Pharmacokinetic/pharmacodynamic relationship of marbofloxacin against Pasteurella multocida in a tissue‐cage model in yellow cattle

The fluoroquinolone antimicrobial drug marbofloxacin was administered to yellow cattle intravenously and intramuscularly at a dose of 2 mg/kg of body weight in a two‐period crossover study. The pharmacokinetic properties of marbofloxacin in serum, inflamed tissue‐cage fluid (exudate), and noninflamed tissue‐cage fluid (transudate) were studied by using a tissue‐cage model. The in vitro and ex vivo activities of marbofloxacin in serum, exudate, and transudate against a pathogenic strain of Pasteurella multocida (P. multocida) were determined. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the area under the curve (AUC)/MIC for serum, exudate, and transudate of 155.75, 153.00, and 138.88, respectively, after intravenous dosing and 160.50, 151.00, and 137.63, respectively, after intramuscular dosing. After intramuscular dosing, the maximum concentration/MIC ratios for serum, exudate, and transudate were 21.13, 9.13, and 8.38, respectively. The ex vivo growth inhibition data after intramuscular dosing were fitted to the inhibitory sigmoid E_max equation to provide the values of AUC/MIC required to produce bacteriostasis, bactericidal activity, and elimination of bacteria. The respective values for serum were 17.25, 31.29, and 109.62, and slightly lower values were obtained for transudate and exudate. It is proposed that these findings might be used with MIC₅₀ or MIC₉₀ data to provide a rational approach to the design of dosage schedules which optimize efficacy in respect of bacteriological as well as clinical cures.     

The immune response and protective efficacy of oral alginate microparticle Aeromonas sobria vaccine in soft-shelled turtles (Trionyx sinensis)

Aeromonas sobria is an important bacterial pathogen of soft-shelled turtles (Trionyx sinensis). The effect of an oral alginate microparticle A. sobria vaccine (MAV) on immune response and protection efficacy of soft-shelled turtles was investigated. The formalin-killed cultures of A. sobria strain Z-1 (FKC) were incorporated into alginate microparticles, and the encapsulated vaccine was orally used for immunizing turtles. The serum agglutinating antibody titers, bactericidal activity of blood leucocytes and relative percent survival (RPS) post-challenge with virulent live bacteria of control and immunized turtles were detected. The serum agglutinating antibody titers and bactericidal activity of the leucocytes in the turtles orally immunized with MAV reached a level equivalent to those of the turtles injected with FKC and were significantly higher than those of control group. The RPS of turtles immunized orally with the MAV and intraperitoneally with FKC was 89.5 and 94.7%, respectively, while 95% of the control turtles had died. These results demonstrated that oral alginate microparticle A. sobria vaccine was immunogenic, and could confer protective immunity in soft-shelled turtles.     

Pharmacokinetic/pharmacodynamic relationship of cefquinome against Pasteurella multocida in a tissue‐cage model in yellow cattle

The cephalosporin antimicrobial drug cefquinome was administered to yellow cattle intravenously (i.v.) and intramuscularly (i.m.) at a dose of 1 mg/kg of body weight in a two‐period crossover study. The pharmacokinetic (PK) properties of cefquinome in serum, inflamed tissue‐cage fluid (exudate), and noninflamed tissue‐cage fluid (transudate) were studied using a tissue‐cage model. The in vitro and ex vivo activities of cefquinome in serum, exudate, and transudate against a pathogenic strain of Pasteurella multocida (P. multocida) were determined. A concentration‐independent antimicrobial activity of cefquinome was confirmed for levels lower than 4 × MIC. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the time that drug levels remain above the MIC (T > MIC) in serum was 14.10 h after intravenous and 14.46 h after intramuscular dosing, indicating a likely high level of effectiveness in clinical infections caused by P. multocida of MIC 0.04 μg/mL or less. These data may be used as a rational basis for setting dosing schedules, which optimize clinical efficacy and minimize the opportunities for emergence of resistant organisms.     

