Pharmacokinetics of enrofloxacin after single intravenous and intramuscular administration in young domestic ostrich (Struthio camelus)

A Critical Review of the Pharmacokinetics, Pharmacodynamics, and Safety Data of Antibiotics in Avian Species

In avian medicine, the use of antibiotic dosing regimens based on species-specific pharmacological studies is ideal. However, due to a lack of such studies, dose extrapolation, which may cause inefficacy and toxicity, is common practice. Multiple searches were performed using the PubMed and Web of Science databases to extract relevant pharmacological studies performed in exotic avian species. The pharmacokinetics (PK), pharmacodynamics (PD), and safety data of the selected antibiotics (enrofloxacin, marbofloxacin, gentamicin, amikacin, ceftiofur, doxycycline, and amoxicillin/clavulanate) from these studies were reviewed. This review aimed to identify trends amenable for safe inter-species dose extrapolation and provide updated findings on dosing regimens that are safe and efficacious for various exotic avian species. We observed that the half-life of antibiotics appears to be shorter in the common ostrich and that amikacin may be amenable to inter-species dose extrapolation as it is safe and shows little inter-species PK and PD variation. Species-specific enrofloxacin dosing regimens that were not listed in the Exotic Animal Formulary (5th ed.) were found for Caribbean flamingos, African penguins, southern crested caracaras, common ostriches, and greater rheas. Specific dosing regimens recommended for psittacine birds (doxycycline 130 mg/kg medicated water) and ratites (PO doxycycline 2–3.5 mg/kg q12 h, PO enrofloxacin 1.5–2.5 mg/kg q12 h and IM enrofloxacin 5 mg/kg q12 h) in the formulary may not be effective in budgerigars and common ostriches, respectively. Apart from the lack of species-specific pharmacological studies, a lack of multiple dose studies was also noted.

Pharmacokinetic Behaviour of Enrofloxacin after Single Intramuscular Dosage in American Black Vultures (Coragyps atratus)

The aim of the study was to investigate the intramuscular pharmacokinetics of enrofloxacin in black vultures (Coragyps atratus). The pharmacokinetics of a single intramuscular dose (10 mg/kg) of enrofloxacin was studied in six vultures. Plasma concentrations of enrofloxacin and its active metabolite, ciprofloxacin, were determined by high-performance liquid chromatography (HPLCuv). Pharmacokinetic parameters were estimated using non-compartmental and compartmental analysis. After intramuscular administration, enrofloxacin showed a rapid and complete absorption, reaching a Cmax value of 3.26 ± 0.23 μg/mL at 1.75 ± 0.53 h. A long terminal half-life of 19.58 h has been observed. Using previously published MIC values to perform a PK/PD analysis, cumulative fraction responses obtained after Monte Carlo simulation for AUC/MIC > 30, 50 and 125 were 72.93%, 72.34% and 30.86% for E. coli and 89.29%, 88.89% and 58.57% for Mycoplasma synoviae, respectively. Cumulative fraction responses obtained for Cmax/MIC index were 33.93% and 40.18% for E. coli and M. synoviae, respectively. The intramuscular administration of 10 mg/kg could be appropriate to treat infectious diseases caused by gram-positive bacteria with MIC value lower than 1 µg/mL; however, although enrofloxacin showed a slow elimination in black vultures, plasma concentrations were insufficient to reach the gram-negative stablished breakpoints.

The influence of age and body weight gain on enrofloxacin pharmacokinetics in turkeys-Allometric approach to dose optimization

