Pharmacokinetic evaluation of oral deracoxib in geese (Anser anser domesticus)

The integration of pain management in veterinary practice, driven by heightened animal welfare concerns, extends to avian species where subtle and nonspecific behavioral signs pose challenges. Given that safety concerns with classical NSAIDs highlight the need for more targeted alternatives in birds, this study explores the pharmacokinetic (PK) properties of Deracoxib (DX), a COX-2 selective NSAID approved for use in dogs, following a single oral administration in geese. Six healthy female geese received 4 mg/kg DX. Blood was drawn from the left wing vein to heparinized tubes at 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, and 24 h. Plasma DX concentrations were measured using HPLC coupled to an UV detector, and the data were pharmacokinetically analyzed using PKanalix™ software in a non-compartmental approach. The results indicated a terminal half-life of 6.3 h and a Tmax of 1 h, with no observed adverse effects. While refraining from claiming absolute safety based on a single dose, it is worth highlighting that further safety studies for DX in geese are warranted, suggesting a possibility for intermittent use. In addition, drawing conclusions on efficacy and suitability awaits further research, particularly in understanding COX-2 selectivity and protein binding characteristics specific to geese.

Disposition kinetics of robenacoxib following intravenous and oral administration in geese (Anser anser domesticus)

Robenacoxib (RX) is a veterinary cyclooxygenase-2 selective inhibitor drug. It has never been tested on birds and is only labelled for use in cats and dogs. The purpose of this study was to assess its pharmacokinetics in geese after single intravenous (IV) and oral (PO) administrations. Four-month healthy female geese (n = 8) were used. Geese were subjected to a two-phase, single-dose (2 mg/kg IV, 4 mg/kg PO), open, longitudinal study design with a four-month washout period between the IV and the PO phases. Blood was collected from the left wing vein to heparinized tubes at 0, 0.085 (for IV only), 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, and 24 h. Plasma RX concentrations were measured using HPLC coupled to an UV detector, and the data were pharmacokinetically analysed using ThothPro™ 4.3 software in a non-compartmental approach. Following IV administration, terminal elimination half-life, volume of distribution, and total clearance were 0.35 h, 0.34 L/kg, and 0.68 L/h/kg, respectively. For the PO route, the mean peak plasma concentration was 6.78 μg/mL at 0.50 h. The t1/2λz was very short and significantly different between the IV and PO administrations (0.35 h IV vs. 0.99 h PO), suggesting the occurrence of a flip-flop phenomenon. The Cl values corrected for the F% were significantly different between IV and PO administrations. It might have been a consequence of the longitudinal study design and the altered physiological and environmental conditions after a 4-month washout period. The absolute oral F% computed with the AUC method surpassed 150%, but after normalizing it to t1/2λz, it was 46%. In conclusion, the administration of RX might not be suitable for geese, due to its short t1/2λz.

Robenacoxib pharmacokinetics in sheep following oral, subcutaneous, and intravenous administration

The aim of this study was to evaluate the pharmacokinetics (PK) of robenacoxib (RX), a COX-2 selective non-steroidal anti-inflammatory drug, in sheep after single subcutaneous (SC), oral (PO), and intravenous (IV) administration. Five healthy female sheep underwent a three-phase parallel study design with a washout period of 4 weeks, in which sheep received a 4 mg/kg SC dose in phase 1, a 4 mg/kg PO administration in phase 2, and a 2 mg/kg IV administration in phase 3. Plasma RX concentrations were measured over a 48 h period for each treatment using HPLC coupled to a UV multiple wavelength detector, and the PK parameters were estimated using a non-compartmental method. Following IV administration, terminal elimination half-life, volume of distribution at steady state, and total clearance were 2.64 h, 0.077 L/kg, and 0.056 L/h kg, respectively. The mean peak plasma concentrations following SC and PO administrations were 7.04 and 3.01 μg/mL, respectively. The mean bioavailability following SC and PO administrations were 45.98% and 16.58%, respectively. The SC route may be proposed for use in sheep. However, the multi-dose and pharmacodynamic studies are necessary to establish more accurately its safety and efficacy in sheep.

