Felbamate Suspension
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Questions & Answers
Side Effects & Adverse Reactions
See Boxed Warning regarding aplastic anemia and hepatic failure.
Antiepileptic drugs should not be suddenly discontinued because of the possibility of increasing seizure frequency.
Suicidal Behavior and Ideation
Antiepileptic drugs (AEDs) including felbamate, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.
Pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted Relative Risk 1.8, 95% CI:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide.
The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.
The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary substantially by age (5 to 100 years) in the clinical trials analyzed.
Table 1 shows absolute and relative risk by indication for all evaluated AEDs.
| Table 1 Risk by Indication for Antiepileptic Drugs in the Pooled Analysis | ||||
| Indication | Placebo Patientswith Events Per 1000 Patients | Drug Patients with Events Per1000 Patients | Relative Risk:Incidence ofEvents in DrugPatients/Incidencein Placebo Patients | Risk Difference:Additional DrugPatients withEvents Per 1000Patients |
| Epilepsy | 1 | 3.4 | 3.5 | 2.4 |
| Psychiatric | 5.7 | 8.5 | 1.5 | 2.9 |
| Other | 1 | 1.8 | 1.9 | 0.9 |
| Total | 2.4 | 4.3 | 1.8 | 1.9 |
The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications.
Anyone considering prescribing felbamate or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated.
Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to healthcare providers.
Legal Issues
There is currently no legal information available for this drug.
FDA Safety Alerts
There are currently no FDA safety alerts available for this drug.
Manufacturer Warnings
There is currently no manufacturer warning information available for this drug.
FDA Labeling Changes
There are currently no FDA labeling changes available for this drug.
Uses
Felbamate oral suspension is not indicated as a first line antiepileptic treatment (see Warnings). Felbamate oral suspension is recommended for use 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.
If these criteria are met and the patient has been fully advised of the risk, and has provided written acknowledgment, felbamate oral suspension can be considered for either monotherapy or adjunctive therapy in the treatment of partial seizures, with and without generalization, in adults with epilepsy and as adjunctive therapy in the treatment of partial and generalized seizures associated with Lennox-Gastaut syndrome in children.
History
There is currently no drug history available for this drug.
Other Information
Felbamate is an antiepileptic available as a 600 mg/5 mL suspension for oral administration. Its chemical name is 2-phenyl-1,3-propanediol dicarbamate.
Felbamate is a white to off-white crystalline powder with a characteristic odor. It is very slightly soluble in water, slightly soluble in ethanol, sparingly soluble in methanol, and freely soluble in dimethyl sulfoxide. The molecular weight is 238.24; felbamate's molecular formula is C11H14N2O4; its structural formula is:
The inactive ingredients for felbamate oral suspension 600 mg/5 mL are bubble gum flavor, carboxymethyl cellulose sodium, FD&C Yellow No. 6, FD&C Red No. 40, glycerin, methylparaben, microcrystalline cellulose, polysorbate 80, propylparaben, purified water, saccharin sodium, simethicone, and sorbitol.
Sources
Felbamate Suspension Manufacturers
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Amneal Pharmaceuticals
![Felbamate Suspension [Amneal Pharmaceuticals]](/wp-content/themes/bootstrap/assets/img/loading2.gif)
Felbamate Suspension | Amneal Pharmaceuticals Of New York, Llc
Felbamate oral suspension has been studied as monotherapy and adjunctive therapy in adults and as adjunctive therapy in children with seizures associated with Lennox-Gastaut syndrome. As felbamate oral suspension is added to or substituted for existing AEDs, it is strongly recommended to reduce the dosage of those AEDs in the range of 20% to 33% to minimize side effects (see Drug Interactions subsection).
Dosage Adjustment in the Renally Impaired: Felbamate should be used with caution in patients with renal dysfunction. In the renally impaired, starting and maintenance doses should be reduced by one-half (See CLINICAL PHARMACOLOGY / Pharmacokinetics and PRECAUTIONS). Adjunctive therapy with medications which affect felbamate plasma concentrations, especially AEDs, may warrant further reductions in felbamate daily doses in patients with renal dysfunction.
Adults (14 years of age and over)
The majority of patients received 3600 mg/day in clinical trials evaluating its use as both monotherapy and adjunctive therapy.
Monotherapy: (Initial therapy) Felbamate oral suspension has not been systematically evaluated as initial monotherapy. Initiate felbamate oral suspension at 1200 mg/day in divided doses three or four times daily. The prescriber is advised to 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 if clinically indicated.
Conversion to Monotherapy: Initiate felbamate oral suspension at 1200 mg/day in divided doses three or four times daily. Reduce the dosage of concomitant AEDs by one-third at initiation of felbamate oral suspension therapy. At week 2, increase the felbamate oral suspension dosage to 2400 mg/day while reducing the dosage of other AEDs up to an additional one-third of their original dosage. At week 3, increase the felbamate oral suspension dosage up to 3600 mg/day and continue to reduce the dosage of other AEDs as clinically indicated.
Adjunctive Therapy: Felbamate oral suspension should be added at 1200 mg/day in divided doses three or four times daily while reducing present AEDs by 20% in order to control plasma concentrations of concurrent phenytoin, valproic acid, phenobarbital, and carbamazepine and its metabolites. Further reductions of the concomitant AEDs dosage may be necessary to minimize side effects due to drug interactions. Increase the dosage of felbamate oral suspension by 1200 mg/day increments at weekly intervals to 3600 mg/day. Most side effects seen during felbamate oral suspension adjunctive therapy resolve as the dosage of concomitant AEDs is decreased.
Table 6 Dosage Table (adults) Dosage reduction of concomitant AEDs WEEK 1 REDUCE original dose by 20% to 33%* WEEK 2 REDUCE original dose by up to an additional 1/3* WEEK 3 REDUCE as clinically indicated Felbamate Oral SuspensionDosage 1200 mg/day Initial dose 2400 mg/day Therapeutic dosage range 3600 mg/day Therapeutic dosage range *See Adjunctive and Conversion to Monotherapy sections.While the above felbamate oral suspension conversion guidelines may result in a felbamate oral suspension 3600 mg/day dose within 3 weeks, in some patients titration to a 3600 mg/day felbamate oral suspension dose has been achieved in as little as 3 days with appropriate adjustment of other AEDs.
Children with Lennox-Gastaut Syndrome (Ages 2 to 14 years)
Adjunctive Therapy: Felbamate oral suspension should be added at 15 mg/kg/day in divided doses three or four times daily while reducing present AEDs by 20% in order to control plasma levels of concurrent phenytoin, valproic acid, phenobarbital, and carbamazepine and its metabolites. Further reductions of the concomitant AEDs dosage may be necessary to minimize side effects due to drug interactions. Increase the dosage of felbamate oral suspension by 15 mg/kg/day increments at weekly intervals to 45 mg/kg/day. Most side effects seen during felbamate oral suspension adjunctive therapy resolve as the dosage of concomitant AEDs is decreased.
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