Pharmacokinetics after intravenous, intramuscular and subcutaneous administration of difloxacin in sheep

Pharmacokinetics of difloxacin in Japanese quails (Coturnix japonica) after single intravenous and oral administration

Pharmacokinetics of difloxacin (DF), a fluoroquinolone antibiotic, were investigated in Japanese quails (Coturnix japonica) after a single intravenous (IV) and oral (PO) administration of 10 mg/kg bodyweight. Plasma concentration profiles of DF were analyzed by a compartmental pharmacokinetic method. Following IV injection, the plasma concentration vs time profile was best described by a two-compartment open model. Elimination half-life (t1/2β), total body clearance (Cltot), volume of distribution at steady state (Vdss) and mean residence time (MRT) of DF were 5.45 ± 0.14 h, 0.22 ± 0.01 L/kg/h, 1.54 ± 0.06 L/kg and 6.92 ± 0.19 h, respectively. Following PO administration, DF was rapidly absorbed, with peak plasma concentration (Cmax) of 3.67 μg/mL attained at 1.90 h (Tmax) after administration. Absorption half-life (t1/2ab), elimination half-life (t1/2el), mean absorption time (MAT) were 0.5 h, 5.26 h and 1.11 h, respectively. The bioavailability (F) following PO administration of DF was high (84.40%). For a successful clinical effect of DF in quails, a multiple dosage regimen of 10 mg/kg bodyweight, administered orally every 24 h is recommended to maintain effective plasma concentrations with bacterial infections, in which MIC90 is <0.2 μg/mL.

Susceptibility and PK/PD relationships of Staphylococcus aureus strains from ovine and caprine with clinical mastitis against five veterinary fluoroquinolones

Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of veterinary fluoroquinolones as enrofloxacin, its metabolite ciprofloxacin, danofloxacin, difloxacin and marbofloxacin against Staphylococcus aureus strains (n=24) isolated from milk of sheep and goats affected by clinical mastitis were evaluated. The authors have used the MIC and MPC, as well as the pharmacokinetic-pharmacodynamic relationships in plasma and milk. MIC values were significantly different between drugs, unlike MPC values. Lower MIC values were obtained for danofloxacin and difloxacin, middle and higher values for enrofloxacin, ciprofloxacin and marbofloxacin. However, differences in MPC values were not found between drugs. At conventional doses, the AUC₂₄/MIC and AUC₂₄/MPC ratios were close to 30-80 hours and 5-30 hours, with exception of danofloxacin, in plasma and milk. The time inside the mutant selection window (T_MSW) was close to 3-6 hours for enrofloxacin, ciprofloxacin and marbofloxacin, near to 8 hours for danofloxacin and 12-22 hours for difloxacin. From these data, the mutant selection window could be higher for danofloxacin and difloxacin compared with the other fluoroquinolones tested. The authors concluded that enrofloxacin and marbofloxacin, at conventional doses, could prevent the selection of bacterial subpopulations of S aureus, unlike danofloxacin and difloxacin, where higher doses could be used.

Pharmacokinetics of difloxacin in olive flounder Paralichthys olivaceus at two water temperatures

In this study, the pharmacokinetics profiles of difloxacin in the olive flounder (Paralichthys olivaceus) were investigated following intravenous and oral administration (10 mg/kg BW) at 14 and 22 °C water temperatures. Plasma and tissue samples (muscle, liver, and kidney) were analyzed using an HPLC method. The results showed that the plasma concentration-time data for difloxacin were described commendably by two-compartment open model at the two water temperatures. The absorption half-life (t(1/2ka)) of difloxacin after oral administration were 2.08 and 1.10 h at 14 and 22 °C, respectively; whereas the elimination half-life (t(1/2β)) was 4.41 and 2.38 h, respectively. The muscle concentration of 1.35 ± 0.19 μg/g was observed at 9 h at 14 °C, and 2.11 ± 0.33 μg/g at 6 h at 22 °C, respectively. For liver, the peak concentration of difloxacin 2.43 ± 0.30 μg/g occurred at 6 h at 14 °C, which was lower than the 3.34 ± 0.24 μg/g peak that occurred at 4 h at 22 °C. The calculated bioavailability of difloxacin was 68.07% at 22 °C, which was higher than the 53.43% calculated for 14 °C. After intravenous administration, the t(1/2β) were 4.79 and 2.81 h at 14 and 22 °C, respectively. The results indicate that the peak concentrations in muscle and liver at 14 °C are approximately half of those achieved at 22 °C. However, the C(max) in kidney at 14 and 22 °C were similar. The Vd values were 1.20 and 1.75 L/kg at 14 and 22 °C, respectively. These data indicated that both temperature and drug administration had significant effects on the elimination of difloxacin, and lower temperature or oral administration resulted in lower elimination.