Enrofloxacin is a concentration-dependent antimicrobial used in bacterial infections in poultry. During a few months of a turkey's life, pharmacokinetics of drugs undergoes substantial changes which may compromise their efficacy due to variability in internal exposure (measured by area under the concentration-time curve, AUC). The aim of this study was to describe the effects of age on the pharmacokinetics of a single intravenous (i.v.) and oral administration of enrofloxacin at a dose of 10 mg/kg to turkeys. It was found that during a 2.5-month-long period of growth from 1.4 to 14.6 kg, the AUC after i.v. administration increased almost threefold due to a significant decrease in the body clearance (from a mean of 0.76-0.28 L hr^-1  kg^-1 ). Over the same period, the mean elimination half-life was prolonged from 2.65 to 7.03 hr. Oral administration resulted in a similar trend in pharmacokinetic parameters. For both routes, formation of the major metabolite, ciprofloxacin, was marginal. Protein binding was not age-dependent and never exceeded 50%. Body clearance, volume of distribution and elimination half-life were subjected to an allometric analysis and a novel, nonlinear dosage protocol has been proposed to improve the internal exposure to the drug in different age groups of turkeys.

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 (t_1/2β), total body clearance (Cl_tot), volume of distribution at steady state (V_dss) 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 (C_max) of 3.67 μg/mL attained at 1.90 h (T_max) after administration. Absorption half-life (t_1/2ab), elimination half-life (t_1/2el), 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.

PHARMACOKINETICS OF A SINGLE DOSE OF ORAL AND SUBCUTANEOUS ENROFLOXACIN IN CARIBBEAN FLAMINGOS (PHOENICOPTERUS RUBER RUBER)

Enrofloxacin is a fluoroquinolone antimicrobial that is widely used in veterinary medicine because of its bactericidal activity and safety in a broad range of species. Caribbean flamingos, a member of the order Phoenicopteriformes, are popular in zoological collections and suffer from a variety of conditions that can result from or lead to bacterial infection. In this study, two groups of 7 adult captive Caribbean flamingos received a single dose of 15 mg/kg enrofloxacin, administered either orally or subcutaneously. Plasma concentrations of enrofloxacin and its metabolite, ciprofloxacin, were measured using liquid chromatography and mass spectrometry. Pharmacokinetic analysis was performed using noncompartmental methods. The pharmacokinetic parameters for both routes of administration were similar, with a mean peak plasma concentration (C_max) of 5.25 and 5.77 μg/ml, a mean time to peak plasma concentration (T_max) of 1.49 and 1.1 hr, a mean area under the curve (AUC) of 49.9 and 47.3 hr·μg/ml, and a mean terminal half-life (t_1/2) of 5.83 and 6.46 hr for oral and subcutaneous dosing, respectively. Conversion to ciprofloxacin was minimal, with the AUC of ciprofloxacin representing <3% of the enrofloxacin AUC for both routes of administration. Based on the results of the present study, a dose of 15 mg/kg enrofloxacin delivered either orally or subcutaneously in the Caribbean flamingo every 24 hr is recommended for susceptible bacterial pathogens with a minimal inhibitory concentration ≤ 0.25 μg/ml.

Pharmacokinetics of enrofloxacin and marbofloxacin in Japanese quails and common pheasants

The pharmacokinetics of enrofloxacin and marbofloxacin was studied in Japanese quails and common pheasants. Healthy mature birds from both species and both genders were treated intravenously and orally with enrofloxacin (10 mg/kg) and marbofloxacin (5 mg/kg). After intravenous administration enrofloxacin was extensively metabolised to ciprofloxacin. Metabolites of marbofloxacin were not detected. Values of volume of distribution were respectively 4.63 l/kg and 3.67 l/kg for enrofloxacin and 1.56 l/kg and 1.43 l/kg for marbofloxacin. In quails, total body clearance values were higher than those in pheasants and other avian species. After oral application enrofloxacin was rapidly absorbed in quails, more rapidly than marbofloxacin. Pheasants absorbed both antimicrobials at a lower rate. Higher bioavailability was observed for marbofloxacin (118%). Relatively low bioavailability was established in quails for enrofloxacin (26.4%), accompanied by extensive conversion to ciprofloxacin. Generally, quails absorbed and eliminated both fluoroquinolones more rapidly than pheasants; the latter showed pharmacokinetics similar to poultry. Because of favourable pharmacokinetic properties, marbofloxacin should be preferred for oral administration in Japanese quails and pheasants for treatment of infections caused by equally susceptible pathogens.

