Use of a pharmacokinetic/pharmacodynamic approach in the cat to determine a dosage regimen for the COX-2 selective drug robenacoxib

Robenacoxib versus meloxicam following ovariohysterectomy in cats: A randomised, prospective clinical trial involving owner-based assessment of pain

BACKGROUND

Injectable non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed to queens undergoing ovariohysterectomy (OVH), but the requirement for postoperative administration is unclear and practices vary. Existing studies assessing efficacy rely on pain scoring by experienced clinicians. However, following OVH, most cats are discharged within hours of recovery.

METHODS

Cats undergoing OVH were randomly assigned to two treatment groups: MEL and ROB. Cats in the MEL group (n = 76) received meloxicam (0.2 mg/kg) and those in the ROB group (n = 65) received robenacoxib (2 mg/kg). Owners were contacted by a blinded assessor 3 days postoperatively and asked to identify physical or behavioural changes and to assign pain scores using a numerical rating scale.

RESULTS

More cats in the ROB group displayed abnormal behaviours than cats in the MEL group (p = 0.03). Most owners assigned a pain score of 0 (72%) (n = 101), but pain scores were significantly higher in the ROB group than in the MEL group (p = 0.005).

LIMITATION

Methods of owner assessment of pain in cats have not been validated.

CONCLUSIONS

Both meloxicam and robenacoxib are effective in controlling postoperative pain. Meloxicam may have improved efficacy in certain patient populations. Applying a blanket approach to prescribing NSAIDs to cats undergoing OVH postoperatively may not be necessary. This has safety, environmental and cost implications.

Effects of selective cyclooxygenase-2 inhibitor robenacoxib on primary cells derived from feline injection-site sarcoma

Feline injection-site sarcomas (FISSs) are highly invasive malignant mesenchymal neoplasms that arise from injection sites in cats. Although the tumorigenesis of FISSs is still uncertain, there is a consensus that FISS is associated with chronic inflammation caused by irritation of injection-related trauma and foreign chemical substances. Chronic inflammation can provide a proper microenvironment for tumour development, which has been known as one of the risk factors of tumorigenesis in many tumours. To investigate the tumorigenesis of FISS and screen for its potential therapeutic targets, cyclooxygenase-2 (COX-2), an inflammation-enhancing enzyme, was selected as a target for this study. In vitro experiments using FISS- and normal tissue-derived primary cells and robenacoxib, a highly selective COX-2 inhibitor, were performed. The results demonstrated that expression of COX-2 could be detected in formalin-fixed and paraffin-embedded FISS tissues and FISS-derived primary cells. Cell viability, migration and colony formation of FISS-derived primary cells were inhibited, and cell apoptosis was enhanced by robenacoxib in a dose-dependent manner. However, susceptibility to robenacoxib varied in different lines of FISS primary cells and was not completely correlated with COX-2 expression. Our results suggest that COX-2 inhibitors could be potential adjuvant therapeutics against FISSs.

Pharmacology, safety, efficacy and clinical uses of the COX-2 inhibitor robenacoxib

Robenacoxib is a veterinary‐approved non‐steroidal anti‐inflammatory drug (NSAID) of the coxib group. It possesses anti‐hyperalgesic, anti‐inflammatory and anti‐pyretic properties. Robenacoxib inhibits the cyclooxygenase (COX)‐2 isoform of COX selectively (in vitro IC₅₀ ratios COX‐1:COX‐2, 129:1 in dogs, 32:1 in cats). At registered dosages (2 mg/kg subcutaneously in dogs and cats, 1–4 mg/kg orally in dogs and 1–2.4 mg/kg orally in cats), robenacoxib produces significant inhibition of COX‐2 whilst sparing COX‐1. The pharmacokinetic (PK) profile of robenacoxib is characterized by a high degree of binding to plasma proteins (>98%) and moderate volume of distribution (at steady state, 240 ml/kg in dogs and 190 ml/kg in cats). In consequence, the terminal half‐life in blood (<2 h) is short, despite moderate body clearance (0.81 L/kg/h) in dogs and low clearance (0.44 L/kg/h) in cats. Excretion is principally in the bile (65% in dogs and 72% in cats). Robenacoxib concentrates in inflamed tissues, and clinical efficacy is achieved with once‐daily dosing, despite the short blood terminal half‐life. In dogs, no relevant breed differences in robenacoxib PK have been detected. Robenacoxib has a wide safety margin; in healthy laboratory animals daily oral doses 20‐fold (dog, 1 month), eight‐fold (cat, 6 weeks) and five‐fold (dog, 6 months) higher than recommended clinical doses were well tolerated. Clinical efficacy and safety have been demonstrated in orthopaedic and soft tissue surgery, and in musculoskeletal disorders in dogs and cats.

PHARMACOKINETIC, PHARMACODYNAMIC, AND TOXICOLOGY STUDY OF ROBENACOXIB IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

