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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 therapy for seizures associated with LGS. Commonly FDA-approved agents include Clobazam, Rufinamide, Topiramate, Felbamate, Lamotrigine, and Cannabidiol (CBD).
## Adult Dosing
* **Clobazam:** 10–20 mg/day; may titrate up to 40 mg/day.
* **Rufinamide:** Start 400–800 mg/day; titrate by 400–800 mg every 2 days to max 3200 mg/day.
* **Cannabidiol:** Starting dose 2.5 mg/kg BID (5 mg/kg/day); may increase to 10 mg/kg BID (20 mg/kg/day) based on tolerance.
## Pediatric Dosing
* **Clobazam (≥2 yrs):** Weight-based: ≤30 kg: Start 5 mg/day, titrate to 20 mg/day. >30 kg: Start 10 mg/day, titrate to 40 mg/day.
* **Rufinamide (≥1 yr):** Start ~10 mg/kg/day divided BID; titrate to max of 45 mg/kg/day or 3200 mg/day (whichever is lower).
* **Cannabidiol (≥1 yr):** Start 2.5 mg/kg BID (5 mg/kg/day); increase after 1 week to 10 mg/kg BID (20 mg/kg/day).
* **Topiramate (≥2 yrs):** 5–9 mg/kg/day divided twice daily. Start low and titrate slowly to minimize cognitive side effects.
## Dose Adjustments
* **Hepatic/Renal Impairment:** Required for most agents (e.g., Clobazam, Rufinamide). Dosage must often be reduced or titration slowed in moderate-to-severe hepatic impairment.
* **Drug Interactions:** Dose reductions are frequently required when co-administering with potent CYP inhibitors (e.g., stiripentol, valproate).
## Contraindications
* **General:** Known hypersensitivity to the specific agent.
* **Specific:** Felbamate (history of aplastic anemia or hepatotoxicity); Rufinamide (Short QT Syndrome).
## Adverse Effects
* **Common:** Somnolence, fatigue, dizziness, ataxia, and irritability.
* **Serious:** Suicidal ideation (all anticonvulsants), DRESS syndrome (especially with Lamotrigine), hepatotoxicity (Felbamate, Valproate, Cannabidiol), and aplastic anemia (Felbamate).
## Key Drug Interactions
* **Clobazam/Cannabidiol/Valproate:** These agents exhibit significant PK interactions. Valproate inhibits the metabolism of clobazam (increasing active metabolite N-desmethylclobazam). Cannabidiol can increase levels of clobazam and its metabolite.
* **Enzyme Inducers:** Phenytoin, carbamazepine, and phenobarbital decrease levels of many LGS medications, requiring higher doses.
## Monitoring
* **Labs:** Baseline and periodic LFTs for agents with hepatotoxic potential (especially Cannabidiol, Felbamate, Valproate). Serum drug levels (if clinical plateau occurs).
* **Safety:** Monitor for worsening depression or suicidal behavior.
* **Cardiac:** ECG monitoring for patients on Rufinamide if concerns for cardiac conduction arise.
## Clinical Pearls
* **Polypharmacy is the norm:** Most patients require combinations of 2–4 antiepileptic drugs (AEDs).
* **Refractory Nature:** LGS is notoriously therapy-resistant; aggressive titration can lead to dose-limiting side effects (sedation being most common).
* **Titration:** "Start low, go slow" is the universal rule to maximize tolerability.
* **Protocols:** Specific titration schedules vary by institution; always consult local institutional protocols or the most recent package insert for weight-based titration increments.
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**Educational Disclaimer:** This information is for educational purposes and does not constitute medical advice. Prescribing information, drug interactions, and safety protocols change frequently. Always consult the most recent FDA-approved package inserts, official clinical guidelines, or a clinical pharmacist before initiating or adjusting therapy.
