The chemistry, pharmacology, pharmacokinetics, clinical use, adverse effects, drug interactions, and dosage of
felbamate are discussed.
Felbamate (2-phenyl-1,3-propanediol dicarbamate) is chemically unrelated to any of the other currently marketed
antiepileptic drugs (AEDs). It appears that
felbamate, like
phenobarbital and
valproic acid, decreases the frequency of
seizures by decreasing seizure spread and increasing seizure threshold. Oral
felbamate is at least 90% absorbed, and peak concentrations are reached in one to six hours. The half-life is a little less than one day. A therapeutic range of plasma concentrations has not been determined.
Felbamate has been used effectively as monotherapy and adjunctive
therapy in patients with
partial seizures with or without secondary generalization and as adjunctive
therapy in children with partial or
generalized seizures associated with
Lennox-Gastaut syndrome.
Felbamate may also be safe and effective in patients with generalized, absence, atypical absence, juvenile myoclonic, infantile, and gelastic
seizures. The most frequently reported adverse effects of
felbamate include
nausea,
anorexia,
vomiting,
headache,
fatigue,
somnolence,
insomnia, and increased serum
aspartate aminotransferase levels. The frequency of adverse effects is greater in patients receiving other AEDs in addition to
felbamate.
Felbamate affects the pharmacokinetics of
phenytoin,
carbamazepine,
valproic acid, and
methsuximide; other AEDs also affect the pharmacokinetics of
felbamate. The dosage of
felbamate should begin at 400 mg orally three times daily and then increase by 600 mg/day every two weeks to up to 3600 mg/day. If the patient is receiving other AEDs concurrently, their dosage should be decreased as the dosage of
felbamate is increased. If the goal is to switch to
felbamate, the dosage should be increased weekly as the dosages of other AEDs are reduced.
Felbamate offers a safe and effective alternative to other AEDs in the treatment of partial and secondarily
generalized seizures; partial and
generalized seizures associated with
Lennox-Gastaut syndrome; and atypical absence
seizures, gelastic
seizures, and other difficult to control
seizures.