Anticonvulsant levels and reloading

Revision as of 22:28, 20 April 2014 by Ostermayer (talk | contribs) (Loading)


  • IV load can be performed with phenobarbital, phenytoin, valproate, levetiracetam
  • Oral loading can be spread over day or more to avoid GI upset


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

Desired Level

  • 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


Drug (With Selected References) Loading Dose and Route of Administration
Carbamazepine Tegretol 8 mg/kg oral suspension, single oral load; IV not available
Gabapentin (Neurontin) 900 mg/day oral (300 mg tid) for 3 days; IV not available
Lacosamide (Vimpat) Oral and IV formulations available and safe; loading dosages not studied
Lamotrigine (Lamicta)l 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) 1,500 mg oral load; rapid IV loading safe and well tolerated in doses up to 60 mg/kg
Phenytoin (Dilantin) 20 mg/kg divided in maximum doses of 400 mg every 2 h orally, or 18 mg/kg IV at maximum rate of 50 mg/min
Fosphenytoin (Cerebyx) 18 PE/kg IV at maximum rate of 150 PE/min; IM administration possible
Valproate (Depacon) Up to 30 mg/kg IV at max rate of 10 mg/kg/min IV

See Also


  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.