Update on the use of cyclooxygenase-2-selective nonsteroidal anti-inflammatory drugs in horses

Functional infrared thermography imaging can be used to assess the effectiveness of Maxicam Gel® in pre-emptively treating transient synovitis and lameness in horses

Introduction

Diagnosing and treating lameness in horses is essential to improving their welfare. In equine orthopedic practice, infrared thermography (IRT) can indirectly detect soreness. Non-steroidal anti-inflammatory drugs can treat painful and inflammatory processes in horses. Using IRT, the efficacy of meloxicam (Maxicam Gel®) was evaluated in pre-treating transient synovitis in horses induced by a middle carpal joint injection of lipopolysaccharides (LPS) from E. coli 055:B5 at a dose of 10 endotoxin units.

Methods

In a cross-over design, six healthy horses were randomly assigned to receive either 0.6 mg/kg of oral Maxicam Gel® (MAXVO) or a mock administration (control group, C) following a two-week washout period. IRT of the middle carpal joint, visual lameness assessment and joint circumference were recorded over time. Clinical and hematological evaluations were performed. Synovial fluid aspirates were analyzed for total nucleated cell count, total protein, and prostaglandin E2. A mixed effects analysis of variance was performed for repeated measures over time, followed by Tukey's test. A multinomial logistic regression was conducted to determine whether there is a relationship between a thermography temperature change and the lameness score.

Results

There were no changes in joint circumference. The MAXVO group showed a lower rectal temperature 4 h after synovitis induction. The C group presented an increase in neutrophils and a decrease in total hemoglobin and hematocrit 8 h after induction. No changes were observed in the synovial fluid between groups. The horses that received meloxicam did not show clinically significant lameness at any time, while the C group showed an increase in lameness 2, 4, and 8 h after synovitis induction.

Discussion

IRT indicated that the skin surface temperature of the middle carpal joint was lower in horses who received meloxicam, suggesting a reduction in the inflammatory process induced by LPS. It was observed that the maximum temperature peaks in the dorsopalmar and lateropalmar positions can be utilized to predict the severity of lameness, particularly when the temperature rises above 34°C. Horses pre-treated with meloxicam showed either reduced or no indication of mild to moderate pain and presented a lowehr thermographic temperature, which indicates the effectiveness of Maxicam Gel® as an anti-inflammatory.

A Preliminary Study on the Relationship between Gastric Lesions and Anti-Inflammatory Drug Usage in Heavy Pigs

Gastric lesions in pigs cause welfare and economic losses. Their prevalence in heavy pigs reared for premium products (e.g., Parma ham) requires further investigation. Stress, nutrition, and farm management are known risk factors, but the effects of steroidal and non-steroidal anti-inflammatory drugs (NSAIDs) are largely unknown. The aim of this study was to evaluate the prevalence of gastric lesions in Italian heavy pigs and their possible association with the use of anti-inflammatory drugs. A total of 9371 pig stomachs from 76 farms were evaluated. Among these, 20.3% showed no lesions, while 30.7%, 42.1%, and 6.8% were scored 1, 2 and 3, respectively. A tendency for an inverse relationship with farm size emerged. The use of steroids and NSAIDs was estimated by calculating a treatment incidence per 1000 (TI1000) in a subset of 36 farms. At least one prescription for NSAIDs and/or steroids was found in 80.6% of the farms (55.6% used NSAIDs and 63.9% used steroids). Median TI1000 was 0.07 (range: 0-30.1) and 0.18 (range: 0-6.2) for NSAIDs and steroids, respectively. Gastric scores were positively associated with NSAID use, but not with steroid use. Although the role of these drugs in gastric lesions needs to be further clarified, these findings suggest a cautious use of non-selective NSAIDs.

