Pharmacokinetics of intranasal and intramuscular flunixin in healthy grower pigs.

Flunixin meglumine is a nonsteroidal anti-inflammatory drug approved to manage pyrexia associated with swine respiratory disease. In the United States, no analgesic drugs are approved for use in swine by the FDA, although they are needed to manage painful conditions. This study evaluated the pharmacokinetics and relative bioavailability of intranasal versus intramuscular flunixin in grower pigs. Six pigs received 2.2 mg/kg flunixin either intranasally via atomizer or intramuscularly before receiving flunixin via the opposite route following a 5-day washout period. Plasma samples were collected over 60 h and analysed using ultra-performance liquid chromatography and tandem mass spectrometry to detect flunixin plasma concentrations. A non-compartmental pharmacokinetic analysis was performed. The median Cmax was 4.0 µg/mL and 2.7 µg/mL for intramuscular and intranasal administration, respectively, while the median AUCinf was 6.9 h µg/mL for intramuscular administration and 4.9 h µg/mL for intranasal administration. For both routes, the median Tmax was 0.2 h, and flunixin was detectable in some samples up to 60 h post-administration. Intranasal delivery had a relative bioavailability of 88.5%. These results suggest that intranasal flunixin has similar, although variable, pharmacokinetic parameters to the intramuscular route, making it a viable route of administration for use in grower swine.

Pharmacokinetics of intravenous, oral transmucosal, and intranasal buprenorphine in healthy male dogs.

Effective management of pain in animals is of critical importance but options are limited for treating acute pain in dogs on an outpatient basis. The objective of this study was to compare the plasma concentrations and pharmacokinetics of a concentrated solution of buprenorphine, 1.8 mg/ml (Simbadol™) administered intravenously, intranasally, and via the oral transmucosal (OTM) route in healthy male dogs. Five healthy castrated adult male Beagle-cross dogs were included in this randomized blocked crossover study. The dogs received 0.03 mg/kg body weight buprenorphine intravenously, intranasally, or via the OTM route, with a minimum 72-h washout period between treatments. Blood samples were collected at multiple intervals up to 24 h post administration and buprenorphine plasma concentrations were determined by liquid chromatography tandem mass spectrometry. Non-compartmental pharmacokinetic analysis revealed that the area under the curve of intravenous, intranasal, and OTM routes were 28.0 (15.1-41.3) h × ng/ml, 16.1 (3.4-28.7) h × ng/ml and 10.8 (8.8-11.8) h × ng/ml, respectively. The bioavailability of intranasal and OTM routes were 57.5 (22.7-93.7)% and 41.1 (25.5-69.4)%, respectively. Intranasal and OTM routes of administration of concentrated buprenorphine in dogs may allow for the provision of analgesic care at home.

Pharmacokinetic/pharmacodynamic modeling of ketoprofen and flunixin at piglet castration and tail-docking.

This study performed population-pharmacokinetic/pharmacodynamic (pop-PK/PD) modeling of ketoprofen and flunixin in piglets undergoing routine castration and tail-docking, utilizing previously published data. Six-day-old male piglets (8/group) received either ketoprofen (3.0 mg/kg) or flunixin (2.2 mg/kg) intramuscularly. Two hours post-dose, piglets were castrated and tail docked. Inhibitory indirect response models were developed utilizing plasma cortisol or interstitial fluid prostaglandin E2 (PGE2) concentration data. Plasma IC50 for ketoprofen utilizing PGE2 as a biomarker was 1.2 µg/ml, and ED50 for was 5.83 mg/kg. The ED50 calculated using cortisol was 4.36 mg/kg; however, the IC50 was high, at 2.56 µg/ml. A large degree of inter-individual variability (124.08%) was also associated with the cortisol IC50 following ketoprofen administration. IC50 for flunixin utilizing cortisol as a biomarker was 0.06 µg/ml, and ED50 was 0.51 mg/kg. The results show that the currently marketed doses of ketoprofen (3.0 mg/kg) and flunixin (2.2 mg/kg) correspond to drug responses of 33.97% (ketoprofen-PGE2), 40.75% (ketoprofen-cortisol), and 81.05% (flunixin-cortisol) of the maximal possible responses. Given this information, flunixin may be the best NSAID to use in mitigating castration and tail-docking pain at the current label dose.

Intravenous dexmedetomidine, morphine, or a combination can result in gallbladder wall thickening; with no significant association with plasma histamine concentrations.