Pharmacokinetic/pharmacodynamic assessments of 10 mg/kg tramadol intramuscular injection in yellow‐bellied slider turtles (Trachemys scripta scripta)

In reptiles, administration of opioid drugs has yielded unexpected results with respect to analgesia. The aims of this study were to assess the pharmacokinetic/pharmacodynamic (PK/PD) properties of tramadol and its active metabolite M1 and to evaluate the effect of the renal portal system on the PK/PD parameters in yellow‐bellied slider turtles. Turtles (n = 19) were randomly assigned to four treatment groups, according to a masked, single‐dose, four‐treatment, unpaired, four‐period crossover design. Group A (n = 5) received a single i.m. dose of tramadol (50 mg/mL) at 10 mg/kg in the proximal hindlimb. Group B (n = 5) received the same i.m. dose but in the forelimb. Groups C (n = 5) and D (n = 4) received a single i.m. injection of saline (NaCl 0.9%) of equivalent volume to the volumes of tramadol injected in the hind‐ and forelimb, respectively. Groups were rotated (1‐month washout period) until the completion of the crossover study. Tramadol plasma concentrations were evaluated by a validated HPLC‐FL method. An infrared thermal stimulus was applied to the plantar surface of the turtles' hindlimbs to evaluate the thermal withdrawal latency (TWL). The two PK profiles of tramadol differed in the first 2 h following administration, but overlapped in the elimination phases. The metabolite M1 was formed in both the treatment groups, showing similar pharmacokinetic trends, although the amount of M1 was significantly higher (20%) in the hindlimb vs. forelimb group. Turtles given tramadol in the hind‐ and forelimb showed a significant increase in TWL over the periods of 0.5–48 and 8–48 h, respectively. The calculated % maximal possible response (% MPR) was low (about 24%). The PK/PD correlations between M1 plasma concentrations vs. % MPR appeared to show a counterclockwise hysteresis loop shape.     

Pharmacokinetic behavior and pharmacokinetic/pharmacodynamic integration of marbofloxacin after subcutaneous administration in goats

The pharmacokinetic behavior of marbofloxacin was studied in goats after single-dose subcutaneous (SC) administration of 2mg/kg bodyweight. Drug concentration in plasma was determined by high performance liquid chromatography and the data obtained were subjected to non-compartmental kinetic analysis. Marbofloxacin peak plasma concentration (C(max)=1.77+/-0.24microg/mL) was reached 1.25+/-0.50h (T(max)) after SC administration. The elimination half-life (t(1/2beta)) and area under curve (AUC) were 5.74+/-1.21h and 8.15 vs 2.33microg h/mL, respectively. Taking into account the values obtained for the efficacy indices, it was concluded that a SC dose of 2mg/kg/24h of marbofloxacin could be adequate to treat infections caused by high susceptible bacteria like Escherichia coli or Salmonella spp.     

Effects of acute cold exposure on oxidative balance and total antioxidant capacity in juvenile Chinese soft‐shelled turtle,Pelodiscus sinensis

Acute cold exposure may disturb the physiological homeostasis of the body in ectotherms. To date, there has been no information on the effects of cold exposure on homeostasis of reactive oxygen species (ROS) or antioxidant defense response in the Chinese soft‐shelled turtle, Pelodiscus sinensis. In this study, P. sinensis juveniles were acclimated at 28 °C, transferred to 8 °C as cold exposure for 12 h, then moved back to 28 °C rewarming for 24 h. We measured the ROS level and total antioxidant capacity (TAC) in the brain, liver, kidney and spleen at 2 and 12 h cold exposure, and at the end of the rewarming period. Malonaldehyde (MDA) and carbonyl protein were used as markers of oxidative damage. Turtles being maintained simultaneously at 28 °C were used as the control group. Cold exposure did not disturb the ROS balance in all 4 tissues, while rewarming raised the ROS level in the brain and kidney of P. sinensis. Cold exposure and rewarming decreased the TAC in the brain, liver and spleen but did not change the TAC in the kidney. MDA and carbonyl protein levels did not increase during the treatment, indicating no oxidative damage in all 4 tissues of P. sinensis. Our results indicated that extreme cold exposure did not impact the inner oxidative balance of P. sinensis, but more ROS was produced during rewarming. P. sinensis showed good tolerance to the harsh temperature change through effective protection of its antioxidant defense system to oxidative damage. This study provides basic data on the stress biology of P. sinensis.     

