Preparation of a newly formulated long-acting ceftiofur hydrochloride suspension and evaluation of its pharmacokinetics in pigs

Intestinal Exposure to Ceftiofur and Cefquinome after Intramuscular Treatment and the Impact of Ceftiofur on the Pig Fecal Microbiome and Resistome

Optimization of antimicrobial treatment during a bacterial infection in livestock requires in-depth knowledge of the impact of antimicrobial therapy on the pathogen and commensal microbiota. Once administered antimicrobials and/or their metabolites are excreted either by the kidneys through urine and/or by the intestinal tract through feces, causing antimicrobial pressure and possibly the emergence of resistance in the gastro-intestinal tract. So far, the excretion of ceftiofur and cefquinome in the intestinal tract of pigs has not been described. The objective of this study was to investigate the excretion of ceftiofur and cefquinome in the different segments of the gut and feces after intramuscular administration. Therefore, 16 pigs were treated either with ceftiofur (n = 8) or cefquinome (n = 8), and feces were collected during the entire treatment period. The presence of ceftiofur and desfuroylceftiofuracetamide or cefquinome were quantified via liquid chromatography−tandem mass spectrometry. At the end of the treatment, pigs were euthanized, and samples from the duodenum, jejunum, ileum and cecum were analyzed. In feces, no active antimicrobial residues could be measured, except for one ceftiofur-treated pig. In the gut segments, the concentration of both antimicrobials increased from duodenum toward the ileum, with a maximum in the ileum (187.8 ± 101.7 ng·g−1 ceftiofur-related residues, 57.8 ± 37.5 ng·g−1 cefquinome) and sharply decreased in the cecum (below the limit of quantification for ceftiofur-related residues, 6.4 ± 4.2 ng·g−1 cefquinome). Additionally, long-read Nanopore sequencing and targeted quantitative polymerase chain reaction (qPCR) were performed in an attempt to clarify the discrepancy in fecal excretion of ceftiofur-related residues between pigs. In general, there was an increase in Prevotella, Bacteroides and Faecalibacterium and a decrease in Escherichia and Clostridium after ceftiofur administration (q-value < 0.05). The sequencing and qPCR could not provide an explanation for the unexpected excretion of ceftiofur-related residues in one pig out of eight. Overall, this study provides valuable information on the gut excretion of parenteral administered ceftiofur and cefquinome.

Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Methods for the Quantification of Cefquinome, Ceftiofur, and Desfuroylceftiofuracetamide in Porcine Feces with Emphasis on Analyte Stability

Cefquinome and ceftiofur are β-lactam antibiotics used for the treatment of bacterial infections in swine. Although these antimicrobials are administered intramuscularly, the exposure of the gut microbiota to these cephalosporins is not well described. This exposure can contribute to the emergence and spread of antimicrobials in the environment and to the possible spread of antimicrobial resistance genes. To assess the impact of drug administration on the intestinal excretion of these antimicrobials it is essential to measure the amounts of native compound and metabolites in feces. Two (ultra)-high-performance liquid chromatography-tandem mass spectrometry ((U)HPLC–MS/MS) methods were developed and validated, one for the determination of cefquinome and ceftiofur and the other for the determination of ceftiofur residues, measured as desfuroylceftiofuracetamide, in porcine feces. The matrix-based calibration curve was linear from 5 ng g⁻¹ to 1000 ng g⁻¹ for cefquinome (correlation coefficient (r) = 0.9990 ± 0.0007; goodness of fit (gof) = 3.70 ± 1.43) and ceftiofur (r = 0.9979 ± 0.0009; gof = 5.51 ± 1.14) and quadratic from 30 ng g⁻¹ to 2000 ng g⁻¹ for desfuroylceftiofuracetamide (r = 0.9960 ± 0.0020; gof = 7.31 ± 1.76). The within-day and between-day precision and accuracy fell within the specified ranges. Since β-lactam antibiotics are known to be unstable in feces, additional experiments were conducted to adjust the sampling protocol in order to minimize the impact of the matrix constituents on the stability of the analytes. Immediately after sampling, 500 µL of an 8 µg mL⁻¹ tazobactam solution in water was added to 0.5 g feces, to reduce the degradation in matrix.

