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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 is typically adjunctive, as monotherapy is rarely effective.
## Primary Indications
Adjunctive treatment for seizures associated with LGS. First-line agents include valproate, lamotrigine, and clobazam. Second-line/adjunctive agents include topiramate, rufinamide, felbamate, and cannabidiol.
## Adult Dosing
* **Clobazam:** Start 5 mg/day; titrate to 20 mg/day (divided BID).
* **Rufinamide:** Start 400–800 mg/day; titrate to 1600–3200 mg/day (divided BID).
* **Cannabidiol:** 10–20 mg/kg/day (divided BID).
* **Felbamate:** 1200 mg/day; titrate to 3600 mg/day (divided TID/QID).
* **Topiramate:** 5–9 mg/kg/day or up to 400 mg/day (divided BID).
## Pediatric Dosing
* **Clobazam (≥2 years):** Start 0.2 mg/kg/day; titrate to 1 mg/kg/day (max 40 mg/day).
* **Rufinamide (≥1 year):** Start 10 mg/kg/day; titrate to 45 mg/kg/day (max 3200 mg/day).
* **Cannabidiol (≥1 year):** Start 2.5 mg/kg BID; target 10 mg/kg BID.
* **Felbamate (≥2 years):** Start 15 mg/kg/day; titrate to 45 mg/kg/day (max 3600 mg/day).
* **Topiramate (≥2 years):** Start 1–3 mg/kg/day; titrate to 5–9 mg/kg/day.
## Dose Adjustments
* **Renal/Hepatic:** Most AEDs require significant dose reductions in hepatic impairment. Renal adjustments vary sharply by agent (e.g., lower topiramate and rufinamide doses in severe renal failure).
* **Titration:** Most agents require slow titration to minimize CNS effects (drowsiness, dizziness).
## Contraindications
* **Felbamate:** History of aplastic anemia or hepatic failure.
* **Rufinamide:** Short QT syndrome (can shorten the QT interval).
* **General:** Known hypersensitivity to specific drug classes.
## Adverse Effects
* **CNS:** Somnolence, dizziness, ataxia, fatigue, irritability.
* **Serious:** Aplastic anemia/liver failure (felbamate); SJS/TEN (lamotrigine); suicidal ideation (all AEDs); status epilepticus (abrupt withdrawal).
* **Cannabidiol:** Elevated transaminases, diarrhea, decreased appetite.
## Key Drug Interactions
* **Valproate:** Major inhibitor of glucuronidation; significantly increases lamotrigine levels (high risk of rash).
* **Enzyme Inducers/Inhibitors:** Use caution with CYP3A4 substrates (most AEDs modulate this pathway).
* **Clobazam:** Potentiation of CNS depressants (opioids, alcohol).
## Monitoring
* **Laboratory:** Baseline/periodic LFTs (felbamate, cannabidiol, valproate). CBC with diff (felbamate). Serum concentrations for select drugs (valproate, carbamazepine, phenytoin if used).
* **Safety:** Monitor for mood changes, worsening seizure control, and signs of hypersensitivity (rash).
## Clinical Pearls
* **Baseline:** Obtain baseline LFTs and CBC before starting felbamate and monitor monthly thereafter.
* **Tapering:** Never discontinue AEDs abruptly in LGS patients, as this carries a high risk of precipitating status epilepticus.
* **Polypharmacy:** LGS often requires multi-mechanism therapy (e.g., combining a sodium channel blocker with a GABAergic agent and a glutamate antagonist).
* **Precision:** Dosing for many agents is weight-based in pediatrics and requires frequent reassessment as the patient grows.
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**Disclaimer**: This information is for educational purposes only. Always verify current prescribing information, institutional protocols, and patient-specific contraindications via official FDA labeling or clinical drug databases (e.g., Lexicomp, Micromedex) before prescribing or administering medication.
