The influence of the site of drug administration on florfenicol pharmacokinetics in turkeys

Florfenicol is a broad-spectrum antibacterial drug used in the treatment of farm animals, including poultry. This drug is poorly soluble in water, therefore, administration in drinking water may lead to high variability of concentrations in treated individuals. The use of injection preparations, however, requires individual administration and may have a negative effect on the quality of the carcass. In addition, the renal portal system in birds may reduce the bioavailability of the drug administered in the caudofemoral region of the body. The aim of this study was to compare the pharmacokinetics of florfenicol in turkeys after a single intravenous, intramuscular, and subcutaneous administration at a dose of 15 mg/kg body weight. Additionally, to evaluate the effect of renal portal system on drug kinetics, the intramuscular administration was divided into pectoral and caudofemoral administration. The study showed that the area under the concentration-time curve (AUC) was similar regardless of the route of administration. The mean values for clearance and volume of distribution were 0.33 L/kg/h and 0.92 L/kg, respectively. The mean residence time (MRT) was 2.87 h for an intravenous bolus, while for the extravascular administrations it was approx. 5.5 h. The elimination half-life was approx. 4 h regardless of the route of administration. The maximum plasma concentration did not differ statistically between intramuscular (approx. 6.8 mg/L) and subcutaneous (8.2 mg/L) administrations, while the time to appear for this concentration was the longest for caudofemoral administration (1.5 h). The bioavailability was 88.64% for subcutaneous administration, 77.95% for pectoral administration and 85.30% for caudofemoral administration. Overall, all 3 routes of extravascular administration allowed for efficient drug absorption. There was no evidence of an influence of the renal portal system on the kinetic parameters of the drug administered to the lower extremities of the body.

Pharmacokinetics of florfenicol and thiamphenicol after single oral and intravenous, as well as multiple oral administrations to geese

1. This study evaluated the pharmacokinetic profiles of florfenicol (FF) and thiamphenicol (TP), which are synthetic bacteriostatic antimicrobial drugs, in geese after a single intravenous or oral administration, as well as seven oral doses administered at 12 h intervals. For all treatments, the dose was 30 mg/kg. 2. After single IV administration, clearance and volume of distribution were low (0.23 ± 0.03 l/h/kg and 0.57 ± 0.08 l/kg for FF, and 0.23 ± 0.04 l/h/kg and 0.59 ± 0.08 l/kg for TP, respectively). The elimination half-life was similar between products and short (2.91 ± 0.41 and 2.84 ± 0.64 h for FF and TP, respectively). 3. The single oral administration resulted in efficient absorption (bioavailability of 83.15 ± 11.48 for FF and 75.21 ± 19.56% for TP) with high maximal concentrations of 30.47 ± 2.47 and 20.02 ± 3.87 μg/ml for FF and TP, respectively. The area under the curve was 108.36 ± 14.96 and 101.81 ± 26.48 mg×h/l for FF and TP, respectively. 4. For both drugs, the two latter parameters were found to be higher compared to earlier studies on terrestrial birds. This suggested that FF and TP may be efficient in treating infections in geese caused by certain bacteria sensitive to chloramphenicol. 5. Neither drug accumulated in tissues following the oral seven doses and no adverse effects were noted in any treated animals. Thus, the selected FF and TP dosage may be considered as a safe treatment for geese.

Pharmacokinetics of florfenicol, thiamphenicol, and chloramphenicol in turkeys

The pharmacokinetics of florfenicol (FF), thiamphenicol (TP) and chloramphenicol (CP) after single intravenous (i.v.) or oral (p.o.) administration was studied in an independent cross-over study in broiler turkeys. All the fenicol antibiotics were administered at a dose of 30 mg/kg b.w. and their concentrations in plasma samples were assayed using the same validated high-performance liquid chromatography method. Pharmacokinetic parameters were calculated by a noncompartmental method. The kinetic profiles of the compounds were compared with the results of the structure-activity relationship. According to the proposed mathematical description, no differences in plasma clearance values for the studied antibiotics were observed. The mean residence time values of FF, TF, and CP after i.v. injection were 3.37+/-0.63, 2.43+/-0.29, and 2.12+/-0.21 h, respectively. The mean values of Varea for FF (1.39+/-0.31 L/kg) and TP (1.31+/-0.19 L/kg) were similar, but significantly different from that of CP (1.04+/-0.12 L/kg). The bioavailabilities of FF, TP, and CP after oral administration were 82%, 69%, and 45%, respectively. Differences in the bioavailability values of the compared fenicol antibiotics correspond to the ratio of the apolar/polar surface areas of their particles.