Pharmacology - Epilepsy

Flashcards reviewing key vocabulary and concepts related to antiepileptic drugs (AEDs), their mechanisms, clinical uses, and adverse effects.

Treatment Goals for Epilepsy

No Seizures & No Side Effects

Excitatory Control in Epilepsy

Glutamate receptors (NMDA, non-NMDA)

Inhibitory Control in Epilepsy

GABAA - major inhibitory neurotransmitter

Criteria for Choosing an AED

Efficacy, Toxicity, Drug Interactions, Dosing schedule, Clinical impression, Co-morbid condition(s)

Categorization of AEDs by Mechanism of Action

Enhance sodium channel inactivation, Enhance inhibitory GABA transmission, Block calcium channel, Other mechanisms

Phenytoin (PHT, Dilantin®)

Na+ channel; Enzyme Inducer; Partial & Generalized; nystagmus, ataxia, gingival hyperplasia, osteomalacia

Carbamazepine (CBZ, Tegretol®, Carbatrol®, Equetro®)

Na+ channel; Enzyme Inducer; Partial > Generalized; dizziness, diplopia, leukopenia; may worsen Primary Generalized Seizures

Oxcarbazepine (OCBZ, Trileptal®)

Na+ Channels; influenced by others; Partial > Generalized; dizziness, diplopia, ataxia, hyponatremia; monitor Na+

Lamotrigine (LTG, Lamictal®)

Na+ Channels, Glutamate; influenced by others; Partial & Generalized; sedation, diplopia, ataxia, nausea - Rash; slow taper - especially Valproate

Topiramate (TPM, Topamax®)

Na+ Channels, Glutamate, GABA, Carbonic anhydrase inhibition; influenced by others; Partial & Generalized; difficulty concentrating, kidney stones, weight loss; fluids

Zonisamide (ZNS, Zonegran®)

Na+ and T-calcium channels, Carbonic anhydrase inhibition; not clinically significant; Partial; somnolence, dizziness, kidney stones, weight loss; fluids

Phenobarbital (PB, Various Manufs)

GABAA; Enzyme Inducer; Partial & Generalized; sedation, paradoxical hyperactivity, osteomalacia; better options available

Ethosuximide (Zarontin®)

Reduces T-type Ca++ current; Can be induced and inhibited; Generalized - Absence; sedation, GI (nausea, vomiting, pain); drug of choice for absence seizures

Valproic Acid (VPA, Depakote®, Depakene®, Depakote ER®)

Ca++, Na+ channel, GABA; Enzyme Inhibitor; Partial & Generalized; sedation, N/V, weight gain, hair loss, tremor, thrombocytopenia; ≠ woman childbearing age

Gabapentin (GBP, Neurontin®)

Presynaptic alpha2-delta site of voltage-gated calcium channels (≠ GABA); none with AEDs; Partial; fatigue, dizziness, ataxia; adjust for renal function

Pregabalin (PGB, Lyrica®)

Presynaptic alpha2-delta site of voltage-gated calcium channels (≠ GABA); none; Partial; dizziness, ataxia, weight gain; adjust for renal function

Levetiracetam (LEV, Keppra®)

Synaptic vessel protein (SV2A) - Modifies release of glutamate and GABA; none; Partial & Generalized; somnolence, dizziness, behavioral changes; adjust dose for renal function

Unfavorable Kinetics of 1st Generation AEDs

Saturable metabolism, Narrow Therapeutic Range, Adverse CNS Effects, Drug-Interactions

Summary of 2nd Generation AEDs

Safer, Less drug interactions, Use outside of Epilepsy (Psychiatry, Headache, Pain, etc.)