Pharmacokinetics of famciclovir and penciclovir in tears following oral administration of famciclovir to cats: A pilot study

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14 Scopus citations

Abstract

Objective To validate a means of collecting tears from cats, develop an assay for quantifying famciclovir and penciclovir in tears, and to assess famciclovir and penciclovir concentrations and pharmacokinetics in the tears of cats being treated orally with famciclovir for suspected herpetic disease. Animals Seven client-owned cats. Procedures Cats were treated orally with a median (range) dose of 40 (39-72)mg of famciclovir/kg three times daily for at least 24h. At various time points following famciclovir administration, tear samples were collected using Schirmer tear test strips. Tear famciclovir and penciclovir concentrations were measured using liquid chromatography-mass spectrometry, and concentration-time profiles were analyzed noncompartmentally. The relationship between famciclovir dose and tear penciclovir concentration near its maximum was evaluated using least squares linear regression. Results Maximum tear famciclovir concentration of 0.305μg/mL occurred at 2.64h; elimination half-life was 2.28h. Maximum tear penciclovir concentration (0.981μg/mL) occurred 2.25h following oral administration of famciclovir; elimination half-life was 2.77h. A significant positive correlation was noted between famciclovir dose and tear penciclovir concentration at various time points between 0.5 and 3.75h following drug administration (P=0.025). Tear penciclovir concentration exceeded the concentration shown to have in vitro efficacy against feline herpesvirus (FHV-1) (0.304μg/mL) in about half of samples collected. Conclusions Oral administration of 40mg of famciclovir/kg to cats resulted in a tear penciclovir concentration-time profile that approximated the plasma penciclovir concentration-time profile and frequently achieved a penciclovir concentration at the ocular surface likely to be effective against FHV-1.

Original languageEnglish (US)
Pages (from-to)299-306
Number of pages8
JournalVeterinary Ophthalmology
Volume15
Issue number5
DOIs
StatePublished - Sep 2012

Keywords

  • Antiviral drugs
  • Feline
  • Feline herpesvirus-1
  • FHV-1
  • Herpesvirus
  • Pharmacology
  • Tear film

ASJC Scopus subject areas

  • veterinary(all)

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