Pharmacokinetic behavior of enrofloxacin and its metabolite ciprofloxacin in urutu pit vipers (Bothrops alternatus) after intramuscular administration

Enrofloxacin is widely used in veterinary medicine and is an important alternative to treating bacterial infections, which play an important role as causes of disease and death in captive snakes. Its extralabel use in nontraditional species has been related to its excellent pharmacokinetic and antimicrobial characteristics. This can be demonstrated by its activity against gram-negative organisms implicated in serious infectious diseases of reptile species with a rapid and concentration-dependent bactericidal effect and a large volume of distribution. Pharmacokinetic parameters for enrofloxacin were investigated in seven urutu pit vipers (Bothrops alternatus), following intramuscular injections of 10 mg/kg. The plasma concentrations of enrofloxacin and its metabolite, ciprofloxacin, were measured using high-performance liquid chromatography. Blood samples were collected from the ventral coccygeal veins at 0.5, 1, 2, 4, 8, 12, 24, 36, 48, 72, 96, 108, and 168 hr. The kinetic behavior was characterized by a relatively slow absorption (time of maximal plasma concentration = 4.50 +/- 3.45 hr) with peak plasma concentration of 4.81 +/- 1.12 microg/ml. The long half-life during the terminal elimination phase (t1/2 lambda = 27.91 +/- 7.55 hr) of enrofloxacin after intramuscular administration, calculated in the present study, could suggest that the antibiotic is eliminated relatively slowly and/or the presence of a slow absorption in urutu pit vipers. Ciprofloxacin reached a peak plasma concentration of 0.35 microg/ml at 13.45 hr, and the fraction of enrofloxacin metabolized to ciprofloxacin was 13.06%. If enrofloxacin's minimum inhibitory concentration (MIC90) values of 0.5 microg/ml were used, the ratios AUC(e+c): MIC90 (276 +/- 67 hr) and Cmax(e+c): MIC90 (10 +/- 2) reach the proposed threshold values (125 hr and 10, respectively) for optimized efficacy and minimized resistance development when treating infections caused by Pseudomonas. The administration of 10 mg/kg of enrofloxacin by the i.m. route should be considered to be a judicious choice in urutu pit vipers against infections caused by microorganisms with MIC values < or = 0.5 microg/ml. For less susceptible bacteria, a dose increase and/or an interval reduction should be evaluated.

Pharmacokinetic-pharmacodynamic integration of orbifloxacin in Japanese quail (Coturnix japonica) following oral and intravenous administration

The pharmacokinetics of single-dose administration of orbifloxacin were determined in Japanese quail (Coturnix japonica) at dosages of 5 mg/kg intravenous (i.v. n = 12) and 7.5 mg/kg oral (p.o.; n = 5), 10 mg/kg p.o. (n = 5), 15 mg/kg p.o. (n = 12) and 20 mg/kg p.o. (n = 5) via HPLC. Orbifloxacin minimal inhibitory concentrations (MICs) against 22 microbial isolates from various bird species were performed to calculate pharmacodynamic surrogate markers. The concentration-time data were analyzed using a naïve pooled data (NPD) approach and compartmental and noncompartmental methods. Steady-state volume of distribution (Vd(ss)) and total body clearance (Cl) after i.v. administration were estimated to be 1.27 L/kg and 0.60 L/h·kg, respectively. Following 15 and 20 mg/kg p.o. dose, bioavailability was 102% and 117%, respectively. The harmonic mean of the corresponding terminal half-lives (T(1/2) λ(z) ) across all the dose groups was 1.71 h. The C(max) /MIC(90) and AUC(0∞24) /MIC(90) for the 15 and 20 mg/kg p.o. doses were ≥5.22 and ≥8.98, and ≥25.80 and ≥39.37 h, respectively. The results of this study suggest that 20 mg/kg orbifloxacin p.o. would be a rational daily dose to treat susceptible infections in Japanese quail not intended for food consumption. For more sensitive bacterial organisms, 15 mg/kg p.o. may also be effective.

