Meloxicam: influence on arachidonic acid metabolism. Part II. In vivo findings

A 2022 Systematic Review and Meta-Analysis of Enriched Therapeutic Diets and Nutraceuticals in Canine and Feline Osteoarthritis

With osteoarthritis being the most common degenerative disease in pet animals, a very broad panel of natural health products is available on the market for its management. The aim of this systematic review and meta-analysis, registered on PROSPERO (CRD42021279368), was to test for the evidence of clinical analgesia efficacy of fortified foods and nutraceuticals administered in dogs and cats affected by osteoarthritis. In four electronic bibliographic databases, 1578 publications were retrieved plus 20 additional publications from internal sources. Fifty-seven articles were included, comprising 72 trials divided into nine different categories of natural health compound. The efficacy assessment, associated to the level of quality of each trial, presented an evident clinical analgesic efficacy for omega-3-enriched diets, omega-3 supplements and cannabidiol (to a lesser degree). Our analyses showed a weak efficacy of collagen and a very marked non-effect of chondroitin-glucosamine nutraceuticals, which leads us to recommend that the latter products should no longer be recommended for pain management in canine and feline osteoarthritis.

Inflammation: A Target for Treatment in Spinal Cord Injury

Spinal cord injury (SCI) is a significant cause of disability, and treatment alternatives that generate beneficial outcomes and have no side effects are urgently needed. SCI may be treatable if intervention is initiated promptly. Therefore, several treatment proposals are currently being evaluated. Inflammation is part of a complex physiological response to injury or harmful stimuli induced by mechanical, chemical, or immunological agents. Neuroinflammation is one of the principal secondary changes following SCI and plays a crucial role in modulating the pathological progression of acute and chronic SCI. This review describes the main inflammatory events occurring after SCI and discusses recently proposed potential treatments and therapeutic agents that regulate inflammation after insult in animal models.

Preliminary Investigation into a Novel Sustained-Release Formulation of Meloxicam in Sheep (Ovis aries)-Pharmacokinetic Profile

Simple Summary

Meloxicam is an effective non-steroidal anti-inflammatory drug (NSAID) suitable for ameliorating pain in sheep. Pain caused by husbandry procedures and other inflammatory conditions in sheep can persist for an extended time beyond the duration of action of currently available formulations of NSAIDs. This study investigates a novel sustained-release formulation of meloxicam to determine its potential for extended pain alleviation. Compared to a conventional formulation of meloxicam, the sustained-release formulation provided extended half-life making it a suitable candidate for providing extended pain relief.

Abstract

This study is a preliminary investigation describing the pharmacokinetic profile of a novel subcutaneous sustained-release meloxicam formulation (SRMF) in sheep. Six merino ewe hoggets (41.5 ± 4.6 kg) were treated with a novel subcutaneous SRMF at 2 mg/kg bodyweight (BW). Blood samples were collected at t = 0, 2, 4, 6, 8, 10, 12, 24, 48, 96, 144, 168, 192, and 336 h following treatment, and interstitial (ISF) fluid samples were collected at periods of 8 to 12 h, 12 to 24 h, 24 to 48 h, 48 to 52 h, and 92 to 96 h following treatment. High-pressure liquid chromatography (HPLC) analysis with ultraviolet detection was utilised to determine the concentration of meloxicam in plasma and ISF. The SRMF exhibited the following mean (±SD) pharmacokinetic indices: C_max of 1.58 μg/mL (±0.82 μg/mL) at a T_max of 10.0 h (±1.79 h), and half life (t_1/2) of 31.4 h (±13.17 h) in sheep plasma. Interstitial fluid samples were collected from three of the six sheep, with a decrease in meloxicam concentration exhibited over 52 h. This study demonstrates a variable extended t_1/2, a delayed T_max, and a lower C_max of the SRMF, as compared to that of a conventional meloxicam formulation (CMF) in sheep, as previously referenced (t_1/2: 14.28 h; T_max: 5 h; C_max: 15.94 μg/mL). Further research to determine the clinical efficacy and safety of the SRMF in sheep is warranted.

Pharmacokinetics of Meloxicam Tablets in Healthy Chinese Adults in the Fasting and Fed States: A Single-Site, Single-Dose, Randomized, Open, 2-Period, 2-Sequence, Crossover Bioequivalence Study

Meloxicam is an enolate nonsteroidal anti-inflammatory agent. This trial investigated the pharmacokinetics, safety, and bioequivalence of single oral doses of Aomei meloxicam (15 mg) and Mobic meloxicam (15 mg) in healthy volunteers under fasting and fed conditions. A single-site, single-dose, randomized, open, 2-period, 2-sequence, crossover bioequivalence study was performed: 24 healthy volunteers were enrolled in each of the fasting and fed arms. Each HV was randomly assigned to receive the Aomei drug (test) in one period and the Mobic drug (reference) in the other period. The concentration of meloxicam in plasma was detected using liquid chromatography-tandem mass spectrometry. The primary pharmacokinetic parameters were calculated using a noncompartmental model. In the fasting arm, the 90% confidence interval of the geometric mean ratios of maximum plasma concentration, area under the concentration-time curve from time 0 to the last measurable plasma concentration, and area under the concentration-time curve from time 0 to infinity between the test and reference products were 99.5% to 111.7%, 101.2% to 106.8%, and 101.8% to 108.3%, respectively. In the fed arm, the 3 parameters were 94.1% to 102.4%, 97.6% to 103.0%, and 97.5% to 103.7%, respectively. These parameters were in the range of 80% to 125%, and the 2 products were considered bioequivalent in both the fasting and fed states and were well tolerated. The severity of all adverse events was mild. Aomei meloxicam tablets and Mobic meloxicam tablets were bioequivalent in healthy Chinese volunteers.

