Anti-convulsants used in treating status epilepticus

Medication Doses Kinetics Complications Comments
Phenytoin 15-20 mg/kg
<50 mg/min
Maintenance level >20
Effect in 10-30 min
Peak effect in 1 h
Elimination half-life 24-48 h
Cardiac arrhythmias
Bolus lasts
6-24 h
Best in following level of consciousness
Worse for cardiac disease
Fosphenytoin 15-20 mg PE/kg 150 mg PE/min Peak effect in 10 min (IV)
Peak effect in 30min (IM)
Elimination half-life 24-48 h
Cardiac arrhythmias
Can be administered IM
Phenobarbital 10-20 mg/kg<100 mg/min
Maintenance level >40 µg/mL
Effect in 5-20 min
Peak in 1 h
Elimination half-life 120 h
Respiratory depression, hypotension (possible synergy with benzodiazepines) Slower than benzodiazepines
Depression of consciousness can be prolonged after loading
Valproic acid 25 mg/kg or higher, up to 100 mg/min
Maintenance level >100 µg/mL
Peak effect in 15 min
Elimination half-life 24 h
Multiple interactions with other anticonvulsants (phenytoin, phenobarbital, lamotrigine) No respiratory depression, arrhythmia or cardiac depression
Diazepam 10 mg (0.25 mg/kg)
Repeat q15 min;up to ? 40 mg<5 mg/min
Effect in 1-2 min
Peak in 20-30 min
Metabolite half-life 36 h
Sedation, respiratory depression, hypotension
Recurrent symptoms as it wears off
Very rapid interruption of convulsions
Needs to be followed by maintenance anti-convulsants
Lorazepam 4-8 mg (0.1-0.2 mg/kg)<2 mg/min Effect in 2-5 minPeak in 15-30 min
Elimination half-life 12-15 h
Same as diazepam; less sudden More prolonged protection (up to 12 h) against seizure recurrence
No active toxic metabolites
Pentobarbital Load 3-5 mg/kg
Maintenance. 1-4 mg/kg/h
Effect in minutes
Elim-ination half-life 20-40 h
Respiratory depression
Uniformly effective
High mortality due to underlying disease
Duration of treatment unknown (? 24-48 h)

PE = phenytoin equivalent

Adapted from: Drislane FW. Status epilepticus. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 149-172. With permission from Elsevier (

Authored By: 
Frank W. Drislane MD
Reviewed By: 
Thaddeus Walczak MD
Wednesday, December 31, 2003