Postoperative antinociception control in fish is currently suboptimal, as commonly used antiinflammatory drugs last for only a few hours at tested temperatures. Therefore, long-acting anti-inflammatory drugs, such as robenacoxib, could improve the welfare of fish. The pharmacokinetics, duration of antinociceptive action, and potential adverse effects of robenacoxib were evaluated through two prospective randomized blinded trials in rainbow trout (Oncorhynchus mykiss). Six healthy rainbow trout received a single IM administration of robenacoxib (2 mg/kg), and two control fish received the same volume of saline IM. Blood samples were collected at predetermined time points for 5 d. Plasma robenacoxib concentrations were measured using high-performance liquid chromatography-high-resolution hybrid orbitrap mass spectrometry and noncompartmental pharmacokinetic analysis. Ten additional rainbow trout received an intralabial injection of 0.05 ml of 2% acetic acid following a previously validated nociceptive model. The treated group (n = 6) received 2 mg/kg of robenacoxib IM and the control group (n = 4) received an equivalent volume of saline IM. The behavior, appetite, and opercular rate of the fish were evaluated every hour for 5 h, then once daily for 3 d. All 12 treated trout and 6 controls underwent histopathologic evaluation. Average maximum plasma concentration (C_max) was 329.9 ± 137.3 ng/ml observed at 2.1 ± 0.7 h (T_max) and terminal half-life was 12.6 ± 2.27 h. Plasma concentrations described as antinociceptive in domestic carnivores were measured for 3-4 d. This dose was associated with a significant decrease in rocking behavior (P = 0.017). No adverse effects were detected clinically nor on histopathology. Robenacoxib administered IM at 2 mg/kg appears to be safe and may provide an antinociceptive effect in rainbow trout. This study presents a new therapeutic option to provide long-lasting antinociception in rainbow trout.

Robenacoxib shows efficacy for the treatment of chronic degenerative joint disease-associated pain in cats: a randomized and blinded pilot clinical trial

The main objective of this pilot clinical trial was to evaluate outcome measures for the assessment of the nonsteroidal anti-inflammatory drug (NSAID) robenacoxib in cats with degenerative joint disease-associated pain (DJD-pain). Otherwise healthy cats (n = 109) with DJD-pain entered a parallel group, randomized, blinded clinical trial. Cats received placebo (P) or robenacoxib (R) for two consecutive 3-week periods. Treatment groups were PP, RR, and RP. Actimetry and owner-assessment data were collected. Data were analyzed using mixed-effects and generalized mixed-effects linear models. Activity data showed high within-cat and between-cat variability, and 82.4% of the values were zero. Compared to placebo, mean total activity was higher (5.7%) in robenacoxib-treated cats (p = 0.24); for the 80th percentile of activity, more robenacoxib-treated cats had a > 10% increase in activity after 3 (p = 0.046) and 6 weeks (p = 0.026). Robenacoxib treatment significantly decreased owner-assessed disability, (p = 0.01; 49% reduction in disability; effect size ~ 0.3), and improved temperament (p = 0.0039) and happiness (p = 0.021) after 6 weeks. More robenacoxib-treated cats were successes at 6 weeks (p = 0.018; NNT: 3.8). Adverse effect frequencies were similar across groups. Results identified suitable endpoints for confirmatory studies, while also indicating efficacy of robenacoxib in cats with DJD-pain.

Safety evaluation of the interchangeable use of robenacoxib in commercially-available tablets and solution for injection in cats

Background

Robenacoxib (Onsior™) is a non-steroidal anti-inflammatory drug developed for canine and feline use for the control of pain and inflammation. It is available as both tablets and solution for injection.

The objective of this study was to evaluate the safety of the interchangeable use of commercially available robenacoxib formulations when administered to cats orally using 6 mg tablets and subcutaneously using a solution for injection containing 20 mg/mL. Thirty-four naïve healthy 4-month old cats were enrolled in this 37-day study and were randomized to four groups (three robenacoxib and one control). One robenacoxib group received the maximum recommended dose (MRD) rate of each formulation, while the other two received two and three times this dose rate. The cats underwent three 10-day treatment cycles comprised of seven days of once daily oral administration followed by three days of subcutaneous administration. The third cycle was followed by an additional seven days of oral treatment. The control group received oral empty gelatin capsules or subcutaneous saline injections. Assessment of safety was based on general health observations, clinical observations, physical, ophthalmic, electrocardiographic and neurological examinations, clinical pathology evaluations, food consumption, body weight, and macroscopic and microscopic examinations. Blood samples were collected for toxicokinetic evaluation.

Results

Blood concentrations of robenacoxib confirmed systemic exposure of all treated cats. All cats were in good health through study termination and there were no serious adverse events during the study. There were no changes in body weight, food consumption, ophthalmic, physical or neurological examinations during the study. Treatment-related abnormalities were of low occurrence at all doses and included injection site changes (transient edema with minimal or mild, subacute/chronic inflammation histologically) and prolongation of the QT interval. These findings were consistent with previously observed findings in studies with robenacoxib administered separately orally or subcutaneously in cats. Thus, there were no adverse effects that could be attributed specifically to the interchangeable use of oral and injectable robenacoxib.

Conclusions

This 37-day laboratory study supports the safety of interchanging robenacoxib injection at a daily dose of 2 mg/kg with robenacoxib tablets at a daily dose of 1 mg/kg, or vice versa.

Use of nociceptive threshold testing in cats in experimental and clinical settings: a qualitative review

OBJECTIVE

The objective of this study was to review the scientific articles on the use of nociceptive threshold testing (NTT) in cats and to summarize the clinical and experimental applications in this species.

DATABASES USED

Pertinent literature was searched with PubMed, Scopus, Web of Science, Universitätsbibliothek Basel (swissbib Basel Bern) and Google Scholar. The search was then refined manually based first on article titles and abstracts, and subsequently on full texts.

CONCLUSIONS

Of the four classical acute nociceptive models used for NTT, thermal and mechanical are most commonly used in cats. Thermal stimulation is applicable in experimental settings and has been used in pharmacodynamics studies assessing feline antinociception. Although mechanical stimulation is currently less used in cats, in the future it might play a role in the evaluation of clinical feline pain. However, the low response reliability after stimulus repetition within a narrow time interval represents a major limitation for the clinical use of mechanical thresholds in this species. Challenges remain when thermal thresholds are used to investigate analgesics that have the potential to affect skin temperature, such as opioids and α2-adrenergic agonists, and when a model of inflammatory pain is reproduced in experimental cats with the purpose of evaluating non-steroidal anti-inflammatory drugs as analgesics.

