Tablet
- Strengths
- 400, 600 mg
- Product note
- Reserved for selected refractory epilepsy because of aplastic-anemia and liver-failure risks.
Felbamate
Felbatol
DailyMed-verified antiseizure indications
Indication / use
- Label / evidence summary
- Felbatol: focal seizures with or without generalization in adults, as monotherapy or adjunctive therapy; adjunctive treatment of focal and generalized seizures associated with Lennox-Gastaut syndrome in children. Reserved for severe epilepsy inadequately responsive to alternatives, with explicit acknowledgment of serious risks; not first-line therapy.
- Role
- Maintenance
- Class
- Proposed NMDA-receptor modulation; full antiseizure mechanism unknown
Indications checked 26 September 2026. Product, route, age, and treatment-role limits apply. A DailyMed listing alone does not establish FDA approval.
- Felbatol tablet/suspension U.S. label
Focal seizures · 14 years and older · MaintenanceSevere refractory epilepsy; specialist risk acknowledgment.
- Felbatol suspension/tablet U.S. label
Lennox-Gastaut syndrome · 2 years and older (through 14 years) · MaintenanceAdjunctive pediatric LGS; severe refractory epilepsy.
Formulations & strengths
U.S. products unless another country is named. Strengths are per unit or stated volume.
Oral suspension
- Strengths
- 600 mg/5 mL (120 mg/mL)
- Product note
- Shake well.
Brand & formulation labels
Each link names the product and formulation it covers. Archived labels do not establish current availability.
Dosing & administration
- Adult / product-specific schedule
- Age ≥14, initial monotherapy: 1,200 mg/day in 3–4 doses, increasing by 600 mg/day every 2 weeks to 2,400 mg/day, then 3,600 mg/day if indicated. Adjunctive therapy and conversion to monotherapy use different schedules and reductions of existing ASMs; see label.
- Pediatric
- LGS ages 2–14: start 15 mg/kg/day in 3–4 doses; increase 15 mg/kg/day weekly to 45 mg/kg/day (max 3,600 mg/day). Reduce concomitant ASMs according to the label.
- Titration / repeat dosing
- Adults: 1,200 mg/day divided 3–4 times; increase by 600 mg/day every 2 weeks to 2,400–3,600 mg/day. Children with LGS: 15 mg/kg/day; increase by 15 mg/kg weekly to 45 mg/kg/day (max 3,600 mg/day).
Dose adjustment & concentrations
- Renal impairment
- Reduce initial and maintenance doses by 50%.
- Hepatic impairment
- Contraindicated with hepatic dysfunction/history.
- Serum reference information
- 30–60 mcg/mL (laboratory-dependent)
Safety
- Boxed warning
- Boxed warnings: aplastic anemia and acute hepatic failure, which can be fatal. Absolute individual risk is not reliably known; this is reserved for severe epilepsy after explicit risk discussion and written acknowledgment.
- Contraindications
- Hypersensitivity to felbamate/carbamates; history of blood dyscrasia or hepatic dysfunction.
- Serious precautions & monitoring
- Written risk acknowledgment before treatment. Baseline CBC (including platelets/reticulocytes) and liver testing, with frequent follow-up; normal monitoring cannot reliably prevent aplastic anemia. Stop for bone-marrow depression; stop for AST/ALT ≥2 times upper limit of normal or clinical liver failure. See boxed warning.
Common / selected adverse effects
- Anorexia
- Vomiting
- Insomnia
- Nausea
- Headache
- Weight decrease
Drug interactions: toxicity & clinical action
| Partner / combination | Clinical effect | Clinical action |
|---|---|---|
| Phenytoin, phenobarbital or valproate | Increased exposure and dose-related CNS or other toxicity. | Reduce background ASMs using the label’s initiation/conversion schedule; monitor concentrations and symptoms. |
| Carbamazepine | Parent level falls while active epoxide rises. | Monitor clinical toxicity; consider epoxide levels rather than relying only on parent drug. |
| Hormonal contraceptives (gestodene-containing studied) | Reduced progestin exposure. | Review contraceptive protection and alternatives. |
Pregnancy & contraception
- Fetal / neonatal risk
- The Felbatol label reports no studies in pregnant women. Animal studies found reduced pup survival or growth at maternally toxic exposures; use in pregnancy only when clearly needed.
- Contraception
- At 2,400 mg/day, felbamate reduced gestodene exposure by 42% in one combined-contraceptive study. No ovulation was detected, but contraceptive reliability cannot be inferred from that small study.
Clinical evidence
Research summaries describe studied populations and outcomes; they do not add indications or constitute treatment recommendations.
Direct pivotal trial
Trial summary
- Study design / duration
- Randomized, double-blind, placebo-controlled adjunctive studies in refractory focal seizures and Lennox-Gastaut syndrome, with seizure diaries and frequency by seizure subtype.
- Primary endpoint
- No single pivotal endpoint is identified in the cited source.
- Results
- Pivotal adjunctive Lennox-Gastaut syndrome and focal-seizure trials showed significant reductions in atonic and total seizures; in LGS, atonic seizures decreased about 34% versus little change with placebo.
Trial publications
Mechanism of action
- The label describes in-vitro antagonistic interaction at the strychnine-insensitive glycine recognition site of the NMDA receptor complex. Glycine here is an NMDA co-agonist; this is not blockade of inhibitory spinal glycine receptors.
- The human antiseizure mechanism remains unknown. Receptor-binding observations do not establish which action accounts for clinical seizure control.
Pharmacology
Adult values unless specified. Vd/F denotes apparent oral distribution volume.
Pharmacokinetics
- Bioavailability
- Well absorbed orally, but absolute oral-versus-IV bioavailability has not been measured. Tablets and suspension are bioequivalent to the studied capsule.
- Elimination half-life
- 20–23 hours; prolonged with renal impairment.
- Volume of distribution
- Apparent volume approximately 0.756 ± 0.082 L/kg after a 1,200 mg oral dose.
- Active metabolite(s)
- No clinically established active antiseizure metabolite. Potentially reactive/toxic metabolites should not be confused with therapeutic active metabolites.
- Active-metabolite half-life
- Not applicable — no clinically established active metabolite.
- Protein binding
- 22–25%
- Metabolism / elimination
- Hepatic oxidation/conjugation; CYP interactions
Metabolite activity does not predict the serious aplastic-anemia or hepatic-failure risks.
Molecular structure
NIH PubChem structure and record ↗
Product history
- Initial U.S. approval
- 1993
- Brands
- Felbatol
- Manufacturer / marketer
- Viatris/Meda (Felbatol)
- Generic availability
- Yes
- Related drugs
- Dicarbamate structurally related to meprobamate but pharmacologically distinct.
Sources & review status
Representative sources are selected product labels, not an exhaustive list of generic manufacturers. Consult the exact product and formulation prescribed. Brand-name package inserts are linked separately.
Brand reference: Felbatol tablets / suspension ↗
Indications and DailyMed PDFs checked: 2026-09-26. Other profile sources reviewed: 2026-09-15 · label revision noted at that review: 8/2025. This is a draft reference; final review is pending.