THERAPEUTICS

Brands

• Fetbatol, Taloxa

Generic?

• Yes

Class

• Antiepileptic drug (AED)

Commonly Prescribed for

(FDA approved in bold)

• Complex partial seizures (adjunctive)

• Partial and generalized seizures associated with Lennox-Gastaut syndrome (children)

• Infantile spasms (West syndrome)

How the Drug Works

• The exact mechanism of action in epilepsy is unknown. Felbamate may reduce seizure spread or increase seizure threshold. Putative mechanisms include changes in binding at calcium (L-type) channel, sodium channel, GABA receptors and blockade of NMDA-activated glutamate receptors

How Long Until It Works

• Seizures: 2 weeks

If It Works

• Seizures: goal is the decrease or remission of seizures. Continue as long as effective and well tolerated

If It Doesn't Work

• Increase to highest tolerated dose. If not effective discontinue

Best Augmenting Combos for Partial Response or Treatment-Resistance

• Epilepsy: generally used in combination with other agents for severe epilepsy. Keep drug interactions in mind

Tests

• Obtain liver function testing and CBC before starting, and monitor frequently – especially in the first months after initiating treatment

• Repeat liver function testing whenever new medications are added

ADVERSE EFFECTS (AEs)

How the Drug Causes AEs

• CNS AEs may be caused by binding changes at GABA, benzodiazepine, or NMDA receptors

• Aplastic anemia may be related to a reactive metabolite, 2-phenylpropenal

Notable AEs

• Most common: anorexia, weight loss, vomiting, insomnia, headache, dizziness, anxiety

• Less common: rash, acne, edema, rhinitis, otitis media, diplopia, abnormal taste or vision

Life-Threatening or Dangerous AEs

• Liver failure, often with rapid onset (2–4 weeks)

• Aplastic anemia, often fatal and usually beginning 5–30 weeks after starting treatment

Weight Gain

• Unusual

Sedation

• Common

• Usually dose related

What to Do About AEs

• Most AEs resolve with reduction in dose

• For serious AEs discontinue drug

Best Augmenting Agents to Reduce AEs

• Most AEs do not respond to an augmenting agent