Felbamate
Dicarbamate
Also known as: Felbatol · Taloxa · Felbamyl · AD-03055 · W-554
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Seizures (As either add-on therapy or monotherapy) | 15 mg/kg PO q8h. Dose can be increased in 15 mg/kg increments every 2 weeks until seizures are controlled. Doses as high as 70 mg/kg q8h are required and tolerated in some dogs. | PO | q8h | — | 🌎 NA |
| Seizures (As a third choice antiepileptic agent) | 15-65 mg/kg PO q8h | PO | q8h | — | 🌎 NA |
| Seizures (For patients on phenobarb and bromides and seizure activity unchanged or having intolerable side effects) | 5-20 mg/kg PO three times daily | PO | TID | — | 🌎 NA |
- Seizures (As either add-on therapy or monotherapy): Starting dose is 15 mg/kg.
- Seizures (As a third choice antiepileptic agent): Steady state reached after 4th oral dose. Monitor CBC and liver function tests as you would for phenobarbital. Therapeutic serum concentration reported to be 15-100 micrograms/mL.
- Seizures (For patients on phenobarb and bromides and seizure activity unchanged or having intolerable side effects): If intolerable side effects, do levels and decrease the dose of the one that is in the high end of the range. Then add felbamate.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Felbamate is a unique dicarbamate anticonvulsant used primarily as a 2nd- or 3rd-line antiseizure medication in dogs.
- Particularly useful for complex partial seizures and generalized seizures.
- Clinical Pearl: Unlike many other anticonvulsants, felbamate does not typically cause additive sedation when combined with phenobarbital or potassium bromide, making it an attractive add-on therapy.
- Due to its short half-life, it requires strict three-times-daily (TID) dosing.
- Cost and accessibility can be limiting factors for veterinary patients.
- Because of its limited use in veterinary medicine, the full adverse effect profile may be incomplete.
Mechanism of action
Felbamate reduces excitatory neurotransmission and enhances inhibitory pathways.
- Increases activation of voltage-gated sodium channels → decreases sustained high-frequency firing of action potentials.
- NMDA Receptor Antagonism: Blocks the NR2B subunit of the NMDA receptor → prevents glutamate-mediated excitation.
- GABA_A Modulation: Acts as a positive allosteric modulator at GABA_A receptors → enhances chloride influx and neuronal hyperpolarization.
Safety & warnings
Contraindications
- Hypersensitivity to felbamate or other carbamates (e.g., meprobamate)
Adverse effects
- Keratoconjunctivitis sicca (KCS)
- Liver enzyme induction
- Tremor
- Limb rigidity
- Salivation
- Restlessness and agitation (at high doses)
- Blood dyscrasias (thrombocytopenia, lymphopenia, leukopenia)
- Sedation (usually when combined with other anticonvulsants)
- Vomiting/nausea (usually when combined with other anticonvulsants)
Precautions
Warning: May cause liver enzyme induction. Half-life may decrease over time, requiring dose adjustments.
- Use with caution in patients with pre-existing hepatic dysfunction or a history of blood dyscrasias.
- Pregnancy Category C: Use only if potential benefits outweigh risks. Excreted in maternal milk, but adverse consequences to nursing puppies appear remote.
Drug interactions
Felbamate may increase phenobarbital levels. Phenobarbital may decrease felbamate levels.
Felbamate may increase phenytoin levels. Phenytoin may decrease felbamate levels.
Felbamate can cause increases in valproic acid levels.
Monitoring
- Liver function tests (q2-3 months recommended by some clinicians)
- Complete Blood Count (CBC) (q2-3 months recommended by some clinicians)
- Therapeutic drug levels (25-100 micrograms/mL range, though usefulness is questionable)
- Seizure frequency and severity
Pharmacokinetics
Half-life
Absorption
Well absorbed after oral administration in dogs.
Distribution
Crosses the blood-brain barrier to exert CNS effects.
Metabolism
Undergoes hepatic metabolism. Can induce liver enzymes, which may decrease its own half-life over time.
Elimination
Excreted in the urine (about 50% unchanged and 50% as metabolites).
Overdose
Limited veterinary information is available.
- In humans, a massive overdose (12 grams over 12 hours) resulted only in mild gastric distress and a slightly increased heart rate.
- Treatment should be supportive and symptomatic. Consider gastric decontamination if ingestion is recent and the patient is neurologically stable.
Available products
Formulations
- Tablets
- Oral suspension
Human-labeled
- Felbamate Tablets: 400 mg & 600 mg (Felbatol®)
- Felbamate Suspension: 120 mg/mL in 240 & 960 mL (Felbatol®)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store preparations at room temperature. The oral suspension should be shaken well before use.
Client information
- Strict Schedule: It is critical to give this medication exactly as prescribed, usually every 8 hours (three times a day). Because it leaves the body quickly, missing doses can lead to breakthrough seizures.
- Side Effects: Watch for signs of dry eye (squinting, thick eye discharge), tremors, restlessness, or vomiting. Contact your veterinarian if you notice these signs.
- Blood Tests: Your veterinarian may recommend periodic blood tests to monitor liver function and blood cell counts, especially if your dog is taking other seizure medications.
- Do Not Stop Abruptly: Never stop seizure medications suddenly without consulting your veterinarian, as this can trigger severe, life-threatening seizures.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.