Anti-inflammatory compounds reduce equine herpesvirus type 1 replication and cell-to-cell spread

Equine herpesvirus type 1 (EHV-1) is a highly transmissible pathogen that leads to a variety of clinical disease outcomes in infected horses. A major sequela that can occur after an EHV-1 infection is a neurological disease termed equine herpesvirus myeloencephalopathy (EHM). Clinical manifestations of EHM include fever, ataxia, incontinence, and partial to full paralysis, which may ultimately lead to the euthanization of the infected horse. To develop an effective treatment strategy for EHM, it is critical that the specific virus-host interactions that lead to EHM be investigated so that safe and effective therapeutic interventions can be developed and delivered. In this study, we examined the ability of four non-steroidal anti-inflammatory drugs (NSAIDs), a steroidal anti-inflammatory drug (dexamethasone), a Rho-kinase (ROCK) inhibitor, and a JAK/STAT inhibitor (AG490) to reduce EHV-1 virus yields and cell-to-cell spread. We show that the NSAID, flunixin meglumine (FM), and the JAK/STAT inhibitor, AG490, significantly reduced virus yields in endothelial and epithelial cell lines, and this inhibition was similar for two neurologic and two non-neurologic EHV-1 strains. In addition to reducing virus yields, AG490 and FM also significantly reduced the ability of EHV-1 to spread laterally from cell to cell.

The Clinical Pharmacology and Therapeutic Evaluation of Non-Steroidal Anti-Inflammatory Drugs in Adult Horses

This review firstly examines the underlying pathophysiology of pain and inflammation associated with orthopedic disease and endotoxemia. Then, it reviews the clinical pharmacology (pharmacokinetics and pharmacodynamics) of both conventional and non-conventional NSAIDs in the adult horse, and finally provides an overview of different modalities to evaluate the therapeutic efficacy of NSAIDs in research.

Synopsis of the pharmacokinetics, pharmacodynamics, applications, and safety of firocoxib in horses

According to in vitro and in vivo investigations, firocoxib (FX), a second-generation coxib, is a highly selective COX-2 inhibitor in horses. With a COX-1/COX-2 IC₅₀ ratio of 643 in horses, FX spares the COX-1 inhibitory effects. It is approved for the treatment of musculoskeletal problems and lameness in horses and dogs with osteoarthritis (OA). For the treatment of OA in horses, both an injectable formulation for IV administration at a dose of 0.09 mg/kg for five days and an oral paste formulation at a dose of 0.1 mg/kg for 14 days are licensed. Numerous analytical methods were reported in the literature to quantify FX in biological fluids, using HPLC and LC-MS. FX presents remarkable pharmacokinetics and pharmacodynamics compared to other coxibs. It has an oral bioavailability of 80% or higher and is effectively absorbed by horses. Its volume of distribution is around 2 L/kg, and it is slowly eliminated. Due to the long elimination half-life (around 2 days), which allows a once daily dosing, a single 0.3 mg/kg loading dose has been recommended. This enables the establishment of steady-state drug concentrations within 24 h, making it appropriate for acute treatment as well. Its IC₈₀ is equal to 103 ng/mL in whole blood and, with an EC₅₀ of 27 ng/mL, it has the highest affinity for its receptor compared to the other commonly administered NSAIDs in horses.

Non-Steroidal Anti-Inflammatory Drugs and Associated Toxicities in Horses

Effective pain management in horses can be a challenge despite the understanding that appropriate analgesia improves animal welfare and increases treatment success. The administration of NSAID drugs, particularly phenylbutazone and flunixin, are common practice in equine veterinary patients. Known for their analgesic and anti-inflammatory properties, NSAIDs are used for the treatment of a variety of conditions in horses, from gastrointestinal to orthopedic pain. Despite extensive usage, NSAIDs have a narrow margin of safety and the body of literature documenting the efficacy and side effects of different NSAIDs is broad. The three main side effects associated with excessive or prolonged NSAID usage in horses include gastroduodenal ulceration, right dorsal colitis (RDC) and renal papillary necrosis. The use of cyclooxygenase-2 selective NSAIDS, such as firocoxib, are theoretically safer. The aim of this paper is to review the current literature on the use and efficacy of different NSAIDs, summarise the associated side effects of NSAID usage and evaluate the current state of knowledge for the diagnosis and treatment of such toxicities.

