Anticonvulsant levels and reloading

Revision as of 13:45, 25 August 2015 by Rossdonaldson1 (talk | contribs) (See Also)


  • IV load can be performed with phenobarbital, phenytoin, valproate, levetiracetam
  • Oral loading can be spread over day or more to avoid GI upset
  • May use IV vs PO reload at physican discretion[1]

Initial Loading[1]

Drug (with brand name) Loading Dose and Route of Administration
Carbamazepine (Tegretol) PO: 8 mg/kg suspension in single oral load

IV: not available

Gabapentin (Neurontin) PO: 900 mg/day oral (300 mg tid) for 3 days

IV: not available

Lacosamide (Vimpat) PO: dosages not studied

IV: not studied

Lamotrigine (Lamictal) PO: 6.5 mg/kg single oral load if on lamotrigine for >6 mo without a history of rash or intolerance in the past and only off lamotrigine for <5 days

IV: not available

Levetiracetam (Keppra) PO: 1,500 mg oral load

IV: rapid IV loading safe and well tolerated in doses up to 60 mg/kg

Phenytoin (Dilantin) PO: 20 mg/kg divided in maximum doses of 400 mg every 2 hours

IV: 18 mg/kg at maximum rate of 50 mg/min

Fosphenytoin (Cerebyx) PO:

IV: 18 PE/kg IV at maximum rate of 150 PE/min IM: administration possible

Valproate (Depacon) PO:

IV: Up to 30 mg/kg IV at max rate of 10 mg/kg/min


Medications with verifiable levels include:

  1. Phenytoin
  2. Carbamazepine
  3. Phenobarbital
  4. Valproate

Desired Levels

  • Pt's optimal level = desired level
    • If optimal level unknown target upper end of therapeutic range:
      • Phenytoin = 20 mcg/mL
      • Valproate = 100 mcg/mL
      • Phenobarbital = 40 mcg/mL
      • Carbamazepine = 12 mcg/mL



Dose (mg) = ideal body weight (kg) X Vd X [desired level - current level (mcg/mL)]

Volume of Distribution

Volume of Distribution
Phenytoin (dilantin) 0.8
Carbamazepine (tegretol) 0.8
Phenobarbital 0.6
Valproate (depakote) 0.2

See Also


  1. 1.0 1.1 Seizures ACEP Policy committee . Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Seizures. Ann Emerg Med. 2014;63(4):437–447.e15. doi:10.1016/j.annemergmed.2014.01.018.