Robenacoxib in the treatment of pain in cats and dogs: safety, efficacy, and place in therapy

Robenacoxib is a novel nonsteroidal anti-inflammatory drug (NSAID) of coxib class developed for the control of inflammation and pain in dogs and cats. It shows high selectivity for the cyclooxygenase-2 (COX-2) enzyme in rats, cats, and dogs. Robenacoxib is available in both injectable and tablet formulations. This review initially focuses on the preclinical pharmacology of robenacoxib in rats that includes its high affinity for COX-2 enzyme and weaker and rapidly reversible binding for COX-1 enzyme in in vitro and ex vivo models of inflammation and its pharmacokinetics in the blood and inflammatory exudate, selective tissue distribution, and safety. These basic pharmacological profiles highlight the suitability of robenacoxib for use in target species, such as cats and dogs. Since the level of expression and activity of COX enzymes is species specific, COX-2-selective inhibition and the resultant effects of coxibs must be studied in target species. The pharmacological and toxicological profiles of robenacoxib in cats and dogs have been discussed prior to reviewing its clinical efficacy and safety. Large, multicenter field trials conducted in cats and dogs demonstrated the noninferior efficacy and safety of robenacoxib compared with noncoxib NSAIDs used in dogs and cats. These trials investigated the efficacy of robenacoxib against various acute and chronic painful conditions. Robenacoxib produced superior efficacy to placebo and COX-2 preferential inhibitors in postsurgical cats. The tissue-selective anti-inflammatory activity of robenacoxib has been demonstrated in dogs with osteoarthritis. Robenacoxib has also been shown to be safe in healthy dogs and cats receiving antihypertensive drugs and loop diuretics that could cause renal injury. The developmental objective of coxibs, comparable efficacy but superior safety to less selective/nonselective NSAIDs, is well established with robenacoxib in preclinical studies. More studies need to be conducted to fully explore the benefits of robenacoxib in clinical subjects.

Six-month safety evaluation of robenacoxib tablets (Onsior™) in dogs after daily oral administrations

Background

Robenacoxib is a non-steroidal anti-inflammatory drug available for canine and feline use for the control of pain and inflammation marketed as Onsior™. The aim of this target animal safety study was to evaluate the 6-month safety profile of oral robenacoxib administration. It was a randomized, negative-controlled, parallel group study. Thirty-two healthy, young, experimentally naïve, purebred Beagle dogs were administered 0 (sham control, Group 1), 2, 6, and 10 mg/kg robenacoxib (corresponding to the upper end of the dosage range [1X, Group 2] and multiples thereof [3X and 5X, Group 3 and 4]), orally once daily for 6 months. Assessment of safety included general health and clinical observations, physical, neurological, ophthalmological and electrocardiographic examinations, gross and histopathological examinations and clinical pathology evaluations. Blood samples were collected for toxicokinetic assessment of robenacoxib.

Results

No serious adverse events were reported. When compared with control, no treatment effect was observed for body weight, feed or water consumption, clinical pathology, urinalysis and fecal examination parameters. There were no treatment-related changes in stifle joint tissues and microscopic/histopathology examinations of all tissues/organs were normal. Salivation and soft feces were noted in all groups but observed more frequently in the treated groups as compared with control. On Day 178, increased buccal mucosal bleeding times were observed in two treated animals (Group 3 and 4) and one dog in Group 4 displayed a retinal change. Decreased hopping and conscious proprioception was noted in four treated dogs. One dog in Group 2 had ventricular premature complexes. Post-mortem changes included mild, red foci on the cecum in one dog (Group 3) and minimal duodenal discoloration in one dog (Group 4), with no corresponding histological findings in either dog. Ovarian weights were decreased in females from Group 3 and 4 with no gross or histological changes in the ovaries. Blood concentrations of robenacoxib confirmed systemic exposure of treated dogs. Exposure increased with increasing doses and there were no accumulation of robenacoxib in blood.

Conclusions

Robenacoxib was well tolerated at doses from 2 to 10 mg/kg/day and this 6-month study supports the safe use of Onsior™ (robenacoxib) tablets in dogs for the intended dosing regimen.

Safety evaluation of the interchangeable use of robenacoxib (Onsior™) tablets and solution for injection in dogs

BACKGROUND

Robenacoxib (Onsior™) is a non-steroidal anti-inflammatory drug developed for canine and feline use for the control of pain and inflammation. It is available as both tablets and solution for injection. The objective of this safety study was to investigate the interchangeable use of two robenacoxib formulations in dogs using a novel study design alternating between oral tablets and subcutaneous injections. Thirty-two naïve healthy 4-month dogs were enrolled in this 88-day study and were randomized among four groups to be untreated or to receive robenacoxib at the highest recommended or elevated dose rates. The dogs were administered three 20-day treatment cycles each separated by a 14-day washout period. Each 20-day cycle was comprised of 10 days of once daily oral administration, 3 days of subcutaneous administration, followed by further 7 days of oral administration (Groups 2 to 4). The control group (Group 1) received oral empty gelatin capsules or subcutaneous saline injections. Assessment of safety was based on general health observations, clinical observations, physical and neurological examinations including ophthalmological examinations, electrocardiographic examinations and clinical pathology evaluations, food and water consumption, body weight, and macroscopic and microscopic examinations. Blood samples were collected for pharmacokinetic evaluation.