Effects of local or systemic administration of meloxicam on mammary gland inflammatory responses to lipopolysaccharide-induced mastitis in dairy cows

Nonsteroidal anti-inflammatory drugs (NSAID) are commonly used in combination with antimicrobial mastitis treatments to reduce pain. Little is known about whether meloxicam, an NSAID designed for the preferential inhibition of cyclooxygenase-2 over cyclooxygenase-1, affects the mammary immune response. The objective of this study was to analyze the mammary immune response to intramammary (local) or intravenous (systemic) administration of meloxicam with or without immune activation by lipopolysaccharide (LPS). We challenged 108 quarters of 30 cows with or without a low or high dose of LPS from Escherichia coli (0.1 or 0.2 µg/quarter), with or without meloxicam via intramammary administration (50 mg/quarter) or intravenous injection (0.5 mg/kg of body weight; ~300 mg/cow). Intramammary administration of meloxicam alone did not trigger an acute inflammatory response, verified by unchanged somatic cell count (SCC) and lactate dehydrogenase (LDH), BSA, and IgG concentrations in milk, which are normally augmented during mastitis due to an opening of the blood-milk barrier. Similarly, intramammary meloxicam did not change the mRNA abundance of inflammatory factors in mammary gland tissue. As expected, quarters challenged with either dose of LPS showed increased leukocyte infiltration (SCC); increased LDH, BSA, IgG, Na, and Cl concentrations; and diminished K concentrations in milk. In contrast to our hypothesis, the addition of intramammary or intravenous meloxicam did not reduce these markers of mastitis in milk. Instead, intramammary meloxicam appeared to accelerate the SCC response to LPS, but only at the lower LPS dose. Moreover, the mRNA expression of inflammatory factors in mammary tissue was not modified by the intramammary application of meloxicam compared with the contralateral quarters that were challenged with LPS only. We demonstrated for the first time that intramammary meloxicam at a dose of 50 mg/quarter did not trigger an immune response in the mammary glands of dairy cows. At the doses we used, meloxicam (intramammary or systemic) did not lower inflammatory responses. The intramammary administration of meloxicam seemed to stimulate leukocyte recruitment into the milk in quarters challenged with a low dose of LPS. The integrity of the blood-milk barrier was not protected by meloxicam in LPS-stimulated quarters. This study provides the first indications that meloxicam does not limit the inflammatory response in the mammary gland, although it does not impair the mammary immune system.

Cyclooxygenases 1 and 2 inhibition and analgesic efficacy of dipyrone at different doses or meloxicam in cats after ovariohysterectomy

OBJECTIVE

To evaluate the cyclooxygenases (COX) inhibition, adverse effects and analgesic efficacy of dipyrone or meloxicam in cats undergoing elective ovariohysterectomy.

STUDY DESIGN

Prospective, blinded, randomized, clinical study.

ANIMALS

A total of 30 healthy young cats.

METHODS

The cats were randomly assigned to three postoperative groups: D25 (dipyrone 25 mg kg^-1 every 24 hours), D12.5 (dipyrone 12.5 mg kg^-1 every 12 hours) and M (meloxicam 0.1 mg kg^-1 every 24 hours). In the first 24 hours, the drugs were administered intravenously (IV), and then orally for 6 (dipyrone) or 3 days (meloxicam). Prostanoids thromboxane B₂ and prostaglandin E₂ concentrations served as indicators of COX activity and, with physiological variables and pain and sedation scores, were measured for 24 hours after first analgesic administration. Rescue analgesia (tramadol, 2 mg kg^-1 IV) was provided if Glasgow feline composite measure pain scale (CMPS-Feline) ≥5. Laboratory tests included symmetric dimethylarginine and adverse effects were evaluated regularly up to 7 and 10 days after surgery, respectively. Parametric and nonparametric data were analyzed with two-way anova and Kruskal-Wallis tests, respectively (p < 0.05).

RESULTS

In the first half hour after analgesic administration, COX-1 activity was close to zero and remained significantly lower than before drug administration for 24 hours in all groups. The inhibition of COX-2 activity was significant for 30 minutes in all groups and up to 4 hours in group M. No alterations in laboratory tests or significant adverse effects were observed. Pain scores and need for rescue analgesia did not differ statistically among groups.

CONCLUSIONS

Dipyrone at both doses and meloxicam provided a nonselective inhibition of COX-1 and -2 activities and effective analgesia without causing significant adverse effects or laboratory tests alterations.

CLINICAL RELEVANCE

Dipyrone at both doses provides equally effective analgesia without causing adverse effects in cats undergoing ovariohysterectomy.

Brain Structural and Functional Alterations in Mice Prenatally Exposed to LPS Are Only Partially Rescued by Anti-Inflammatory Treatment

Aberrant immune activity during neurodevelopment could participate in the generation of neurological dysfunctions characteristic of several neurodevelopmental disorders (NDDs). Numerous epidemiological studies have shown a link between maternal infections and NDDs risk; animal models of maternal immune activation (MIA) have confirmed this association. Activation of maternal immune system during pregnancy induces behavioral and functional alterations in offspring but the biological mechanisms at the basis of these effects are still poorly understood. In this study, we investigated the effects of prenatal lipopolysaccharide (LPS) exposure in peripheral and central inflammation, cortical cytoarchitecture and behavior of offspring (LPS-mice). LPS-mice reported a significant increase in interleukin-1β (IL-1β) serum level, glial fibrillary acidic protein (GFAP)- and ionized calcium-binding adapter molecule 1 (Iba1)-positive cells in the cortex. Furthermore, cytoarchitecture analysis in specific brain areas, showed aberrant alterations in minicolumns’ organization in LPS-mice adult brain. In addition, we demonstrated that LPS-mice presented behavioral alterations throughout life. In order to better understand biological mechanisms whereby LPS induced these alterations, dams were treated with meloxicam. We demonstrated for the first time that exposure to LPS throughout pregnancy induces structural permanent alterations in offspring brain. LPS-mice also present severe behavioral impairments. Preventive treatment with meloxicam reduced inflammation in offspring but did not rescue them from structural and behavioral alterations.

