Pharmacokinetics and pharmacokinetic/pharmacodynamic integration of danofloxacin in Lohi sheep

Abstract

Background: Danofloxacin is exclusively used in animals worldwide because of its broad antimicrobial spectrum but not still used in Pakistan. The current study aimed to investigate the pharmacokinetic behavior and pharmacokinetic/pharmacodynamic integration of danofloxacin in order to optimize the dosage regimen in indigenous species of sheep (Lohi) under local environment of Pakistan. Methods and materials: Eight, healthy, adult and non-lactating sheep of Lohi breed with a weight of 35–50 kg were selected. Danofloxacin at a dose of 2.5 mg/kg was injected intravenously to each animal. 2 mL of blood was collected at specific time interval. Plasma was separated by centrifugation. In vitro plasma protein binding was determined at different concentrations of danofloxacin (50, 100, 150, 200, 250 μg/mL) in pooled sheep plasma by ultrafiltration method. Danofloxacin concentration was determined by HPLC technique. Different concentrations of danofloxacin (0.5–8 μg/mL) were used to determine in vitro bacterial killing against bacterial isolate of Mannheimia haemolytica WOO221 during 24 h incubation period. A range of danofloxacin dilutions (0.02–16 μg/mL) were employed to determine the MIC90 value against the tested strain of Mannheimia haemolytica WOO221. The sigmoid Emax equation was used to determine the three antibacterial levels of danofloxacin in Lohi sheep. Results: The average unbound drug was 19.2% in plasma of sheep. The distribution half life was (0.21 ± 0.004 h) and Vdarea of 6.41 ± 0.0.94 L/Kg. Total body clearance was 1.15 ± 0.19 L/h/Kg with elimination half life of 0.54 ± 0.27 L/h. Concentration dependent in vitro activity of danofloxacin was observed. Danofloxacin concentration (8 μg/mL) showed the maximum antibacterial activity by decreasing the bacterial count to 2 CFU/mL after 12 h incubation period. The MIC90 of tested strains was calculated as 0.125 μg/mL. Our in vitro results on the tested strains show that a high AUC24/MIC leads of 88 lead to a complete eradication of bacteria in vitro. Whereas AUC24/MIC of 73 and 39 correspond to a bactericidal and bacteriostatic action on the strain tested in vitro. Conclusion: Based upon a first step of investigation of PK/PD parameters, a dose of 10 mg/kg body weight every 24 h time interval can be used for further investigation of an optimal dosage in Lohi sheep.