Comparison of plasma and tissue disposition of enrofloxacin in rainbow trout (Oncorhynchus mykiss) and common carp (Cyprinus carpio) after a single oral administration

The enrofloxacin pollution control from fish to environment

Enrofloxacin (ENR) is used to prevent and treat fish diseases widely. However, its pollution is increasing public concern on human health and aquatic ecosystem safety. This review aims to find its pollution mechanisms and control way. It is found: (1) The excessive ENR administration is the main source, the sediment ENR escaping from photolysis is the secondary ENR pollution source; (2) The ENR-rich fishes were benthic lipid-rich fishes which can simultaneously absorb administration ENR and sediment ENR, the ENR bioaccumulation is positively related to the fish habitats ENR level and fish lipids content; (3) The ENR t1/2 varies with fish age, body weight, feedstuff lipids and crude fiber level, temperature, salinity, administration mode and dose; Consequently, the first control way is to conduct the minimum inhibitory concentration ENR, combining herbal medicines with antibacterial and detoxification functions. The second way is to develop the enrichment and removal techniques for sediment ENR.

Therapeutic efficacy of enrofloxacin in treatment of Francisella orientalis infections in juvenile Nile tilapia (Oreochromis niloticus L.)

Outbreaks of infections by Francisella orientalis represent one of the main obstacles to Nile tilapia (Oreochromis niloticus L.) farming. It is responsible for acute mortality in fingerlings and juveniles. The main control measure available is oral antibiotic therapy. This study compared the therapeutic efficacy of the antibiotics enrofloxacin and oxytetracycline, the most commonly used antimicrobial, against francisellosis in juvenile Nile tilapia (O. niloticus). Fish were challenged with a virulent isolate of F. orientalis and treated with medicated feed containing one of two doses of oxytetracycline (100 or 300 mg/kg of live weight (LW)) or 10 mg/kg of LW of enrofloxacin. The positive and negative control groups received feed without antibiotics; the negative control group was unchallenged. The results showed that enrofloxacin at a dose of 10 mg/kg of LW is effective against francisellosis in juvenile Nile tilapia (O. niloticus). Treatment with oxytetracycline did not eliminate the pathogen from the infected host, and the surviving fish became carriers. Enrofloxacin was able to cure the fish of infection with F. orientalis. This study suggests that enrofloxacin is a better option for treating francisellosis in Nile tilapia (O. niloticus L.). It controls mortality and avoids the carrier state in the fish, thus reducing the possibility of recurrence in the affected batches.

Plasma and tissue kinetics of enrofloxacin and its metabolite, ciprofloxacin, in yellow catfish (Pelteobagrus fulvidraco) after a single oral administration at different temperatures

The objective of this study was to examine the pharmacokinetic (PK) properties of enrofloxacin (EF) and its metabolite, ciprofloxacin (CF), in yellow catfish (Pelteobagrus fulvidraco) after a single oral dose of EF at 20 mg/kg at 20, 25, and 30 °C. Samples were collected at pre-designed time points and determined by high-performance liquid chromatography with a fluorescent detector. Results showed that most concentrations of EF and CF in plasma and tissues at the same time point at different temperatures were statistically significant. With the increase in temperature, the terminal half-life (T_1/2λz) of EF and CF was first reduced from 20 to 25 °C but elevated from 25 to 30 °C in plasma, muscle + skin, gill, liver, and kidney, respectively. The area under the plasma concentration-time curves (AUC_last) of EF were all decreased in plasma, muscle + skin, and gill except for that of EF in the liver and kidney. However, the AUC_last and the apparent metabolic rate of CF were exhibited first elevated and then decreased trend. The apparent volume of distribution (Vz_F) of EF was first reduced from 20 to 25 °C but increased at 30 °C. The apparent total body clearance (CL_F) of EF was increased from 0.15 to 0.32 L/h·kg with the temperature elevation. These indicated that increased temperature markedly affected the PKs of EF and CF in yellow catfish. Through in-depth analysis, the EF dosage of 20 mg/kg is appropriate to use in yellow catfish at 20 and 25 °C but 30 °C.

