No

Anticonvulsant, Miscellaneous

Not as a first-line antiepileptic treatment; only in those patients who respond inadequately to alternative treatments and whose epilepsy is so severe that a substantial risk of aplastic anemia and/or liver failure is deemed acceptable in light of the benefits conferred by its use. Patient must be fully advised of risk and has signed written informed consent. Felbamate can be used as either monotherapy or adjunctive therapy in the treatment of partial seizures, with and without generalization, in adults with epilepsy, and as an adjunctive therapy in the treatment of partial and generalized seizures associated with Lennox-Gastaut syndrome in children.

C

Hypersensitivity to felbamate or its ingredients; use with caution in those patients who have demonstrated hypersensitivity reactions to other carbamates

Use with caution in patients allergic to other carbamates (eg, meprobamate); antiepileptic drugs should not be suddenly discontinued because of the possibility of increasing seizure frequency; reported 10 cases of aplastic anemia in the U.S. after 21/2 to 6 months of therapy; Carter Wallace and the FDA recommended the use of this agent be suspended unless withdrawal of the product would place a patient at greater risk as compared to the frequently fatal form of anemia

>10%:

Central nervous system: Somnolence, headache, fatigue, dizziness

Gastrointestinal: Nausea, anorexia, vomiting, constipation

1% to 10%:

Cardiovascular: Chest pain, palpitations, tachycardia

Central nervous system: Depression or behavior changes, nervousness, anxiety, ataxia, stupor, malaise, agitation, psychological disturbances, aggressive reaction

Dermatologic: Skin rash, acne, pruritus

Gastrointestinal: Xerostomia, diarrhea, abdominal pain, weight gain, taste perversion

Neuromuscular & skeletal: Tremor, abnormal gait, paresthesia, myalgia

Ocular: Diplopia, abnormal vision

Respiratory: Sinusitis, pharyngitis

Miscellaneous: SGPT increase

<1%: Euphoria, hallucinations, suicide attempts, migraine, urticaria, lymphadenopathy, leukopenia, leukocytosis, thrombocytopenia

Symptoms of overdose include sedation, gastrointestinal upset, and tachycardia. Provide general supportive care.

CYP2C19 enzyme inhibitor

Felbamate increases serum phenytoin, phenobarbital, and valproic acid concentrations which may result in toxicity; consider decreasing phenytoin or phenobarbital dosage by 25%; a decrease in valproic acid dosage may also be necessary; monitor for valproic acid toxicity (confusion, irritability, restlessness)

Felbamate may decrease carbamazepine levels and increase levels of the active metabolite of carbamazepine (10,11-epoxide) resulting in carbamazepine toxicity; monitor for signs of carbamazepine toxicity (dizziness, ataxia, nystagmus, drowsiness)

Mechanism of action is unknown but has properties in common with other marketed anticonvulsants; 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.

Absorption: Oral: Rapidly and almost completely absorbed after oral administration, food has no effect upon the tablet's absorption

Peak serum concentrations: Within 3 hours

Half-life: 20-23 hours average

Monotherapy: Children >14 years and Adults:

Initial: 1200 mg/day in divided doses 3 or 4 times/day; titrate previously untreated patients under close clinical supervision, increasing the dosage in 600 mg increments every 2 weeks to 2400 mg/day based on clinical response and thereafter to 3600 mg/day in clinically indicated

Conversion to monotherapy: Initiate at 1200 mg/day in divided doses 3 or 4 times/day, reduce the dosage of the concomitant anticonvulsant(s) by 20% to 33% at the initiation of felbamate therapy; at week 2, increase the felbamate dosage to 2400 mg/day while reducing the dosage of the other anticonvulsant(s) up to an additional 33% of their original dosage; at week 3, increase the felbamate dosage up to 3600 mg/day and continue to reduce the dosage of the other anticonvulsant(s) as clinically indicated

Adjunctive therapy: Children with Lennox-Gastaut and ages 2-14 years:

Week 1:

Felbamate: 15 mg/kg/day divided 3-4 times/day

Concomitant anticonvulsant(s): Reduce original dosage by 20% to 30%

Week 2:

Felbamate: 30 mg/kg/day divided 3-4 times/day

Concomitant anticonvulsant(s): Reduce original dosage up to an additional 33%

Week 3:

Felbamate: 45 mg//kg/day divided 3-4 times/day

Concomitant anticonvulsant(s): Reduce dosage as clinically indicated

Adjunctive therapy: Children >14 years and Adults:

Week 1:

Felbamate: 1200 mg/day initial dose

Concomitant anticonvulsant(s): Reduce original dosage by 20% to 33%

Week 2:

Felbamate: 2400 mg/day (Therapeutic range)

Concomitant anticonvulsant(s): Reduce original dosage by up to an additional 33%

Week 3:

Felbamate: 3600 mg/day (Therapeutic range)

Concomitant anticonvulsant(s): Reduce original dosage as clinically indicated

Food does not affect absorption

Not necessary to routinely monitor serum drug levels, since dose should be titrated to clinical response

Anxiety and dizziness are common; may cause drowsiness, insomnia, or depression

Carbamazepine may decrease effects of felbamate; may increase effects of valproic acid

No information available to require special precautions

No effects or complications reported

Take exactly as directed (do not increase dose or frequency or discontinue without consulting prescriber). While using this medication, do not use alcohol and other prescription or OTC medications (especially pain medications, sedatives, antihistamines, or hypnotics) without consulting prescriber. Maintain adequate hydration (2-3 L/day of fluids unless instructed to restrict fluid intake). You may experience drowsiness, dizziness, or blurred vision (use caution when driving or engaging in tasks requiring alertness until response to drug is known); nausea, vomiting, loss of appetite, or dry mouth (small frequent meals, frequent mouth care, chewing gum, or sucking lozenges may help). Wear identification of epileptic status and medications. Report CNS changes, mentation changes, or changes in cognition; muscle cramping, weakness, tremors, changes in gait; persistent GI symptoms (cramping, constipation, vomiting, anorexia); rash or skin irritations; unusual bruising or bleeding (mouth, urine, stool); cough, runny nose, sore throat, or difficulty breathing; worsening of seizure activity, or loss of seizure control. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Breast-feeding is not recommended.

Use with caution in patients allergic to other carbamates (eg, meprobamate); antiepileptic drugs should not be suddenly discontinued because of the possibility of increasing seizure frequency; reported 10 cases of aplastic anemia in the U.S. after 21/2 to 6 months of therapy; Carter Wallace and the FDA recommended the use of this agent be suspended unless withdrawal of the product would place a patient at greater risk as compared to the frequently fatal form of anemia

Monitor serum levels of concomitant anticonvulsant therapy

Stability: Store medication in tightly closed container at room temperature away from excessive heat

Suspension, oral: 600 mg/5 mL (240 mL, 960 mL)

Tablet: 400 mg, 600 mg