Meloxicam affects the inflammatory responses of bovine mammary epithelial cells

Nonsteroidal anti-inflammatory drugs are used as supportive therapy with antimicrobial treatments for mastitis in cows to alleviate pain of the inflamed mammary gland. They act mainly by inhibition of cyclooxygenases. Meloxicam (MEL) is a drug designed for cyclooxygenase-2 selectivity, which is upregulated upon inflammation, acting as a key enzyme for the conversion of arachidonic acid to prostaglandins. Although some studies in dairy cows showed positive results in recovery from mastitis when MEL was added to the treatments, direct effects of MEL on the immune system of mastitic cows are unknown. The aim of this study was to investigate effects of MEL on the immune response of bovine mammary epithelial cells (MEC) with or without simultaneous immune stimulation by pathogen-associated molecular patterns of common mastitis pathogens. Mammary epithelial cells from 4 cows were isolated and cultured. To evaluate dose effects of MEL, MEC were challenged with or without 0.2 µg/mL lipopolysaccharide (LPS; serotype O26:B6 from Escherichia coli) with addition of increasing concentrations of MEL (0, 0.25, 0.5, 1.0, 1.5, or 2.0 mg/mL). The addition of MEL prevented the increase of mRNA expression of key inflammatory factors in LPS-challenged MEC in a dose-dependent manner. To investigate the effects of MEL on pathogen-specific immune responses of MEC, treatments included challenges with LPS from E. coli and lipoteichoic acid from Staphylococcus aureus with or without 1.5 mg/mL MEL for 3, 6, and 24 h. Meloxicam prevented the increase of mRNA abundance of key inflammatory mediators in response to LPS and lipoteichoic acid, such as tumor necrosis factor, serum amyloid A, inducible nitric oxide synthase, and the chemokines IL-8 and CXC chemokine ligands 3 and 5. The prostaglandin E₂ synthesis in challenged and nonchallenged cells was reduced by MEL within 24 h. Furthermore, MEL reduced the viability and consequently the total RNA yield of the cells. However, mRNA abundance of apoptosis-related enzymes was not affected by any treatment. Meloxicam had clear dose-dependent effects on the immune response of MEC to pathogen-associated molecular patterns of common mastitis pathogens by preventing increased expression of important factors involved in inflammation. This nonsteroidal anti-inflammatory drug also has detrimental effects on cell viability. How these effects would influence the elimination of pathogens from an infected mammary gland during mastitis therapy with meloxicam needs to be further investigated.

Early experience with topical meloxicam and lidocaine combination for the treatment of vulvodynia

INTRODUCTION

We report our early clinical observations on the use of topical meloxicam and lidocaine gel for patients with vulvodynia.

METHODS

This is an early experience in participants with a history of vulvodynia evaluated and treated at the Queen's University Pelvic and Bladder Pain Clinic. Combination meloxicam 0.3% and lidocaine 5% were provided to the participants and they were instructed to apply 5 cc to the vulvar area twice daily. Standardized assessment was conducted for each participant before the start of the topical therapy and again at one week, and included Interstitial Cystitis Symptom Index (ICSI), Interstitial Cystitis Problem Index (ICPI), and pain scoring (Likert) for vulvar pain, in addition to a subjective global assessment after a week of treatment.

RESULTS

Of the eight participants, six had a subjective improvement in their symptoms with the use of the combination gel. They reported between one- and four-point reductions on the Likert pain scale and mild to moderate improvement of symptoms. Common side effects reported were burning and stinging.

CONCLUSIONS

The results from this early experience are promising for a potentially effective topical treatment for vulvodynia.

Polymeric nanocapsules as a technological alternative to reduce the toxicity caused by meloxicam in mice

This study determined whether meloxicam in nanocapsules modifies stomach and liver damage caused by free meloxicam in mice. Male Swiss mice were treated with blank nanocapsules or meloxicam in nanocapsules or free meloxicam (10 mg/kg, intragastrically, daily for five days). On the seventh day, blood was collected to determine biochemical markers (glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, total bilirubin, unconjugated bilirubin, albumin and alkaline phosphatase). Stomachs and livers were removed for histological analysis. There was no significant difference in the biochemical markers in the plasma of mice. Meloxicam in nanocapsules did not have an ulcerogenic potential in the stomach or cause lipid peroxidation in the stomach and liver. Free meloxicam increased the ulcerogenic potential in the stomach and lipid peroxidation in the stomach and liver. Meloxicam in nanocapsules caused less histological changes than free meloxicam. In conclusion, polymeric nanocapsules can represent a technological alternative to reduce the toxicity caused by meloxicam.

Meloxicam fails to augment the reno-protective effects of soluble epoxide hydrolase inhibition in streptozotocin-induced diabetic rats via increased 20-HETE levels

The pro-inflammatory cyclooxygenase (COX)-derived prostaglandins and the anti-inflammatory cytochrome P450 epoxygenase-derived epoxyeicosatrienoic acids (EETs) play an important role in the regulation of renal injury. The current study examined whether COX inhibition augments the reno-protective effects of increased EETs levels via inhibiting EETs degradation by soluble epoxide hydrolase (sEH) in diabetic rats. Streptozotocin (50mg/kg, i.v) was used to induce diabetes in male Sprague Dawley rats. Rats were then divided into 5 groups (n=6-8); control non diabetic, diabetic, diabetic treated with the sEH inhibitor trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), diabetic treated with the COX inhibitor meloxicam and diabetic treated with meloxicam plus t-AUCB for 2 months. Glomerular albumin permeability and urinary albumin and nephrin excretion levels were significantly elevated in diabetic rats together with decreased glomerular α3 integrin and nephrin expression levels. Inhibition of sEH reduced glomerular albumin permeability, albumin and nephrin excretion levels and restored the decrease in glomerular α3 integrin and nephrin expression in diabetic rats. Meloxicam failed to reduce renal injury or even to synergize the reno-protective effects of sEH inhibition in diabetic rats. Furthermore, inhibition of sEH reduced the elevation in renal collagen deposition and urinary MCP-1 excretion levels together with a reduction in the number of renal TUNEL positive cells in diabetic vs. control rats (P<0.05). Meloxicam did not reduce renal inflammation or apoptosis in diabetic rats or even exacerbate the anti-inflammatory and anti-apoptotic effects of sEH inhibition. Renal 20-hydroxyeicosatetranoic acid (20-HETE) levels were elevated in diabetic rats and meloxicam further exacerbated this elevation. In conclusion, our study suggests that inhibition of COX failed to provide renal protection or to augment the reno-protective effects of sEH inhibition in diabetic rats, at least in part, via increased inflammatory 20-HETE levels.

