Pharmacokinetics of ketorolac tromethamine in horses after intravenous,intramuscular, and oral single‐dose administration

Nonsteroidal anti‐inflammatory drugs (NSAIDs) are an integral component of equine analgesia, yet currently available NSAIDs are both limited in their analgesic efficacy and have adverse effects. The NSAID ketorolac tromethamine (KT) is widely used in humans as a potent morphine‐sparing analgesic drug but has not been fully evaluated in horses. The purpose of this study was to determine the pharmacokinetic profile of KT in horses after intravenous (i.v.), intramuscular (i.m.), and oral (p.o.) administration. Nine healthy adult horses received a single 0.5‐mg/kg dose of KT via each route of administration. Plasma was collected up to 48 h postadministration and analyzed for KT concentration using HPLC/MS/MS. Noncompartmental analysis of i.v. dosage indicated a mean plasma clearance of 8.4 (mL/min)/kg and an estimated mean volume of distribution at steady‐state of 0.77 L/kg. Noncompartmental analysis of i.v., i.m., and p.o. dosages indicated mean residence times of 2.0, 2.6, and 7.1 h, respectively. The drug was rapidly absorbed after i.m. and p.o. administration, and mean bioavailability was 71% and 57% for i.m. and p.o. administration, respectively. Adverse effects were not observed after i.v., i.m., and p.o. administration. More studies are needed to evaluate the analgesic and anti‐inflammatory properties of KT in horses.     

Pharmacokinetics of florfenicol in blunt‐snout bream (Megalobrama amblycephala) at two water temperatures with single‐dose oral administration

The pharmacokinetics and residue elimination of florfenicol (FFC) and its metabolite florfenicol amine (FFA) were studied in healthy blunt‐snout bream (Megalobrama amblycephala, 50 ± 10 g). The study was conducted with a single‐dose (25 mg/kg) oral administration at a water temperature of 18 or 28°C, while in the residue elimination study, fish were administered at 25 mg/kg daily for three consecutive days by oral gavage to determine the withdrawal period (WDT) at 28°C. The FFC and FFA levels in plasma and tissues (liver, kidneys and muscle) were analysed using high‐performance liquid chromatography (HPLC). A no‐compartment model was used to analyse the concentration versus time data of M. amblycephala. In the two groups at 18 and 28°C, the maximum plasma concentration (C_max) of FFC was 5.89 and 6.21 μg/ml, while the time to reach C_max (T_max) was 5.97 and 2.84 hr, respectively. These suggested that higher temperature absorbed more drug and more quickly at M. amblycephala. And the elimination half‐life (T_1/2kβ) of FFC was calculated as 26.75 and 16.14 hr, while the total body clearance (CL) was 0.09 and 0.15 L kg^?1 hr^?1, and the areas under the concentration–time curves (AUCs) were 265.87 and 163.31 μg hr/ml, respectively. The difference demonstrated that the elimination rate of FFC in M. amblycephala at 28°C was more quickly than that at 18°C. The results of FFA showed the same trend in tissues of M. amblycephala. After multiple oral doses (25 mg/kg daily for 3 days), the k (eliminate rate constant) of FFA in M. amblycephala muscle was 0.017, the C₀ (initial concentration) was 3.07 mg/kg, and the WDT was 10 days (water temperature 28°C).     

Ketoprofen pharmacokinetics of R‐ and S‐isomers in juvenile loggerhead sea turtles (Caretta caretta) after single intravenous and single‐ and multidose intramuscular administration