RESULTS

Blood concentrations of robenacoxib confirmed systemic exposure of all treated dogs. All dogs were in good health through study termination and there were no serious adverse events during the course of the study. No changes in body weight, food consumption, ophthalmic, neurological examinations, electrocardiograms, buccal mucosal blood times, clinical pathology or organ weight were attributable to robenacoxib formulation administration. Primary treatment-related abnormalities were of low incidence at all doses. They were confined to macroscopic and microscopic changes observed locally at the subcutaneous injection sites and microscopic findings within the gastrointestinal tract. These findings were as expected based on previous studies with robenacoxib solution for injection alone and the known properties of this class of compound and mode of administration. There were no adverse effects which could be attributed specifically to the interchangeable use of oral and injectable robenacoxib.

CONCLUSIONS

Alternating regimens of robenacoxib tablets and solution for injection were well tolerated in healthy young dogs.

Modeling of Large Pharmacokinetic Data Using Nonlinear Mixed-Effects: A Paradigm Shift in Veterinary Pharmacology. A Case Study With Robenacoxib in Cats

The objective of this study was to model the pharmacokinetics (PKs) of robenacoxib in cats using a nonlinear mixed-effects (NLME) approach, leveraging all available information collected from cats receiving robenacoxib s.c. and/or i.v.: 47 densely sampled laboratory cats and 36 clinical cats sparsely sampled preoperatively. Data from both routes were modeled sequentially using Monolix 4.3.2. Influence of parameter correlations and available covariates (age, gender, bodyweight, and anesthesia) on population parameter estimates were evaluated by using multiple samples from the posterior distribution of the random effects. A bicompartmental disposition model with simultaneous zero and first-order absorption best described robenacoxib PKs in blood. Clearance was 0.502 L/kg/h and the bioavailability was high (78%). The absorption constant point estimate (Ka  = 0.68 h-1 ) was lower than beta (median, 1.08 h-1 ), unveiling flip-flop kinetics. No dosing adjustment based on available covariates information is advocated. This modeling work constitutes the first application of NLME in a large feline population.

Evaluation of injectable robenacoxib for the treatment of post-operative pain in cats: results of a randomized, masked, placebo-controlled clinical trial

Background

Few pharmaceuticals are registered in cats for the management of post-operative pain and inflammation. The objective of this study was to assess the field efficacy and safety of an injectable formulation of the nonsteroidal anti-inflammatory drug robenacoxib in cats undergoing surgery. The study was a multi-center, prospective, randomized, masked, parallel-group, placebo-controlled clinical trial. A total of 349 cats were enrolled and underwent surgery comprising forelimb onychectomy, as an example of orthopedic surgery, plus either ovariohysterectomy or castration. All cats received butorphanol prior to anesthesia and forelimb four-point regional nerve blocks with bupivacaine after induction of general anesthesia. Cats were randomized to receive daily subcutaneous (s.c.) injection of robenacoxib, at a target dosage of 2.0 mg/kg (n = 174), or placebo (n = 175) once prior to surgery and for an additional two days post-operatively.

Results

Significantly (P = 0.037) fewer cats administered robenacoxib received additional analgesia rescue therapy (34 of 173, 19.7 %) compared to cats given placebo (73 of 175, 41.7 %). The percentage of treatment success was therefore 80.3 % with robenacoxib and 58.3 % with placebo. Behavior, posture, pain on palpation of the paw and soft tissue surgery sites, and overall pain were significantly (P < 0.05) improved versus placebo at various time points within the first 8 h in cats receiving robenacoxib. The most frequently reported adverse events were incision site infection/dehiscence, bleeding, vomiting, decreased appetite and lethargy. Frequencies of reported adverse clinical signs, hematology, serum chemistry and urinalysis variables, and body weight changes were similar between groups. There were no significant changes from baseline with robenacoxib in hepatic, hematological or renal clinical pathology variables.

Conclusions

Robenacoxib by s.c. injection was effective and well tolerated in the control of post-operative pain associated with orthopedic, ovariohysterectomy and castration surgery in cats.

Systematic review of the behavioural assessment of pain in cats

OBJECTIVES

The objectives were to review systematically the range of assessment tools used in cats to detect the behavioural expression of pain and the evidence of their quality; and to examine behavioural metrics (considering both the sensory and affective domains) used to assess pain.

METHODS

A search of PubMed and ScienceDirect, alongside articles known to the authors, from 2000 onwards, for papers in English was performed. This was followed by a manual search of the references within the primary data sources. Only peer-reviewed publications that provided information on the assessment tool used to evaluate the behavioural expression of pain in cats, in conscious animals (not anaesthetised cats), were included.

RESULTS

No previous systematic reviews were identified. One hundred papers were included in the final assessment. Studies were primarily related to the assessment of pain in relation to surgical procedures, and no clear distinction was made concerning the onset of acute and chronic pain. Ten broad types of instrument to assess pain were identified, and generally the quality of evidence to support the use of the various instruments was poor. Only one specific instrument (UNESP-Botucatu scale) had published evidence of validity, reliability and sensitivity at the level of a randomised control trial, but with a positive rather than placebo control, and limited to its use in the ovariohysterectomy situation. The metrics used within the tools appeared to focus primarily on the sensory aspect of pain, with no study clearly discriminating between the sensory and affective components of pain.

CONCLUSIONS AND RELEVANCE

Further studies are required to provide a higher quality of evidence for methods used to assess pain in cats. Furthermore, a consistent definition for acute and chronic pain is needed. Tools need to be validated that can detect pain in a range of conditions and by different evaluators (veterinary surgeons and owners), which consider both the sensory and emotional aspects of pain.

