Florfenicol Residues in Nile Tilapia after 10‐d Oral Dosing in Feed: Effect of Fish Size

Abstract

Nile tilapia Oreochromis niloticus were medicated with florfenicol (AQUAFLOR type A medicated article; Schering-Plough Animal Health, Summit, New Jersey) via a medicated ration at 15 mg florfenicol x kg fish body weight(-1) d(-1) for 10 d to compare the elimination kinetics of the test article in different size fish held at 25 degrees C. The groups of fish used in the study had mean weights of approximately 100, 250, and 500 g. In each trial, the fish were provided the medicated ration and 15 fish were processed at each of seven time points postfeeding for determination of the florfenicol concentration in serum and the florfenicol residue in the edible portion (composite muscle and skin). There was a trend toward shorter half-lives of elimination in the smaller fish. The elimination times in muscle-skin (times to reach the established tolerance concentration for channel catfish Ictalurus punctatus and salmonids of 1.0 microg florfenicol residue/g) and half-lives were 9.2 and 1.2 d (100 g), 8.6 and 1.7 d (250 g), and 12.7 and 2.2 d (500 g), respectively.

Pharmacokinetic Study of Florfenicol in Healthy and Vibriosis-infectedPseudosciaena croceaafter Oral Administration

“…This is probably because the liver has digestive and metabolic functions and therefore, the drug enters first into the liver before it reaches the muscle, kidney, and other tissues. This was consistent with the results reported in previous studies (Elema, 1996;Bowser, 2009;Sun et al, 2010). The drug concentration in the liver declined, eventually peaking H: healthy; D: diseased; A and B: intercepts of the two phases; α and β: the rate constants of the distribution and elimination phases; K a : absorption rate constant; K 10 : the elimination rate constant from the central compartment; K 12 : the first-order rate constant of transporting from central to periphery compartment; K 21 : the first-order rate constant of transporting from periphery to central compartment; T 1/2α and T 1/2β : half-lives of the two phases; T 1/ 2Ka : half-lives of the absorption; C max : the peak concentration of a drug after administration; T peak: time to reach the maximum concentration; AUC: the area under the curve to infinity; CLs: total body clearance; Vd: volume of distribution at steady-state after 10 h oral administration owing to enterohepatic circulation.…”

“…There are some reports of its pharmacokinetics determined in Oncorhynchus mykiss, Piaractus brachypomus, P. crocea, Gadus morhua, Salmo salar, Acipenser baeri, Anguilla anguilla, Tilapia, Silurus asotus, and Crucian carp (Horsberg et al, 1996;Lunden and Bylund, 2000;Samuelsen et al, 2003;Lewbart et al, 2005;Park et al, 2006;Feng and Jia, 2008;Bowser, 2009;Sun et al, 2010;Qin et al, 2010;Xie et al, 2012).…”

In Vitro and In Vivo Efficacy of Florfenicol for Treatment of Francisella asiatica Infection in Tilapia

“…As previously described, tilapia receiving medicated feed at 15 mg/kg of body weight contained florfenicol concentrations greater than 10 g/ml in tilapia serum, muscle, and skin (4,16), which is significantly greater than the 2 g/ml MIC determined in this study. Moreover, in less than 24 h after a single oral dose of florfenicol at 10 mg/kg of body weight, freshwater-reared tilapia presented 5.21 g/g, 5.27 g/g, 4.59 g/g, and 5.50 g/g concentrations of the antibiotic in the liver, gill, muscle, and kidney, respectively (10).…”

“…Therefore, maintaining concentrations in plasma above the MIC seems advisable to control F. asiatica in tilapia. Recent pharmacokinetic work has shown that serum, skin, and muscle of tilapia medicated with florfenicol via a medicated ration at 15 mg of florfenicol per kg of fish body weight for 10 days contain concentrations higher than the in vitro MIC (2 g/ml) for F. asiatica for the duration of the treatment (4,16). In these studies, at the midpoint of the 10-day treatment period (T5), the mean concentrations of florfenicol in serum (g/ml) and florfenicol residue in muscle-skin (g/g) were 7.14 Ϯ 2.49 and 9.98 Ϯ 2.23, respectively, in 100 g of tilapia fed the medicated feed (4).…”

Antimicrobial susceptibility of Francisella noatunensis subsp. noatunensis strains isolated from Atlantic cod Gadus morhua in Norway

“…In comparison, a single dose of 10 mg kg −1 florfenicol to tilapia (Oreochromis niloticus × O. aureus) gave C max concentrations of 4.46 µg ml −1 in plasma, 6.88 µg g −1 in muscle and 5.87 µg g −1 in liver and faster elimination with t 1/2 β values of 10 h in plasma, 11 h in muscle and 14 h in liver (Feng & Jia 2009), which is considerably lower than the values found in cod. However, according to Bowser et al (2009) resulted in plasma and tissue concentrations in tilapia similar to or higher than those found in cod by Samuelsen & Bergh (2004). Furthermore, a medication regime of 15 mg kg −1 daily for 10 consecutive days showed high efficacy in the treatment of a Francisella asiatica infection in tilapia if the drug was administered during the early stages of infection (1 to 3 d post challenge) (Soto et al 2010).…”