Ketoprofen is a nonsteroidal anti‐inflammatory and analgesic agent that nonselectively inhibits cyclooxygenase, with both COX‐1 and COX‐2 inhibition. Recent studies on COX receptor expression in reptiles suggest that nonselective COX inhibitors may be more appropriate than more selective inhibitors in some reptiles, but few pharmacokinetic studies are available. The goal of this study was to determine single‐ and multidose (three consecutive days) pharmacokinetics of racemic ketoprofen administered intravenously and intramuscularly at 2 mg/kg in healthy juvenile loggerhead turtles (Caretta caretta). The S‐isomer is the predominant isomer in loggerhead sea turtles, similar to most mammals, despite administration of a 50:50 racemic mixture. Multidose ketoprofen administration demonstrated no bioaccumulation; therefore, once‐daily dosing will not require dose adjustment over time. S‐isomer pharmacokinetic parameters determined in this study were C_max of 10.1 μg/ml by IM injection, C₀ of 13.4 μg/ml by IV injection, AUC of 44.7 or 69.4 μg*hr/ml by IM or IV injection, respectively, and T½ of 2.8 or 3.6 hr by IM or IV injection, respectively. Total ketoprofen plasma concentrations were maintained for at least 12 hr above concentrations determined to be effective for rats and humans. A dose of 2 mg/kg either IM or IV every 24 hr is likely appropriate for loggerhead turtles.     

Pharmacokinetics of levosulpiride after single‐dose administration in goats (Capra hircus) by different routes of administration

Levosulpiride (LSP) is the l‐enantiomer of sulpiride, and LSP recently replacing sulpiride in several EU countries. Several studies about LSP in humans are present in the literature, but neither pharmacodynamic nor pharmacokinetic data of LSP is present for veterinary species. The aim of this study was to assess the pharmacokinetic profile of LSP after intravenous (IV), intramuscular (IM), and oral (PO) administration in goats. Animals (n = 6) were treated with 50 mg LSP by IV, IM, and PO routes according to a randomized cross‐over design (3 × 3 Latin‐square). Blood samples were collected prior and up to 24 hr after LSP administration and quantified using a validated HPLC method with fluorescence detection. IV and IM administration gave similar concentration versus time curve profiles. The IM mean bioavailability was 66.97%. After PO administration, the drug plasma concentrations were detectable only in the time range 1.5–4 hr, and the bioavailability (4.73%) was low. When the AUC was related to the administered dose in mg/kg, there was a good correlation in the IV and IM groups, but very low correlation for the PO route. In conclusion, the IM and IV administrations result in very similar plasma concentrations. Oral dosing of LSP in goats is probably not viable as its oral bioavailability was very low.     

Pharmacokinetics of florfenicol and its metabolite,florfenicol amine,in rice field eel (Monopterus albus) after a single‐dose intramuscular or oral administration

The pharmacokinetics of florfenicol (FF) and its metabolite, florfenicol amine (FFA), were studied in rice field eel (Monopterus albus) after a single dose (20 mg/kg) by intramuscular (i.m.) or oral gavage (p.o.) dose at 25 °C. The elimination half‐lives (t_1/2β), peak concentration of FF (C_max), and time to reach FF peak concentration (T_max) in plasma were estimated as 18.39 h, 10.83 μg/mL, and 7.00 h, respectively, after i.m. injection and 13.46 h, 8.37 μg/mL, and 5 h, respectively, after p.o. administration. The T_max values of FF in tissues (i.e., kidney, muscle, and liver) were larger for i.m. injection compared with those for p.o. administration. The t_1/2β had the following order kidney > muscle > liver for i.m. administrated and kidney > liver > muscle for p.o. administrated. The largest area under the concentration–time curve (AUC) was calculated to be 384.29 mg · h/kg after i.m. dosing, and the mean residence time (MRT) was 42.46 h by oral administration in kidney. FFA was also found in all tissues with a lower concentration than FF for both i.m. and p.o. administrations throughout the study. The elimination of FFA was slow with a t_1/2β between 18.19 and 47.80 h in plasma and tissues. The mean metabolic rate of FFA for i.m. and p.o. administrations was >23.30%.     

