Felbamate
**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.
Mecanismo: 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.
Dosificación por especie
- 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 · Starting dose is 15 mg/kg.
- Seizures (As a third choice antiepileptic agent) · 15-65 mg/kg PO q8h · PO · q8h · 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) · 5-20 mg/kg PO three times daily · PO · TID · 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.
Las dosis son una referencia clínica para médicos veterinarios. Confirme siempre con la información vigente del producto y el paciente individual.
Vías de administración
Contraindicaciones
- Hypersensitivity to felbamate or other carbamates (e.g., meprobamate)
Efectos adversos
- 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)
Interacciones farmacológicas
- Phenobarbital · Felbamate may increase phenobarbital levels. Phenobarbital may decrease felbamate levels.
- Phenytoin · Felbamate may increase phenytoin levels. Phenytoin may decrease felbamate levels.
- Valproate · Felbamate can cause increases in valproic acid levels.
Monitoreo
- 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
Sobredosis
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.
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.