Comparison of Flunixin Meglumine, Meloxicam and Ketoprofen on Mild Visceral Post-Operative Pain in Horses

Simple Summary

Pain management following surgical intervention is key. In horses, several anti-inflammatories (flunixin meglumine, meloxicam and ketoprofen) are available for the management of pain following castration. However, their analgesic efficacy remains unclear for mild visceral pain. The aim of this study was to compare the analgesic efficacy of the above-mentioned anti-inflammatory drugs, following a simple surgery (inguinal castration). Horses were administered a randomly assigned anti-inflammatory drug before and after surgery. A pain score was recorded using a previously described pain assessment scale (PASPAS) before administration, and after the first and second administrations by a senior clinician and a veterinary student. Thirty horses were evaluated, and there was no significant effect of the drug administered on the pain score. Horse welfare was not compromised regardless of drug assigned. Horses showed mild pain post-operatively, which decreased significantly within 24 h. Pain scores were significantly different when assessed by a veterinary student and a senior clinician. The authors found that the anti-inflammatory drug studied provided a similar level of analgesia for the management of mild visceral pain in horses, but that the pain scale used is not suitable for junior evaluators or, by extension, owners.

Abstract

The analgesic efficacy of meloxicam and ketoprofen against equine visceral pain is unclear. The aim of this study was to compare the analgesic efficacy of meloxicam (M) and ketoprofen (K) to flunixin meglumine (F) following inguinal castration. Horses undergoing inguinal castration under general anesthesia were randomly assigned F (1.1 mg/kg), M (0.6 mg/kg) or K (2.2 mg/kg) intravenously two hours pre-operatively and 24 h later. A pain score (out of 31) was recorded blindly by a senior clinician and veterinary student before NSAIDs administration (T₀), and after the first (T₁) and second (T₂) administrations, using a modified post-abdominal surgery pain assessment scale (PASPAS). Pain was classified as mild (score ≤ 7), moderate (score = 8–14) or severe (score > 14). Thirty horses (12 F, 10 M, 8 K) aged 6.2 ± 4.9 years, mostly warmbloods, were included. Horse welfare was not compromised regardless of the drug assigned. There was no statistically significant effect of NSAIDs on pain score. Mean pain scores were significantly higher at T₁ than T₀ for each NSAID (F: 5.08 ± 2.50 vs. 1.58 ± 1.38 (p < 0.001); M: 4.60 ± 2.32 vs. 1.10 ± 1.20 (p < 0.001); K: 5.25 ± 1.39 vs. 1.50 ± 1.51 (p < 0.0001)) and lower at T₂ than T₁ for F (2.92 ± 2.423 vs. 5.08 ± 2.50 (p < 0.001)) and M (2.90 ± 1.37 vs. 4.60 ± 2.32 (p < 0.0325)). At T₁, senior pain scores were significantly different than for junior (5.56 ± 0.54 vs. 3.22 ± 0.62, p = 0.005). This study indicates that meloxicam and ketoprofen provide a similar level of analgesia to flunixin meglumine for the management of mild visceral pain in horses. PASPAS is not reliable for junior evaluators.

Protective Effect of Silibinin on Lipopolysaccharide-Induced Inflammatory Responses in Equine Peripheral Blood Mononuclear Cells, an In Vitro Study

Simple Summary

Natural compounds are often an important source of biologically active molecules, which can find important applications in the treatment or pharmacological prevention of several pathologies. Silibinin is a natural polyphenolic flavonoid that is extracted from plant milk thistle, Silybum marianum. Silibinin has been reported to have antioxidant and immunomodulatory and anti-inflammatory activities. In horses, in particular, inflammation secondary to bacterial infection or translocation is one of the most frequent causes of morbidity and mortality. The aim of this study was to test the effect of silibinin on lipopolysaccharide (LPS)-induced inflammatory response in equine peripheral blood mononuclear cells (PBMCs). Taken together, our results showed an interesting prospective in therapeutic use of silibinin in equine inflammatory disease. Furthermore, the results from this study support the evidence of use equine PBMCs as an in vitro model to study inflammatory and immune response and for drug screening into the target specie.