Role of preferential cyclooxygenase-2 inhibition by meloxicam in ischemia/reperfusion injury of the rat liver

BACKGROUND

Ischemia/reperfusion injury (IRI) is one of the major clinical problems in liver and transplant surgery. Livers subjected to warm ischemia in vivo often show a severe dysfunction and the release of numerous inflammatory cytokines and arachidonic acid metabolites. Cyclooxygenase (COX)-2 is the inducible isoform of an intracellular enzyme that converts arachidonic acid into prostaglandins. The aim of the study was to evaluate the effect of COX-2 inhibition and the role of Kupffer cells in IRI of the liver.

METHODS

Male Wistar rats [250- 280 g body weight (BW)] were anesthetized and subjected to 30-min warm ischemia of the liver (Pringle's maneuver) and 60-min reperfusion after median laparotomy. The I/R group received no additional treatment. In the COX-2 inhibitor (COX-2I) group, the animals received 1 mg/kg BW meloxicam prior to operation. Gadolinium chloride (GdCl3) (10 mg/kg BW) was given 24 h prior to operation in the GdCl3 and GdCl3 + COX-2I groups for the selective depletion of Kupffer cells. The GdCl3 + COX-2I group received both GdCl3 and meloxicam treatment prior to operation. Blood and liver samples were obtained at the end of the experiments for further investigations.

RESULTS

After 30 min of warm ischemia in vivo, severe hepatocellular damage was observed in the I/R group. These impairments could be significantly prevented by the selective COX-2 inhibition and the depletion of Kupffer cells. Alanine aminotransferase was significantly reduced upon meloxicam and GdCl3 treatment compared to the I/R group: I/R, 3,240 ± 1,262 U/l versus COX-2I, 973 ± 649 U/l, p < 0.001; I/R versus GdCl3, 1,611 ± 600 U/l, p < 0.05, and I/R versus GdCl3 + COX-2I, 1,511 ± 575 U/l, p < 0.01. Plasma levels of tumor necrosis factor alpha (TNF-α) were significantly reduced in the COX-2I treatment group compared to I/R (3.5 ± 1.5 vs. 16.3 ± 11.7 pg/ml, respectively; p < 0.05). Similarly, the amount of TxB2, a marker for COX-2 metabolism, was significantly reduced in the meloxicam treatment groups compared to the I/R group: I/R, 22,500 ± 5,210 pg/ml versus COX-2I, 1,822 ± 938 pg/ml, p < 0.001, and I/R versus GdCl3 + COX-2I, 1,530 ± 907 pg/ml, p < 0.001. All values are given as mean ± SD (n = 6).

CONCLUSION

These results suggest that the inhibition of COX-2 suppressed the initiation of an inflammatory cascade by attenuating the release of TNF-α, which is an initiator of the inflammatory reaction in hepatic IRI. Therefore, we conclude that preferential inhibition of COX-2 is a possible therapeutic approach against warm IRI of the liver.

Timing matters: NSAIDs interfere with the late proliferation stage of a repaired rotator cuff tendon healing in rats

INTRODUCTION

Rotator cuff (RC) tear is a common problem that causes pain and can limit shoulder function. Non-steroidal anti-inflammatory drugs (NSAIDs) are often prescribed for musculoskeletal pain, including the pain subsequent to RC repair. NSAIDs have been reported to affect bone metabolism and fracture healing(,) but there is little evidence about their effect on tendon healing. We investigated the effect of meloxicam (non-steroidal anti-inflammatory drug) on the healing of RC tendons when given immediately after surgical repair.

MATERIALS AND METHODS

Thirty-nine rats underwent acute RC tear and repair. Group A (n = 13) received daily intraperitoneal (IP) injections of meloxicam for the first 10 postoperative days. Group B (n = 13) received IP injections of meloxicam starting from postoperative day 11. Group C (n = 13, controls) received daily IP injections of saline for 3 weeks. The animals were killed 3 weeks after surgery and the RC was evaluated by gross inspection, biomechanical testing and histological examination.

RESULTS

Group B displayed a significantly lower mean maximal load at 3 weeks than group C (P = 0.02) and group A (P = 0.05). Stiffness was significantly lower in B group as compared to A group (P = 0.05). Qualitative examination of histology specimens did not disclose any apparent differences with respect to cellularity, vascularity, healing, and collagen orientation.

CONCLUSIONS

We conclude that meloxicam decreases the biomechanical strength of repaired rat RCs when administered between 11 and 20 days after the repair.

Meloxicam Does Not Affect the Antiplatelet Effect of Aspirin in Healthy Male and Female Volunteers

This study determined if meloxicam, a selective cyclooxygenase (COX)-2 inhibitor, interferes with the antiplatelet effect of aspirin using platelet aggregation and thromboxane (Tx) B(2) endpoints in healthy volunteers. Eight male and 8 female volunteers participated in this open-label, randomized, two-treatment, two-way crossover trial. Treatment 1 was meloxicam (15 mg qd) over 4 days, and then aspirin (100 mg qd) was ingested 2 hours after meloxicam for an additional 7 days. Blood samples were taken 2, 6, and 24 hours after the last dose. Treatment 2 consisted of only aspirin (100 mg) over 2 days. Samples were taken at the same time points. Each subject received both treatments with a 2-week washout between the treatment periods. Treatments were safe and well tolerated. The initial 4-day treatment with meloxicam had no effect on platelet aggregation but reduced serum TxB(2) by 64% +/- 19%. Addition of aspirin (100 mg qd) for 7 days resulted in complete inhibition of aggregation and TxB(2) for 24 hours. Two-day treatment with only 100 mg aspirin also resulted in complete inhibition of platelet aggregation and TxB(2). These results indicate that meloxicam does not affect the ability of aspirin to inhibit COX-1 in platelets, thereby allowing aspirin to effectively prevent platelet aggregation and reduce TxB(2) levels, and that meloxicam is selective for COX-2.