Pharmacokinetics of the amoxicillin–clavulanic acid combination after intravenous and oral administration in cats

The pharmacokinetic properties of amoxicillin (AMX) and clavulanic acid (CLV) were studied in healthy cats following single intravenous and oral dosage of 10 mg/kg of AMX and 2.5 mg/kg of CLV. The drug concentrations in plasma were determined by a high‐performance liquid chromatographic – tandem mass spectrometry (LC‐MS‐MS) method validated for canine plasma and further subjected to noncompartmental analysis. After intravenous injection, no significant difference (p > 0.05) was found in the volume of distribution of these two compounds. In addition, AMX and CLV were both rapidly eliminated from plasma with a clearance of 0.453 and 0.921 L hr^?1 kg^?1, respectively; however, a quicker elimination was observed for CLV (p < 0.01). After oral administration, both drugs were characterized by rapid absorption with an absorption half‐life of 1.10 and 0.70 hr for AMX and CLV, respectively. Significant differences were observed between their absorption rates (p < 0.05). However, the oral bioavailabilities of AMX and CLV (75.57% and 98.15%, respectively) were not statistically different (p > 0.05). A total intravenous or oral dose at 12.5 mg/kg of AMX and CLV (4:1) is predicted to be effective for treating those bacterial species isolated from cats with a minimum inhibitory concentration (MIC) of ≤0.25 μg/ml for 12 hr, based on a time above the MIC (T > MIC) of 40%.     

Pharmacokinetics of tapentadol in laying hens and its residues in eggs after multiple oral dose administration

1. The aim of the study was to evaluate the pharmacokinetics (PKs) of tapentadol (TAP), a novel opioid analgesic, in laying hens after intravenous (IV) and oral (PO) administration and to quantify the concentrations of TAP residues in eggs.

2. Twenty healthy laying hens were divided into three groups: A (n = 6), B (n = 6) and C (n = 8). The study was conducted in two phases. Groups A and B received TAP by IV and PO routes at the dose of 1 and 5 mg/kg, respectively.

3. No visible adverse effects were observed after administration of the drug. TAP plasma concentrations were detectable up to 4 h following administration. Following IV administration, TAP plasma concentrations were only higher than the minimal effective concentration (148 ng/ml) reported for humans for 1 h. After single PO administration, plasma concentrations of TAP would not conform to software algorithms and the PK parameters were not calculated. TAP concentration following multiple PO doses at 5 mg/kg for 5 d was found to be higher and more persistent (12 h vs. 7 h) in yolk compared with albumen.

4. This is the first PK study on the novel atypical opioid TAP in laying hens. Further studies are required to investigate the analgesic efficacy and actual effective plasma concentration of TAP in this species.     

Expression of VEGFR and PDGFR‐α/‐β in 187 canine nasal carcinomas

Radiotherapy represents the standard of care for intranasal carcinomas. Responses to tyrosine kinase inhibitors (TKIs) have been reported but data on expression of target receptor tyrosine kinases (rTKs) is limited. This study characterizes the expression of vascular endothelial growth factor receptor (VEGFR), platelet‐derived growth factor receptor (PDGFR)‐α and PDGFR‐β in canine intranasal carcinomas. Histological samples from 187 dogs were retrieved. Immunohistochemistry was performed using commercially available antibodies. Expression of rTKs was classified into weak, moderate or intense and additionally recorded as cytoplasmic, membranous, cytoplasmic‐membranous, nuclear or stromal. VEGFR was expressed in 158 dogs with predominantly moderate expression (36.9%) and a cytoplasmic‐membranous expression pattern (70.9%). PDGFR‐α was detected in 133 with predominantly weak expression (57.9%) and cytoplasmic pattern (87.9%). PDGFR‐β was identified in 74 patients with a predominantly moderate expression (17.6%) and cytoplasmic expression pattern (63.5%). Co‐expression of rTKs was common. These results confirm expression of VEGFR, PDGFR‐α and PDGFR‐β in canine intranasal carcinomas and support the utility of TKIs.     

