Anticonvulsant levels and reloading

Background

Dose

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

Volume of Distribution

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

Desired Level

1. Pt's optimal level = = desired level
   1. If optimal level unknown target upper end of therapeutic range:
      1. Phenytoin = 20 mcg/mL
      2. Valproate = 100 mcg/mL
      3. Phenobarbital = 40 mcg/mL

Treatment

1. IV load can be performed with phenobarbital, phenytoin, valproate, levetiracetam
2. Oral loading can be spread over day or more to avoid GI upset
   1. (e.g. phenytoin PO 400 mg Q4 to reach the final dosage)

See Also

Seizure (Peds)

Febrile Seizure

Dilantin Load

Depakote Loading

Source

DONALDSON 3/08 (from emedicine; Treiman 1997; Bourgeois, 1996)