Pharmacokinetic behaviour of enrofloxacin in greater rheas following a single-dose intramuscular administration

The pharmacokinetic behaviour of enrofloxacin in greater rheas was investigated after intramuscular (IM) administration of 15 mg/kg. Plasma concentrations of enrofloxacin and its active metabolite, ciprofloxacin, were determined by high performance liquid chromatography. Enrofloxacin peak plasma concentration (C(max)=3.30+/-0.90 microg/mL) was reached at 24.17+/-9.17 min. The terminal half-life (t(1/2lambda)) and area under the curve (AUC) were 2.85+/-0.54 h and 4.18+/-0.69 microg h/mL, respectively. The AUC and C(max) for ciprofloxacin were 0.25+/-0.06 microg/mL and 0.66+/-0.16 microg h/mL, respectively. Taking into account the values obtained for the efficacy indices, an IM dose of 15 mg/kg of enrofloxacin would appear to be adequate for treating infections caused by highly susceptible bacteria (MIC(90)<0.03 microg/mL) in greater rheas.

Pharmacokinetics of enrofloxacin following intravenous and intramuscular administration in Angora rabbits

The pharmacokinetic behaviour and bioavailability of enrofloxacin (ENR) were determined after single intravenous (iv) and intramuscular (im) administrations of 5mg/kg bw to six healthy adult Angora rabbits. Plasma ENR concentrations were measured by high performance liquid chromatography. The pharmacokinetic data were best described by a two-compartment open model. ENR pharmacokinetic parameters were similar (p>0.05) for iv and im administrations in terms of AUC0-infinity, t1/2beta and MRT. ENR was rapidly (t1/2a, 0.05 h) and almost completely (F, 87%) absorbed after im injection. In conclusion, the pharmacokinetic properties of ENR following iv and im administration in Angora rabbits are similar to other rabbit breeds, and once or twice daily iv and im administrations of ENR at the dose of 5mg/kg bw, depending upon the causative pathogen and/or severity of disorders, may be useful in treatment of infectious diseases caused by sensitive pathogens in Angora rabbits.

Enrofloxacin-induced retinopathy in a guanaco (Lama guanicoe)

A 4-yr-old male guanaco (Lama guanicoe) in a multispecies exhibit presented with a laceration in the axillary region. The laceration was surgically repaired. Medical treatment was initiated with penicillin G procaine and benzathine (1920 IU/kg, i.m., s.i.d. for 14 days), and enrofloxacin (2.4 mg/kg, i.m., s.i.d. for 14 days). The animal was later treated with trimethoprim-sulfadiazine (24 mg/kg, p.o., s.i.d. for 10 days). Twenty-six days after initial presentation, the guanaco was suspected to be blind. An ophthalmic examination confirmed retinal damage. On postmortem histological evaluation, there was outer retinal atrophy that was most severe in the central retina with localized foci of complete retinal atrophy; lesions were similar to those observed in enrofloxacin retinal toxicity in cats.

Pharmacokinetics of sparfloxacin in broiler chicken

1. The pharmacokinetics of sparfloxacin in broiler chicken was investigated following a single intravenous dose of 10 mg/kg and a single oral dose of 20 mg/kg. The pharmacokinetic parameters (AUC(0-24) or C(max)) were integrated with the pharmacodynamic parameter (MIC(90)) to optimize sparfloxacin dosage in chicken. 2. The apparent volume of distribution, total body clearance, mean residence time and elimination half-life following oral administration were 2.411/kg, 4.55 ml/min per kg, 10.54 and 5.94 h, respectively. Oral bioavailability was 61.7%. 3. Sparfloxacin was found to possess clinically useful pharmacokinetic properties. Based on pharmacokinetic/pharmacodynamic integration an oral dose of 20 mg/kg sparfloxacin for every 24 h might be recommended for a successful clinical effect in chickens.

