Restricted dispensing

Felbamate

FELBATOL

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What it isNMDA glycine-site antagonist and GABA-A positive modulator; refractory Lennox-Gastaut and focal seizures.

Why this oneIts broad efficacy in Lennox-Gastaut can justify use after safer multidrug regimens fail.

What limits itAplastic anemia and hepatic failure demand consent and frequent blood and liver monitoring; it also raises phenytoin and valproate.

FDA-approved for

refractory seizures (1993)

FDA label

Read the full label on DailyMed ↗

BOXED WARNING Aplastic anemia (incidence may be >100-fold higher than untreated population) and acute hepatic failure; reserve for severe refractory epilepsy where the risk is acceptable, with hematologic and hepatic monitoring

FDA dosing	Population	Start	Target	Max
Epilepsy, monotherapy	Adults ≥14 yr	1200 mg/day ÷ TID–QID	2400 mg/day, then 3600 mg/day if indicated	3600 mg/day
Epilepsy, adjunctive	Adults ≥14 yr	1200 mg/day ÷ TID–QID	up to 3600 mg/day	3600 mg/day
Lennox-Gastaut syndrome, adjunctive	Children 2–14 yr	15 mg/kg/day ÷ TID–QID	up to 45 mg/kg/day	45 mg/kg/day (≤3600 mg/day)

Titration Monotherapy: ↑600 mg every 2 wk. Adjunctive: ↑1200 mg/day (adults) or 15 mg/kg/day (children) at weekly intervals

Renal Use with caution; reduce starting and maintenance doses by one-half

Hepatic Contraindicated in hepatic dysfunction; initiate only in patients without active liver disease and with normal baseline transaminases

Instructions

When adding or substituting felbamate, reduce concomitant AEDs by 20–33% to control plasma levels and minimize side effects
Give in divided doses three or four times daily
Monitor AST/ALT at baseline and periodically; discontinue if AST or ALT ≥2x ULN or if signs of liver failure
Discontinue if any evidence of bone marrow depression

Contraindications

History of any blood dyscrasia
History of hepatic dysfunction

Cautions

Aplastic anemia — consider hematologic consultation; discontinue if bone marrow depression occurs
Acute hepatic failure — monitor transaminases; do not prescribe with prior hepatic dysfunction; do not re-treat after hepatocellular injury

Adverse reactions

Anorexia
Vomiting
Insomnia
Nausea
Headache
Dizziness (adjunctive)
Somnolence (adjunctive)

Pregnancy Undefined

Lactation Undefined

⚠ BOXED WARNINGS

Aplastic anemia
Hepatic failure

Cost, est. cash$10–$300/month

Generic entry2011

Classes and tags

Clinical profile

Therapeutic safety burden4 / 4

Overdose danger3 / 4

Weight-gain liability0 / 4

Sedation liability1 / 4

QT / Torsades2 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk2 / 4

Legacy pregnancy categoryC

Defining liabilityAplastic anemia and acute hepatic failure restrict use to severe refractory epilepsy.

Mechanism of action: Felbamate ballicule

Felbamate ballicule: receptor binding, kinetics and half-life diagram

Open Felbamate in the interactive console ↗

Memory aids: mascots and interaction avatars

Felbamate FELBATOL mascot mnemonic cartoon — **“Fell bat / Fell bam!”**
Risk of hepatic failure (very rare)
Risk of aplastic anemia (very rare)

CYP2C19 inhibitor (moderate)

Open Felbamate in the interactive console ↗