The gallbladder is routinely evaluated during ultrasonographic examinations in dogs. However, published studies describing the effects of sedative agents on gallbladder wall thickness are currently lacking. The aims of this prospective, blinded, randomized crossover pilot study were to test hypotheses that IV morphine would result in gallbladder wall thickening, that morphine administration would increase plasma histamine concentrations, and that combining IV morphine with dexmedetomidine would potentiate gallbladder wall thickening. Six healthy Beagle dogs were sedated with intravenous (IV) morphine 0.4 mg/kg (group M), dexmedetomidine 7 µg/kg (group D), or a combination of the two (group MD). Physiologic parameters were measured at baseline and at regular intervals until the last ultrasonographic scan. Ultrasonographic scans were performed at baseline, 90 s, and at 5, 15, 30, 45, 60, 90, and 120 min. Plasma histamine samples were taken at baseline, 90 s, and 5 and 60 min. Cochran's Q-test was used to compare gallbladder wall thickening between groups, while the association between histamine plasma concentration and gallbladder wall thickness was compared with a mixed-effects model. Baseline gallbladder wall thickness was not significantly different between groups. Six of 18 treatments/dogs (33%) developed gallbladder thickening, with no difference between groups. There was no significant difference in baseline plasma histamine concentrations between groups, and no association between plasma histamine concentration and gallbladder wall thickness. Gallbladder wall thickening was observed in at least one dog in each group, therefore caution is recommended for gallbladder wall thickness ultrasonographic interpretation in dogs when these drugs have been administered.

Pharmacokinetic and safety assessment of carboplatin-impregnated calcium sulfate hemihydrate beads in eight rats.

OBJECTIVE: Evaluate local tissue toxicity and plasma platinum (Pt) in vivo after subcutaneous implantation of carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads. STUDY DESIGN: In vivo experimental study. ANIMALS: Eight male Sprague-Dawley rats. METHODS: CI-CSH beads were implanted subcutaneously (5 mg carboplatin/rat; 13.5 mg/kg carboplatin; 7.08 mg/kg Pt; 1.18 mg/m2 Pt) in eight rats (d0). Wound healing (daily), radiographic bead dissolution (weekly), systemic Pt uptake (plasma-Pt), local tissue Pt (d28), and histologic changes compared to nonincised and incised catheterization sites (d28) were assessed. Blood and tissue samples were analyzed by inductively coupled plasma mass spectrometry for Pt, and pharmacokinetic analysis was performed using noncompartmental methods. RESULTS: One rat died at d10, the remainder survived until d28. No wound complications were seen. The CI-CSH implantation site had higher histopathology scores than the other sites for necrosis (p = .013) and fibrosis (p = .013). Beads decreased in density radiographically (d0 to d28) (p = .062). Peak plasma-Pt concentration was 225.78 ng/ml at 12 h, and decreased over time, but Pt was still detectable on d28. The elimination half-life was 5.03 ± 1.13 days. Only 1.69% of implanted Pt remained in the beads at d28. CONCLUSIONS: CI-CSH beads incited microscopic mild inflammation but wound healing was not impaired. Pt was absorbed systemically and the release from the beads was near complete at d28. CLINICAL SIGNIFICANCE: Piled CI-CSH bead implantation is well tolerated in rats with similar elution profile as previously described. Beads were radiographically visible at d28. Minimal Pt was detected systemically suggesting Pt release does not match bead dissolution.

Sterility and concentration of liposomal bupivacaine single-use vial when used in a multiple-dose manner.