Plasma and muscle tissue disposition of enrofloxacin in Nile tilapia (Oreochromis niloticus) after intravascular, intraperitoneal, and oral administrations

The aim of the study was to investigate the plasma and muscle pharmacokinetic of enrofloxacin (ENR) and its active metabolite ciprofloxacin (CIP) in Nile tilapia (Oreochromis niloticus) following single intravascular (IV), intraperitoneal (IP), or oral (PO) administration at 30 ± 1 °C. In this study, 234 healthy Nile tilapia (120-150 g) were used. The fish received a single IV, IP, or PO treatment of ENR at a dose of 10 mg/kg. The plasma and muscle tissue concentrations of ENR and CIP were measured using high-performance liquid chromatography with fluorescence detection and were evaluated using non-compartmental analysis. The elimination half-life, volume of distribution at steady state, and total body clearance of ENR were 21.7 h, 2.69 L/kg, and 0.09 L/h/kg, respectively. The peak plasma concentrations of ENR after IP or PO administration were 6.11 and 4.21 µg/mL at 0.25 and 2 h, respectively. The bioavailability of ENR for IP or PO routes was 78% and 86%, respectively. AUC_{(0-120)muscle}/AUC_{(0-120)plasma} ratios following the IV, IP, or PO administrations were 1.43, 1.49, and 1.07, respectively. CIP was detected after all routes, but the AUC_0-last ratios of CIP to ENR were <1.0% for plasma and muscle. ENR was detected up to 120 h following the IV, IP, or PO administrations. The long residence time of ENR after single IV, IP, or PO administration ensured the plasma concentration was ≥1 × MIC for bacteria with threshold MIC values of 0.92, 0.72, and 0.80 μg/mL over the whole 120 h observed. However, further studies are necessary to determine the optimum pharmacokinetic/pharmacodynamics data of ENR for the treatment of infections caused by susceptible bacteria in tilapia.

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.

Pharmacokinetics and Tissue Distribution of Enrofloxacin Following Single Oral Administration in Yellow River Carp (Cyprinus carpio haematoperus)

The pharmacokinetics and tissue distribution of enrofloxacin were determined in Yellow River carp (Cyprinus carpio haematopterus) reared at 20°C after single oral administration of enrofloxacin at 10 mg·kg−1 body weight (BW). Plasma, bile, and different tissue samples, including liver, kidney, gill, gut, and skin-muscle, were collected at predetermined times points. An HPLC method was developed to simultaneously determine the concentrations of enrofloxacin and its metabolite, ciprofloxacin. However, ciprofloxacin was only detectable in some liver samples with trace levels. Then the average enrofloxacin concentrations vs. time data were subjected to a non-compartmental analysis using WinNonLin 5.2 software. Multiple peaking profiles were observed in all enrofloxacin concentration-time curves. The peak concentration (Cmax) values were observed as 0.79, 1.01, 2.09, 2.85, 4.34, 10.78, and 13.07 μg·ml−1 (or g−1) in plasma, skin-muscle, gill, kidney, liver, bile, and gut, respectively, and the corresponding time to reach peak concentration (Tmax) was 8, 8, 1, 8, 1, 72, and 4 h, respectively. The values of elimination half-life (T1/2λZ) of enrofloxacin in different tissues was in the following order: gill (291.13 h) &gt; liver (222.29 h) &gt; kidney (157.22 h) &gt; plasma (129.44 h) &gt; gut (91.47 h) &gt; skin-muscle (87.77 h) &gt; bile (86.22 h). The present results showed that enrofloxacin had a wide distribution in different tissues, however slow absorption and elimination in Yellow River carp. Additionally, enrofloxacin exhibited large distribution in bile, indicating that bile excretion might be the primary elimination route of enrofloxacin in Yellow River carp. A withdrawal period was calculated as 379.2 °C-day for single oral dosing of enrofloxacin at 10 mg/kg BW. Based on the calculated PK/PD indices of AUC/MIC or Cmax/MIC, the current enrofloxacin dosing regimen might have a positive therapeutic effect on the infection of Flavobacterium columnare, Aeromonas sobria, or Aeromonas hydrophila. However, the depletion study following multiple oral doses should be carried out in Yellow River carp reared at lower temperatures, and the withdrawal period should also be further calculated.

Pharmacokinetics and Pharmacokinetic/Pharmacodynamic Integration of Enrofloxacin Following Single Oral Administration of Different Doses in Brown Trout (Salmo trutta)

Simple Summary

The pharmacokinetic/pharmacodynamic studies report the use of enrofloxacin at higher doses than 10 mg/kg in fish. Pharmacokinetic data for increasing doses of enrofloxacin can facilitate suggestions regarding the dose for the treatment of infections in brown trout. This study aims to determine single oral pharmacokinetics of enrofloxacin at 10, 20, and 40 mg/kg doses in brown trout and pharmacodynamics against Aeromonas hydrophila and A. sobria. Enrofloxacin exhibited non-linear and dose-disproportional pharmacokinetics. The long action of enrofloxacin following the single oral administration at 10 and 20 mg/kg doses may provide the unique dosage regimen to minimize handling, thereby reducing the cost of administration and stress in brown trout.