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.

Clinical safety of robenacoxib in cats with chronic musculoskeletal disease

Background

Evaluate the clinical safety of robenacoxib in cats with chronic musculoskeletal disease (CMSD).

Animals

Four hundred forty‐nine client‐owned cats with CMSD.

Methods

Pooled analysis of safety variables from 4 prospective randomized blinded clinical trials of robenacoxib (n = 222) versus placebo (n = 227), administered orally once daily for 4 to 12 weeks. Safety was evaluated from reported adverse events (AEs) and abnormalities detected on hematology and serum and urine chemistry analyses.

Results

The number of cats with at least 1 AE was not significantly different (P = .15) with robenacoxib (n = 106, 47.8%) compared to placebo (n = 93, 41.0%). The relative risk of at least 1 AE (incidence robenacoxib/placebo) was 1.15 (95% confidence interval 0.93‐1.43). There was no significant difference between groups in the number of clinical signs (range, 0‐9) per cat (P = .23). Serum creatinine concentrations were higher during robenacoxib administration compared to placebo (+4.36 μmol/L, 95% confidence interval 0.21‐8.50), but no related adverse clinical effects were detected. In the subgroup of 126 cats with evidence of chronic kidney disease, the relative risk of at least 1 AE (robenacoxib/placebo) was 1.09 (95% confidence interval 0.78‐1.52, P = .61).

Conclusions and Clinical Importance

Robenacoxib was not associated with increased risk of AEs compared to placebo when administered for 4 to 12 weeks to cats with CMSD. The generalizability of the results to general practice is limited by the fact that cases with severe and uncontrolled concomitant diseases were not included.

Rofecoxib-Induced Deleterious Effects Escape Detection by Organismal Performance Assays

BACKGROUND

Organismal Performance Assays (OPAs) are a unique toxicity quantification method used to assess the safety of potentially toxic compounds, such as pharmaceuticals. OPAs utilize genetically diverse wild mice (Mus musculus) housed in semi-natural enclosures wherein exposed individuals compete directly with controls for resources. Previously, OPAs have been successful in detecting adverse effects in mice that were exposed to paroxetine. Here, we further test OPAs utility in pharmaceutical safety assessment by testing OPAs with rofecoxib, a drug with known adverse effects in humans.

METHODS

We exposed mice to rofecoxib (~37.5 mg/kg/day) during gestation and into early adulthood. Exposure ceased when individuals were released into enclosures. Five independent populations were established and rofecoxib-exposed individuals (n = 58) competed directly with control individuals (n = 58) over 28 weeks. Organismal performance was determined by quantifying reproduction, survival and male competitive ability.

RESULTS

In enclosures, rofecoxib-exposed males had equal reproduction, survival and competitive ability. Rofecoxib-exposed females had equal survival compared to controls but experienced 40% higher reproductive output.

CONCLUSIONS

The adverse health effects of rofecoxib seen in humans escaped detection by OPAs, just as they had during traditional preclinical assays. These results may be explained by the exposure design (in enclosures, all animals were on the control diet), the relatively short duration of exposure, species differences, or because the health benefits of the drug negated the side effects. Similarly to numerous assays used in preclinical trials, OPAs cannot reveal all maladies, despite their demonstrated sensitivity in detecting cryptic toxicity from numerous exposures.

Mitochondria of a human multidrug-resistant hepatocellular carcinoma cell line constitutively express inducible nitric oxide synthase in the inner membrane