PHARMACOKINETICS AND CLINICAL SAFETY OF A SUSTAINED-RELEASE FORMULATION OF CEFTIOFUR CRYSTALLINE FREE ACID IN RINGNECK DOVES (STREPTOPELIA RISORIA) AFTER A SINGLE INTRAMUSCULAR INJECTION

Ceftiofur crystalline free acid (CCFA) is a third-generation, oil-based, cephalosporin antimicrobial marketed as a once weekly treatment in cattle and swine, and as a two-time dose with 10-day duration in horses. Because handling and restraint times can be reduced, long-acting antibiotic preparations are particularly useful for treatment of nondomestic species. This study evaluated the pharmacokinetics of CCFA in ringneck doves (Streptopelia risoria). A single intramuscular (IM) injection of CCFA at 50 mg/kg was administered to each of 30 doves, and blood was collected from subsamples of 6 birds at predetermined sampling times (i.e., with a postinjection range of 0.5 to 192 hr). All ringneck doves were scheduled for euthanasia because of reasons unrelated to the study; this was performed at the conclusion of the study; and complete postmortem and histopathologic examinations were performed. Plasma concentrations of CCFA remained above the minimum inhibitory concentration (1.0 µg/ml; observed for most avian pathogenic bacteria) for 108 hr. No abnormalities were identified on individual birds before and after clinical pathology results (i.e., hematocrits and plasma biochemistry profiles), and only minimal gross and histopathologic changes such as mild tissue inflammation at the injection site were observed. Based on these results, one IM injection of CCFA at 50 mg/kg seems to be a potential option for treatment of ringneck doves.

Pharmacokinetics and relative bioavailability of meloxicam oil suspension in pigs after intramuscular administration

This study aimed to develop one novel meloxicam (MEL) oil suspension for sustained-release and compare the pharmacokinetic characteristics of it with MEL conventional formulation in pigs after a single intramuscular administration. Six healthy pigs were used for the study by a crossover design in two periods with a withdrawal interval of 14 days. Plasma concentrations of MEL were measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Pharmacokinetic parameters were calculated by noncompartmental methods. The difference was statistically significant (p < .05) between MEL oil suspension and MEL conventional formulation in pharmacokinetic parameters of mean residence time (6.16 ± 4.04) hr versus (2.66 ± 0.55) hr, peak plasma concentration (C_max ) (0.82 ± 0.12) µg/ml versus (1.12 ± 0.22) µg/ml, time needed to reach C_max (T_max ) (2.33 ± 0.82) hr versus (0.59 ± 0.18) hr, and terminal elimination half-life (t_1/2λz ) (3.74 ± 2.66) hr versus (1.55 ± 0.37) hr. The mean area under the concentration-time curve (AUC_0-∝ ) of MEL oil suspension and MEL conventional formulation was 5.35 and 3.43 hr µg/ml, respectively, with a relative bioavailability of 155.98%. Results of the present study demonstrated that the MEL oil suspension could prolong the effective time of drugs in blood, thereby reducing the frequency of administration on a course of treatment. Therefore, the novel MEL oil suspension seems to be of great value in veterinary clinical application.

Bioequivalence evaluation of two 5% ceftiofur hydrochloride sterile suspension in pigs

The purpose of this study was to evaluate the bioequivalence of 5% ceftiofur hydrochloride sterile suspension in two formulations, a test formulation (Saifukang 5% CEF, Hvsen) and a reference formulation (Excenel^®RTU 5% CEF, Pfizer). Twenty-four healthy pigs were assigned to a two-period, two-treatment crossover parallel trial, and both formulations were administered at a single intramuscular dose of 5 mg/kg weight, with a 7-day washout period. Blood samples were collected consecutively for up to 144 hr after administration. The concentrations of ceftiofur- and desfuroylceftiofur-related metabolites in the plasma were determined by high-performance liquid chromatography. In addition, the major pharmacokinetic parameters (C_max, AUC_0-t and AUC_0-∞) were computed and compared via analysis of variance, with 90% confidence intervals. Bioequivalence evaluation of T_max was statistically analyzed with the nonparametric test. The comparison values between test and reference formulation for AUC_0-t, AUC_0-∞, C_max, and T_max were 376.7 ± 75.3 µg·hr/ml, 390.5 ± 78.6 µg·hr/ml, 385.9 ± 79.2 µg·hr/ml, 402.7 ± 80.4 µg·hr/ml, 34.6 ± 5.5 µg/ml, 36.1 ± 6.2 µg/ml, 1.27 ± 0.18 hr, and 1.26 ± 0.21 hr, respectively, and we observed no significant differences between the two formulations. The 90% CI values were within the recommended range of 80–125% (P>0.05), and the relative bioavailability of the test product was 96.47 ± 10.92% according to AUC_0-t values. Based on our results, the two formulations exhibit comparable pharmacokinetic profiles, and the test product is bioequivalent to the reference formulation.