OBJECTIVE: To evaluate the sterility of bupivacaine liposome injectable suspension (Nocita®) used in a multiple-dose fashion for 5 days. STUDY DESIGN: Triplicate liposomal bupivacaine vials were stored under two conditions, (1) room temperature (24°C) and (2) refrigerated temperature (5°C). A 3-mL aliquot was withdrawn from each vial daily. Samples were inoculated in tryptic soy broth in triplicate and then incubated for 24 hours at 37°C and subcultured every 48 hours onto blood agar and Sabouraud dextrose agar, respectively. Separate 1.5-mL aliquots of liposomal bupivacaine were centrifuged at 3500 g to separate liposome-encapsulated bupivacaine from the solution. Concentration of unencapsulated bupivacaine was analyzed via high-pressure liquid chromatography. Data were analyzed by using mixed effects procedure with multiple comparisons. SAMPLE POPULATION: Ten 20-mL vials of bupivacaine liposome injectable suspension stored under two conditions, (1) room temperature (24°C) and (2) refrigerated temperature (5°C). RESULTS: Five days of repeated withdrawal from the single-use vials yielded no bacterial growth. One control vial, which was opened and punctured once on the last day of the experiment, yielded fungal growth of an Aspergillus spp, likely an environmental contaminant. The concentration of free bupivacaine did not significantly differ until the fifth day of sampling. CONCLUSION: When aseptic technique was used, liposomal bupivacaine remained sterile for 5 days. Concentrations of free bupivacaine were unchanged from baseline for 4 days in both refrigerated and room temperature conditions. CLINICAL SIGNIFICANCE: Single-use liposomal bupivacaine vials can be used extralabel in a multiple-dose fashion for up to 4 days when stored either refrigerated or room temperature when sterile technique is used.

Pharmacokinetics and pharmacodynamics of alfaxalone after a single intramuscular or intravascular injection in mallard ducks (Anas platyrhynchos).

Pharmacokinetics and pharmacodynamics of alfaxalone was performed in mallard ducks (Anas platyrhynchos) after single bolus injections of 10 mg/kg administered intramuscularly (IM; n = 10) or intravenously (IV; n = 10), in a randomized cross-over design with a washout period between doses. Mean (±SD) Cmax following IM injection was 1.6 (±0.8) µg/ml with Tmax at 15.0 (±10.5) min. Area under the curve (AUC) was 84.66 and 104.58 min*mg/ml following IV and IM administration, respectively. Volume of distribution (VD ) after IV dose was 3.0 L/kg. The mean plasma clearance after 10 mg/kg IV was 139.5 (±67.9) ml min-1  kg-1 . Elimination half-lives (mean [±SD]) were 15.0 and 16.1 (±3.0) min following IV and IM administration, respectively. Mean bioavailability at 10 mg/kg IM was 108.6%. None of the ducks achieved a sufficient anesthetic depth for invasive procedures, such as surgery, to be performed. Heart and respiratory rates measured after administration remained stable, but many ducks were hyperexcitable during recovery. Based on sedation levels and duration, alfaxalone administered at dosages of 10 mg/kg IV or IM in mallard ducks does not induce clinically acceptable anesthesia.

Pharmacokinetics and pharmacodynamic effects in koi carp (Cyprinus carpio) following immersion in propofol.

OBJECTIVE: To test the hypothesis that plasma propofol concentration (PPC) is associated with anesthetic effect in koi carp administered propofol by immersion. STUDY DESIGN: Prospective study. ANIMALS: Twenty mature koi carp (mean ± standard deviation, 409.4 ± 83.7 g). METHODS: Fish were immersed in propofol (5 mg L-1). Physiological variables and induction and recovery times were recorded. In phase I, blood was sampled for PPC immediately following induction and at recovery. In phase II, following induction, fish were maintained with propofol (4 mg L-1) via a recirculating system for 20 minutes. Following established induction, blood was sampled at 1, 10 and 20 minutes. In phase III (n = 19), fish were anesthetized as in phase II with blood sampled nine times in a sparse sampling strategy. Simultaneously, a pharmacodynamics rubric was used to evaluate anesthetic depth. PPC was determined using high performance liquid chromatography with fluorescence detection. Following evaluation of normality, data were analyzed using paired t test or Spearman correlation test (significance was set at p < 0.05). RESULTS: In phase I, mean PPCs at induction (20.12 µg mL-1) and recovery (11.62 µg mL-1) were different (p < 0.001). In phase II, only mean PPCs at induction (17.92 µg mL-1) and 10 minutes (21.50 µg mL-1) were different (p = 0.013). In phase III, a correlation between PPCs and the pharmacodynamic rubric scores was found (p < 0.001, r = -0.93). There was no correlation between PPCs and recovery time (p = 0.057, r = 0.433). A two-compartment open model was chosen for the pharmacokinetic model. Absorption rate constant, elimination rate constant and intercompartmental rate constant were 0.48, 0.006 and 0.02 minute-1, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Measurable PPCs were achieved in koi carp anesthetized with propofol by immersion. Anesthetic depth of fish was negatively correlated with PPCs, but recovery time was not.

Pharmacokinetics of a continuous intravenous infusion of hydromorphone in healthy dogs.