Mitochondria play a crucial role in pathways of stress conditions. They can be transported from one cell to another, bringing their features to the cell where they are transported. It has been shown in cancer cells overexpressing multidrug resistance (MDR) that mitochondria express proteins involved in drug resistance such as P-glycoprotein (P-gp), breast cancer resistant protein and multiple resistance protein-1. The MDR phenotype is associated with the constitutive expression of COX-2 and iNOS, whereas celecoxib, a specific inhibitor of COX-2 activity, reverses drug resistance of MDR cells by releasing cytochrome c from mitochondria. It is possible that COX-2 and iNOS are also expressed in mitochondria of cancer cells overexpressing the MDR phenotype. This study involved experiments using the human HCC PLC/PRF/5 cell line with and without MDR phenotype and melanoma A375 cells that do not express the MDR1 phenotype but they do iNOS. Western blot analysis, confocal immunofluorescence and immune electron microscopy showed that iNOS is localized in mitochondria of MDR1-positive cells, whereas COX-2 is not. Low and moderate concentrations of celecoxib modulate the expression of iNOS and P-gp in mitochondria of MDR cancer cells independently from inhibition of COX-2 activity. However, A375 cells that express iNOS also in mitochondria, were not MDR1 positive. In conclusion, iNOS can be localized in mitochondria of HCC cells overexpressing MDR1 phenotype, however this phenomenon appears independent from the MDR1 phenotype occurrence. The presence of iNOS in mitochondria of human HCC cells phenotype probably concurs to a more aggressive behaviour of cancer cells.

Synthesis of Deuterated Benzopyran Derivatives as Selective COX-2 Inhibitors with Improved Pharmacokinetic Properties

We designed a series of specifically deuterated benzopyran analogues as new COX-2 inhibitors with the aim of improving their pharmacokinetic properties. As expected, the deuterated compounds retained potency and selectivity for COX-2. The new molecules possess improved pharmacokinetic profiles in rats compared to their nondeuterated congeners. Most importantly, the new compounds showed pharmacodynamic efficacy in several murine models of inflammation and pain. The benzopyran derivatives were separated into their enantiomers, and the activity was found to reside with the S-isomers. To streamline the synthesis of the desired S-isomers, an organocatalytic asymmetric domino oxa-Michael/aldol condensation reaction was developed for their preparation.

Imaging COX-2 expression in cancer using PET/SPECT radioligands: current status and future directions

The role of cyclooxygenase (COX)-2 as a driving force in early tumourigenesis and the current interest in the combination of COX-2 inhibitors with standard therapy in clinical trials creates an urgent need to establish clinically relevant diagnostic tests for COX-2 expression. Molecular imaging using small-molecule probes radiolabelled for both positron emission tomography (PET) and single photon emission computed tomography (SPECT) offers the potential to meet this need, providing a minimally invasive readout for the whole disease burden. This review summarises current approaches to the radiolabelling of small-molecule COX-2 inhibitors and their analogues for PET and SPECT imaging, and gives an overview of their biological evaluation and likely success of clinical application.

The 2'-Trifluoromethyl Analogue of Indomethacin Is a Potent and Selective COX-2 Inhibitor

Indomethacin is a potent, time-dependent, nonselective inhibitor of the cyclooxygenase enzymes (COX-1 and COX-2). Deletion of the 2′-methyl group of indomethacin produces a weak, reversible COX inhibitor, leading us to explore functionality at that position. Here, we report that substitution of the 2′-methyl group of indomethacin with trifluoromethyl produces CF₃–indomethacin, a tight-binding inhibitor with kinetic properties similar to those of indomethacin and unexpected COX-2 selectivity (IC₅₀ mCOX-2 = 267 nM; IC₅₀ oCOX-1 > 100 μM). Studies with site-directed mutants reveal that COX-2 selectivity results from insertion of the CF₃ group into a small hydrophobic pocket formed by Ala-527, Val-349, Ser-530, and Leu-531 and projection of the methoxy group toward a side pocket bordered by Val-523. CF₃–indomethacin inhibited COX-2 activity in human head and neck squamous cell carcinoma cells and exhibited in vivo anti-inflammatory activity in the carrageenan-induced rat paw edema model with similar potency to that of indomethacin.

Hospitalizations for gastrointestinal and cardiovascular events in the CADEUS cohort of traditional or Coxib NSAID users

AIMS

To assess hospital admission rates for gastrointestinal (GI) or cardiovascular (CV) events in real-life use of nonsteroidal anti-inflammatory drugs (NSAIDs).

METHODS

CADEUS is a real-life population-based cohort study of 23 535 coxib (celecoxib or rofecoxib) and 22 919 traditional NSAID (tNSAID) users. Each hospitalization reported between index day (NSAID delivery) and questionnaire submission (median = 75 days) was explored using hospital discharge summaries. An expert committee validated blindly serious GI and CV events according to predefined criteria.