Cortisol and interferon tau regulation of endometrial function and conceptus development in female sheep

During early pregnancy in sheep, the elongating conceptus secretes interferon-τ (IFNT) and the conceptus as well as endometrial epithelia produce prostaglandins (PG) via PG synthase 2 (PTGS2) and cortisol via hydroxysteroid (11-β) dehydrogenase 1 (HSD11B1). Ovarian progesterone induces and PG and IFNT stimulates endometrial HSD11B1 expression and keto-reductase activity as well as many epithelial genes that govern trophectoderm proliferation, migration, and attachment during elongation. The primary aim of these studies was to test the hypothesis that HSD11B1-derived cortisol has a biological role in endometrial function and conceptus development during early pregnancy in sheep. In study 1, cyclic ewes received vehicle, cortisol, PF 915275 (PF; a selective inhibitor of HSD11B1), cortisol and PF, meloxicam (a selective inhibitor of PTGS2), cortisol and meloxicam, recombinant ovine IFNT, or IFNT and PF into the uterus from day 10 to day14 after estrus. Cortisol and IFNT stimulated endometrial HSD11B1 expression and activity, increased endometrial PTGS2 activity and the amount of PG in the uterine lumen, and up-regulated many conceptus elongation-related genes in the endometrium. Some effects of cortisol and IFNT were mediated by PTGS2-derived PG. In study 2, bred ewes received PF 915275 or recombinant ovine IFNT and into the uterus from day 10 to day 14 after mating. Inhibition of HSD11B1 activity in utero prevented conceptus elongation, whereas IFNT rescued conceptus elongation in PF-infused ewes. These results suggest that HSD11B1-derived cortisol mediates, in part, actions of ovarian progesterone and the conceptus on endometrial function and support the hypothesis that IFNT, PG, and cortisol coordinately regulate endometrial functions important for conceptus elongation and implantation during early pregnancy in sheep.

Effects of hexahydrocurcumin in combination with 5-fluorouracil on dimethylhydrazine-induced colon cancer in rats

AIM: To investigate the effects of hexahydrocurcumin (HHC), and its combination with 5-fluorouracil (5-FU) on dimethylhydrazine (DMH)-induced colon cancer in rats.

METHODS: Male Wistar rats weighing 100-120 g were used as subject models. Aberrant crypt foci (ACF), early preneoplastic lesions of colon cancer, were induced by subcutaneous injection of DHM (40 mg/kg) twice a week for two weeks. After the first DMH injection, rats were treated daily with vehicle (n = 12), curcumin (CUR) (50 mg/kg) (n = 12), HHC (50 mg/kg) orally (n = 12), and treated weekly with an intraperitoneal injection of 5-FU (50 mg/kg) (n = 12), or a combination of 5-FU plus CUR (n = 12) and HHC (n = 12) at the same dosage(s) for 16 wk. The total number of ACF and large ACF were assessed. Cyclooxygenase (COX)-1 and COX-2 expression were detected by immunohistochemistry in colon tissues. The quantitative data of both COX-1 and COX-2 expression were presented as the percentage of number of positive-stained cells to the total number of cells counted. Apoptotic cells in colon tissues were also visualized using the dUTP-biotin nick end labeling method. Apoptotic index (AI) was determined as the percentage of labeled nuclei with respect to the total number of nuclei counted.

RESULTS: The total number of ACF was highest in the DMH-vehicle group (1558.20 ± 17.37), however, the number of ACF was significantly reduced by all treatments, 5-FU (1231.20 ± 25.62 vs 1558.20 ± 17.37, P < 0.001), CUR (1284.20 ± 25.47 vs 1558.20 ± 17.37, P < 0.001), HHC (1086.80 ± 53.47 vs 1558.20 ± 17.37, P < 0.001), DMH-5-FU + CUR (880.20 ± 13.67 vs 1558.20 ± 17.37, P < 0.001) and DMH-5-FU + HHC (665.80 ± 16.64 vs 1558.20 ± 17.37, P < 0.001). Interestingly, the total number of ACF in the combined treatment groups, the DMH-5-FU + CUR group (880.20 ± 13.67 vs 1231.20 ± 25.62, P < 0.001; 880.20 ± 13.67 vs 1284.20 ± 25.47, P < 0.001) and the DMH-5-FU + HHC group (665.80 ± 16.64 vs 1231.20 ± 25.62, P < 0.001; 665.80 ± 16.64 vs 1086.80 ± 53.47, P < 0.001) were significantly reduced as compared to 5-FU or each treatment alone. Large ACF were also significantly reduced in all treatment groups, 5-FU (111.00 ± 7.88 vs 262.20 ± 10.18, P < 0.001), CUR (178.00 ± 7.33 vs 262.20 ± 10.18, P < 0.001), HHC (186.60 ± 21.51 vs 262.20 ± 10.18, P < 0.001), DMH-5-FU + CUR (122.00 ± 5.94 vs 262.20 ± 10.18, P < 0.001) and DMH-5-FU + HHC (119.00 ± 17.92 vs 262.20 ± 10.18, P < 0.001) when compared to the vehicle group. Furthermore, in the DMH-5-FU + CUR and DMH-5-FU + HHC groups the formation of large ACF was significantly reduced when compared to CUR (122.00 ± 5.94 vs 178.00 ± 7.33, P < 0.005) or HHC treatment alone (119.00 ± 17.92 vs 186.60 ± 21.51, P < 0.001), however, this reduction was not statistically different to 5-FU monotherapy (122.00 ± 5.94 vs 111.00 ± 7.88, P = 0.217; 119.00 ± 17.92 vs 111.00 ± 7.88, P = 0.619, respectively). The levels of COX-1 protein after all treatments were not different from normal rats. A marked increase in the expression of COX-2 protein was observed in the DMH-vehicle group. Over-expression of COX-2 was not significantly decreased by 5-FU treatment alone (95.79 ± 1.60 vs 100 ± 0.00, P = 0.198). However, over-expression of COX-2 was significantly suppressed by CUR (77.52 ± 1.68 vs 100 ± 0.00, P < 0.001), HHC (71.33 ± 3.01 vs 100 ± 0.00, P < 0.001), 5-FU + CUR (76.25 ± 3.32 vs 100 ± 0.00, P < 0.001) and 5-FU + HHC (68.48 ± 2.24 vs 100 ± 0.00, P < 0.001) in the treated groups compared to the vehicle group. Moreover, CUR (77.52 ± 1.68 vs 95.79 ± 1.60, P < 0.001), HHC (71.33 ± 3.01 vs 95.79 ± 1.60, P < 0.001), 5-FU + CUR treatments (76.25 ± 3.32 vs 95.79 ± 1.60, P < 0.001) and 5-FU + HHC (68.48 ± 2.24 vs 95.79 ± 1.60, P < 0.001) markedly decreased COX-2 protein expression more than 5-FU alone. Furthermore, the AI in all treated groups, 5-FU (38.86 ± 4.73 vs 23.56 ± 2.12, P = 0.038), CUR (41.78 ± 6.92 vs 23.56 ± 2.12, P < 0.001), HHC (41.06 ± 4.81 vs 23.56 ± 2.12, P < 0.001), 5-FU + CUR (49.05 ± 6.75 vs 23.56 ± 2.12, P < 0.001) and 5-FU + HHC (53.69 ± 8.59 vs 23.56 ± 2.12, P < 0.001) significantly increased when compared to the DMH-vehicle group. However, the AI in the combination treatments, 5-FU + CUR (49.05 ± 6.75 vs 41.78 ± 6.92, P = 0.192; 49.05 ± 6.75 vs 38.86 ± 4.73, P = 0.771) and 5-FU + HHC (53.69 ± 8.59 vs 41.06 ± 4.81, P = 0.379; 53.69 ± 8.59 vs 38.86 ± 4.73, P = 0.245) did not reach significant levels as compared with each treatment alone and 5-FU monotherapy, respectively.