Introduction: Dosing recommendations for hydromorphone intravenous constant rate infusion (IV CRI) are derived from simulations following IV bolus administration. While this extrapolated dose regimen has been described clinically, pharmacokinetics (PK) of hydromorphone infusions in dogs are not yet described. The study objective was to describe the PK of hydromorphone in healthy dogs receiving an IV bolus followed by an IV CRI for 48 h. Methods: A prospective, experimental study was performed involving the administration of hydromorphone (0.1 mg/kg IV bolus then IV CRI 0.01 mg/kg/h over a 48 h period) to 6 healthy Beagle dogs. Blood samples were collected at 16 time points between 0 and 58 h relative to the initial bolus. Plasma hydromorphone concentrations were analyzed by high pressure liquid chromatography with tandem mass spectrometry detection. Pharmacokinetic parameter estimates were obtained with compartmental methods using commercially available software. Results: A two-compartment model with first order elimination was used. At the end of the infusion, median (range) plasma hydromorphone concentrations were 6.8 (5.5-19.6) ng/mL. The median total body clearance was 30.4 (19.8-36.7) mL/min/kg; volume of distribution at steady state was 4.5 (3.2-7.8) L/kg; and terminal elimination half-life was 11.2 (7.6-24.3) h. Conclusion: Hydromorphone (0.1 mg/kg IV bolus then IV CRI of 0.01 mg/kg/h) maintained steady-state plasma concentrations above the minimum human analgesic target in healthy Beagle dogs with minimal side effects. Further studies are needed to determine the effective plasma concentrations of hydromorphone in painful dogs.

Systemic absorption of triamcinolone acetonide is increased from intrasynovial versus extrasynovial sites and induces hyperglycemia, hyperinsulinemia, and suppression of the hypothalamic-pituitary-adrenal axis.

Steroid-associated laminitis remains a major concern with use of corticosteroids in horses. Individual case factors such as joint pathology, pre-existing endocrinopathies, or corticosteroid type, dose, and timing influencing steroid-induced laminitis risk have not been investigated. This study aimed to determine if systemic absorption of triamcinolone acetonide (TA) varies between intrasynovial (antebrachiocarpal) and extrasynovial (sacroiliac) injection sites, and to determine the effects of TA absorption on glucose, insulin, cortisol, and adrenocorticotropic hormone (ACTH). Twenty adult horses were randomized into antebrachiocarpal or sacroiliac joint injection groups, and each horse received bilateral injections with a total dose of 18 mg triamcinolone. Blood was collected prior to injection and at 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 36, 48, 60, and 72 h post-injection. Peak TA absorption occurred at 8 h in both groups, and was significantly higher in the intrasynovial group compared to the extrasynovial group (1.397 ng/mL, 0.672 ng/mL, p < 0.05). Plasma TA levels were significantly higher in the intrasynovial group from 8 to 36 h post-injection (p < 0.05). There was no difference in glucose, insulin, cortisol, or ACTH between groups at any time point. Insulin and glucose were significantly increased from baseline at all timepoints from 10-72 h and 1-72 h post-injection, respectively. Horses with elevated baseline insulin values (>20 µU/mL) from both groups experienced a more marked hyperinsulinemia, reaching a mean peak insulin of 197.5 µU/mL as compared to 90.06 µU/mL in those with normal baseline insulin. Cortisol and ACTH were significantly decreased from baseline at timepoints from 4-72 h post-injection in both groups. This study is the first to evaluate drug absorption from the sacroiliac site and demonstrates that drug absorption varies between intrasynovial and extrasynovial injection sites. TA absorption causes metabolic derangements, most notably a marked hyperinsulinemia that is more severe in horses with elevated baseline insulin values. The influence of baseline endocrinopathies on response to corticosteroid administration as well as the effect of corticosteroid-induced metabolic derangements warrant further investigation as risk factors for corticosteroid-associated laminitis.

Pharmacokinetics and efficacy of orally administered acetaminophen (paracetamol) in adult horses with experimentally induced endotoxemia.

