Table 55-3.

Summary of Antiepileptic Drug Therapy in Cats

DRUG	INDICATIONS	ADMINISTRATION	MONITORING	POTENTIAL ADVERSE EFFECTS
Phenobarbital	Identification of a structural lesion Status epilepticus Two or more isolated seizures within a 6-week period The first observed seizure is within a week of head trauma Prolonged, severe, or unusual postictal periods	Initial oral doses 2.5–5 mg/kg PO daily (once or divided q12h) IV loading dose: Total mg IV = (Body weight [kg] × (0.9 L/kg) × (15 mg/ml)	Measure trough serum phenobarbital Therapeutic range is 10–30 mg/mL Evaluate serum chemistry panel at 45 days and every 6 months	Transient: lethargy, behavior change Persistent: polyuria, polydipsia, polyphagia, weight gain, excessive sedation Severe: hepatotoxicity
Potassium bromide	Persistent seizure activity with steady state trough serum phenobarbital concentration >20 mg/mL for at least 1 month Hepatotoxicity from phenobarbital or primary hepatic disease Severe cluster seizures Poor toleration of adverse effects of phenobarbital	Potassium bromide in capsule formulation at 100 mg per capsule Dose: 20–30 mg/kg/day PO with food as initial dose	Measure trough serum concentrations at 21 days, 90 days and every 6 months after initiation Therapeutic range: 100–200 mg/dL (1.0–2.0 mg/mL) with concurrent phenobarbital: >200 mg/dL (2.0 mg/mL) as sole therapy	Lethargy Polydipsia Polyuria Pancreatitis Ataxia Stupor Cough
Diazepam	IV: Generalized cluster epileptic seizures Status epilepticus PO: Maintenance treatment as for phenobarbital therapy	0.5 mg/kg IV 0.5 to 2.0 mg/kg PO q12h or q8h	Plasma nordiazepam concentration can be measured, but rapid elimination half-life makes interpretation difficult Liver enzyme changes should be monitored at 7, 15, 45 days after start and every 6 months to evaluate for hepatotoxicity	Lethargy and sedation Polydipsia Polyuria Polyphagia Weight gain Idiosyncratic hepatotoxicity
Clorazepate	Maintenance treatment as for phenobarbital therapy	3.75 to 7.5 mg PO q6–8h	As for diazepam	As for diazepam

From Podell M: Antiepileptic drug therapy. Clin Tech Small Anim Pract 13:185, 1998.

© 2006

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