Felbamate
Mechanism :
Receptor-binding studies in vitro indicate that felbamate has weak inhibitory effects on GABA-receptor binding, benzodiazepine receptor binding, and is devoid of activity at the MK-801 receptor binding site of the NMDA receptor-ionophore complex. However, felbamate does interact as an antagonist at the strychnine-insensitive glycine recognition site of the NMDA receptor-ionophore complex.
Indication :
- Seizures
- Lennox-Gastaut Adjunctive Therapy
Contraindications :
Contraindicated in patients with known hypersensitivity to its ingredients or known sensitivity to other carbamates. It should not be used in patients with a history of any blood dyscrasia or hepatic dysfunction.
Dosing :
Seizures:
>14 years: As adults
Initial 1200 mg/day orally in 3-4 divided doses.
Increase over 3 weeks to no more than 3600 mg/day.
Decrease dose of concomitant anticonvulsants by 20-33%.
Lennox-Gastaut Adjunctive Therapy:
Under 2 years: Safety & efficacy not established.
2-14 years: Initial: 15 mg/kg/day orally in three divided doses. May increase by 15 mg/kg/day every week to 45 mg/kg/day.
Adverse Effect :
Common Reactions: Headache, nausea/vomiting, anorexia, somnolence, dizziness, insomnia, fatigue, dyspepsia, constipation, nervousness/anxiety, taste changes, tremor, abdominal pain, abnormal gait, visual disturbance, depression, diarrhea, ataxia, paraesthesia, ALT elevation, chest pain, xerostomia, myalgia, fever, otitis media, rash, purpura, abnormal thinking, hiccups, cough, leukopenia.
Serious Reactions: Hepatic failure, aplastic anemia, hemolytic anemia, pancytopenia, depression, suicidal tendency, anaphylactoid reaction, Stevens-Johnson syndrome, toxic epidermal necrolysis, rhabdomyolysis, acute renal failure, withdrawal seizures if abruptly discontinued.
Interaction :
Phenytoin: An increase in steady-state phenytoin plasma concentrations.
Carbamazepine: Causes a decrease in the steady-state carbamazepine plasma concentrations and an increase in the steady-state carbamazepine epoxide plasma concentration.
Valproate: Causes an increase in steady-state valproate concentrations.
Phenobarbital: Coadministration of felbamate with phenobarbital causes an increase in phenobarbital plasma concentrations.
Hepatic Dose :
Children =2 years and Adolescents: Use is contraindicated in patients with hepatic impairment.