Influence of Escherichia coli Endotoxin-Induced Endotoxaemia on the Pharmacokinetics of Enrofloxacin after Intravenous Administration in Rabbits

The main goal of present study was to determine the effects of an Escherichia coli endotoxin-induced endotoxaemic status on disposition of enrofloxacin after a single intravenous dose (5 mg/kg) in rabbits. Septic shock was induced by the i.v. bolus administration at a single dose of E. coli lipopolysaccharide. Six adult New Zealand White rabbits were used. Concentrations of drug in plasma were determined by HPLC. The plasma pharmacokinetic values for enrofloxacin were best represented using a two-compartment open model. Total plasma clearance (Cl(T)) decreased from 2.11 (l/h/kg) in healthy animals to 1.50 (l/h/kg) in rabbits with septic shock, which is related to an increase in the AUC(0-->infinity). In endotoxaemic rabbits, volume of distribution at steady state (V(dss) = 3.61 l/kg) was significantly lower (P < 0.05) than in healthy animals (V(dss) = 4.97 l/kg). However, the elimination half-life of enrofloxacin was not affected by lipopolysaccharide administration.

The pharmacokinetic behaviour of marbofloxacin in Eurasian buzzards (Buteo buteo) after intraosseous administration

This study reports on the administration of a single dose of marbofloxacin (2 mg/kg) to five adult Eurasian buzzards (Buteo buteo) by the intraosseous (IO) route, which has been proposed as a rapid and efficient means for the parenteral delivery of antimicrobial drugs. The drug was rapidly absorbed. Peak marbofloxacin concentration (C(max)) in plasma and area under the concentration-time curve (AUC) of 1.92+/-0.78 microg/mL and 8.53+/-2.73 microg h/mL, respectively. The time marbofloxacin remained in the plasma after IO administration was relatively short (elimination half-life, t(1/2beta)=4.91+/-0.65 h; mean residence time (MRT)=5.38+/-0.57 h). Single dose marbofloxacin gave values for C(max)/minimum inhibitory concentration (MIC) of 19.2 and an AUC/MIC value of 85.3h after IO administration. The IO route appears to be practical and effective for the rapid delivery of marbofloxacin to buzzards.

Pharmacokinetics of marbofloxacin after intravenous and intramuscular administration to ostriches

The pharmacokinetics of marbofloxacin was investigated after intravenous (IV) and intramuscular (IM) administration, both at a dose rate of 5 mg/kg BW, in six clinically healthy domestic ostriches. Plasma concentrations of marbofloxacin was determined by a HPLC/UV method. The high volume of distribution (3.22+/-0.98 L/kg) suggests good tissue penetration. Marbofloxacin presented a high clearance value (2.19+/-0.27 L/kgh), explaining the low AUC values (2.32+/-0.30 microgh/mL and 2.25+/-0.70 microgh/mL, after IV and IM administration, respectively) and a short half life and mean residence time (t(1/2 beta)=1.47+/-0.31 h and 1.96+/-0.35 h; MRT=1.46+/-0.02 h and 2.11+/-0.30 h, IV and IM, respectively). The absorption of marbofloxacin after IM administration was rapid and complete (C(max)=1.13+/-0.29 microg/mL; T(max)=0.36+/-0.071 h; MAT=0.66+/-0.22 h and F (%)=95.03+/-16.89).

Pharmacokinetics of enrofloxacin following intravenous administration to greater rheas: a preliminary study

The pharmacokinetic behaviour of enrofloxacin (ENR) and its active metabolite ciprofloxacin (CIP) were determined in six greater rheas following a single intravenous (i.v.) dose of 15 mg/kg bw. Plasma concentrations of ENR and CIP were simultaneously determined by a HPLC/u.v. method. Following i.v. administration, the plasma drug concentrations were best fitted by an open two-compartment model with a rapid distribution phase. The high volume of distribution (V(ss)=5.01 L/Kg) suggests good tissue penetration. ENR presents a high clearance (3.95 L/kg h) explaining the low AUC values (3.57 mg h/L) and a short permanence (t(1/2beta)=2.66 h and MRT=1.23 h). Ciprofloxacin comprised 14% of the total fluoroquinolone (ENR+CIP).