Transdermal levetiracetam can be a viable alternative to other forms of anticonvulsant medication for cats with seizures.
Medicating cats regularly for chronic diseases can be very difficult for owners and stressful for pets. For cats with seizures, there may be a better option. A recent study from the University of Wisconsin-Madison College of Veterinary Medicine evaluated the pharmacokinetics of transdermal administration of levetiracetam to healthy cats, and the results show blood concentrations sufficient to warrant clinical usein veterinary patients.
Six healthy cats were enrolled in the study. Levetiracetam was compounded into a 400-mg/mL lipophilic liposomal cream by the University of Wisconsin-Madison Veterinary Pharmacy Hospital. The transdermal dose protocol was 60 mg/kg every 8 hours. Using a gloved finger, the experimenter applied the cream to one or both pinnae and rubbed into the pinnae until the gel was no longer visible. Serum levetiracetam concentrations were measured on day 7 of this dosing regimen, at times 0 (prior to dosing), 0.5, 1, 2, 3 and 4 hours post-dosing.
All six cats completed the study. Median serum concentrations for all six cats at all time points ranged from 14.8 to 17.4 µg/mL. The lowest serum concentration was 6.8 µg/mL and the highest was 39.6 µg/mL. All of these concentrations are higher than the 5-µg/mL lower limit of the human therapeutic range (therapeutic ranges for levetiracetam in cats are not known). Adverse effects were minimal and included sedation in one cat that resolved without dose adjustment and mild crusting on the pinnae of one cat.
Although the small sample size limits reliable extrapolation, based on serum concentrations in this study, transdermal levetiracetam has appropriate pharmacokinetic profiles to warrant clinical use in cats with seizures. Adverse effects were minimal. Drawbacks to transdermal administration primarily include the increased cost ($227 for a 14-day supply for a 4.5-kg cat) and difficulty of administering the medication to cats weighing more than 5 kg due to the volume of cream required for dosing.
Smith C, Barnes-Heller HL, Reif N, et al. Serum levetiracetam concentrations after transdermal levetiracetam administration, 3 times daily, to healthy cats. J Vet Intern Med 2019;33:827-830. Link to article: https://europepmc.org/articles/pmc6430925
Dr. Packer is an associate professor of neurology/neurosurgery at Colorado State University College of Veterinary Medicine and Biomedical Sciences in Fort Collins. She is active in clinical and didactic training of veterinary students and residents and has developed a comparative neuro-oncology research program at Colorado State University.