Pharmacokinetics of ceftiofur crystalline free acid after single and multiple subcutaneous administrations in healthy alpacas (Vicugna pacos)

Pharmacokinetics of Orally Administered Prednisolone in Alpacas

This study aimed to determine the pharmacokinetics of prednisolone following intravenous and oral administration in healthy adult alpacas. Healthy adult alpacas were given prednisolone (IV, n = 4), as well as orally (PO, n = 6). Prednisolone was administered IV once (1 mg/kg). Oral administration was once daily for 5 days (2 mg/kg). Each treatment was separated by a minimum 4 month washout period. Samples were collected at 0 (pre-administration), 0.083, 0.167, 0.25, 0.5, 0.75, 1, 2, 4, 8, 12, and 24 h after IV administration, and at 0 (pre-administration), 0.25, 0.5, 0.75, 1, 2, 4, 8, 12, 24 after the first and 5^th PO administration. Samples were also taken for serial complete blood count and biochemistry analysis. Prednisolone concentration was determined by high pressure liquid chromatography. Non-compartmental pharmacokinetic parameters were then determined. After IV administration clearance was 347 mL/kg/hr, elimination half-life was 2.98 h, and area under the curve was 2,940 h^*ng/mL. After initial and fifth oral administration elimination half-life was 5.27 and 5.39 h; maximum concentration was 74 and 68 ng/mL; time to maximum concentration was 2.67 and 2.33 h; and area under the curve was 713 and 660 hr^*ng/mL. Oral bioavailability was determined to be 13.7%. Packed cell volume, hemoglobin, and red blood cell counts were significantly decreased 5 days after the first PO administration, and serum glucose was significantly elevated 5 days after the first PO administration. In conclusion, serum concentrations of prednisolone after IV and PO administration appear to be similar to other veterinary species. Future research will be needed to determine the pharmacodynamics of prednisolone in alpacas.

Pharmacokinetic Modeling of Ceftiofur Sodium Using Non-linear Mixed-Effects in Healthy Beagle Dogs

Ceftiofur (CEF) sodium is a third-generation broad-spectrum cephalosporin commonly used in an extra-label manner in dogs for the treatment of respiratory and urinary system infections. To contribute to the literature supporting CEF use in companion animals, we have developed a compartmental, non-linear mixed-effects (NLME) model of CEF pharmacokinetics in dogs (PK). We then used the mathematical model to predict (via Monte Carlo simulation) the duration of time for which plasma concentrations of CEF and its pharmacologically active metabolites remained above minimum inhibitory concentrations (respiratory tract Escherichia coli spp.). Twelve healthy beagle dogs were administered either 2.2 mg/kg ceftiofur-sodium (CEF-Na) intravenously (I.V) or 2.2 mg/kg CEF-Na subcutaneously (S.C). Plasma samples were collected over a period of 72 h post-administration. To produce a measurement of total CEF, both CEF and CEF metabolites were derivatized into desfuroylceftiofur acetamide (DCA) before analysis by UPLC-MS/MS. No adverse effects were reported after I.V or S.C dosing. The NLME PK models were parameterized using the stochastic approximation expectation maximization algorithm as implemented in Monolix 2018R2. A two-compartment mamillary model with first-order elimination and first-order S.C absorption best described the available kinetic data. Final parameter estimates indicate that CEF has a low systemic clearance (0.25 L/h/kg) associated with a low global extraction ratio E = 0.02) and a moderate volume of distribution (2.97 L/kg) in dogs. The absolute bioavailability after S.C administration was high (93.7%). Gender was determined to be a significant covariate in explaining the variability of S.C absorption. Our simulations predicted that a dose of 2.2 mg/kg CEF-Na S.C would produce median plasma concentrations of CEF of at least 0.5 μg/mL (MIC₅₀) for ~30 h.

