Antiepileptics on the NCLEX
Phenytoin, valproate, levetiracetam, carbamazepine: levels, side effects, pregnancy.
Antiepileptic drugs have narrow therapeutic indices for some, broader for others. NCLEX tests phenytoin level, valproate teratogenicity, and Stevens-Johnson with carbamazepine.
Phenytoin (Dilantin)
Therapeutic level 10-20 mcg/mL. Gingival hyperplasia, hirsutism, ataxia, nystagmus. Many drug interactions. Free phenytoin level if albumin low.
Valproate (Depakote)
Therapeutic 50-100 mcg/mL. Teratogenic (neural tube defects). Hepatotoxic. Pancreatitis. Hyperammonemia. Weight gain.
Levetiracetam (Keppra)
Generally well-tolerated. Behavioral side effects (irritability, depression). Renally dosed.
Carbamazepine (Tegretol)
Stevens-Johnson Syndrome, screen HLA-B*1502 in Asians. Hyponatremia (SIADH). Aplastic anemia rare.
Lamotrigine
Rash → Stevens-Johnson. Slow titration mandatory.
Status epilepticus
Lorazepam IV first-line. Then phenytoin/fosphenytoin load.
Frequently asked
Pregnancy and AEDs?
Lamotrigine and levetiracetam relatively safer. Valproate avoided. Folic acid 4 mg/day for women of childbearing age on AEDs.
Phenytoin IV push?
Slow, max 50 mg/min adult (max 25 mg/min if elderly). Cardiac monitoring. Don't mix with D5W (precipitates).
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