中华鳖对温和气单胞菌口服微球缓释疫苗的免疫应答

以中华鳖温和气单胞菌 (Aeromonas sobria,As) Z- 1株灭活全菌液 ,采用生物降解性高分子材料制成缓释微球疫苗 ,口服免疫中华鳖 ,测定血清中凝集抗体、血液中白细胞杀菌率以及对活菌攻击的免疫保护率。结果表明 ,中华鳖口服微球疫苗 ,其血清中凝集抗体效价和血液中白细胞杀菌百分率均可达到灭活菌液注射组相当的水平 (P>0 .0 5 ) ,显著高于对照组 (P<0 .0 1) ;微球疫苗口服组和灭活菌液注射组的免疫保护率分别为 94 .7%和 89.5 % ,两者差异不显著 (P>0 .0 5 ) ,而对照组小鼠 95 %死亡。采用可生物降解微球作为中华鳖气单胞菌口服疫苗的载体系统是可行的。     

Division of Chinese soft‐shelled turtle intestine with molecular markers is slightly different from the morphological and histological observation

The Chinese soft‐shelled turtle (Pelodiscus sinensis) is a commercially important species in Asian countries. Knowledge of its nutritional requirements and physiology is essential for determining the appropriate content of the feed for this animal. However, the lack of functional characterization of the intestine of this turtle limits the understanding of its absorption and utilization of nutritional materials. To solve this problem, this work utilized anatomical and histological methods to characterize 9 segments sampled along the anterior–posterior axis of the intestine. Furthermore, 9 genes, which have been well documented in the intestine division of mammals and fish, were employed to functionally characterize the 9 sampled segments. Our results suggest that regions covering from the starting site to S3 (position at 29.9% of the total length from the starting of the intestine) are the equivalent of mammalian dedumonen, and those covering S4 (40.2%) and S5 (65.4%), posterior to S8 (92.7%), are the equivalent of the mammalian ileum and the large intestine, respectively. As to the region spaning S6 (81.3%) and S7 (87.3%), its functional equivalent (small intestine or large intestine) may be variable and depends on the functional genes. This molecular characterization in relation to the division of the intestine of Chinese soft‐shelled turtle may contribute to the understanding of the nutritional physiology of the turtle, and promote Chinese soft‐shelled turtle production.     

Comparative activity of pradofloxacin and marbofloxacin against coagulase‐positive staphylococci in a pharmacokinetic–pharmacodynamic model based on canine pharmacokinetics

Körber‐Irrgang, B., Wetzstein, H.‐G., Bagel‐Trah, S., Hafner, D., Kresken, M. Comparative activity of pradofloxacin and marbofloxacin against coagulase‐positive staphylococci in a pharmacokinetic–pharmacodynamic model based on canine pharmacokinetics. J. vet. Pharmacol. Therap.  35 , 571–579. Pradofloxacin (PRA), a novel veterinary 8‐cyano‐fluoroquinolone (FQ), is active against Staphylococcus pseudintermedius, the primary cause of canine pyoderma. An in vitro pharmacokinetic–pharmacodynamic model was used to compare the activities of PRA and marbofloxacin (MAR) against three clinical isolates of S. pseudintermedius and reference strain Staphylococcus aureus ATCC 6538. Experiments were performed involving populations of 10¹⁰ CFU corresponding to an inoculum density of approximately 5 × 10⁷ CFU/mL. The time course of free drug concentrations in canine serum was modelled, resulting from once daily standard oral dosing of 3 mg of PRA/kg and 2 mg of MAR/kg. In addition, experimentally high doses of 6 mg of PRA/kg and 16 mg of MAR/kg were tested against the least susceptible strain. Viable counts were monitored over 24 h. At concentrations associated with standard doses, PRA caused a faster and more sustained killing than MAR of all strains. The ratios of free drug under the concentration–time curve for 24 h over MIC and the maximum concentration of free drug over MIC were at least 90 and 26, and 8.5 and 2.1 for PRA and MAR, respectively. At experimentally high doses, PRA was superior to MAR in terms of immediate killing. Subpopulations with reduced susceptibility to either FQ did not emerge. We conclude that PRA is likely to be an efficacious therapy of canine staphylococcal infections.     

