Anti-convulsants used in treating status epilepticus

Medication Doses Kinetics Complications Comments
Phenytoin 15-20 mg/kg


Maintenance level >20

µg/mL
Effect in 10-30 min

Peak effect in 1 h

Elimination half-life 24-48 h
Cardiac arrhythmias

Hypotension
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

Hypotension
Can be administered IM
Phenobarbital 10-20 mg/kg
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
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) 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

Hypotension

Hypothermia
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 (www.elsevier.com).

Authored by: Frank W Drislane MD
Reviewed by: Thaddeus Walczak MD on 1/2004