Objective—To determine whether therapeutic concentrations of levetiracetam can be achieved in cats and to establish reasonable IV and oral dosing intervals that would not be associated with adverse effects in cats.
Animals—10 healthy purpose-bred cats.
Procedures—In a randomized crossover study, levetiracetam (20 mg/kg) was administered orally and IV to each cat. Blood samples were collected 0, 10, 20, and 40 minutes and 1, 1.5, 2, 3, 4, 6, 9, 12, and 24 hours after administration. Plasma levetiracetam concentrations were determined via high-performance liquid chromatography.
Results—Mean ± SD peak concentration was 25.54 ± 7.97 μg/mL. The mean y-intercept for IV administration was 37.52 ± 6.79 μg/mL. Half-life (harmonic mean ± pseudo-SD) was 2.95 ± 0.95 hours and 2.86 ± 0.65 hours for oral and IV administration, respectively. Mean volume of distribution at steady state was 0.52 ± 0.09 L/kg, and mean clearance was 2.0 ± 0.60 mL/kg/min. Mean oral bioavailability was 102 ± 39%. Plasma drug concentrations were maintained in the therapeutic range reported for humans (5 to 45 μg/mL) for at least 9 hours after administration in 7 of 10 cats. Only mild, transient hypersalivation was evident in some cats after oral administration.
Conclusions and Clinical Relevance—Levetiracetam (20 mg/kg) administered orally or IV to cats every 8 hours should achieve and maintain concentrations within the therapeutic range for humans. Levetiracetam administration has favorable pharmacokinetics for clinical use, was apparently tolerated well, and may be a reasonable alternative antiepileptic drug in cats.