Photodynamic detection of canine mammary gland tumours after oral administration of 5‐aminolevulinic acid

5‐Aminolevulinic acid (5‐ALA) is widely used in photodynamic detection (PDD) and therapy. We evaluated the pharmacokinetics of 5‐ALA‐induced porphyrins and its effectiveness in PDD in dogs with mammary gland tumours (MGTs) following oral administration. Healthy dogs and those with MGTs (nine each) were orally administered 4 mg kg^?1 5‐ALA. Protoporphyrin IX (PpIX) was not detected in the plasma of healthy dogs but it peaked in dogs with MGT at 2 h after 5‐ALA administration. In the PDD study, 16 dogs with MGT were orally administered 40 mg kg^?1 5‐ALA, and MGT but not normal tissue showed red fluorescence after 2–4 h. Photon counts were 6635–63 890 and 59–4011 (median, 19 943 and 919) for MGT and non‐tumour tissues, respectively. Cell density strongly correlated with PpIX photon counts of MGT tissue of the dogs (R = 0.743, P = 0.0009). We suggest that 5‐ALA‐PDD might be an effective diagnostic tool for MGTs.     

Pharmacokinetics of single‐dose sildenafil administered orally in clinically healthy dogs: Effect of feeding and dose proportionality

Basic information related to the pharmacokinetics of sildenafil in dogs is scarce. This study aimed to describe the pharmacokinetic properties of oral sildenafil and determine the effect of feeding and dose proportionality. The effect of feeding on pharmacokinetics of sildenafil (1 mg/kg) was investigated using a crossover study with six dogs. In addition, the dose proportionality of sildenafil ranging 1–4 mg/kg was evaluated using five dogs in the fasted states. The plasma concentrations of sildenafil were determined using high‐performance liquid chromatography, and pharmacokinetic parameters were calculated using a noncompartmental analysis. Sildenafil administrations were well tolerated in all studies. Feeding reduced the area under the curve extrapolated to infinity (AUC_inf) and the maximum plasma concentration (C_max) significantly. The elimination half‐life (T_1/2) did not differ between the fasted and the fed states. For dose proportionality, nonproportional increases in AUC_inf and C_max at 1–4 mg/kg doses were detected by a power model analysis.     

Pharmacokinetics of acetaminophen after intravenous and oral administration in fasted and fed Labrador Retriever dogs

Acetaminophen (paracetamol) is used in dogs to manage fever and mild pain. The aim of this study was to assess the pharmacokinetics of acetaminophen in both fed and fasted Labrador Retrievers after a single intravenous and oral administration (20 mg/kg). Six healthy dogs underwent three treatments in a randomized block study (a, n = 2; b, n = 2; c, n = 2). In phase one, group a received acetaminophen intravenously, group b and c orally after being fasted and fed, respectively. In phase two and three, groups were swapped, and the experiment was repeated. At the end of the trial, each dog received the same treatment. Acetaminophen plasma concentrations were detected using a validated HPLC‐UV method. The pharmacokinetic analysis was performed using a noncompartmental model. Clearance, volume at steady state and half‐life of acetaminophen in Labrador Retrievers were 0.42 L/kg hr, 0.87 L/kg and 1.35 hr, respectively. No significant statistical differences were found between fasted and fed dogs regarding maximum plasma concentration, time at maximum concentration and bioavailability as measured by the AUC. Feeding does not significantly affect the acetaminophen oral pharmacokinetics.     