Pharmacokinetics of marbofloxacin after a single oral dose to loggerhead sea turtles (Caretta caretta)

The single-dose disposition kinetics of marbofloxacin (MBX) were determined in clinically healthy loggerhead sea turtles (n = 5) after oral (PO) administration of 2 mg kg⁻¹ bodyweight. Marbofloxacin plasma concentrations were determined by DAD–HPLC (LOD/LOQ 0.015/0.05 μg ml⁻¹). Data were subjected to non-compartmental analysis. Following PO administration, marbofloxacin achieved maximum plasma concentrations of 11.66 ± 2.53 mg L⁻¹ at 15.00 ± 3.00 h. The absence of general adverse reactions in the turtles of the study, and the favourable pharmacokinetic properties (long half-life and high maximum plasma concentration) of MBX administered PO at the single-dose of 2 mg kg⁻¹ suggest the possibility of its safe and effective clinical use in loggerhead sea turtles.     

Pharmacokinetic/pharmacodynamic evaluation of marbofloxacin as a single injection for Pasteurellaceae respiratory infections in cattle using population pharmacokinetics and Monte Carlo simulations

Population pharmacokinetic of marbofloxacin was investigated with 52 plasma concentration–time profiles obtained after intramuscular administration of Forcyl® in cattle. Animal's status, pre‐ruminant, ruminant, or dairy cow, was retained as a relevant covariate for clearance. Monte Carlo simulations were performed using a stratification by status, and 1000 virtual disposition curves were generated in each bovine subpopulation for the recommended dosage regimen of 10 mg/kg as a single injection. The probability of target attainment (PTA) of pharmacokinetic/pharmacodynamic (PK/PD) ratios associated with clinical efficacy and prevention of resistance was determined in each simulated subpopulation. The cumulative fraction of response (CFR) of animals achieving a PK/PD ratio predictive of positive clinical outcome was then calculated for the simulated dosage regimen, taking into account the minimum inhibitory concentration (MIC) distribution of Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni. When considering a ratio of AUC_0‐24 hr/MIC (area under the curve/minimum inhibitory concentration) greater than 125 hr, CFRs ranging from 85% to 100% against the three Pasteurellaceae in each bovine subpopulation were achieved. The PTA of the PK/PD threshold reflecting the prevention of resistances was greater than 90% up to MPC (mutant prevention concentration) values of 1 μg/ml in pre‐ruminants and ruminants and 0.5 μg/ml in dairy cows.     

Pharmacokinetic–pharmacodynamic relationship of marbofloxacin for Escherichia coli and Pasturella multocida following repeated intramuscular administration in goats

