Evaluation of a Tasteless Enrofloxacin Pharmaceutical Preparation for Cats. Naive Pooled-Sample Approach to Study Its Pharmacokinetics

SIMPLE SUMMARY: Enrofloxacin has low oral bioavailability in cats. Additionally, its unpleasant taste is linked to profuse salivation and vomiting, and the cat’s refusal to accept the following dose. In this trial, the pharmacokinetics (PK) of a new pharmaceutical preparation of enrofloxacin-alginate dried beads (DABE) is presented. It eliminates the unpleasant responses of cats to standard oral enrofloxacin. Its PK was carried out under a naive pooled sampling model. PK of DABEs (10 mg/kg/day) concealed in the cat’s food or morsels, complies well with the PK/pharmacodynamics ratios required for most pathogens, i.e., Cmax/CMI > 10. No rejection of DABEs was observed. The retinopathy associated with enrofloxacin appears to be dose-dependent. However, the reported Cmax values observed after the SC administration of 5 mg/kg/day, are notoriously similar to the obtained Cmax value obtained for DABEs (2.3 µg/mL). Hence the higher dose utilized PO is likely to result in similar toxicity as the dose utilized after parenteral administration, with the added benefit of an effortless drug administration and lack of tissue reactions in the injection site. ABSTRACT: Available pharmaceutical preparations of enrofloxacin injected SC or IM to cats are likely to cause adverse tissue reactions in the injection sites (pH of the drug preparations is ≥10.4). Tablets often induce abundant ptyalism and vomiting, casting doubt on the efficacy of the drug administration maneuver. In addition, the reported oral bioavailability is very low. In this trial, the oral pharmacokinetics of dried alginate beads of enrofloxacin (DABE) administered by concealing them in the cat’s moist food or morsels, is described. A naïve polled sampling approach was chosen with fourteen adult healthy cats. Neither their housing nor their feeding habits were altered. A single pharmacokinetic profile was obtained with 5 samples per designated bleeding time, sampling each cat 2–3 times only. None of the cats rejected their medicated food or morsels. Plasma profile of enrofloxacin exhibited an AUC(0–24) value of 12.4 µg·h/mL and an AUC(0–∞) value of 19.2 µg·h/mL, which are comparatively greater than values previously referred for kittens. In contrast, λ and elimination t½ were almost identical (0.12 1/h and 6.1 h). Pharmacokinetics/pharmacodynamics ratios taking the breakpoint of Staphylococcus epidermidis as a surrogate (0.5 µg/mL), can be regarded as borderline or low, but perhaps adequate in cats, as higher concentrations may be linked to toxicity (AUC(0–24)/MIC = 24.8; Cmax/MIC = 4.6).