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  • Author or Editor: Eden C. Bermingham x
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Abstract

Objective—To compare pharmacokinetics of enrofloxacin administered IV and in various oral preparations to ewes.

Animals—5 mature Katahdin ewes weighing 42 to 50 kg.

Procedure—Ewes received 4 single-dose treatments of enrofloxacin in a nonrandomized crossover design followed by a multiple-dose oral regimen. Single-dose treatments consisted of an IV bolus of enrofloxacin (5 mg/kg), an oral drench (10 mg/kg) made from crushed enrofloxacin tablets, oral administration in feed (10 mg/kg; mixture of crushed enrofloxacin tablets and grain), and another type of oral administration in feed (10 mg/kg; mixture of enrofloxacin solution and grain). The multiple-dose regimen consisted of feeding a mixture of enrofloxacin solution and grain (10 mg/kg, q 24 h, for 7 days). Plasma concentrations of enrofloxacin and ciprofloxacin were measured by use of high-performance liquid chromatography.

Results—Harmonic mean half-life for oral administration was 14.80, 10.80, and 13.07 hours, respectively, for the oral drench, crushed tablets in grain, and enrofloxacin solution in grain. Oral bioavailability for the oral drench, crushed tablets in grain, and enrofloxacin in grain was 47.89, 98.07, and 94.60%, respectively, and median maximum concentration (Cmax) was 1.61, 2.69, and 2.26 µg/ml, respectively. Median Cmax of the multiple-dose regimen was 2.99 µg/ml.

Conclusions and Clinical Relevance—Enrofloxacin administered orally to sheep has a prolonged half-life and high oral bioavailability. Oral administration at 10 mg/kg, q 24 h, was sufficient to achieve a plasma concentration of 8 to 10 times the minimum inhibitory concentration (MIC) of any microorganism with an MIC ≤ 0.29 µg/ml. (Am J Vet Res 2002; 63:1012–1017)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the pharmacokinetics of enrofloxacin administered IV and orally to foals.

Animals—5 clinically normal foals.

Procedure—A 2-dose cross-over trial with IV and oral administration was performed. Enrofloxacin was administered once IV (5 mg/kg of body weight) to 1-week-old foals, followed by 1 oral administration (10 mg/kg) after a 7-day washout period. Blood samples were collected for 48 hours after the single dose IV and oral administrations and analyzed for plasma enrofloxacin and ciprofloxacin concentrations by use of high-performance liquid chromatography.

Results—For IV administration, mean ± SD total area under the curve (AUC0-∞) was 48.54 ± 10.46 µg · h/ml, clearance was 103.72 ± 0.06 ml/kg/h, halflife (t1/2β) was 17.10 ± 0.09 hours, and apparent volume of distribution was 2.49 ± 0.43 L/kg. For oral administration, AUC0-∞ was 58.47 ± 16.37 µg · h/ml, t1/2β was 18.39 ± 0.06 hours, maximum concentration (Cmax) was 2.12 ± 00.51 µg/ml, time to Cmax was 2.20 ± 2.17 hours, mean absorption time was 2.09 ± 0.51 hours, and bioavailability was 42 ± 0.42%.

Conclusions and Clinical Relevance—Compared with adult horses given 5 mg of enrofloxacin/kg IV, foals have higher AUC0-∞, longer t1/2β, and lower clearance. Concentration of ciprofloxacin was negligible. Using a target Cmax to minimum inhibitory concentration ratio of 1:8 to 1:10, computer modeling suggests that 2.5 to 10 mg of enrofloxacin/kg administered every 24 hours would be effective in foals, depending on minimum inhibitory concentration of the pathogen. (Am J Vet Res 2000;61: 706–709)

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in American Journal of Veterinary Research