Pharmacokinetics and milk penetration of difloxacin after a long-acting formulation for subcutaneous administration to lactating goats

The single-dose disposition kinetics of difloxacin were determined in clinically normal lactating goats (n=6) after intravenous (IV) and subcutaneous (SC) administration and subcutaneous administration of a long-acting poloxamer 407 gel formulation (P407). Difloxacin concentrations were determined by HPLC with fluorescence detection. Minimum inhibitory concentrations of difloxacin against 14 strains of Staphylococcus aureus isolated from mastitic goats' milk in Spain were determined to compute pharmacodynamic surrogate markers. The concentration-time data were analyzed by compartmental and noncompartmental pharmacokinetic methods. Following SC and P407 administration, difloxacin achieved maximum milk concentrations of 1.34+/-0.12 and 2.97+/-1.18 mg/L, respectively, at 4.00+/-0.00 h (SC) and 3.60+/-0.89 h (P407) after administration. The absolute bioavailabilities after SC and P407 administration were 81.74+/-15.60% and 72.58+/-20.45%, respectively. Difloxacin penetration from the blood into the milk was good and high concentrations were found in milk secretions. From these data, a 15 mg/kg dose of difloxacin P407 would appear to be effective against Staphylococcus aureus isolated from mastitic goats' milk with minimum inhibitory concentrations <or=0.25mg/L.

Plasma disposition and tissue depletion of difloxacin and its metabolite sarafloxacin in the food producing animals, chickens for fattening

Chickens were used to investigate plasma disposition of difloxacin after single intravenous (IV) and oral dose (10 mg/kg body weight (BW)) and to study residue depletion of difloxacin and its major metabolite sarafloxacin after multiple oral doses (10 mg difloxacin/kg BW, daily for 5 days). Plasma and tissue samples were analyzed using a HPLC method. After IV and oral administration, plasma drug concentration-time curves were best described by a two-compartment open model. Mean (± SD) elimination half-lives (t(½)β) of difloxacin were 9.53±1.00 and 12.23±1.81 h after IV and oral administration. Maximum plasma concentration was 2.34±0.50 μg/ml and interval from oral administration until maximal concentration was 1.34±0.03 h. Oral bioavailability was found to be 68.89±15.21%. Difloxacin was converted to sarafloxacin. After multiple oral dose (10mg difloxacin/kg BW, daily for 5 days), mean kidney, liver, muscle and skin + fat tissue concentrations of difloxacin and sarafloxacin ranging between 604.8±132.5 and 368.1±52.5 μg/kg and 136.4±18.3 and 10.4±1.2 μg/kg, respectively, were measured 1 day after administration of the final dose of difloxacin. A withdrawal time of 5 days was necessary to ensure that the residues of difloxacin were less than the maximal residue limits (MRL) or tolerance established by the European Union.

