title: Therapeutic serum phenobarbital concentrations obtained using chronic transdermal administration of phenobarbital in healthy cats.
abstract: Seizures are a common cause of neurologic disease, and phenobarbital (PB) is the most commonly used antiepileptic drug. Chronic oral dosing can be challenging for cat owners, leading to poor compliance. The purpose of this study was to determine if the transdermal administration of PB could achieve serum PB concentrations of between 15 and 45 μg/ml in healthy cats. Nineteen healthy cats were enrolled in three groups. Transdermal PB in pluronic lecithin organogel (PLO) was applied to the pinnae for 14 days at a dosage of 3 mg/kg q12h in group 1 (n = 6 cats) and 9 mg/kg q12h in group 2 (n = 7 cats). Transdermal PB in Lipoderm Activemax was similarly applied at 9 mg/kg q12h for 14 days in group 3 (n = 6 cats). Steady-state serum PB concentrations were measured at trough, and at 2, 4 and 6 h after the morning dose on day 15. In group 1, median concentrations ranged from 6.0-7.5 μg/ml throughout the day (observed range 0-11 μg/ml). Group 2 median concentrations were 26.0 μg/ml (observed range 18.0-37.0 μg/ml). For group 3, median concentrations ranged from 15.0-17.0 μg/ml throughout the day (range 5-29 μg/ml). Side effects were mild. One cat was withdrawn from group 2 owing to ataxia and sedation. These results show therapeutic serum PB concentrations can be achieved in cats following chronic transdermal administration of PB in PLO at a dosage of 9 mg/kg q12h. More individual variation was noted using Lipoderm Activemax. Transdermal administration may be an alternative for cats that are difficult to medicate orally.
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI, USA.
authors.forename: Joy A
authors.initials: JA
authors.lastname: Delamaide Gasper
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI, USA barnesh@vetmed.wisc.edu.
authors.forename: Heidi L
authors.initials: HL
authors.lastname: Barnes Heller
authors.affiliation: UW Veterinary Care Pharmacy, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Robertson
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Trepanier
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D000927:Anticonvulsants / Q000008:administration & dosage* / Q000097:blood; D001682:Biological Availability; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats / Q000097:blood*; D010634:Phenobarbital / Q000008:administration & dosage* / Q000097:blood*; D012640:Seizures / Q000188:drug therapy* / Q000662:veterinary*
chemical_list: D000927:Anticonvulsants; D010634:Phenobarbital
references.citation: Probl Vet Med. 1989 Oct-Dec;1(4):628-49
references.pmid: 2520139
references.citation: J Am Vet Med Assoc. 2008 Nov 15;233(10):1591-7
references.pmid: 19014293
references.citation: Can J Vet Res. 1990 Jan;54(1):132-8
references.pmid: 2306662
references.citation: J Carcinog. 2011;10:12
references.pmid: 21712958
references.citation: Aust Vet J. 2009 Nov;87(11):445-9
references.pmid: 19857237
references.citation: Vet Clin North Am Small Anim Pract. 1996 Jul;26(4):811-25
references.pmid: 8813751
references.citation: Vet Clin North Am Small Anim Pract. 2010 Jan;40(1):161-79
references.pmid: 19942062
references.citation: J Feline Med Surg. 2009 May;11(5):385-94
references.pmid: 19389638
references.citation: J Am Vet Med Assoc. 2014 Jan 15;244(2):195-9
references.pmid: 24378029
references.citation: J Feline Med Surg. 2013 Apr;15(4):267-73
references.pmid: 23090332
references.citation: Can J Vet Res. 1990 Jun;54(3):309-12
references.pmid: 2143097
references.citation: J Vet Intern Med. 2004 Sep-Oct;18(5):651-5
references.pmid: 15515580
references.citation: J Feline Med Surg. 2010 Dec;12(12):910-6
references.pmid: 20822944