BACKGROUND: Acetaminophen has been evaluated in horses for treatment of musculoskeletal pain but not as an antipyretic. OBJECTIVES: To determine the pharmacokinetics and efficacy of acetaminophen compared to placebo and flunixin meglumine in adult horses with experimentally induced endotoxemia. ANIMALS: Eight university owned research horses with experimentally induced endotoxemia. METHODS: Randomized placebo controlled crossover study. Horses were treated with acetaminophen (30 mg/kg PO; APAP), flunixin meglumine (1.1 mg/kg, PO; FLU), and placebo (PO; PLAC) 2 hours after administration of LPS. Plasma APAP was analyzed via LC-MS/MS. Serial CBC, lactate, serum amyloid A, heart rate and rectal temperature were evaluated. Serum IL-1ß, IL-6, IL-8, IL-10, and TNF-α were evaluated by an equine-specific multiplex assay. RESULTS: Mean maximum plasma APAP concentration was 13.97 ± 2.74 µg/mL within 0.6 ± 0.3 hour after administration. At 4 and 6 hours after treatment, both APAP (P = <.001, P = .03, respectively) and FLU (P = .0045 and P < .001, respectively) had a significantly greater decrease in rectal temperature compared to placebo. FLU caused greater heart rate reduction than APAP at 4 and 6 hours (P = .004 and P = .04), and PLAC at 4 hours (P = .05) after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: The pharmacokinetics of acetaminophen in endotoxemic horses differ from those reported by previous studies in healthy horses. Acetaminophen is an option for antipyresis in clinical cases, particularly when administration of traditional NSAIDs is contraindicated.

The effect of a ketamine constant rate infusion on cardiovascular variables in sheep anesthetized at the minimum alveolar concentration of sevoflurane that blunts adrenergic responses.

OBJECTIVE: To evaluate the effect of a constant rate infusion of ketamine on cardiac index (CI) in sheep, as estimated using noninvasive cardiac output (NICO) monitoring by partial carbon dioxide rebreathing, when anesthetized with sevoflurane at the previously determined minimum alveolar concentration that blunts adrenergic responses (MACBAR). ANIMALS: 12 healthy Dorset-crossbred adult sheep. PROCEDURES: Sheep were anesthetized 2 times in a balanced placebo-controlled crossover design. Anesthesia was induced with sevoflurane delivered via a tight-fitting face mask and maintained at MACBAR. Following induction, sheep received either ketamine (1.5 mg/kg IV, followed by a constant rate infusion of 1.5 mg/kg/h) or an equivalent volume of saline (0.9% NaCl) solution (placebo). After an 8-day washout period, each sheep received the alternate treatment. NICO measurements were performed in triplicate 20 minutes after treatment administration and were converted to CI. Blood samples were collected prior to the start of NICO measurements for analysis of ketamine plasma concentrations. The paired t test was used to compare CI values between groups and the ketamine plasma concentrations with those achieved during the previous study. RESULTS: Mean ± SD CI of the ketamine and placebo treatments were 2.69 ± 0.65 and 2.57 ± 0.53 L/min/m2, respectively. No significant difference was found between the 2 treatments. Mean ketamine plasma concentration achieved prior to the NICO measurement was 1.37 ± 0.58 µg/mL, with no significant difference observed between the current and prior study. CLINICAL RELEVANCE: Ketamine, at the dose administered, did not significantly increase the CI in sheep when determined by partial carbon dioxide rebreathing.

Preliminary evaluation of the effects of grapiprant compared with carprofen on acute pain and inflammation following ovariohysterectomy in dogs.

OBJECTIVE: To compare the analgesic efficacy of grapiprant to carprofen for the treatment of postoperative pain and inflammation in dogs following ovariohysterectomy. ANIMALS: 12 purpose-bred adult sexually intact female Beagles. PROCEDURES: Dogs were randomly assigned to 1 of 2 treatment groups: grapiprant (2 mg/kg, PO; n = 6) or carprofen (4.4 mg/kg, PO; n = 6), 1.5 hours prior to ovariohysterectomy (OVH) and every 24 hours afterward for 3 total doses. An ultrafiltration probe was placed within the OVH incision to collect interstitial fluid (ISF). Pain and inflammation were assessed by masked investigators via mechanical nociceptive threshold testing and the short form of the Glasgow Composite Pain Scale before drug administration and at multiple time points for 72 hours following dosing and surgery. ISF samples were collected at the same time points to assess prostaglandin E2 concentrations at the site of inflammation. RESULTS: In both groups, pain scale scores were highest in the immediate postoperative period and decreased over time. In both treatment groups, there were significant (P = 0.003) differences in mechanical nociceptive threshold results over time when compared with baseline, but there was no difference between groups. Prostaglandin E2 concentrations in ISF were higher in dogs receiving grapiprant compared with carprofen (P < 0.001). One dog in the carprofen group required rescue analgesia. CLINICAL RELEVANCE: Results of this preliminary study suggested both carprofen and grapiprant may be effective for postoperative pain following OVH in dogs; however, additional studies are warranted to determine grapiprant's effectiveness in a larger and more diverse population of dogs.