CONCLUSION: The combined effects of HHC with 5-FU exhibit a synergistic inhibition by decreasing ACF formation mediated by down-regulation of COX-2 expression.

Pharmacokinetics and adverse effects of oral meloxicam tablets in healthy adult horses

The objective of this study was to assess the pharmacokinetic profile and determine whether any adverse effects would occur in seven healthy adult horses following oral meloxicam tablet administration once daily for 14 days at a dose of 0.6 mg/kg·bwt. Horses were evaluated for health using physical examination, complete blood count, serum chemistry, urinalysis, and gastroscopy at the beginning and end of the study. Blood was collected for the quantification of meloxicam concentrations with liquid chromatography and mass spectrometry. The mean terminal half-life was 4.99 ± 1.11 h. There was no significant difference between the mean Cmax , 1.58 ± 0.71 ng/mL at Tmax 3.48 ± 3.30 h on day 1, 2.07 ± 0.94 ng/mL at Tmax 1.24 ± 1.24 h on day 7, and 1.81 ± 0.76 ng/mL at 1.93 ± 1.30 h on day 14 (P = 0.30). There was a statistically significant difference between the Tmax on the sample days (P = 0.04). No statistically significant increase in gastric ulcer score or laboratory analytes was noted. Oral meloxicam tablets were absorbed in adult horses, and adverse effects were not statistically significant in this study. Further studies should evaluate the adverse effects and efficacy of meloxicam tablets in a larger population of horses before routine use can be recommended.

Effects of meloxicam (Metacam®) on post-farrowing sow behaviour and piglet performance

Farrowing is an intrinsically risky process for both the sow and the piglets that can cause welfare and economic problems. The effects of the non-steroidal anti-inflammatory drug meloxicam on post-farrowing behaviour of sows, and the performance of piglets were investigated. A total of 48 sows were randomly allocated at the day of farrowing (day 0) into two homogeneous groups regarding parity, and treated with either meloxicam or saline solution as placebo. For each sow, number of position changes, total time lying and standing or sitting, feed intake and rectal temperature (RT) were recorded during 3 days after farrowing. Piglets were individually weighed at farrowing and at weaning. The number of position changes did not show significant differences between treatments (P = 0.79). Sows spent significantly less time lying during day +3 after farrowing in the meloxicam group than in the placebo group (P = 0.04). Feed intake and RT showed a parity effect (P < 0.001 in both cases); however, no treatment effect was observed (P = 0.67 and P = 0.47, respectively). Pre-weaning mortality rate in piglets was not affected by treatment. In litters from multiparous sows, piglets of low birth weight (defined as percentile 15: BW <1180 g) had an average daily gain significantly higher in the meloxicam group than in the placebo group (196.6 ± 7.2 v. 166.6 ± 9.1 g/day; P = 0.03). Although the administration of meloxicam 90 min after farrowing showed a positive effect on the total time lying of the sows, additional investigations are required to better qualify relevant indicators of pain following farrowing in sows and to specify the analgesic effects of meloxicam on piglet performance.

Neuromodulatory role of endogenous interleukin-1β in acute seizures: possible contribution of cyclooxygenase-2

The function of endogenous interleukin-1β (IL-1β) signaling in acute seizure activity was examined using transgenic mice harboring targeted deletions in the genes for either IL-1β (Il1b) or its signaling receptor (Il1r1). Acute epileptic seizure activity was modeled using two mechanistically distinct chemoconvulsants, kainic acid (KA) and pentylenetetrazole (PTZ). KA-induced seizure activity was more severe in homozygous null (-/-) Il1b mice compared to their wild-type (+/+) littermate controls, as indicated by an increase in the incidence of sustained generalized convulsive seizure activity. In the PTZ seizure model, the incidence of acute convulsive seizures was increased in both Il1b and Il1r1-/- mice compared to their respective +/+ littermate controls. Interestingly, the selective cyclooxygenase (COX)-2 inhibitor, rofecoxib, mimicked the effect of IL-1β deficiency on PTZ-induced convulsions in Il1r1+/+ but not -/- mice. Together, these results suggest that endogenous IL-1β possesses anticonvulsive properties that may be mediated by arachidonic acid metabolites derived from the catalytic action of COX-2.