Modelling concentrations of antimicrobial drugs: comparative pharmacokinetics of cephalosporin antimicrobials and accuracy of allometric scaling in food-producing and companion animals

Background

To optimize antimicrobial dosing in different animal species, pharmacokinetic information is necessary. Due to the plethora of cephalosporin antimicrobials and animal species in which they are used, assessment of pharmacokinetics in all species is unfeasible. In this study we aimed to describe pharmacokinetic data of cephalosporins by reviewing the available literature for food producing and companion animal species. We assessed the accuracy of interspecies extrapolation using allometric scaling techniques to determine pharmacokinetic characteristics of cephalosporins in animal species for which literature data is unavailable. We assessed the accuracy of allometric scaling by comparing the predicted and the published pharmacokinetic value in an animal species/humans not included in the allometric modelling.

Results

In general, excretion of cephalosporins takes place mainly through renal mechanisms in the unchanged form and volume of distribution is limited in all animal species. Differences in plasma protein binding capacity and elimination half-life are observed but available information was limited. Using allometric scaling, correlations between body weight (BW) and volume of distribution (Vd) and clearance (Cl) were R² > 0.97 and R² > 0.95 respectively for ceftazidime, ceftiofur, cefquinome and cefepime but not ceftriaxone. The allometric exponent ranged from 0.80 to 1.31 for Vd and 0.83 to 1.24 for Cl. Correlations on half-life ranged from R² 0.07–0.655 (literature) and R² 0.102–0.876 (calculated).

Conclusions

Allometric scaling can be applied for interspecies extrapolation of cephalosporin pharmacokinetic parameters Vd and Cl, but not elimination half-life. We hypothesize that the accuracy could be improved by using more refined scaling techniques.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0817-2) contains supplementary material, which is available to authorized users.

Preclinical Development and In Vivo Efficacy of Ceftiofur-PLGA Microparticles

Drug delivery systems based on polymeric microparticles represent an interesting field of development for the treatment of several infectious diseases for humans and animals. In this work, we developed PLGA microparticles loaded with ceftiofur (PLGA-cef), a third- generation cephalosporin that is used exclusively used in animals. PLGA-cef was prepared by the double emulsion w/o/w method, and exhibited a diameter in the range of 1.5–2.2 μm, and a negative ζ potential in the range of -35 to -55 mV. The loading yield of PLGA-cef was ~7% and encapsulation efficiency was approximately 40%. The pharmacokinetic study demonstrated a sustained release profile of ceftiofur for 20 days. PLGA-cef administrated in a single dose was more effective than ceftiofur non-encapsulated in rats challenged with S. Typhimurium. The in vivo toxicological evaluation showed that PLGA-cef did not affect the blood biochemical, hematological and hemostasis parameters. Overall, the PLGA-cef showed slow in vivo release profile, high antibacterial efficacy, and low toxicity. The results obtained supports the safe application of PLGA-cef as sustained release platform in the veterinary industry.

Evaluation of ceftiofur-PHBV microparticles in rats

Despite the high number of antibiotics used for the treatment of infectious disease in animals, the development of slow release formulations presents a significant challenge, particularly in using novel biomaterials with low cost. In this report, we studied the pharmacokinetics, toxicity, and therapeutic activity of ceftiofur–PHBV (ceftiofur–poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) in rats. The pharmacokinetic study demonstrated a sustained release of ceftiofur into the bloodstream, with detectable levels over the minimum inhibitory concentration for at least 17 days after a single intramuscular injection of ceftiofur–PHBV (10 mg/kg weight). In addition, the toxicological evaluation of biochemical, hematological, and coagulation blood parameters at the therapeutic dose demonstrated the safety of ceftiofur–PHBV, with no adverse effects. In addition, ceftiofur–PHBV exhibited a therapeutic effect for a longer time period than the nonencapsulated ceftiofur in rats challenged with Salmonella Typhimurium. The slow release of ceftiofur from the ceftiofur–PHBV, its low toxicity in the blood parameters evaluated, and the efficacy in the rats infected with Salmonella Typhimurium make ceftiofur–PHBV a strong candidate for biotechnological applications in the veterinary industry.