Alterations in activated T‐cell cytokine expression in healthy dogs over the initial 7 days of twice daily dosing with oral cyclosporine

Cyclosporine is a powerful T‐cell inhibitor used in the treatment of immune‐mediated and inflammatory diseases in the dog. There is limited information on how to best monitor patients on cyclosporine therapy. Currently, pharmacokinetic and pharmacodynamic assays are available. Pharmacokinetic assays that measure the concentration of cyclosporine in the blood are used to assess if an appropriate drug concentration has been achieved; however, target blood drug concentrations have not been shown to reliably correlate with suppression of T‐cell function in the dog. In human transplant recipients, therapeutic drug monitoring has shifted to include pharmacodynamic‐based monitoring. Our laboratory has validated a RT‐qPCR assay to measure the pharmacodynamic effects of cyclosporine in the dog. In this study, activated T‐cell expression of IL‐2 and IFN‐γ was measured using RT‐qPCR daily for 7 consecutive days in 8 healthy Walker hounds receiving oral cyclosporine at a dosage of 10 mg/kg every 12 hr. Cytokine production was found to be markedly decreased within 24 hr after the initiation of cyclosporine and remained significantly decreased for the duration of the project. Based on these results, cyclosporine causes a rapid drop in T‐cell cytokine production that is sustained with continued dosing in healthy dogs. Although performed in healthy dogs, this study demonstrated a marked decrease in cytokine suppression within 24 hr of drug administration, suggesting that pharmacodynamic monitoring of cyclosporine's effects on T cells could be considered within several days of commencing therapy in dogs suffering from life‐threatening immune‐mediated disorders.     

Effects of maternal treatment with β‐hydroxy‐β‐metylbutyrate and 2‐oxoglutaric acid on femur development in offspring of minks of the standard dark brown type

The aim of the study was to evaluate the effect of the diet, mother type and sex of the offspring on the mechanical and geometric parameters of long bones as well as bone tissue density in minks. Primiparous and multiparous dams were supplemented with β‐hydroxy β‐methylbutyrate (a metabolite of leucine, at the daily dosage of 0.02 g/kg of body weight) and/or 2‐oxoglutaric acid (a precursor of glutamine, at the daily dosage of 0.4 g/kg of body weight) during gestation. The diet did not influence bone tissue density and the length of the humerus. An increase in the length of the femur was noted in male offspring delivered by multiparous dams. The diet resulted in an increase in the weight of the humerus in males from multiparous dams and a decrease in offspring from primiparous dams. Heavier femora were noted in male offspring delivered by both types of dams. The maximum elastic strength of the humerus was higher in the offspring delivered by multiparous than primiparous dams, irrespective of the offspring sex. The diet resulted in reduction in the ultimate strength of the femur in the male offspring delivered by primiparous dams. Only females born by multiparous dams, irrespective of the diet, showed a significant increase in the cross‐sectional area of the humerus, while a significant decline was noted in males delivered by multiparous dams and in all the offspring delivered by primiparous dams. An increase in the cross‐sectional area of the femur was noted in the offspring delivered by multiparous dams, while reduction was observed in the offspring delivered by primiparous dams. These results have shown for the first time that the presence of β‐hydroxy‐β‐methylbutyrate or 2‐oxoglutaric acid in the diet of pregnant primiparous or multiparous dams unambiguously affects the geometry and mechanical properties of offspring's long bones.     

Effect of oral administration of probiotics on growth performance,apparent nutrient digestibility and stress‐related indicators in Holstein calves