Metabolism and excretion kinetics of 14C-labeled and non-labeled difloxacin in pigs after oral administration, and antimicrobial activity of manure containing difloxacin and its metabolites

Fluoroquinolones are amongst the most important antibiotics used in veterinary medicine. On this account the behavior of difloxacin (DIF) and its metabolites was investigated by administering the (14)C-labeled and non-labeled veterinary drug to fattening pigs. The excretion kinetics were determined after daily collection of manure. Sarafloxacin (SAR) was found to be the major metabolite, three further trace metabolites were also recovered, applying high-resolution (HR) mass spectrometric technique. The identification of DIF and SAR was confirmed by comparison with the spectroscopic and chromatographic data of the authentic references. The identification of the three trace metabolites was performed by HR-MS/MS. Only 8.1% of the administered radioactivity remained in the pig after 10 days and DIF accounted for 95.9% of the radioactivity excreted. More than 99% of the labeled compounds were detected and identified in the manure. The mean recoveries for all single electrolytes were 94%. Linearity was established over concentration range 10-10,000 microg/kg manure with a correlation coefficient 0.99. By using in vitro antimicrobial activity tests against a group of standard pathogenic control strains, the results showed that the residual antibiotic concentrations in the manure of pigs are high enough to exhibit antibacterial activity.

Pharmacokinetics and intramuscular bioavailability of difloxacin in dromedary camels (Camelus dromedarius)

Single-dose disposition kinetics of difloxacin (5mg/kg bodyweight) were determined in clinically normal male dromedary camels (n=6) following intravenous (IV) and intramuscular (IM) administration. Difloxacin concentrations were determined by high performance liquid chromatography with fluorescence detection. The concentration-time data were analysed by compartmental and non-compartmental kinetic methods. Following a single IV injection, the plasma difloxacin concentration-time curve was best described by a two-compartment open model, with a distribution half-life (t(1/2alpha)) of 0.22+/-0.02h and an elimination half-life (t(1/2beta)) of 2.97+/-0.31h. Steady-state volume of distribution (V(dss)) and total body clearance (Cl(tot)) were 1.02+/-0.21L/kg and 0.24+/-0.07L/kg/h, respectively. Following IM administration, the absorption half-life (t(1)(/)(2ab)) and the mean absorption time (MAT) were 0.44+/-0.03h and 1.53+/-0.22h, respectively. The peak plasma concentration (C(max)) of 2.84+/-0.34microg/mL was achieved at 1.42+/-0.21h. The elimination half-life (t(1/2el)) and the mean residence time (MRT) was 3.46+/-0.42h and 5.61+/-0.23h, respectively. The in vitro plasma protein binding of difloxacin ranged from 28-43% and the absolute bioavailability following IM administration was 93.51+/-11.63%. Difloxacin could be useful for the treatment of bacterial infections in camels that are sensitive to this drug.

Comparative pharmacokinetics of an injectable cephalexin suspension in beef cattle

This study describes and compares the pharmacokinetics of a single 7.5mg/kg dose of cephalexin monohydrate oil-based 20% suspension after its administrations to six cows by the intramuscular (i.m.) and subcutaneous (s.c.) routes, and to five calves by the i.m. route. Significantly (P<0.05) higher peak plasma concentrations (5.6+/-0.79microg/ml versus 3.93+/-1.24microg/ml) and lower half-life (1.81+/-0.56h versus 4.21+/-0.82h) and mean residence time (4.12+/-1.07h versus 6.63+/-0.85h) were obtained after i.m. administration when compared to the s.c. administration to cows. No differences were found between pharmacokinetic parameters calculated for cows and calves. Cephalexin plasma concentrations remained above 0.5-0.75microg/ml for 11-14h and 8-9h after the s.c. and i.m. administrations, respectively. Thus, route of administration may be an important issue to be considered when calculating dosage schedules for successful treatments and safe withdrawal times for veterinary medicines.

Allometric scaling of marbofloxacin, moxifloxacin, danofloxacin and difloxacin pharmacokinetics: a retrospective analysis

The purpose of this study was to examine the allometric analyses of marbofloxacin, moxifloxacin, danofloxacin and difloxacin using pharmacokinetic data from the literature. The parameters of interest (half-life, clearance and volume of distribution) were correlated across species as a function of body weight using an allometric approach (Y = aWb). Results of the allometric analysis indicated similarity between clearance and volume of distribution as they relate to body weight for all drugs. The elimination half-life was independent of body mass for all fluoroquinolones except moxifloxacin. Results of the analysis suggest that allometric scaling can be used as a tool for predicting pharmacokinetic parameters for fluoroquinolones.