Meloxicam, a COX-2 inhibitor, ameliorates ischemia/reperfusion injury in non-heart-beating donor livers

BACKGROUND/AIMS

Chronic organ donor shortage has led to the consideration to expand the donor pool with livers from non-heart-beating donors (NHBD), although a higher risk of graft dys- or nonfunction is associated with these livers. We examined the effects of selective cyclooxygenase-2 (COX-2) inhibition on hepatic warm ischemia (WI) reperfusion (I/R) injury of NHBD.

METHODS

Male Wistar rats were used as donors and meloxicam (5 mg/kg body weight) was administered into the preservation solution. Livers were excised after 60 min of WI in situ, flushed and preserved for 24 h at 4°C. Reperfusion was carried out in vitro at a constant flow for 45 min. During reperfusion (5, 15, 30 and 45 min), enzyme release of alanine aminotransferase and glutamate lactate dehydrogenase were measured as well as portal venous pressure, bile production and oxygen consumption. The production of malondialdehyde was quantified and TUNEL staining was performed. Quantitative PCR analyzed COX-2 mRNA. COX-2 immunohistochemistry and TxB(2) detection completed the measurements.

RESULTS

Meloxicam treatment led to better functional recovery concerning liver enzyme release, vascular resistance and metabolic activity over time in all animals. Oxidative stress and apoptosis were considerably reduced.

CONCLUSION

Cold storage using meloxicam resulted in significantly better integrity and function of livers retrieved from NHBD. Selective COX-2 inhibition is a new therapeutic approach achieving improved preservation of grafts from NHBD.

Effects of CYP2C9*1/*13 on the pharmacokinetics and pharmacodynamics of meloxicam

AIMS

To determine the effects of the CYP2C9*1/*13 genotype on the pharmacokinetics and pharmacodynamics of meloxicam in Korean subjects.

METHODS

Meloxicam (15 mg) was orally administered to 21 healthy Korean volunteers with either the CYP2C9*1/*1 or the CYP2C9*1/*13 genotype. Plasma meloxicam concentrations were analysed by HPLC-UV for 72 h after drug administration. The pharmacodynamic effects of meloxicam were determined by measuring TXB(2) generated in blood.

RESULTS

The AUC(0,∞) and C(max) of meloxicam were 2.43- and 1.46-fold higher in the CYP2C9*1/*13 group than in the CYP2C9*1/*1 group, respectively. The oral clearance of meloxicam was significantly lower in the CYP2C9*1/*13 group (37.9% of wild type) than in the CYP2C9*1/*1 group. The t(1/2) of meloxicam was 1.84-fold longer in the CYP2C9*1/*13 group than in the CYP2C9*1/*1 group. The rate of TXB(2) production was significantly lower in the CYP2C9*1/*13 group than in the CYP2C9*1/*1 group.

CONCLUSIONS

The CYP2C9*1/*13 genotype is associated with decreased metabolism and increased pharmacodynamic effects of meloxicam.

Postoperative complications in a lamb after major surgery

INTRODUCTION

Anaesthesia in lambs undergoing experimental surgery may develop problems associated with age-related immune incompetency: a postoperative complication in a 3 week old Scottish blackface lamb after spinal surgery is presented. CASE HISTORY AND MANAGEMENT: Both lamb and ewe were in good condition. The ewe was vaccinated against Clostridium perfringens and Clostridium tetani 5 weeks pre-partum. There were no apparent problems with the lamb's intake of colostrum. Pre-anaesthetic medication was intramuscular medetomidine (10 μg kg(-1)). Anaesthesia was induced and maintained with sevoflurane in oxygen. Morphine (0.5 mg kg(-1)), meloxicam (0.6 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 μg kg(-1) minute(-1)) were administered intravenously (IV) for perioperative analgesia. Atracurium (0.5 mg kg(-1) IV, followed by 0.17 mg kg(-1) injected when the first twitch of the four, train-of four count was palpated) was used to improve muscle relaxation. The lamb's trachea was intubated and the lungs mechanically ventilated to maintain normocapnia. Intrathecal morphine (0.2 mg kg(-1)), IV meloxicam (0.3 mg kg(-1)) and edrophonium (0.5 mg kg(-1)) were administered before recovery. Operative and initial recovery periods were unremarkable. Three hours after surgery the lamb became depressed. Tachycardia (180-250 beats minute(-1)), tachypnoea (30 breaths minute(-1)), poor peripheral perfusion and cold pelvic limb extremities were present mimicking severe pain, and/or hypovolaemic shock. Analgesics - morphine (total dose 1.3 mg kg(-1)) - and IV fluid therapy boluses - crystalloids (300 mL), colloids (120 mL) and fresh whole blood (60 mL) - failed to ameliorate clinical signs and so the lamb was euthanized 10 hours after surgery. Post-mortem findings supported a possible diagnosis of peracute Clostridium perfringens enterotoxaemia.

CONCLUSION

Clostridium perfringens enterotoxaemia should be considered when clinical signs of severe pain and/or hypovolaemic shock fail to respond to analgesics and fluid resuscitation in lambs after major surgery.

