Oral Partial seizures with or without secondary generalisation
Adult: In severe cases unresponsive to other drugs: As monotherapy: Initially, 1,200 mg daily in 3 or 4 divided doses, may increase in increments of 600 mg daily every 2 weeks for up to 2,400 mg daily depending on patient response and tolerability. Max: 3,600 mg daily. As adjunctive therapy: Initially, 1,200 mg daily in 3 or 4 divided doses, may increase in increments of 1,200 mg daily at weekly intervals depending on patient response and tolerability. Reduce the dose of concomitant antiepileptic drugs (AEDs) by 1/3 (20-33%) when initiating felbamate therapy. Child: ≥14 years Same as adult dose.
Oral Seizures associated with the Lennox-Gastaut syndrome
Child: 2-<14 years In severe cases unresponsive to other drugs: As adjunctive therapy: Initially, 15 mg/kg daily in 3 or 4 divided doses, may increase in increments of 15 mg/kg at weekly intervals. Max: 45 mg/kg daily. Reduce the dose of concomitant AEDs by 20% when initiating felbamate therapy.
Renal Impairment
Reduce initial and maintenance doses by 50%.
Hepatic Impairment
Contraindicated.
Contraindications
Hypersensitivity to carbamates. History of blood dyscrasia. Hepatic impairment.
Special Precautions
Avoid abrupt withdrawal. Renal impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Suicidal behaviour and ideation. Blood and lymphatic system disorders: Leucopenia. Cardiac disorders: Chest pain. Ear and labyrinth disorders: Otitis media. Eye disorders: Miosis, diplopia, visual disturbance. Gastrointestinal disorders: Vomiting, nausea, dyspepsia, constipation, hiccups, dysgeusia, abdominal pain, diarrhoea, dry mouth. General disorders and administration site conditions: Fatigue, fever. Investigations: Increased liver enzymes, decreased weight. Metabolism and nutrition disorders: Anorexia. Musculoskeletal and connective tissue disorders: Myalgia. Nervous system disorders: Drowsiness, headache, dizziness, insomnia, somnolence, tremor, gait disturbance, ataxia, paraesthesia, stupor. Psychiatric disorders: Emotional lability, anxiety, depression. Renal and urinary disorders: UTI. Respiratory, thoracic and mediastinal disorders: Upper respiratory tract infection, pharyngitis, cough, rhinitis, sinusitis. Skin and subcutaneous tissue disorders: Rash, acne, purpura. Potentially Fatal: Aplastic anaemia, acute hepatic failure.
PO: Z (Insufficient data to conclude its safety and risk during pregnancy. Use only when benefits outweigh risks.)
Monitoring Parameters
Monitor therapeutic effectiveness and response (e.g. seizure activity, force, type, duration); serum levels of concomitant antiseizure therapy. Perform LFTs (at baseline, every 2 weeks after therapy initiation for the first 6-12 months of therapy, and periodically thereafter); CBC (at baseline, every 2 weeks for the first 6-12 months of therapy, periodically thereafter, and for a significant period after discontinuation). Monitor for suicidality (e.g. suicidal thoughts, depression, behavioural changes).
May increase serum concentration of phenobarbital, carbamazepine, phenytoin.
Action
Description: Mechanism of Action: Felbamate is a dicarbamate derivative with unknown mechanism. It has weak inhibitory effects on GABA-receptor binding, benzodiazepine receptor binding. It also exhibits NMDA antagonism, and Ca and Na channel inhibition. Pharmacokinetics: Absorption: Well absorbed from the gastrointestinal tract. Bioavailability: >90%. Time to peak plasma concentration: 1-6 hours. Distribution: Enters breast milk. Volume of distribution: 0.7-0.91 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 metabolites). Terminal elimination half-life: 20-23 hours.
Chemical Structure
Felbamate Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 3331, Felbamate. https://pubchem.ncbi.nlm.nih.gov/compound/Felbamate. Accessed Sept. 28, 2022.
N03AX10 - felbamate ; Belongs to the class of other antiepileptics.
References
Anon. Felbamate. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 05/08/2022.Anon. Felbamate. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/08/2022.Buckingham R (ed). Felbamate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/08/2022.Felbatol Tablets, Oral Suspension (Meda Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/08/2022.
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