This study aimed to investigate the effect of dietary supplementation with Lactobacillus plantarum and Bacillus subtilis on growth performance, apparent nutrient digestibility and stress‐related indicators in dairy calves. Twenty‐four neonatal Holstein calves were randomly allocated to three treatments: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 × 10¹⁰ CFU per head per day (CFU/h.d) of L. plantarum GF103 (LB group) or the basal diet supplemented with a mixture of L. plantarum GF103 (1.7 × 10¹⁰ CFU/h.d) and B. subtilis B27 (1.7 × 10⁸ CFU/h.d) (LBS group). Dry matter intake (DMI), average daily gain (ADG), feed conversation ratio (FCR), apparent digestibility of nutrients and stress‐related indicators were measured in this trail. The result indicated that no significant differences were observed in DMI or ADG (p > 0.05), but the FCR was improved in the LB group over the first 12 weeks (p > 0.05). The apparent digestibility of nutrients was not altered by probiotics in week 6 (p > 0.05), but the apparent digestibility of total phosphorus was significantly greater in the LB and LBS groups in week 8 (p > 0.05); additionally, an increase in the apparent digestibility of crude protein was detected in the LBS group (p > 0.05). Oral administration of L. plantarum alone improved the T‐lymphocyte transformation rate on days 58 and 62 (p > 0.05), while adding the mixture of L. plantarum and B. subtilis increased the T‐lymphocyte transformation rate (p > 0.05) but decreased the content of cortisol on day 58 (p > 0.05). No significant differences were detected between the LB and LBS groups in growth performance, apparent digestibility of nutrients and stress‐related indicators (p > 0.05). The results suggested that oral administration of L. plantarum improved growth performance, nutrient digestibility and relieved weaning stress in calves, but no additional effect was obtained by supplementation with B. subtilis.     

β‐hydroxy‐β‐methyl butyrate promotes leucine metabolism and improves muscle fibre composition in growing pigs

The aim of this study was to investigate the effects of excess leucine (Leu) vs. its metabolites α‐ketoisocaproate (KIC) and β‐hydroxy‐β‐methyl butyrate (HMB) on Leu metabolism, muscle fibre composition and muscle growth in growing pigs. Thirty‐two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed 1 of 4 diets for 45 days: basal diet, basal diet + 1.25% L‐Leu, basal diet + 1.25% KIC‐Ca, basal diet + 0.62% HMB‐Ca. Results indicated that relative to the basal diet and HMB groups, Leu and KIC groups exhibited increased Leu concentrations and decreased concentrations of isoleucine, valine and EAAs in selected muscle (p < 0.05) and had lower mRNA levels of MyHC I and higher expression of MyHC IIx/IIb (p < 0.05), and there was no significant difference between the basal and HMB‐supplemented groups. Moreover, the mRNA expression levels of AMPKα and UCP3 were higher but the myostatin mRNA levels were lower in the soleus muscle of the HMB group than those from other groups (p < 0.05). These findings demonstrated that doubling dietary Leu content exerted growth‐depressing effects in growing pigs; dietary KIC supplementation induced muscular branched‐chain amino acid imbalance and promoted muscle toward a more glycolytic phenotype; while dietary HMB supplementation promoted the generation of more oxidative muscle types and increased muscle growth specially in oxidative skeletal muscle, and these effects of HMB might be associated with the AMPKα‐Sirt1‐PGC‐1α axis and mitochondrial biogenesis.     

Effects of oral administration of heat‐killed Enterococcus faecium strain NHRD IHARA in post‐weaning piglets

Probiotic bacteria such as lactic acid bacteria (LAB) have recently received attention as candidates for alternative anti‐microbial feed additives. We previously isolated Enterococcus faecium strain NHRD IHARA (FERM BP‐11090, NHRD IHARA strain) and reported its probiotic efficacy. However, we have not determined the effect of oral administration of heat‐killed cells of this strain. Here, we performed two experiments to investigate the effect of oral administration of the heat‐killed NHRD IHARA strain on post‐weaning piglets. In Experiment 1, there was a significant improvement in growth performance (P = 0.04) and increase in serum immunoglobulin A (IgA) production (P = 0.03) in the group fed heat‐killed cells. These results were similar to previous results we obtained with live cells. We also found changes in serum and fecal IgA production that were unrelated to the patterns of microbiotal change. In Experiment 2, we detected a significant improvement in villus growth in the jejunum (P = 0.0002). In conclusion, oral administration of the heat‐killed NHRD IHARA strain in post‐weaning piglets had the same efficacy as administration of the live strain. The heat‐killed NHRD IHARA strain can be used as feed additives to improve pig growth and health on commercial farms.