title: Evaluation of persistence of terbinafine in the hair of normal cats after 14 days of daily therapy.
abstract: This study determined the residual concentration of terbinafine in cat hair after 14 days of oral treatment. Ten clinically normal cats were administered terbinafine orally at a daily dose of 34-45.7 mg kg(-1) for a total of 14 days. Areas of 15 cm(2) were shaved on the lateral thorax at day 0 and weekly for 8 weeks after the last dose of terbinafine. The hair samples were analysed by high-pressure liquid chromatography to determine the persistence of terbinafine over time. The mean terbinafine concentration in hair was 2.30 ng mg(-1) after 14 days of therapy. The half life was 1.84 weeks after the last dose of terbinafine. With a 99% confidence interval, the concentration of terbinafine remained in the cat hair at or above 0.03 ng mg(-1) (minimal inhibitory concentration (MIC)(90) = 0.03 microg mL(-1)) for 5.3 weeks. Slight deviations in the complete blood cell count and serum chemistry values were not attributed to terbinafine. Four cats experienced vomiting during the terbinafine treatment; two of these cats also experienced intense facial pruritus followed by a macular to papular skin reaction 7-14 days after the discontinuation of terbinafine. In summary, terbinafine persists in hair at concentrations above the MIC for several weeks after stopping medication, even after short-term therapy (14 days). These results suggest that pulse therapy of terbinafine should be further researched and potentially considered as a treatment modality for feline dermatophytosis, an approach that would decrease treatment duration while maintaining effectiveness.
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA. Fousta@mail.vetmed.ufl.edu
authors.forename: Abby L
authors.initials: AL
authors.lastname: Foust
authors.forename: Rosanna
authors.initials: R
authors.lastname: Marsella
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Akucewich
authors.forename: Gail
authors.initials: G
authors.lastname: Kunkle
authors.forename: Amy
authors.initials: A
authors.lastname: Stern
authors.forename: Syamak
authors.initials: S
authors.lastname: Moattari
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Szabo
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000935:Antifungal Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D002415:Cats / Q000378:metabolism*; D004334:Drug Administration Schedule; D005260:Female; D006197:Hair / Q000378:metabolism*; D008297:Male; D009281:Naphthalenes / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D000077291:Terbinafine
chemical_list: D000935:Antifungal Agents; D009281:Naphthalenes; D000077291:Terbinafine