Abstract

The pharmacokinetic of enrofloxacin was investigated in brown trout (Salmo trutta) following oral administration of 10, 20, and 40 mg/kg doses at 11 ± 1.5 °C. Furthermore, MICs of enrofloxacin against Aeromonas hydrophila and A. sobria were determined. The plasma concentrations of enrofloxacin and ciprofloxacin were determined using HPLC–UV and analyzed by non-compartmental method. Following oral administration at dose of 10 mg/kg, total clearance (CL/F), area under the concentration–time curve (AUC_0−∞) and peak plasma concentrations (C_max) were 41.32 mL/h/kg, 242.02 h*μg/mL and 4.63 μg/mL, respectively. When compared to 10 mg/kg dose, the dose-normalized AUC_0–∞ and C_max were increased by 56.30% and 30.08%, respectively, while CL/F decreased by 38.4% at 40 mg/kg dose, suggesting the non-linearity. Ciprofloxacin was not detected in the all of plasma samples. The MIC values of enrofloxacin were ranged 0.0625–4 μg/mL for A. hydrophila and 0.0625–2 μg/mL for A. sobria. The oral administration of enrofloxacin at 10 (for 192 h) and 20 (for 240 h) mg/kg doses provided the AUC of enrofloxacin equal to 1.23 and 1.96-fold MICs, respectively, for A. hydrophila and A. sobria with the MIC₉₀ values of 1 µg/mL. However, further researches are needed on the PK/PD study of enrofloxacin for the successful treatment of infections caused by A. hydrophila and A. sobria in brown trout.

Development and Application of a Water Temperature Related Physiologically Based Pharmacokinetic Model for Enrofloxacin and Its Metabolite Ciprofloxacin in Rainbow Trout

Enrofloxacin (ENR) has been approved for the treatment of infections in aquaculture, but it may cause tissue residue. This research aimed to develop and validate a water temperature related PBPK model, including both ENR and ciprofloxacin (CIP), in rainbow trout, and to predict further their residue concentrations and the withdrawal periods for ENR at different water temperatures. With the published concentrations data, a flow-limited PBPK model including both ENR and CIP sub-models was developed to predict ENR and CIP concentrations in tissues and plasma/serum after intravenous, oral, or immersion administration. A Monte Carlo simulation including 500 iterations was further incorporated into this model. Based on the model and Monte Carlo analysis, the withdrawal intervals were estimated for different dosage regimens and at different water temperatures, ranging from 80 to 272 degree-days. All of these values were shorter than the labeled withdrawal period (500 degree-days) in fish. This model provided a useful tool for predicting the tissue residues of ENR and CIP in rainbow trout under different dosage regimens and at different water temperatures.

Pharmacokinetics and tissue disposition of enrofloxacin in rainbow trout after different routes of administration

Plasma pharmacokinetics (PK) and tissue disposition of enrofloxacin (EFX) was studied in rainbow trout (Oncorhynchus mykiss) after a single oral administration of 10 mg/kg, and by immersion baths of 20 ppm during 2.5 h and 100 ppm during 0.5 h, at water temperature of 16.3 ± 0.3 °C.Concentrations of EFX in plasma and tissues (skin, muscle, liver, kidney and gut) were determined using high performance liquid chromatography (HPLC) with fluorescence detection.Pharmacokinetic parameters were analyzed with a non-compartmental model. After oral administration, t½β, AUC and AUC_tissues/AUC_plasma ratio were 42.98 h, 21.80μg-h/ml and ≤ 18.63, respectively.After immersion baths of 20 ppm during 2.5 h and 100 ppm during 0.5 h, the t½β, AUC and AUC_tissues/AUC_plasma were 42.77 and 44.67, 9.83 and 12.83 μg-h/ml and ≤ 9.81 and ≤ 7.13, respectively.Therefore, oral (10 mg/kg) and bath administration in rainbow trout can provide AUC/MIC of ≥125 and Cmax/MIC of ≥10 to treat diseases caused by susceptible bacteria with MIC ≤ 0.04 μg/ml. This information can be helpful for the right use of EFX in rainbow trout. Also, this is the first study that determines the antibiotic tissue disposition in rainbow trout by using different administration routes.