metabolic:** Monitor serum bicarbonate for topiramate-induced metabolic acidosis.
* **Cardiac:** EKG for patients on rufinamide if clinically indicated.
* **Efficacy:** Seizure diaries to track frequency and severity.
## Clinical Pearls
* LGS is rarely managed with monotherapy; combinations like valproate + clobazam + lamotrigine are common clinical strategies.
* When using valproate and lamotrigine, initiate lamotrigine at lower doses to mitigate the risk of serious skin rashes (SJS/TEN).
* Always taper AEDs slowly to avoid seizure exacerbation or status epilepticus, unless an emergency cessation is indicated by adverse drug events.
* Local protocols vary significantly; verify specific institutional titration schedules.
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**Educational Disclaimer:** This information is for educational purposes only. Always consult the most current official prescribing information (package insert), clinical guidelines, or a board-certified clinical pharmacist before initiating or adjusting medication therapy.