The pharmacokinetics (PK) and pharmacodynamics (PD) of marbofloxacin (MBF) were determined in six healthy female goats of age 1.00–1.25 years after repeated administration of MBF. The MBF was administered intramuscularly (IM) at 2 mg kg^?1 day^?1 for 5 days. Plasma concentrations of MBF were determined by high‐performance liquid chromatography, and PK parameters were obtained using noncompartmental analysis. The MBF concentrations peaked at 1 hr, and peak concentration (C_max) was 1.760 µg/ml on day 1 and 1.817 µg/ml on day 5. Repeated dosing of MBF caused no significant change in PK parameters except area under curve (AUC) between day 1 (AUC_0–∞D1 = 7.67 ± 0.719 µg × hr/ml) and day 5 (AUC_0‐∞D5 = 8.70 ± 0.857 µg × hr/ml). A slight difference in mean residence time between 1st and 5th day of administration and accumulation index (AI = 1.13 ± 0.017) suggested lack of drug accumulation following repeated IM administration up to 5 days. Minimum inhibitory concentration (MIC) demonstrated that Escherichia coli (MIC = 0.04 µg/ml) and Pasturella multocida (MIC = 0.05 µg/ml) were highly sensitive to MBF. Time‐kill kinetics demonstrated rapid and concentration‐dependent activity of MBF against these pathogens. PK/PD integration of data for E. coli and P. multocida, using efficacy indices: C_max/MIC and AUC_0–24hr/MIC, suggested that IM administration of MBF at a dose of 2 mg kg^?1 day^?1 is appropriate to treat infections caused by E. coli. However, a dose of 5 mg kg^?1 day^?1 is recommended to treat pneumonia caused by P. multocida in goats. The study indicated that MBF can be used repeatedly at dosage of 2 mg/kg in goats without risk of drug accumulation up to 5 days.     

Pharmacokinetic/pharmacodynamic integration of cefquinome against Pasteurella Multocida in a piglet tissue cage model

To explore the in vivo antimicrobial activity of cefquinome against Pasteurella multocida in piglets, a piglet tissue cage infection model was used in this study. After the population of P. multocida reached 10⁷ CFU/mL in a tissue cage, piglets received an intramuscular administration of cefquinome at 0.2, 0.4, 0.8, 1, 2, and 4 mg/kg once daily for 3 days. To assess the tissue cage pharmacokinetics (PKTCF) of cefquinome, tissue cage fluid was collected for cefquinome analysis at 1, 3, 6, 9, 12, and 24 hr after each of the 3 daily drug administrations. Bacteria were counted every 24 hr after drug administration and at 48 and 72 hr after the last administration. Evaluation of the relationship between pharmacokinetic/pharmacodynamic (PK/PD) parameters and the antibacterial effect showed that the surrogate of %T > minimum inhibitory concentration (MIC) (R² = 0.981) was the best PK/PD index that correlated with effectiveness of cefquinome against P. multocida. The respective values of %T > MIC required for continuous 1/3‐log, 1/2‐log, and 1‐log reductions were 14.23, 34.45, and 73.44%, respectively, during each 24‐hr treatment period. In conclusion, cefquinome exhibited a potent antibacterial effect against P. multocida. When %T > MIC reached 73.44%, cefquinome exhibited a bactericidal effect against P. multocida after three successive daily administrations.     

Pharmacokinetic/pharmacodynamic evaluation of grapiprant in a carrageenan‐induced inflammatory pain model in the rabbit

Grapiprant is the novel selective EP4 receptor inhibitor recently issued on the veterinary market for dogs affected by osteoarthritis. The aim of this study was twofold: to evaluate the pharmacokinetics and the pharmacodynamics of grapiprant in the induced inflammatory pain model in the rabbit after a single IV injection of 2 mg/kg; to compare the thermal antinociception effect after 2 mg/kg IV grapiprant, with that generated by 0.5 mg/kg meloxicam SC injected. Rabbits (n = 12) were randomly assigned to two crossover studies (single‐dose, two‐period crossover). The first study group A (n = 3) received a single IV dose of grapiprant at 2 mg/kg dissolved in ethanol. Group B (n = 3) received a single IV injection of ethanol (equivalent volume to grapiprant volume) at the same site. The second study group C (n = 3) received a single SC dose of meloxicam at 0.5 mg/kg. Group D (n = 3) received a single SC injection of 15% ethanol (equivalent volume to grapiprant volume) at the same site. After a 2‐week washout period, the groups were rotated and the experiments repeated. Blood samples (0.7 mL) were collected from the right ear artery at assigned times and grapiprant plasma concentrations determined by a validated HPLC‐FL method. Three hours prior to administration of the drugs, inflammation was induced by SC injection of lambda carrageenan (200 μL, 3% in physiological saline) under the plantar surface of the right hind paw. At a similar time to the blood collection, an infrared thermal stimuli (40 °C) was applied to the plantar surface of the rabbits’ hindlimbs to evaluate the thermal withdrawal latency (TWL). The thermal antinociceptive effect was expressed as maximum possible response (% MPR). Grapiprant plasma concentrations were detectable up to the 10‐h time point (concentration range 17–7495 ng/mL). The grapiprant‐treated group showed a significant increase in TWL from 1 h and up to 10 h after drug administration compared to the control. In contrast, the meloxicam group showed a significant increase in TWL from 4 up to 10 h after drug administration, compared to control. The maximal MPR% was not statistically different between the grapiprant and meloxicam group from 4 to 8 h, while significant differences were shown at 1, 1.5, 2, 10 and 24 h. Given these findings, grapiprant appears to be an attractive option for antinociception in rabbits, due to its rapid onset and extended duration of effect.     

