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# Lennox-Gastaut Syndrome (LGS)
## Overview
LGS is a severe form of childhood-onset epilepsy characterized by multiple seizure types (tonic, atonic, absence), cognitive impairment, and a specific EEG pattern (slow spike-and-wave). Management is typically refractory, requiring polypharmacy.
## Primary Indications
Adjunctive treatment of seizures associated with LGS. First-line agents often include valproate, lamotrigine, and clobazam. Newer targeted therapies include rufinamide, topiramate, felbamate, and cannabidiol.
## Adult Dosing (Common Agents)
* **Rufinamide:** Start 400–800 mg/day in two divided doses. Increase by 400–800 mg every 2 days. Max: 3200 mg/day.
* **Clobazam:** Start 5–10 mg/day. Titrate over 2 weeks to 20 mg/day in two divided doses.
* **Cannabidiol:** Start 2.5 mg/kg BID (5 mg/kg/day). Increase to 10 mg/kg/day after 1 week. Max: 20 mg/kg/day.
* **Topiramate:** Start 25 mg/day. Titrate slowly by 25–50 mg/week. Target: 200–400 mg/day in two divided doses.
## Pediatric Dosing (Weight-Based)
* **Rufinamide (≥1 year):** Start ~10 mg/kg/day in two doses. Increase by 10 mg/kg every 2 days. Max: 45 mg/kg/day or 3200 mg/day (whichever is less).
* **Clobazam (≥2 years):** If ≤30 kg: 5 mg/day, increase to 10 mg/day. If >30 kg: 10 mg/day, increase to 20 mg/day. Administer in two divided doses.
* **Cannabidiol (≥1 year):** Start 2.5 mg/kg BID. Target 10 mg/kg BID. Max: 20 mg/kg/day.
* **Lamotrigine:** Highly dependent on concurrent valproate (inhibitor) or enzyme inducers (carbamazepine/phenytoin). Start with low, slow titration to prevent SJS.
## Dose Adjustments
* **Hepatic Impairment:** Reduce starting doses for most agents; monitor LFTs closely, especially with valproate and cannabidiol.
* **Renal Impairment:** Adjust topiramate and levetiracetam based on CrCl.
* **Drug Interactions:** Dose adjustments may be required when initiating or discontinuing cytochrome P450 inducers (e.g., phenytoin, phenobarbital) or inhibitors (e.g., valproate).
## Contraindications
* **Rufinamide:** Familial Short QT syndrome.
* **Topiramate:** Do not use if history of metabolic acidosis (especially on concomitant ketogenic diet).
* **General:** Known hypersensitivity to any component of the specific formulation.
## Adverse Effects
* **Common:** Somnolence, dizziness, fatigue, ataxia, and gastrointestinal distress.
* **Specific:** Cannabidiol (increased LFTs, decreased appetite); Topiramate (cognitive slowing, nephrolithiasis, metabolic acidosis); Rufinamide (shortened QT interval); Felbamate (aplastic anemia/liver failure—requires stringent monitoring).
## Key Drug Interactions
* **Valproate:** Increases lamotrigine serum concentrations significantly; titration must be significantly slower to risk of Stevens-Johnson Syndrome (SJS).
* **Enzyme Inducers:** May decrease levels of clobazam and its active metabolite (N-desmethylclobazam).
* **CNS Depressants:** Additive sedation with clobazam and other benzodiazepines.
## Monitoring
* **Baseline:** CBC, LFTs, renal function, EEG, and baseline ECG (specifically for rufinamide).
* **Ongoing:** Routine LFTs (especially with cannabidiol/valproate), serum therapeutic levels (where applicable), and clinical assessment for suicidality or behavioral changes.
## Clinical Pearls
* **Polysymptomatic Approach:** LGS is rarely controlled with monotherapy; combinations like valproate + clobazam + rufinamide are common.
* **Slow Titration:** Essential for lamotrigine and topiramate to mitigate neurotoxicity and cutaneous adverse reactions.
* **Ketogenic Diet:** Often standard metabolic therapy in LGS patients; ensure no "hidden" carbohydrate-based fillers in liquid medications.
* **Individualized Protocols:** Institutional protocols vary; always consult hospital-specific guidelines for pediatric seizure titration.
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**Educational Disclaimer:** This information is for educational purposes and does not substitute for clinical judgment. Pharmacists and clinicians must verify current prescribing information, package inserts, and hospital-specific protocols before medication administration.