Robenacoxib versus meloxicam for the control of peri-operative pain and inflammation associated with orthopaedic surgery in cats: a randomised clinical trial

Background

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in veterinary medicine. Robenacoxib is a NSAID with high selectivity for the cyclo-oxygenase-2 enzyme. In this study, the efficacy and safety of robenacoxib were evaluated in a prospective, randomised, active- and placebo-controlled masked clinical trial in 147 cats undergoing orthopaedic surgery. Cats were randomised into two treatment groups: Group 1, robenacoxib (2 mg/kg) administered via subcutaneous (s.c.) injection before surgery, followed by robenacoxib tablets (1–2.4 mg/kg) administered post-operatively for approximately 9 days (n = 101) and Group 2, meloxicam (0.3 mg/kg) administered s.c. before surgery, followed by placebo tablets administered post-operatively for approximately 9 days (n = 46). Cats were assessed using numerical rating scales (NRSs) by clinicians before surgery and at 3, 8, 22 and 28 hours after surgery and at the final visit (VF on approximately Day 10), and daily by their owners from Day 1 to the VF.

Results

The primary end point was the global investigator score which was the sum of clinician NRSs for posture, behaviour and pain on palpation/manipulation. The efficacy of the single robenacoxib injection, assessed during 3 to 22 hours, was statistically non-inferior to meloxicam, with a relative efficacy of 1.029 (95% confidence interval, 0.847–1.231). No significant differences were detected during the follow-up treatment with robenacoxib tablets for approximately 9 days compared with placebo via clinician assessments at 28 hours and the VF, or in owner assessments on Days 1–VF. There were no significant differences in frequencies of reported adverse events, clinical observations and haematology or clinical chemistry variables between the groups.

Conclusions

Single s.c. injection of robenacoxib before surgery had non-inferior efficacy compared with meloxicam in controlling post-operative pain and inflammation in cats undergoing orthopaedic surgery. Follow-up treatment with oral robenacoxib tablets for approximately 9 days was well tolerated, but there were no differences in the efficacy scores after Day 1 compared with the group receiving meloxicam s.c. followed by placebo control.

Pharmacokinetic/pharmacodynamic modeling for the determination of a cimicoxib dosing regimen in the dog

BACKGROUND

Cimicoxib is a new coxib anti-inflammatory drug for use in the dog. To determine a preclinical dosage regimen for cimicoxib in dog, a reversible model of kaolin-induced paw inflammation was used. Dosage regimens were established using pharmacokinetic/pharmacodynamic (PK/PD) modeling approach (indirect response model).

RESULTS

Analgesic, anti-inflammatory and antipyretic endpoints investigated with the inflammation model established the efficacy of cimicoxib at a dose of 2 mg/kg administered orally (single dose) in 12 beagle dogs.For both the oral and IV route of administration two groups of dogs to be identified namely Poor Metabolizers (PM) and Extensive Metabolizers (EM).The terminal half-life after oral administration was 8.0 ± 0.6 h for the PM and 4.6 ± 2.6 h for the EM groups, with the corresponding values after the IV route being 5.6 ± 1.7 h and 2.7 ± 0.9 h (mean ± SD).The main pharmacodynamic parameters (potency, efficacy, and sensitivity) were estimated for four endpoints (body temperature, creeping speed, ground vertical reaction force and clinical lameness score). The plasma concentration corresponding to half the maximum of the indirect effect were 239 μg/L for creeping speed, 284 μg/L for the lameness score, 161 μg/L for the ground reaction vertical force and 193 μg/L for the body temperature.To document possible polymorphism of the cimicoxib disposition in the target dog population, cimicoxib was administered by the intravenous route to 40 dogs (four different sized breeds). The cimicoxib half-lives in these 40 dogs were of same order of the magnitude as those of the EM beagle dogs. Thus pharmacokinetic and pharmacodynamic parameters obtained from the EM beagle dogs were selected to simulate the dose-effect relationship of cimicoxib after an oral administration allowing a dosage regimen to be selected for confirmation by a clinical trial.

CONCLUSIONS

Cimicoxib was an efficacious anti-inflammatory, antipyretic and analgesic drug and a dosage regimen of 2 mg/kg daily was determined for confirmatory clinical trials.

Thermal nociception as a measure of non-steroidal anti-inflammatory drug effectiveness in broiler chickens with articular pain

Pain associated with poultry lameness is poorly understood. The anti-nociceptive properties of two non-steroidal anti-inflammatory drugs (NSAIDs) were evaluated using threshold testing in combination with an acute inflammatory arthropathy model. Broilers were tested in six groups (n=8 per group). Each group underwent a treatment (saline, meloxicam (3 or 5mg/kg) or carprofen (15 or 25mg/kg)) and a procedure (Induced (arthropathy-induction) or sham (sham-handling)) prior to testing. Induced groups had Freund's complete adjuvant injected intra-articularly into the left intertarsal joint (hock). A ramped thermal stimulus (1°C/s) was applied to the skin of the left metatarsal. Data were analysed using random-intercept multi-level models. Saline-induced birds had a significantly higher skin temperature (± SD) than saline-sham birds (37.6 ± 0.8°C vs. 36.5 ± 0.5°C; Z=-3.47, P<0.001), consistent with an inflammatory response. Saline was associated with significantly lower thermal thresholds (TT) than analgesic treatment (meloxicam: Z=2.72, P=0.007; carprofen: Z=2.58, P=0.010) in induced birds. Saline-induced birds also had significantly lower TT than saline-sham birds (Z=-2.17, P=0.030). This study found direct evidence of an association between inflammatory arthropathies and thermal hyperalgesia, and showed that NSAID treatment maintained baseline thermal sensitivity (via anti-nociception). Quantification of nociceptive responsiveness in a predictable broiler pain model identified thermal anti-hyperalgesic properties of two NSAIDs, which suggested that therapeutically effective treatment was provided at the doses administered. Such validation of analgesic strategies will increase the understanding of pain associated with specific natural broiler lameness types.