Pharmacokinetic/pharmacodynamic evaluation of marbofloxacin in the treatment of Haemophilus parasuis and Actinobacillus pleuropneumoniae infections in nursery and fattener pigs using Monte Carlo simulations

This study evaluated the theoretical clinical outcome of three marbofloxacin posology regimens in two groups of pigs (weaners and fatteners) for the treatment of Actinobacillus pleuropneumoniae (App) and Haemophilus parasuis (Hp) infection and the appearance of resistant bacteria due to the antibiotic treatment. The probability of target attainment (PTA) for pharmacokinetic/pharmacodynamics (PK/PD) ratios associated with clinical efficacy and with the appearance of antimicrobial resistance for fluoroquinolones at each minimum inhibitory concentration (MIC) or mutant prevention concentration (MPC) were calculated, respectively. The cumulative fraction of response (CFR) was calculated for the three posology regimens against App and they ranged from 91.12% to 96.37% in weaners and from 93% to 97.43% in fatteners, respectively. In the case of Hp, they ranged from 80.52% to 85.14% in weaners and from 82.01% to 88.49% in fatteners, respectively. Regarding the PTA of the PK/PD threshold associated with the appearance of antimicrobial resistance, results showed that marbofloxacin would prevent resistances in most of the animals up to the MPC value of 1 μg/mL.     

Aeromonas hydrophila as cause of hemorrhagic septicemia in a ground-hornbill (Bucorvus abyssinicus)

An acute hemorrhagic septicemia in a captive ground-hornbill (Bucorvus abyssinicus) is reported. Aeromonas hydrophila was isolated from lungs, liver, kidney, and intestines. Postmortem lesions were characterized by hemorrhages in the internal organs. Microscopically, necrotic lesions were found in the liver, lungs, and kidney. Factors that might have contributed to the clinical disease condition are discussed.     

甲鱼“红脖子病”的研究

对某甲鱼养殖场1987年2～6月流行的甲鱼“红脖子病”进行了流行病学、临床,病理学、病原学、血清学等项检查,证明该病是由嗜水气单胞菌嗜水亚种所引起,故命名为甲鱼嗜水气单胞菌感染。     

The use of eugenol against Aeromonas hydrophila and its effect on hematological and immunological parameters in silver catfish (Rhamdia quelen)

The aim of this study was to evaluate the activity of eugenol against the fish pathogen Aeromonas hydrophila and eugenol's effect on hematological and natural immune parameters in silver catfish (Rhamdia quelen). In vitro, eugenol showed weak activity against A. hydrophila, but in vivo, at a subinhibitory concentration (10 mg L^?1), it promoted survival in infected silver catfish. Eugenol (50 μg mL^?1) reduced the hemolytic activity of A. hydrophila supernatant in vitro in fish erythrocytes. Subjecting catfish to eugenol baths (5 and 10 mg L^?1) for five days did not alter the hematological and immunological parameters studied in this work. Based on these results, eugenol can be used to treat or prevent bacterial diseases in fish.