Pharmacokinetics of danofloxacin in African catfish (Clarias gariepinus) after intravenous and intramuscular administrations

Pharmacokinetics of danofloxacin after single oral and intravenous administration in non-laying hens

The current study aimed to explore the pharmacokinetics of danofloxacin in non-laying hens after a single oral (PO) and intravenous (IV) dose, both at 5 mg/kg body weight (BW). Eighteen 13-week-old healthy hens were equally and randomly divided into two groups. After both doses, blood samples (approximately 1 ml) were collected at different time points. Danofloxacin concentrations were quantified by a validated high-performance liquid chromatography (HPLC) method followed by a non-compartmental analysis using the software of WinNonLin. The elimination half-lives (t_1/2λz s) after PO and IV routes were determined as 8.15 ± 3.37 and 7.69 ± 3.40 h, respectively. After IV administration, danofloxacin had an initial concentration (C₀ ) of 3.62 μg/ml, a volume of distribution at steady state (V_SS ) of 3579.72 ± 454.29 ml/kg, and a total body clearance (Cl) of 0.49 ml/h/g. After PO administration, the absolute bioavailability and absorption half-life (t_1/2ka ) were calculated as 100.99% ± 23.10% and 0.82 ± 0.58 h, respectively. Based on the calculated ratio values of AUC/MIC and C_max /MIC, an oral dose of 5 mg/kg danofloxacin would be expected to successfully treat hens infected with strains with MIC values ≤0.1 μg/ml.

Population Pharmacokinetics of Danofloxacin in Yellow River Carp (Cyprinus carpio haematopterus) After One Single Oral Dose

This study aimed to determine the population pharmacokinetics of danofloxacin in healthy Yellow River carp (Cyprinus carpio Haematopterus) after single oral administration at 10 mg/kg body weight (BW). A sparse sampling was applied in this study and plasma samples were randomly collected from the tail veins of six carp at 0.25, 0.5, 1, 2, 4, 6, 8, 12, 16, 24, 36, 48, 72, 96, 120 and 144 h after administration. A maximum of four plasma samples was collected from each carp. Then the concentrations of danofloxacin in plasma samples were determined through an HPLC method. Danofloxacin could be quantified in plasma up to 144 h after administration. The corresponding population pharmacokinetic modeling was developed according to the non-linear mixed effect method, including covariate and covariance models to explain some variations from unknown sources and improve the prediction ability. On the premise of sparse sampling, the typical values of the population (fixed effect) and inter-individual variation (random effect) were described by the current population pharmacokinetic model. The estimated typical values and coefficient of variation between individuals (CV%) of absorption rate constant (tvKa), apparent distribution volume (tvV) and clearance (tvCL) were 2.48 h⁻¹ and 0.203%, 47.8 L/kg and 8.40%, 0.694 L/h/kg and 4.35%, respectively. The current danofloxacin oral dosing (10 mg/kg BW) can provide suitable plasma concentrations to inhibit those pathogens with MIC values below 0.016 μg/ml based on the calculated PK/PD indices of AUC/MIC or C_max/MIC. Further studies are still needed to determine the in vitro and in vivo antibacterial efficacy of danofloxacin against pathogens isolated from Yellow River carp and finally draw a reasonable dosing regimen.