Journal of veterinary pharmacology and therapeutics

Physicochemical characterization and pharmacokinetics in broiler chickens of a new recrystallized enrofloxacin hydrochloride dihydrate.

PMID 25224691


Enrofloxacin, a key antimicrobial agent in commercial avian medicine, has limited bioavailability (60%). This prompted its chemical manipulation to yield a new solvate-recrystallized enrofloxacin hydrochloride dihydrate entity (enroC ). Its chemical structure was characterized by means of mass spectroscopy, Fourier transformed infrared spectroscopy, X-ray powder diffraction, and thermal analysis. Comparative oral pharmacokinetics (PK) of reference enrofloxacin (enroR ) and enroC in broiler chickens after oral administration revealed noticeable improvements in key parameters and PK/PD ratios. Maximum serum concentration values were 2.61xa0±xa00.21 and 5.9xa0±xa00.42xa0μg/mL for enroR and enroC , respectively; mean residence time was increased from 5.50xa0±xa00.26xa0h to 6.20xa0±xa00.71xa0h and the relative bioavailability of enroC was 336%. Considering Cmax /MIC and AUC/MIC ratios and the MIC values for a wild-type Escherichia coli O78/H12 (0.25xa0μg/mL), optimal ratios will only be achieved by enroC (Cmax /MICxa0=xa023.6 and AUC/MICxa0=xa0197.7 for enroC ; vs. Cmax /MICxa0=xa010.4 and AUC/MICxa0=xa078.1 for enroR ). Furthermore, enroC may provide in most cases mutant prevention concentrations (Cmax /MICxa0≥xa016). Ready solubility of powder enroC in drinking water at concentrations regularly used (0.01%) to provide an additional advantage of enroC in the field. Further development of enroC is warranted before it can be recommended for clinical use in veterinary medicine.