Pharmacokinetics of enrofloxacin in neonatal kittens

Authors:
  • KSKelly J. Sigle
    Kelly J. Sigle
  • NGNicole M. Gibson
    Nicole M. Gibson
  • JLJulie K. Levy
    Julie K. Levy
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Abstract
Objective—To determine the pharmacokinetics of enrofloxacin in neonatal kittens and compare the pharmacokinetics of enrofloxacin in young and adult cats.Animals—7 adult cats and 111 kittens (2 to 8 weeks old).Procedure—A single dose of 5 mg of enrofloxacin/kg was administered to adults (IV) and kittens (IV, SC, or PO). Plasma concentrations of enrofloxacin and its active metabolite, ciprofloxacin, were determined.Results—The half-life of enrofloxacin administered IV in 2-, 6-, and 8-week-old kittens was significantly shorter and its elimination rate significantly greater than that detected in adults. The apparent volumes of distribution were lower at 2 to 4 weeks and greater at 6 to 8 weeks. This resulted in lower peak plasma concentration (Cmax) at 6 to 8 weeks; however, initial plasma concentration was within the therapeutic range after IV administration at all ages. Compared with IV administration, SC injection of enrofloxacin in 2-weekold kittens resulted in similar Cmax, half-life, clearance, and area under the curve values. Enrofloxacin administered via SC injection was well absorbed in 6- and 8- week-old kittens, but greater clearance and apparent volume of distribution resulted in lower plasma concentrations. Oral administration of enrofloxacin resulted in poor bioavailability.Conclusions and Clinical Relevance—In neonatal kittens, IV and SC administration of enrofloxacin provided an effective route of administration. Oral administration of enrofloxacin in kittens did not result in therapeutic drug concentrations. Doses may need to be increased to achieve therapeutic drug concentrations in 6- to 8-week-old kittens. (Am J Vet Res2004;65:350–356)

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