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Classification of AEDs
The goal of antiepileptic drugs (AEDs) is seizure control with minimal or no drug toxicity. ≈ 75% of epileptics can achieve satisfactory seizure control with medical therapy.
- “Broad spectrum” (treat a variety of seizure types):
- valproic acid
- lamotrigine (Lamictal®)
- levetiracetam (Keppra®)
- These agents are not considered broad spectrum:
- phenytoin (Dilantin® and others)
- carbamazepine (Tegretol®)
- primary generalized
- a) GTC (generalized tonic-clonic):
- valproic acid (VA) some studies show fewer side effects and better control than PHT
- carbamazepine
- phenytoin (PHT)
- phenobarbital (PB)
- primidone (PRM)
- b) absence:
- ethosuximide
- valproic acid (VA)
- clonazepam
- methsuximide
- c) myoclonic →benzodiazepines
- d) tonic or atonic:
- benzodiazepines
- felbamate
- vigabatrin
- partial (simple or complex, with or without secondary generalization (VA may compare favorably with CBZ for secondarily GTC, but is less effective for complex partial seizures):
- a) carbamazepine (CBZ): most effective, least side effects
- b) phenytoin (PHT): ↓
- c) phenobarbital (PB): ↓
- d) primidone (PRM): slightly less effective, more side effects
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- second line drugs for any of the above seizure types:
- a) valproate
- b) lamotrigine : effective for many types of generalized seizures, but are not FDA approved for this yet
- c) topiramate : effective for many types of generalized seizures, but are not FDA approved for this yet
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General guidelines
- 1. increase a given medication until seizures are controlled or side effects become intolerable
- 2. try monotherapy with a different drugs before resorting to two drugs together. 80% of epileptics can be controlled on monotherapy Only ≈ 10% benefit significantly from the addition of a second drug.9 When >2 AEDs are required, consider nonepileptic seizures
- 3. when first evaluating patients on multiple drugs, withdraw the most sedating ones first (usually barbiturates and clonazepam)
- 4. Without loading dose, it takes about half- lives to reach steady state.
- 5. Discontinue an AED if the GGT exceeds twice normal.
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Phenytoin (PHT) (Dilantin®)
Indications is GTC, S/C-P(simple or complex partial), occasionally in ABS
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