Effects of route of administration and feeding schedule on pharmacokinetics of robenacoxib in cats

OBJECTIVE

To establish pharmacokinetics of robenacoxib after administration to cats via the IV, SC, and oral routes.

ANIMALS

24 cats.

PROCEDURES

In a crossover design, robenacoxib was administered IV, SC, and orally (experiment 1) and orally (experiment 2) to cats with different feeding regimens. Blood robenacoxib concentrations were assayed, with a lower limit of quantification of 3 ng/mL.

RESULTS

In experiment 1, geometric mean pharmacokinetic values after IV administration of robenacoxib were as follows: blood clearance, 0.44 L/kg/h; plasma clearance, 0.29 L/kg/h; elimination half-life, 1.49 hours; and volume of distribution at steady state (determined from estimated plasma concentrations), 0.13 L/kg. Mean bioavailability was 69% and median time to maximum concentration (Cmax) was 1 hour for cats after SC administration of robenacoxib, whereas mean bioavailability was 49% and 10% and median time to Cmax was 1 hour and 30 minutes after oral administration to cats after food withholding and after cats were fed their entire ration, respectively. In experiment 2, geometric mean Cmax was 1,159, 1,201, and 692 ng/mL and area under the curve from 0 to infinity was 1,337, 1,383, and 1,069 ng × h/mL following oral administration to cats after food withholding, cats fed one-third of the daily ration, and cats fed the entire daily ration, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

For treatment of acute conditions in cats, it is recommended to administer robenacoxib by IV or SC injection, orally after food withholding, or orally with a small amount of food to obtain optimal bioavailability and Cmax.

Comparison of the analgesic effects of robenacoxib, buprenorphine and their combination in cats after ovariohysterectomy

The aim of this study was to compare the postoperative analgesic effects of robenacoxib and buprenorphine alone or in combination, in cats after ovariohysterectomy. Thirty healthy cats were randomly assigned to receive buprenorphine (0.02 mg/kg, n=10; GB), robenacoxib (2mg/kg, n=10; GR) or their combination at the same dosages (n=10; GBR) SC. After 30 min cats were sedated with an IM administration of medetomidine (0.02 mg/kg) and ketamine (5mg/kg). General anaesthesia was induced with propofol and after intubation was maintained with isoflurane. Before premedication and at 1, 2, 3, 4, 6, 8, 12 and 24h after extubation, pain and sedation were assessed using a simple descriptive pain scale, ranging from 0 (no pain/no sedation) to 4 (intense pain/ deep sedation). If the pain score was ≥ 3, rescue analgesia was provided using buprenorphine (0.02 mg/kg) administered IM. Pain score was higher in GB at 2, 3, 4, 6 and 8h compared to baseline and compared to GBR at the same study times. Moreover, the pain score was also higher in GB compared to GR at 2, 3, 4 and 6h. Pain score was similar at all study times between GR and GBR. Sedation at 1 and 2h was higher than baseline values in all groups. Cats in GB received rescue analgesia more often than cats assigned to GR or GBR. Robenacoxib was an effective analgesic drug in cats up to 24h after ovariohysterectomy. The addition of buprenorphine did not provide any additional analgesic effects compared to robenacoxib alone.

Evaluation of oral robenacoxib for the treatment of postoperative pain and inflammation in cats: results of a randomized clinical trial

The efficacy and safety of robenacoxib were assessed for the control of postoperative pain and inflammation in cats. The study was a multicenter, prospective, randomized, blinded, and parallel group clinical trial. A total of 249 client-owned cats scheduled for forelimb onychectomy plus either ovariohysterectomy or castration surgeries were included. All cats received butorphanol prior to anesthesia and forelimb four-point regional nerve blocks with bupivacaine after induction of general anesthesia. Cats were randomized to receive daily oral tablet robenacoxib, at a mean (range) dosage of 1.84 (1.03–2.40) mg/kg (n = 167), or placebo (n = 82), once prior to surgery and for two days postoperatively. Significantly (P < 0.05) fewer robenacoxib cats received additional analgesia rescue therapy (16.5%) than placebo cats (46.3%). Pain elicited on palpation of the soft tissue incision site, behavior following social interaction, and posture assessed during the first 8 hours after extubation were significantly (P < 0.05) improved in cats receiving robenacoxib. Frequency of reported adverse clinical signs, hematology, serum chemistry and urinalysis variables, and body weight changes weresimilar between groups. In conclusion, robenacoxib was effective and well tolerated in the control of postoperative pain and inflammation in cats undergoing onychectomy with ovariohysterectomy or castration.

Development and validation of a tissue cage model of acute inflammation in the cat

Four cylindrical silicon tissue cages (TC, internal volume: 6.7 ± 0.11 cm(3)) were inserted subcutaneously in 29 young healthy cats. A mild inflammatory reaction was induced by intracaveal injection of 1 mL of a 2%λ-carrageenan solution. TC exudate was subsequently sampled at predetermined times (up to 120 h) to measure exudate leucocyte counts and the concentrations of protein and eicosanoids. TC remained in situ for 9-10 months and were well tolerated. Leucocyte counts peaked at 34 h (50.1 ± 57.6 × 10(3) cells/mm(3) ) and returned towards baseline after 72 h. Protein concentration increased from 26.2 ± 2.7 g/L to a peak of 35.9 ± 6.0 g/L at 12 h before returning to baseline at 48 h. Exudate prostaglandin (PG)E(2) concentration peaked at 24 h (11.7 ± 13.7 ng/mL) and returned to baseline by 120 h. Repeated collection of fluid from noninjected cages did not increase transudate PGE(2). Ketoprofen (2 mg/kg, subcutaneously) suppressed exudate PGE(2) at 24 h. The carrageenan-stimulated TC model is an ethical and novel means of investigating soft tissue inflammation in the cat, in which exudate PGE(2) acts as surrogate marker of cyclooxygenase-2 activity. This model will facilitate the investigation of in vivo pharmacokinetics and pharmacodynamics of anti-inflammatory drugs in this species.