Abstract

Although inflammation is an important physiological response, it plays a prominent role in several diseases across the mammalian species. In horses, in particular, inflammation secondary to bacterial infection or translocation is one of the most frequent causes of morbidity and mortality. Research in new molecules with anti-inflammatory and immunomodulatory proprieties and safe use profile is constantly an active field; natural compounds are an important source of molecules with peculiar properties such as antioxidants, anti-inflammatory and immune modulating. Silibinin, a natural polyphenolic flavonoid, extracted from plant milk thistle, Silybum marianum, has been reported to have actions such as antioxidant immunomodulatory and anti-inflammatory. The aim of this study was to test the effect of silibinin on lipopolysaccharide (LPS)-induced inflammatory response in equine peripheral blood mononuclear cells (PBMCs). Our results showed the protective effect of silibinin 10 μM and 50 μM in equine PBMCs stimulated with LPS. Silibilinin was able to prevent the LPS induced increased levels of TNF-α, IL-1β, IL-6 and IL-8. The results from this study on LPS-stimulated equine PBMCs showed that silibinin could be a useful pharmacological approach in treatment or prevention of several inflammatory conditions in horse.

Pharmacokinetics of Intravenous, Intramuscular, Oral, and Transdermal Administration of Flunixin Meglumine in Pre-wean Piglets

Castration and tail-docking of pre-wean piglets are common procedures that are known to induce pain and would benefit from pain mitigation. Flunixin meglumine (FM) is a non-steroidal anti-inflammatory drug currently approved in the United States for pyrexia in swine and lameness pain in cattle. The objective of this study was to establish the pharmacokinetic (PK) parameters resulting from intravenous (IV), intramuscular (IM), oral (PO) and transdermal (TD) administration of FM in pre-wean piglets. FM was administered to thirty-nine pre-wean piglets at a target dose of 2.2 mg/kg for IV and IM and 3.3 mg/kg for PO and TD route. Plasma was collected at twenty-seven time points from 0 to 9 days after FM administration and concentrations were determined using ultra-high performance liquid chromatography coupled with mass spectrometry (UPLC-MS). Pharmacokinetic data were analyzed using noncompartmental analysis (NCA) methods and nonlinear mixed-effects (NLME). Initial plasma concentration for IV (C₀) 11,653 μg/L and mean peak plasma concentrations (C_max) 6,543 μg/L (IM), 4,883 μg/L (PO), and 31.5 μg/L (TD) were measured. The time points of peak FM concentrations (t_max) were estimated 30 min, 1 h, and 24 h for IM, PO, and TD, respectively. The bioavailability (F) of PO and IM FM was estimated at >99%, while the bioavailability of TD FM was estimated to be 7.8%. The reported C_max of FM after IM and PO administration is consistent with therapeutic concentration ranges that mitigate pain in other species and adult pigs. However, the low estimated concentration of FM after TD dosing is not expected to mitigate pain in pre-wean piglets. The low F of TD FM suggests that expanding the surface area of application is unlikely to be sufficient to establish an effective TD dose for pain, while the high bioavailability for PO FM should allow for an effective dose regimen to be established.

Effects of Flunixin Meglumine, Firocoxib, and Meloxicam in Equines After Castration

This study is "aimed" to evaluate and compare the efficacy of flunixin meglumine (FM), firocoxib (FX), and meloxicam (MX) after castration of horses. Thirty horses were submitted to open castration and divided into three groups (n = 10) depending on the anti-inflammatory drug administered: group I (GI) (FM, 1.1 mg kg¹, IV, once a day [SID], 5 days); group II (GII) (FX, 0.1 mg kg¹, IV, SID, 5 days), and group III (GIII) (MX, 0.6 mg kg¹, IV, SID, 5 days). Clinical, behavioral, and hematological parameters and the peritoneal fluid (PF) were evaluated before (day [D] 0) and 1, 2, 3, 5, and 7 days afterward. In the postoperative, scores of limb rigidity and prepuce edema of animals of GII and GIII were greater than those of GI. Tachycardia was observed in the horses of GII and GIII and hyperthermia in GIII. An increase in the number of leukocytes, neutrophils, and monocytes without exceeding the reference values and hyperfibrinogenemia was observed in the animals of GI (D7), GII (D1-D7), and GIII (D7). There was reduction in serum protein after castration, together with an increase of this in the PF of the animals of the three groups. The PF on D0 was straw yellow and limpid, became reddish and cloudy on D1, and then gradually moved toward its normal color on the ensuing days, but without returning to normal on D7 in any of the groups. The results showed that castration triggers significant clinical and laboratory changes and that FM, FX, and MX are equally effective in controlling pain and inflammation in horses after castration; however, FM was more advantageous.