Interleukin-1ß in tendon injury enhances reparative gene and protein expression in mesenchymal stem cells.

Tendon injury in the horse carries a high morbidity and monetary burden. Despite appropriate therapy, reinjury is estimated to occur in 50-65% of cases. Although intralesional mesenchymal stem cell (MSC) therapy has improved tissue architecture and reinjury rates, the mechanisms by which they promote repair are still being investigated. Additionally, reevaluating our application of MSCs in tendon injury is necessary given recent evidence that suggests MSCs exposed to inflammation (deemed MSC licensing) have an enhanced reparative effect. However, applying MSC therapy in this context is limited by the inadequate quantification of the temporal cytokine profile in tendon injury, which hinders our ability to administer MSCs into an environment that could potentiate their effect. Therefore, the objectives of this study were to define the temporal cytokine microenvironment in a surgically induced model of equine tendon injury using ultrafiltration probes and subsequently evaluate changes in MSC gene and protein expression following in vitro inflammatory licensing with cytokines of similar concentration as identified in vivo. In our in vivo surgically induced tendon injury model, IL-1ß and IL-6 were the predominant pro-inflammatory cytokines present in tendon ultrafiltrate where a discrete peak in cytokine concentration occurred within 48 h following injury. Thereafter, MSCs were licensed in vitro with IL-1ß and IL-6 at a concentration identified from the in vivo study; however, only IL-1ß induced upregulation of multiple genes beneficial to tendon healing as identified by RNA-sequencing. Specifically, vascular development, ECM synthesis and remodeling, chemokine and growth factor function alteration, and immunomodulation and tissue reparative genes were significantly upregulated. A significant increase in the protein expression of IL-6, VEGF, and PGE2 was confirmed in IL-1ß-licensed MSCs compared to naïve MSCs. This study improves our knowledge of the temporal tendon cytokine microenvironment following injury, which could be beneficial for the development and determining optimal timing of administration of regenerative therapies. Furthermore, these data support the need to further study the benefit of MSCs administered within the inflamed tendon microenvironment or exogenously licensed with IL-1ß in vitro prior to treatment as licensed MSCs could enhance their therapeutic benefit in the healing tendon.

Novel subcutaneous cytarabine infusion with the Omnipod system in dogs with meningoencephalomyelitis of unknown etiology.

OBJECTIVE: To investigate the feasibility and pharmacokinetics of cytarabine delivery as a subcutaneous continuous-rate infusion with the Omnipod system. ANIMALS: 6 client-owned dogs diagnosed with meningoencephalomyelitis of unknown etiology were enrolled through the North Carolina State University Veterinary Hospital. PROCEDURES: Cytarabine was delivered at a rate of 50 mg/m2/hour as an SC continuous-rate infusion over 8 hours using the Omnipod system. Plasma samples were collected at 0, 4, 6, 8, 10, 12, and 14 hours after initiation of the infusion. Plasma cytarabine concentrations were measured by high-pressure liquid chromatography. A nonlinear mixed-effects approach generated population pharmacokinetic parameter estimates. RESULTS: The mean peak plasma concentration (Cmax) was 7,510 ng/mL (range, 5,040 to 9,690 ng/mL; SD, 1,912.41 ng/mL), average time to Cmax was 7 hours (range, 4 to 8 hours; SD, 1.67 hours), terminal half-life was 1.13 hours (SD, 0.29 hour), and the mean area under the curve was 52,996.82 hours X µg/mL (range, 35,963.67 to 71,848.37 hours X µg/mL; SD, 12,960.90 hours X µg/mL). Cmax concentrations for all dogs were more than 1,000 ng/mL (1.0 µg/mL) at the 4-, 6-, 8-, and 10-hour time points. CLINICAL RELEVANCE: An SC continuous-rate infusion of cytarabine via the Omnipod system is feasible in dogs and was able to achieve a steady-state concentration of more than 1 µg/mL 4 to 10 hours postinitiation of cytarabine and a Cmax of 7,510 ng/mL (range, 5,040 to 9,690 ng/mL; SD, 1,912.41 ng/mL). These are comparable to values reported previously with IV continuous-rate infusion administration in healthy research Beagles and dogs with meningoencephalomyelitis of unknown etiology.