RESULTS

Coxib users were older and had more GI history than tNSAID users. There were 21 hospitalizations for GI events, 12 in the coxib cohort and nine in the tNSAID cohort (respectively one and three upper GI haemorrhages and no ulcer perforations). Rates of GI events were 0.39 per 1000 patients [95% confidence interval (CI) 0.18, 0.75] for tNSAID users and 0.51 per 1000 patients (95% CI 0.26, 0.89) for coxib users. There were 21 hospitalizations for CV events, 13 in the coxib cohort and eight in the tNSAID cohort. None was fatal. Rates of CV events were, respectively, 0.59 (95% CI 0.24, 1.22), 0.51 (95% CI 0.19, 1.11) and 0.35 (95% CI 0.15, 0.69) per 1000 patients for celecoxib, rofecoxib and tNSAIDs. GI or CV event rates were not different between products even for patients >60 years old.

CONCLUSIONS

Hospitalization rates for GI bleeding were 10-20 times lower than expected from published randomized clinical trials, probably because of differences in drug usage and concomitant gastroprotection. CV event rates conformed to those expected from general population data. These results emphasize the necessity of developing population healthcare databases to explore such low event rates.

Cyclooxygenases: structural and functional insights

Cyclooxygenase (COX; prostaglandin G/H synthase, EC 1.14.99.1) catalyzes the first two steps in the biosynthesis of prostaglandins (PGs). The two COX isoforms COX-1 and COX-2 are the targets of the widely used nonsteroidal anti-inflammatory drugs, indicating a role for these enzymes in pain, fever, inflammation, and tumorigenesis. The ubiquitous constitutive expression of COX-1 and inducible expression of COX-2 have led to the widely held belief that COX-1 produces homeostatic PGs, while PGs produced by COX-2 are primarily pathophysiological. However, recent discoveries call this paradigm into question and reveal as yet underappreciated functions for both enzymes. This review focuses on some of these new insights.

Incidence of gastroduodenal ulcers in patients with rheumatoid arthritis after 12 weeks of rofecoxib, naproxen, or placebo: a multicentre, randomised, double blind study

BACKGROUND

Previous studies in patients with osteoarthritis have suggested that the selective cyclooxygenase (COX)-2 inhibitor rofecoxib results in less gastrointestinal damage than non-selective non-steroidal antiinflammatory drugs (NSAIDs). This study compared the incidence of endoscopically detected gastroduodenal ulcers in rheumatoid arthritis patients treated with rofecoxib or a non-selective NSAID.

METHODS

In this multicentre, randomised, double blind, 12 week study, patients with rheumatoid arthritis were allocated to rofecoxib 50 mg once daily (n=219), naproxen 500 mg twice daily (n=220), or placebo (n=221). Endoscopy was performed at baseline and at six and 12 weeks. Lifetable analysis and log rank tests were used to analyse the incidence of gastroduodenal ulcers > or =3 mm. Gastric or duodenal ulcers > or =5 mm and erosions were also evaluated as secondary end points. Tolerability was assessed by adverse events.

RESULTS

The cumulative incidence of ulcers > or =3 mm at 12 weeks was significantly higher in patients on naproxen (25.5%) than in patients receiving rofecoxib (6.8%; difference 18.7% (95% confidence interval (CI) 11.7%, 25.7%); p<0.001) or placebo (2.9%; difference 22.6% (95% CI 16.1%, 29.1%); p<0.001). The difference between rofecoxib (6.8%) and placebo (2.9%) did not reach statistical significance (p=0.066). Results were similar for ulcers > or =5 mm and for mean changes from baseline in the number of gastroduodenal erosions. The overall incidence of clinical adverse events was similar among treatment groups (61% of patients on placebo, 62% in patients on rofecoxib, and 66% in patients on naproxen).

CONCLUSIONS

Rofecoxib 50 mg daily (twice the dose recommended for this patient population) resulted in a lower incidence of endoscopically detected gastroduodenal ulcers and erosions than treatment with naproxen 500 mg twice daily.