Sparing the gut: COX-2 inhibitors herald a new era for treatment of horses with surgical colic

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to manage a wide variety of conditions in horses, including management of colic. Flunixin meglumine is by far the most commonly used drug in the control of colic pain and inflammation and has become a go-to for not only veterinarians but also horse-owners and nonmedical equine professionals. NSAID use, however, has always been controversial in critical cases due to a high risk of adverse effects associated with their potent cyclo-oxygenase (COX) inhibition. There are two important COX isoenzymes: COX-1 is generally beneficial for normal renal and gastrointestinal functions and COX-2 is associated with the pain and inflammation of disease. Newer selective NSAIDs can target COX-2-driven pathology while sparing important COX-1-driven physiology, which is of critical importance in horses with severe gastrointestinal disease. Emerging research suggests that firocoxib, a COX-2-selective NSAID labelled for use in horses, may be preferable for use in colic cases in spite of the decades-long dogma that flunixin saves lives.

Analgesic and anti-inflammatory effects and molecular mechanisms of Kadsura heteroclita stems, an anti-arthritic Chinese Tujia ethnomedicinal herb

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by failure of spontaneous resolution of inflammation. The stem of Kadsura heteroclite (KHS) is a well-known anti-arthritic Tujia ethnomedicinal plant, which named Xuetong in folk, has long been used for the prevention and treatment of rheumatic and arthritic diseases.

AIM OF THE STUDY

The analgesic and anti-inflammatory effects and the potential mechanisms behind such effects of KHS would be investigated by using different animal models.

MATERIALS AND METHODS

The abdominal writhing episodes of mice induced by intraperitoneal injection of acetic acid and the tail-flick response induced by radiant heat stimulation were used to evaluate the analgesic effect of KHS. The number of abdominal writhing episodes of mice and the latency of tail-flick in rats were measured and recorded. In acute inflammatory models, the ear edema of mice was induced by applying xylene on the ear surface, while the paw edema of male and female rats was induced by subcutaneous injection of carrageenan into the right hind paws of animals. The carrageenan-induced paw swelling in rats were selected as an anti-acute inflammatory mechanism of KHS. Serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF-α) were measured by ELISA, and protein expression of cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were detected by Western blot.

RESULTS

The maximal tolerated single dose of KHS was determined to be 26 g/kg in both sexes of mice. Pharmacological studies showed that KHS at the dose of 200 mg/kg significantly prolonged the reaction time of rats to radiant heat stimulation and suppressed abdominal writhing episodes of mice induced by intraperitoneal injection of acetic acid. KHS at the dose of 200, 400, and 800 mg/kg, showed dose-dependent inhibition of xylene-induced ear swelling in mice. KHS at the dose of 100, 200, 400, and 800 mg/kg demonstrated dose- and time-dependent suppression of paw edema induced by subcutaneous injection of carrageenan in both all rats. Mechanistic studies revealed that the anti-inflammatory effect of KHS was associated with inhibition of the production of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α and effectively decreased the expression of COX and iNOS proteins in the carrageenan-injected rat serum, paw tissues and inflammatory exudates. The positive reference drug, rotundine at a dosage of 100 mg/kg and indomethacin at a dosage of 10 mg/kg were used in both mice and rat models.

CONCLUSION

These results suggested that KHS has significant effects on analgesia and anti-inflammation with decreasing the pro-inflammation cytokines of IL-1β, IL-6, and TNF-α and inhibiting the proteins expression of COX-2 and iNOS.