Intravenous and sublingual buprenorphine in horses: pharmacokinetics and influence of sampling site.

OBJECTIVE: To describe the pharmacokinetics and adverse effects of intravenous (IV) and sublingual (SL) buprenorphine in horses, and to determine the effect of sampling site on plasma concentrations after SL administration. STUDY DESIGN: Randomized crossover experiment; prospective study. ANIMALS: Eleven healthy adult horses between 6 and 20 years of age and weighing 487-592 kg. METHODS: In the first phase; buprenorphine was administered as a single IV or SL dose (0.006 mg kg(-1)) and pharmacokinetic parameters were determined for each route of administration using a noncompartmental model. In the second phase; the jugular and lateral thoracic veins were catheterized for simultaneous venous blood sampling, following a dose of 0.006 mg kg(-1) SL buprenorphine. For both phases, plasma buprenorphine concentrations were measured using ultra-performance liquid chromatography with mass spectrometry. At each sampling period, horses were assessed for behavioral excitement and gastrointestinal motility. RESULTS: Following IV administration, buprenorphine mean ± SD half-life was 5.79 ± 1.09 hours. Systemic clearance (Cl) following IV administration was 6.13 ± 0.86 mL kg(-1) minute(-1) and volume of distribution at steady-state was 3.16 ± 0.65 L kg(-1). Following IV administration, horses showed signs of excitement. Gastrointestinal sounds were decreased following both routes of administration; however, none of the horses exhibited signs of colic. There was a significant discrepancy between plasma buprenorphine concentrations measured in the jugular vein versus the lateral thoracic vein following phase 2, thus pharmacokinetic parameters following SL buprenorphine are not reported. CONCLUSIONS AND CLINICAL RELEVANCE: Buprenorphine has a long plasma half-life and results in plasma concentrations that are consistent with analgesia in other species for up to 4 hours following IV administration of this dose in horses. While buprenorphine is absorbed into the circulation following SL administration, jugular venous sampling gave a false measurement of the quantity absorbed and should not be used to study the uptake from SL administration.

In vivo assessment of a delayed release formulation of larazotide acetate indicated for celiac disease using a porcine model.

There is no FDA approved therapy for the treatment of celiac disease (CeD), aside from avoidance of dietary gluten. Larazotide acetate (LA) is a first in class oral peptide developed as a tight junction regulator, which is a lead candidate for management of CeD. A delayed release formulation was tested in vitro and predicted release in the mid duodenum and jejunum, the target site of CeD. The aim of this study was to follow the concentration versus time profile of orally administered LA in the small intestine using a porcine model. A sensitive liquid chromatography/tandem mass spectrometry method was developed to quantify LA concentrations in porcine intestinal fluid samples. Oral dosing of LA (1 mg total) in overnight fasted pigs resulted in time dependent appearance of LA in the distal duodenum and proximal jejunum. Peak LA concentrations (0.32-1.76 µM) occurred at 1 hour in the duodenum and in proximal jejunum following oral dosing, with the continued presence of LA (0.02-0.47 µM) in the distal duodenum and in proximal jejunum (0.00-0.43 µM) from 2 to 4 hours following oral dosing. The data shows that LA is available in detectable concentrations at the site of CeD.

Comparative effects of nonsteroidal anti-inflammatory drugs at castration and tail-docking in neonatal piglets.

This study assessed the efficacy of meloxicam, flunixin, and ketoprofen in piglets undergoing routine castration and tail-docking. Six-day-old male piglets (8/group) received one of five randomized treatments: intramuscular saline (SAL PROC), meloxicam (MEL; 0.4 mg/kg), flunixin (FLU; 2.2 mg/kg), ketoprofen (KETO; 3.0 mg/kg) or sham (SAL SHAM; saline injection, no processing). Two hours post-dose, piglets were castrated and tail-docked. Plasma cortisol, interstitial fluid (ISF) prostaglandin E2 (PGE2) and activity levels via Actical® monitoring were used to estimate pain. SAL SHAM and FLU exhibited lower cortisol concentrations than SAL PROC at the time of processing (p = 0.003 and p = 0.049, respectively), and all NSAIDs exhibited lower PGE2 than SAL PROC at 3.69 hours (MEL p = 0.050; FLU p = 0.043 and KETO p = 0.031). While not statistically significant, PGE2 was higher in SAL PROC piglets vs. other treatment groups at most time points. There was also a high degree of variability between piglets, especially for SAL PROC. Activity levels were significantly decreased at multiple time points in SAL PROC and MEL piglets following processing. However, FLU and KETO piglets had increased activity levels closer to that of the SAL SHAM group, suggesting that these NSAIDs are more effective than MEL in providing analgesia. These results demonstrate that management strategies including administration of intramuscular flunixin or ketoprofen to reduce pain associated with processing will likely improve piglet health and welfare in the United States.

