Comparative bioavailability of enrofloxacin in dogs when concealed in noncommercial morsels, either as tablet or as enrofloxacin–alginate dried beads

Abstract

Administration of enrofloxacin tablets concealed in improvised morsels to elude the unpleasant flavor of this drug is likely to diminish maximum plasma concentrations (Cmax ) reached by this drug, jeopardizing treatment efficacy. To avoid this, the hypothesis that alginate dried beads containing enrofloxacin (ADBE) could modify the pharmacokinetics of enrofloxacin in dogs was tested. ADBE were manufactured and pharmaceutically defined as having high entrapment efficiency (>90%) and a drug loading capacity of 56%-67%. Based on the hydrophilic nature of alginate and its interaction with the anionic charge of the amino groups of enrofloxacin, a novel modified release system was obtained in which ADBE give place to both a rapid diffusion releasing of enrofloxacin and a maintained release. The ADBE concealed in a sausage (ADBEs) achieved both the highest Cmax (5.1µg/ml±0.3 SD) and the area under the concentration versus time (AUC0-24 ) (41.2µghr-1 ml-1 ±6.9 SD). The tablet administered alone had a Cmax of 1.9µg/ml±0.3 SD and an AUC0-24 =16.5µgh-1 ml-1 ±3.5 SD, while the tablet concealed in a sausage reached a Cmax of 1.2µg/ml±0.3 SD with an AUC0-24 =12.3µghr-1 ml-1 ±3.8 SD (p<.05 in both cases when confronting ADBEs vs. tablets). Consequently, Cmax /MIC and AUC0-24 /MIC ratios are higher for ADBEs. Other PK parameters were statistically indistinguishable, and other morsels containing enrofloxacin as a tablet or as ADBE rendered less favorable PK parameters. Due to ease of administration and favorable PK for ADBE concealed in a sausage, this pharmaceutical design can be regarded as PK/PD consistent and worthy of clinical studies.