Pharmacological Regulation in the USA and Pharmacokinetics Parameters of Firocoxib, a Highly Selective Cox-2, by Pain Management in Horses

The objective of the study was to conduct a review of the pharmacological regulation and pharmacokinetic parameters of firocoxib when administered orally or intravenously in horses. A search for literature was done in SCOPUS and PubMed for studies that had to evaluate the pharmacological regulation as well as the pharmacokinetic parameters of firocoxib when administered in horses. The nonsteroidal anti-inflammatory drugs have analgesic, anti-inflammatory, antipyretics, and antiendotoxic effects. The newly developed is selective to COX2 characterized by less adverse effects in veterinary patients when administered at the recommended doses and do not exceed the established prescribed time. Firocoxib is authorized by the Food and Drug Administration for the treatment of pain in horses, whereas for humans, there is still no approval. Controversy has arisen because the administration of the same pharmaceutical presentation in horses and dogs has pharmacokinetic differences between animal species. However, special attention must be paid to pharmacokinetic differences between species like in horses and dogs. In the case of the horse, the dosage is 0.1 mg/kg in single dose or up to 14 days in oral paste formulation and can keep maintained on the same concentration for a period of 7-14 days in oral tablet formulation. Thorough knowledge of pharmacological regulations and pharmacokinetic parameters, it allows the posology and effective application of firocoxib in pathologies associated with chronic pain, avoiding the indiscriminate use by owners and in some cases veterinarians, thus reducing the negative impacts on horse's health.

Morphine, but not methadone, inhibits microsomal prostaglandin E synthase-1 and prostaglandin-endoperoxide synthase 2 in lipopolysaccharide-stimulated horse synoviocytes

Osteoarthritis (OA) is one of the main locomotor disorders in horses. Although nonsteroidal anti-inflammatory drugs are the first-line treatment for OA, opioids could also be used. In previous studies, opioids showed promising anti-inflammatory and analgesic effects. In this study, we aimed to investigate the effects of two opioids (morphine and methadone) against inflammation in lipopolysaccharide (LPS)-stimulated synoviocytes by analyzing microsomal prostaglandin E synthase-1 (mPGES-1) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression. Synoviocytes were obtained from the joints at the distal limbs of dead animals. The cytotoxic effects of LPS, morphine, and methadone were investigated by using a cell viability assay with crystal violet dye. Synoviocytes were treated with LPS, LPS plus morphine, or LPS plus methadone for 3, 6, and 12 h, and mPGES-1 and PTGS2 expression was measured using real-time polymerase chain reaction. LPS, and morphine did not affect the viability of synoviocytes, even at high concentrations. LPS treatment increased mPGES-1 and PTGS2 expression, whereas morphine inhibited the increase in mPGES-1 and PTGS2 expression in LPS-stimulated synoviocytes. Methadone did not inhibit mPGES-1 or PTGS2 expression. These results suggest that morphine may exhibit anti-inflammatory effect; therefore, it might be beneficial for the treatment of OA.

Pharmacokinetics of meloxicam after oral administration of a granule formulation to healthy horses

Background

Nonsteroidal anti‐inflammatory drugs are administered in horses for several systemic diseases. Selective cyclooxygenase‐2 inhibitors are preferred because of lower risk of adverse effects. Several meloxicam formulations have been tested in horses, but a recently marketed granule oral formulation has not been studied.

Objective

To characterize the pharmacokinetics of a novel granule meloxicam formulation in fasted and fed horses, and to compare pharmacokinetic features with oral suspension and tablets.

Animals

Seven healthy adult horses.

Methods

Meloxicam was administered at 0.6 mg/kg in fasted or fed horses. Blood samples were collected for pharmacokinetic analysis, and vital signs, hematology, and biochemistry variables were monitored for 72 hours.

Results

No adverse effects were detected. Volume of distribution and clearance after intravenous administration of meloxicam were 0.36 L/kg and 29.12 mL/h/kg, respectively, with a 12.39 hours of terminal half‐life. Protein binding was of 97%. Bioavailability was high for every oral formulation, ranging 70%‐110%, without feed effect. Because of a slower absorption, meloxicam after administration of granules had a longer half‐life (24 and 34 hours, fasted and fed, respectively) and mean residence time (31 and 47 hours), than suspension and tablets (ranging 10‐13 and 13‐15 hours, respectively). In addition, the time above therapeutic concentration was higher for the granule formulation than other formulations.

Conclusions and Clinical Importance

Granule formulation has different PK parameters compared to other oral formulations, which could enable this formulation to be used for different dosage regimens in order to reach a desired clinical effect or decrease the risk of adverse effects.