Paw inflammation model in dogs for preclinical pharmacokinetic/pharmacodynamic investigations of nonsteroidal anti-inflammatory drugs

The goal of the present study was to develop and validate a new canine model of inflammation. The motivation was to make available a scientifically appropriate and ethically acceptable model to conduct pharmacokinetic/pharmacodynamic investigations for testing nonsteroidal anti-inflammatory drugs in dogs. A kaolin-induce paw inflammation model previously developed in cats was adapted to the dog. The paw inflammation developed within a few hours, reached maximum values 24 h and up to 3 days after kaolin administration, and then progressively resolved over 2 months. Five end points of clinical interest (body temperature, creeping time under a tunnel, paw withdrawal latency to a standardized thermal stimulus, lameness score, and vertical force developed during walking on a force plate) were measured regularly over the next 24 h and beyond to characterize the time development of the inflammation either in control conditions (placebo period) or after the administration of meloxicam (test period) according to a crossover design. Pharmacodynamic data were modeled using an indirect response pharmacokinetic/pharmacodynamic model. This model described three effects of meloxicam, namely, classic anti-inflammatory, analgesic, and antipyretic effects. The mean plasma meloxicam IC(50) values were 210 ng/ml for the antipyretic effect, 390 ng/ml for the analgesic effect, and 546 ng/ml for the vertical force exerted by the paw on the ground as measured by force plates. These in vivo IC(50) values require approximately 80 (antipyretic effect) to 90% (all other effects) cyclooxygenase-2 inhibition as calculated ex vivo whole-blood assay data.

Ketoprofen in piglets: enantioselective pharmacokinetics, pharmacodynamics and PK/PD modelling

The chiral pharmacokinetics and pharmacodynamics of ketoprofen were investigated in a placebo-controlled study in piglets after intramuscular administration of 6 mg/kg racemic ketoprofen. The absorption half-lives of both enantiomers were short, and S-ketoprofen predominated over R-ketoprofen in plasma. A kaolin-induced inflammation model was used to evaluate the anti-inflammatory, antipyretic and analgesic effects of ketoprofen. Skin temperatures increased after the kaolin injection, but the effect of ketoprofen was small. No significant antipyretic effects could be detected, but body temperatures tended to be lower in the ketoprofen-treated piglets. Mechanical nociceptive threshold testing was used to evaluate the analgesic effects. The piglets in the ketoprofen-treated group had significantly higher mechanical nociceptive thresholds compared to the piglets in the placebo group for 12-24 h following the treatment. Pharmacokinetic/pharmacodynamic modelling of the results from the mechanical nociceptive threshold testing gave a median IC(50) for S-ketoprofen of 26.7 μg/mL and an IC(50) for R-ketoprofen of 1.6 μg/mL. This indicates that R-ketoprofen is a more potent analgesic than S-ketoprofen in piglets. Estimated ED(50) for racemic ketoprofen was 2.5 mg/kg.

ISFM and AAFP Consensus Guidelines: Long-Term use of NSAIDs in Cats

NSAIDs and cats Non-steroidal anti-inflammatory drugs (NSAIDs) are an important class of drug in feline medicine, having analgesic, anti-inflammatory and antipyretic activity. While most published data on their use in this species relate to short-term (often perioperative) therapy, there is increasing evidence of the value of these drugs in treating chronic pain in cats (for example, that associated with degenerative joint disease), and some NSAIDs have now become licensed for long-term use in cats in some geographies. Most of our knowledge of therapeutic mechanisms or adverse drug reactions associated with NSAIDs is extrapolated from work in other species, and there is a paucity of published data relating to cats.

Guidelines These guidelines have been drawn together by an expert panel, which have reviewed the current literature on long-term NSAID use in cats and other species, and developed guidance on their use based on this information. The aim is to provide practical information for veterinarians to encourage appropriate NSAID therapy whenever cats will benefit from the use of these drugs.

Long-term pain in cats: how much do we know about this important welfare issue?

PRACTICAL RELEVANCE

Long-term pain in cats is an important welfare issue but is often overlooked and undertreated.

AUDIENCE

All practitioners are faced with cats that require analgesic intervention to improve their quality of life.

PATIENT GROUP

Any cat may potentially experience long-term pain and discomfort. Degenerative joint disease and diabetic-related pain is more common in middle-aged or older individuals, whereas persistent postsurgical pain can occur at any age and is seen in young cats following onychectomy.

EVIDENCE BASE

Robust evidence on long-term pain issues in cats - specifically, relating to prevalence, etiology, and treatment protocols and outcomes - is missing from the veterinary literature. The aim of this review is to summarise the current state of knowledge. In doing so, it takes a practical approach, highlighting the obvious, and some not so obvious, causes of long-term pain in cats; some aspects that warrant closer attention; our ability to recognize pain and monitor how this impacts on quality of life; and today's treatment options.

DJD-Associated Pain in Cats

Practical relevance Degenerative joint disease (DJD) has a high prevalence in domestic cats and can be associated with pain. This pain should be addressed wherever possible.

Audience All practitioners are faced with cats that are mobility impaired due to DJD-associated pain.

Patient group Cats of all ages and breeds, and either sex, can experience DJD-associated discomfort.

Clinical challenges Recognizing DJD and assessing DJD-associated pain in cats is a challenge. Owner observations of activity and behavior, careful observation and a logical and thorough orthopedic evaluation are key. Current understanding of the etiology of feline DJD and the mechanisms of DJD-associated pain is incomplete, making the rational choice of treatments a further challenge.