Larazotide acetate induces recovery of ischemia-injured porcine jejunum via repair of tight junctions.

Intestinal ischemia results in mucosal injury, including paracellular barrier loss due to disruption of tight junctions. Larazotide acetate (LA), a small peptide studied in Phase III clinical trials for treatment of celiac disease, regulates tight junctions (TJs). We hypothesized that LA would dose-dependently hasten recovery of intestinal ischemic injury via modulation of TJs. Ischemia-injured tissue from 6-8-week-old pigs was recovered in Ussing chambers for 240-minutes in the presence of LA. LA (1 µM but not 0.1 µM or 10 µM) significantly enhanced transepithelial electrical resistance (TER) above ischemic injured controls and significantly reduced serosal-to-mucosal flux LPS (P<0.05). LA (1 µM) enhanced localization of the sealing tight junction protein claudin-4 in repairing epithelium. To assess for the possibility of fragmentation of LA, an in vitro enzyme degradation assay using the brush border enzyme aminopeptidase M, revealed generation of peptide fragments. Western blot analysis of total protein isolated from uninjured and ischemia-injured porcine intestine showed aminopeptidase M enzyme presence in both tissue types, and mass spectrometry analysis of samples collected during ex vivo analysis confirmed formation of LA fragments. Treatment of tissues with LA fragments had no effect alone, but treatment with a fragment missing both amino-terminus glycines inhibited barrier recovery stimulated by 1 µM LA. To reduce potential LA inhibition by fragments, a D-amino acid analog of larazotide Analog #6, resulted in a significant recovery response at a 10-fold lower dose (0.1 µM) similar in magnitude to that of 1 µM LA. We conclude that LA stimulates repair of ischemic-injured epithelium at the level of the tight junctions, at an optimal dose of 1 µM LA. Higher doses were less effective because of inhibition by LA fragments, which could be subverted by chirally-modifying the molecule, or microdosing LA.

Efficacy of a single session in-series hemoperfusion and hemodialysis in the management of carprofen overdose in two dogs.

OBJECTIVE: To describe the efficacy of in-series hemoperfusion and hemodialysis in 2 dogs with carprofen overdose. CASE SUMMARY: This report describes the treatment of 2 dogs following accidental carprofen overdoses who underwent a single in-series hemoperfusion and hemodialysis session. Serial serum carprofen concentrations were measured before, during, and after the session. The first patient's session lasted 5 hours, with the largest decrease in serum carprofen concentrations occurring during the first hour of treatment. The carprofen clearance during the following 4 hours of treatment decreased substantially compared to the first hour and was not different from the patient's intrinsic clearance of carprofen after the session was completed. Based on the findings from the first case, the second patient was treated with a 1 hour single hemoperfusion and hemodialysis session. Our results support the hypothesis that carprofen is not effectively removed by conventional hemodialysis and the efficacy of hemoperfusion is short lived due to rapid saturation of the charcoal filter. Once filter saturation occurs, the extracorporeal session is no longer efficacious. Using in-series hemoperfusion and hemodialysis is of benefit to correct the side effects seen with hemoperfusion alone, and hourly charcoal filter replacement may extend the efficacy of treatment in removing carprofen. NEW OR UNIQUE INFORMATION PROVIDED: This is the first published report of in-series hemoperfusion and hemodialysis being used to treat carprofen overdose in a dog. In these 2 cases, the intrinsic clearances of the patients were shown to be equivalent to that of standard hemodialysis alone, indicating that hemodialysis does not produce any advantage in carprofen clearance. In this limited report, we suggest that the efficacy of hemoperfusion in removing carprofen is short-lived, and extending the treatment beyond the first hour does not produce any therapeutic benefit. In order to extend the efficacy of hemoperfusion, hourly replacement of the charcoal filter should be considered.