Macgregor, J. M., J. E. Rush, et al. (2008). “Comparison of pharmacodynamic variables following oral versus transdermal administration of atenolol to healthy cats.” Am J Vet Res 69(1): 39-44.
Atenolol is often prescribed for cats with certain types of heart disease, most notably some forms of hypertrophic cardiomyopathy. The drug is typically prescribed as 1/4 of a 25 mg tablet every 12 hours. Long term daily administration of oral medication may be very difficult for some owners to achieve. In recent years, there has been great interest in transdermal formulations of medication for cats. Few studies have reported on the efficacy of transdermal gel medications for cats, and of those that have been published the results are not always promising. In this project, atenolol was administered to 7 healthy cats, either orally or as a transdermal gel. Blood levels of atenolol were tested to determine efficacy of the route of administration. The difference between the two routes of administration was significant, with transdermal atenolol providing lower and inconsistent blood levels compared to oral administration.
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Lecuyer, M., S. Prini, et al. (2006). “Clinical efficacy and safety of transdermal methimazole in the treatment of feline hyperthyroidism.” Can Vet J 47(2): 131-5.