Evidence base Evidence is emerging on the prevalence of feline DJD, and on how to assess the associated pain and mobility impairment. There is a lack of information on the etiology of feline DJD and a relative lack of data on the efficacy of putative treatments.

In vitro and ex vivo inhibition of canine cyclooxygenase isoforms by robenacoxib: a comparative study

In vitro whole blood canine assays were used to quantify the inhibitory actions of the novel non-steroidal anti-inflammatory drug (NSAID) robenacoxib on the cyclooxygenase (COX) isoenzymes, COX-1 and COX-2, in comparison with other drugs of the NSAID class. COX-1 activity was determined by measuring serum thromboxane (Tx)B(2) synthesis in blood samples allowed to clot at 37 degrees C for 1h. COX-2 activity was determined by measuring prostaglandin (PG)E(2) synthesis in blood samples incubated at 37 degrees C for 24h in the presence of lipopolysaccharide. The rank order of selectivity for inhibition of COX-2 versus COX-1 (IC(50) COX-1:IC(50) COX-2) for veterinary drugs was highest with robenacoxib (128.8) compared to deracoxib (48.5), nimesulide (29.2), S+ carprofen (17.6), meloxicam (7.3), etodolac (6.6), R- carprofen (5.8) and ketoprofen (0.88). Selectivity expressed as the clinically relevant ratio IC(20) COX-1:IC(80) COX-2 was highest for robenacoxib (19.8) compared to deracoxib (2.3), S+ carprofen (2.5), R- carprofen (2.1), nimesulide (1.8), etodolac (0.76), meloxicam (0.46) and ketoprofen (0.21). An in vivo pharmacokinetic ex vivo pharmacodynamic study in the dog established dosage and concentration-effect relationships for single oral doses of robenacoxib over the dosage range 0.5-8.0mg/kg. Values of C(max) and AUC were linearly related to dosage over the tested range. Robenacoxib did not inhibit serum TxB(2) synthesis (COX-1) ex vivo at dosages of 0.5-4.0mg/kg and produced only transient inhibition (at the 1h and 2h sampling times) at the 8mg/kg dosage. All dosages of robenacoxib (0.5-8mg/kg) produced marked, significant and dose related inhibition of PGE(2) synthesis (COX-2) ex vivo. The data demonstrate that in the dog robenacoxib is a highly selective inhibitor of the COX-2 isoform of COX, and significantly inhibits COX-2 and spares COX-1 in vivo when administered orally over the dosage range 0.5-4.0mg/kg.

Differential inhibition of cyclooxygenase isoenzymes in the cat by the NSAID robenacoxib

Robenacoxib is a new nonsteroidal anti-inflammatory drug (NSAID) developed for use in companion animal medicine. The objectives of this study were: to quantify the inhibitory actions of robenacoxib on cyclooxygenase (COX) isoenzymes in feline whole blood assays; to establish blood concentration-time profiles of robenacoxib after intravenous and subcutaneous dosing in the cat and; to predict the time courses of inhibition of COX isoforms by robenacoxib. COX-1 and COX-2 activities in heparinized feline whole blood samples were induced with calcium ionophore and lipopolysaccharide, respectively. Inhibition of thromboxane B2 provided a marker of both COX-1 and COX-2 activities and a nonlinear parametric mixed effects modelling approach was used to establish the pharmacodynamic parameters describing this inhibition. Mean values (and prediction intervals) of IC50 were 28.9 (16.4-51.1) microM (COX-1) and 0.058 (0.010-0.340) microM (COX-2). These parameters were used to compute several selectivity indices. Selectivity IC ratios (COX-1:COX-2) were 502.3 (IC50/IC50), 451.6 (IC95/IC95) and 17.05 (IC20/IC80). Based on a clinically recommended dosage regimen of 2 mg/kg, it was predicted that the corresponding mean robenacoxib blood concentration over the first 12 h after drug administration corresponded to 5% inhibition of COX-1 and 90% inhibition of COX-2.

Analytical determination and pharmacokinetics of robenacoxib in the dog

An analytical method was developed and validated for the measurement of the novel analgesic and anti-inflammatory drug robenacoxib in blood and plasma of dogs and cats. To prevent nonreproducible carry-over effects, an initial solid phase extraction procedure was followed by high pressure liquid chromatography analysis for samples with concentrations in the range 500 to 20,000 ng/mL. To improve accuracy, samples of concentration 3 to 100 ng/mL were analyzed by liquid chromatography-mass spectrometry. Applying these methods, blood concentration-time profiles and pharmacokinetic variables of robenacoxib in dogs were determined in a four-phase cross-over study, which compared different routes of administration of the drug, including intravenous (i.v.) injection, oral application with and without feed, and subcutaneous (s.c.) application. After i.v. administration the mean clearance from blood was 0.81 L/kg/h, the volume of distribution was 0.77 L/kg for the elimination phase and 0.24 L/kg for steady-state, and the terminal half-life in blood was 0.63 h. Maximum blood concentrations were obtained in less than 1 h following oral or s.c. application. Absolute bioavailability was 88% after s.c. injection, 84% after oral administration to fasted dogs, but was reduced to 62% when applied orally to fed dogs. In canine and feline plasma the degree of binding of robenacoxib to plasma protein in vitro was greater than 98%. The blood:plasma concentration ratio was 0.44:1 in the dog and 0.65:1 in the cat. In conclusion analytical methods for the quantification of robenacoxib in blood and plasma in the dog and cat were developed and validated. In dogs, robenacoxib has good bioavailability after oral (84%) and subcutaneous (88%) administration.