ACUTE CLINICAL LEPTOSPIROSIS (GRIPPOTYPHOSA SEROVAR) IN AN ADULT DROMEDARY CAMEL (CAMELUS DROMEDARIUS)

A 9-yr-old castrated male dromedary camel (Camelus dromedarius) presented with lethargy and partial anorexia. A diagnostic examination revealed fever, and further workup revealed a neutrophilia, hyperfibrinogenemia, renal azotemia, and a rapid onset of a high Leptospira antibody titer during the acute clinical period (Grippotyphosa serovar). The camel responded clinically to antimicrobial treatment with ceftiofur crystalline free acid injections, but renal azotemia persisted, presumably secondary to chronic renal damage. Subsequent Leptospira polymerase chain reaction testing on urine samples obtained over the following 4 mo revealed no evidence of urinary shedding, so a persistent infection was unlikely. Although often mentioned as a potential cause of reproductive loss, well-documented case reports of clinical leptospirosis in camelids are very rare. In this case, native wildlife contamination of a small watering hole is suspected to have been the source of infection. In response to this experience, the camel and two conspecifics were prescribed a vaccination regimen using an inactivated pentavalent Leptospira vaccine licensed for cattle.

Evaluation of an extended-release formulation of ceftiofur crystalline-free acid in koi (Cyprinus carpio)

The use of an extended release ceftiofur crystalline-free acid formulation (CCFA, Excede For Swine(®) , Pfizer Animal Health) in koi was evaluated after administration of single intramuscular (i.m.) or intracoelomic (i.c.) doses. Twenty koi were divided randomly into a control group and four treatment groups (20 mg/kg i.m., 60 mg/kg i.m., 30 mg/kg i.c., and 60 mg/kg i.c.). Serum ceftiofur-free acid equivalents (CFAE) concentrations were quantified. The pharmacokinetic data were analyzed using a nonlinear mixed-effects approach. Following a CCFA injection of 60 mg/kg i.m., time durations that serum CFAE concentrations were above the target concentration of 4 μg/mL ranged from 0.4 to 2.5 weeks in 3 of 4 fish, while serum CFAE concentrations remained below 4 μg/mL for lower doses evaluated. Substantial inter-individual variations and intra-individual fluctuations of CFAE concentrations were observed for all treatment groups. Histological findings following euthanasia included aseptic granulomatous reactions, but no systemic adverse effects were detected. Given the unpredictable time vs. CFAE concentration profiles for treated koi, the authors would not recommend this product for therapeutic use in koi at this time. Further research would be necessary to correlate serum and tissue concentrations and to better establish MIC data for Aeromonas spp. isolated from naturally infected koi.

Pharmacokinetics of ceftiofur crystalline-free acid (EXCEDE sterile suspension) administered via intramuscular injection in wild California sea lions (Zalophus californianus)

The pharmacokinetics of ceftiofur crystalline-free acid (EXCEDE Sterile Suspension, 200 mg ceftiofur equivalents/ml) were determined for the California sea lion (Zalophus californianus). A single dose of EXCEDE was administered intramuscularly at 6.6 mg/kg to 12 wild California sea lions during rehabilitation. The first 10 animals were each assigned to two blood collection time points, with a total of 10 time points at: 6, 12, 24, 48, 72, 96, 120, 144, 168, and 192 hr after administration of the drug. An additional two animals were sampled 1, 2, 3, 4, 5, and 6 hr postinjection. Plasma was separated within 10 min of blood collection and stored at -20 degrees C until analysis. Plasma concentrations of ceftiofur, desfuroylceftiofur, and related metabolites, were determined using liquid chromatography with tandem mass spectrometry (MS). Maximum plasma concentrations of ceftiofur and related metabolites were observed 24 hr postdosing with a mean concentration of 3.6 microg/ml. The half life (60 hr) and area under the curve (270 microg x hr/ml) were also determined. These data indicate that a single dose of EXCEDE at 6.6 mg/kg i.m. would likely maintain a mean plasma drug level >0.6 microg/ml for 5 days and >0.5 microg/ml for 8 days.