Pharmacokinetics of thiamphenicol in pigs

Maximum levels of cross-contamination for 24 antimicrobial active substances in non-target feed. Part 7: Amphenicols: florfenicol and thiamphenicol

The specific concentrations of florfenicol and thiamphenicol in non-target feed for food-producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield, were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties, are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. The FARSC for florfenicol was estimated. However, due to the lack of data, the calculation of the FARSC for thiamphenicol was not possible until further experimental data become available. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels in feed that showed to have an effect on growth promotion/increased yield were reported for florfenicol, whilst for thiamphenicol no suitable data for the assessment were available. Uncertainties and data gaps associated to the levels reported were addressed. For florfenicol, it was recommended to perform further studies to supply more diverse and complete data related to the requirements for calculation of the FARSC, whereas for thiamphenicol, the recommendation was to generate the data required to fill the gaps which prevented the FARSC calculation.

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.

Capillary electrophoretic determination of thiamphenicol in turkeys serum and its pharmacokinetic application

The pharmacokinetics of thiamphenicol were investigated in 12 healthy turkeys of both sexes, following intravenous (i.v.) and intragastric (p.o.) administration of a single dose of 30 mg/kg body weight (bw). Serum drug concentrations were determined by capillary electrophoresis technique on blood samples collected over 24 h following treatment. The method was statistically validated for its linearity, accuracy, precision and selectivity. The linear range was from 0.2 to 500 microg/ml with correlation coefficients greater than 0.999. The limit of detection of drug was 70 ng/ml, while the quantitative limit was 200 ng/ml, using 0.5 ml sample size. Pharmacokinetic variables of the drug were calculated after both administration routes.