Levetiracetam (Keppra®)

• Dosing
  1. Starting dose is 20 mg/kg q 8 h.
  2. Can increase in 20 mg/kg increments q 2 wk.
  3. Therapeutic range is listed at 5-45 µg/mL.
  4. Has been used in cats at same dose; but small numbers and no long term studies.
  
  
• Side effects
  1. Few side effects reported: ataxia.
  
  
• Pharmacokinetics
  Short half life (~3 to 4 h).
  Undergoes minimal hepatic metabolism; mostly excreted in urine.

• Drugs of choice are benzodiazepines.
  1. Valium
  1. 0.5-2.0 mg/kg IV
  2. Often dosed empirically; 5–10–15 mg for small, medium, and large dogs, respectively.
  3. If 3 doses do not stop seizures, go to constant rate infusion (CRI) at dose of 0.1 to 0.5 mg/kg (rate administered per hour is equal to maintenance fluid requirement).
  4. For CRI, mix with saline or 2.5 % dextrose (calcium may precipitate valium, so do not use with Lactated Ringer's Solution).
  5. Rectal dose is same as IV dose; but dogs already on Pb will likely need 2.0 mg/kg. As rectal valium has a short anti-seizure effect (1/2–1 h), giving oral valium about 1/2 h later at 1 mg /kg lengthens the effect for up to 2h. If breakthrough seizures occur, the protocol can be repeated up to 3 times in 24 h.
  6. Nasal dose is 0.5 mg/kg.
  7. Valium adheres to plastic so dispense required dose in glass bottle.
     
  2. Lorazepam
  1. Longer acting; may prevent seizures for several hours.
  2. More expensive.
  3. Dose is 0.05–0.2 mg/kg IV.
  4. Ineffective when given rectally due to extensive first pass effect.
     
  3. Midazolam
  1. 0.2 mg/kg IV or IM.
  2. Not absorbed rectally.
  
  
• Other Choices
  1. Propofol
  1. Administer as a single IV dose or CRI.
  2. Dose
     1-8 mg/kg IV.
     Give 1/4 of calculated dose over 30s; give next 1/4 over the next 30s; until seizures are controlled.
     Effects are short-lived.
  3. CRI dose is 0.1-0.6 mg/kg/min. Use only with definitive airway control and hemodynamic support, and in situations where patient can be closely monitored.
  4. Must monitor for respiratory depression, as is barbiturate drug.
     
  2. Phenobarbital
  1. For longer term control; will control seizures for 6-12 h.
  2. Dose
     10-20 mg/kg q 4-6 h IV slowly or IM.
     Start at low end of dose range.
     Administer 3-4 doses to achieve therapeutic blood levels.
     Must monitor closely for respiratory depression.
     Begin injectable Pb under any of the following circumstances:
     1) the dog has a history of previous seizure activity.
     2) has been on Pb to control epilepsy prior to status epilepticus.
     3) if seizures are not controlled with 3 doses of injectable diazepam.
     
  3. Sodium pentobarbital
  1. Dose
     3-15 mg/kg IV slowly and to effect; amount will depend on previous drugs given as well as consciousness of the animal.
  2. Watch for respiratory depression. If necessary, use endotracheal tube.
  3. May need to repeat in 4-8 h or use as CRI at 2-5 mg/kg/h.
  4. Disadvantage of rough recoveries that can be difficult to differentiate from recurrent seizures.
  5. Get onto oral meds as soon as pet can swallow.
  
  

Contributed by Linda Shell, DVM, Dip. ACVIM (Neurology)