Felbamate


Generic Medicine Info
Indications and Dosage
Oral
Monotherapy or adjunct in refractory partial seizures with or without secondary generalisation
Adult: In severe cases unresponsive to other drugs: As monotherapy: Initially, 1.2 g daily in 3 or 4 divided doses, may increase gradually by 0.6 g every 2 wk up to 2.4 g daily. May further increase if needed. Max: 3.6 g daily. As adjunctive treatment: Initially, 1.2 g daily in 3 or 4 divided doses, may increase by 1.2 g at wkly intervals up to 3.6 g daily. Reduce the dose of concomitant anticonvulsants by 20-33% when initiating felbamate therapy.
Child: As adjunct in Lennox-Gastaut syndrome: 2-<14 yr Initially, 15 mg/kg daily in 3 or 4 divided doses, may increase gradually in increments of 15 mg/kg at wkly intervals. Max: 45 mg/kg daily. Reduce the dose of concomitant anticonvulsants by 20% when initiating felbamate therapy; ≥14 yr Same as adult dose.
Renal Impairment
Reduce initial and maintenance doses by 50%.
Hepatic Impairment
Contraindicated.
Contraindications
History of blood disorders. Active liver disease or history of hepatic impairment.
Special Precautions
Avoid abrupt withdrawal. Renal impairment. Childn. Pregnancy and lactation.
Adverse Reactions
Nervous: Headache, dizziness, anorexia, insomnia, somnolence, anxiety.
GI: Nausea, vomiting, dyspepsia, constipation or diarrhoea.
Resp: Upper resp tract infection, rhinitis.
Hepatic: Increased SGPT.
Genitourinary: UTI, intramenstrual bleeding.
Ophthalmologic: Diplopia.
Otic: Otitis media.
Dermatologic: Photosensitivity, acne, rash, facial oedema.
Others: Fatigue, decreased wt, hypophosphataemia.
Potentially Fatal: Acute hepatic failure, aplastic anaemia.
Patient Counseling Information
Avoid exposure to UV radiation.
Monitoring Parameters
Perform CBC and LFT prior to and during treatment. Monitor for suicidality (e.g. depression, suicidal thoughts, mood/behavioural changes).
Drug Interactions
Enhanced metabolism w/ enzyme inducers (e.g. phenobarbital, carbamazepine, phenytoin). Prolonged half-life w/ gabapentin.
Action
Description: Felbamate is a carbamate w/ unknown mechanism of action, but has properties similar to other anticonvulsants. It 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.
Pharmacokinetics:
Absorption: Well absorbed from the GI tract. Bioavailability: ≥80%. Time to peak plasma concentration: 1-6 hr.
Distribution: Enters breast milk. Volume of distribution: 0.76 L/kg. Plasma protein binding: Approx 22-25%, mainly to albumin.
Metabolism: Partly metabolised in the liver via hydroxylation and conjugation to inactive metabolites.
Excretion: Mainly via urine (40-50% as unchanged drug, 40% as inactive metabolites); faeces (<5%). Terminal elimination half-life: 16-23 hr.
Chemical Structure

Chemical Structure Image
Felbamate

Source: National Center for Biotechnology Information. PubChem Database. Felbamate, CID=3331, https://pubchem.ncbi.nlm.nih.gov/compound/Felbamate (accessed on Jan. 20, 2020)

Storage
Store between 20-25°C.
MIMS Class
ATC Classification
N03AX10 - felbamate ; Belongs to the class of other antiepileptics.
References
Anon. Felbamate. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 20/02/2017.

Buckingham R (ed). Felbamate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/02/2017.

Felbamate Tablet (Amneal Pharmaceuticals LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 20/02/2017.

McEvoy GK, Snow EK, Miller J et al (eds). Felbamate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 20/02/2017.

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