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. 2025 Jan;26(1):e7.
doi: 10.4142/jvs.24161. Epub 2024 Nov 23.

Evaluation of different PK/PD ratios of three enrofloxacin preparations on the clinical response of pneumonic calves

Lilia Gutiérrez #  1 , Isela Mejía-Arthur #  2 , Eduardo Posadas-Manzano  2 , Noe Rodríguez-Becerril  2 , Reyes López-Ordaz #  3 , Héctor Sumano #  4
Affiliations

Evaluation of different PK/PD ratios of three enrofloxacin preparations on the clinical response of pneumonic calves

Lilia Gutiérrez et al. J Vet Sci. 2025 Jan.

Abstract

Importance: Enrofloxacin preparations are available for administration daily or every 3 days. This study presents clinical evidence to define which preparation is adequate to treat clinical cases of bovine respiratory disease (BRD) in calves.

Objective: To correlate the pharmacokinetics/pharmacodynamics (PK/PD) ratios of three pharmaceutical preparations of enrofloxacin with their clinical efficacy in treating BRD.

Methods: The PK/PD ratios of three enrofloxacin preparations were determined in healthy calves. Then, 48 BRD-affected calves initially treated IV with 2.2 mg/kg of flunixin-meglumine, were randomly assigned to treatment with: enrofloxacin dihydrate-hydrochloride (enro-C) 10% water suspension daily (10 mg/kg subcutaneous for three to six days); enro-C with alginate (enro-C/Al), and reference enrofloxacin (enro-R), both intended for treatment every 72-h in two occasions (10 mg/kg).

Results: The highest maximum plasma concentration (Cmax)/minimum inhibitory concentration (MIC) ratio was obtained with enro-C and the highest area under the curve (AUC)0-72/MIC ratio with enro-R, and enro-C/Al exhibited an AUC0-72/MIC smaller, but Cmax/MIC higher than enro-R. Based on repeated statistical measurements, clinical progress revealed that the best outcomes were observed with enro-C (p < 0.05), and no statistical differences resulted by comparing enro-C/Al with enro-R.

Conclusions and relevance: If the priority in calves affected by BRD is to speed up their recovery, and despite the more significant amount enro-C injected, using of lower doses of enrofloxacin as in the long-acting preparations is unsustainable. This study demonstrates that the clinical efficacy of enrofloxacin in cattle is optimally linked to Cmax/MIC rather than to AUC/MIC, which occurs better when injecting enro-C.

Keywords: Calves; PK/PD-ratios; bovine-respiratory disease; clinical efficacy; enrofloxacin.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Fig. 1
Fig. 1. FLIR images in which body temperature can be measured with a sensitivity of < 0.06°C.
Fig. 2
Fig. 2. Log10 versus time mean serum concentration of enro-C, enro-C/Al, and reference enrofloxacin (enro-R from Baytril Max; Elanco Animal Health) in calves after the S.C. injection of 10 mg/kg in all three cases. The injected volume was divided into equal parts on either side of the neck.
S.C., subcutaneous.
Fig. 3
Fig. 3. The sum of means of clinical signs in time in calves with bovine respiratory complex disease (severity graded 3), and treated with one of the following preparations of enrofloxacin: as enro-C water suspension injected daily; enro-C in 1% alginate injected every 72 h, and enro-R, the reference Baytril Max (Elanco Animal Health) injected every 72 h. All doses were S.C. injected, dividing the 10 mg/kg dose by either side of the neck region. Three evolution gradings are marked as detailed in Table 1.
S.C., subcutaneous.
See this image and copyright information in PMC

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