Meloxicam exerts neuroprotection on spinal cord trauma in rats

Traumatic injury to the central nervous system results in the delayed dysfunction and neuronal death. Impaired mitochondrial function, generation of reactive oxygen species (ROS), and lipid peroxidation occur soon after traumatic spinal cord injury (SCI), while the activation of compensatory molecules that neutralize ROS occurs at later time points. The aim of the current study was to investigate the putative neuroprotective effect of the COX2 inhibitor meloxicam in a rat model of SCI. In order to induce SCI, a standard weight-drop method that induced a moderately severe injury (100 g/cm force) at T10, was used. Injured animals were given either 2 mg/kg meloxicam or saline 30 min postinjury by intraperitoneal injection. At seven days postinjury, neurological examination was performed and rats were decapitated. Spinal cord samples were taken for histological examination or determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and DNA fragmentation. Formation of ROS in spinal cord tissue samples was monitored by using a chemiluminescence (CL) technique. SCI caused a significant decrease in spinal cord GSH content, which was accompanied with significant increases in CL, MDA levels, MPO activity, and DNA damage. On the other hand, meloxicam treatment reversed all these biochemical parameters as well as SCI-induced histopathological alterations. Furthermore, impairment of the neurological functions due to SCI was improved by meloxicam treatment. The present study suggests that meloxicam, reduces SCI-induced oxidative stress and exerts neuroprotection by inhibiting lipid peroxidation, GSH depletion, and DNA fragmentation.

Suppression of matrix metalloproteinase production from synovial fibroblasts by meloxicam in-vitro

The aim of this study was to evaluate the influence of meloxicam on the production of both matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) from human synovial fibroblasts by TNF-α stimulation in-vitro. Synovial fibroblasts (2 times 104 cells/mL) derived from patients with osteoarthritis were stimulated with 20.0 ng mL−1 TNF-α in the presence of various concentrations of meloxicam. After 24 h, the culture supernatants were obtained and assayed for MMP-1, MMP-2, MMP-3, MMP-13, TIMP-1 and TIMP-2 by ELISA. mRNA expression for MMPs and TIMPs in 4-h-cultured cells were examined by real-time polymerase chain reaction. Transcriptional factor (NF-κB and AP-1) activation in 2-h-cultured cells was also examined by ELISA. Meloxicam could suppress MMP production in a dose-dependent manner. The minimum concentration of the agent that showed significant suppression was 0.6 times 10−6  m for MMP-1, MMP-2 and MMP-3, and 1.3 times 10−6  m for MMP-13. The ability of synovial fibroblasts to produce TIMPs was also suppressed by meloxicam as in the case of MMP production. Addition of meloxicam into synovial fibroblast cultures inhibited dose-dependently mRNA expression for MMPs and TIMPs, which were increased by TNF-α stimulation, through the suppression of NF-κB and AP-1 activation. The suppressive effect of meloxicam on the production of MMPs and TIMPs may partly be involved in attenuation of the clinical conditions of osteoarthritis and rheumatoid arthritis.

Effects of steroidal and non-steroidal antiphlogistic drugs on eicosanoid synthesis in irritated skin: studies with the isolated perfused bovine udder

Using the isolated perfused bovine udder as an in-vitro model of skin inflammation, the effects of topically administered arachidonic acid on prostaglandin and leukotriene synthesis have been shown previously. In this study, the effects of indometacin (indomethacin) and clobetasol-17-propionate (administered topically) as well as flunixin meglumine and meloxicam (administered via the perfusion fluid) have been studied. Compared with controls, arachidonic acid caused a significant increase in the dermal prostaglandin E2 (PGE2) and peptidoleukotriene (LTC4/D4/E4) concentration. Topical treatment with indometacin (1.6 mg cm−2) and clobetasol-17-propionate (90 μg cm−2), which were administered 60 min before arachidonic acid administration, inhibited the inflammatory reaction. Flunixin meglumine (1 μg mL−1 perfusion fluid) was administered 30 min after and meloxicam (3 μg mL−1 perfusion fluid) was administered 60 min before arachidonic acid application. Three hours after arachidonic acid administration, a significant inhibition of PGE2 synthesis was induced by flunixin. In contrast, meloxicam showed only a slight effect. The effect of flunixin was comparable with in-vivo results. It is known from animal studies that anti-inflammatory effects of meloxicam are obvious within up to 6 h after treatment. Therefore, the incomplete effect of meloxicam may be explained pharmacokinetically. In conclusion, the described in-vitro model seems to be suitable for studies of pharmacological effects on eicosanoid synthesis in the skin.

Behavioural effects of ovariohysterectomy and oral administration of meloxicam in laboratory housed rabbits

This study aimed to develop a behaviour-based pain assessment system for rabbits following ovariohysterectomy. Behaviour was analysed to assess the severity and duration of pain induced and determine the effects of administration of meloxicam. The results suggest that pain associated with ovariohysterectomy induced changes in the frequency and duration of a number of behaviours. The most indicative was inactive pain behaviour, which was observed very infrequently prior to surgery compared to very frequently immediately following surgery. This strongly suggests that this increase is a direct response to the surgical pain and/or stress. The frequency of inactive pain behaviour also decreased over the four days post-surgery suggesting that pain is decreasing during this time. High dose meloxicam (initial 1mg/kg followed 0.5mg/kg/day) induced some degree of analgesia. However, higher doses of meloxicam or in combination with an opioid may be required to provide consistent analgesia in rabbits following soft-tissue surgery.

Experimental Study of COX-2 Selective and Traditional Non-steroidal Anti-inflammatory Drugs in Total Hip Replacement

This study investigated the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on peri-operative blood loss during elective total hip replacement. Patients were randomized to receive enteric-coated diclofenac 50 mg ( n = 18), rofecoxib 12.5 mg ( n = 17) or placebo ( n = 16) administered orally three times daily for 2 weeks prior to surgery. Severe adverse effects resulting in discontinuation of trial participation occurred in six patients in the diclofenac group, five patients in the rofecoxib group and two patients in the placebo group; all drop-outs occurred at various times after surgery. Compared with placebo, peri-operative blood loss increased by 32% in the diclofenac group and by 7% in the rofecoxib group. Total mean ± SD blood loss was 1040 ± 136 ml in the diclofenac group, 844 ± 83 ml in the rofecoxib group and 789 ± 82 ml in the placebo group. Thus, administering a non-selective NSAID 2 weeks prior to elective total hip replacement significantly increases peri-operative blood loss.

Anti-inflammatory effect of meloxicam on experimental vasospasm in the rat femoral artery

Cerebral vasospasm influences morbidity and mortality following subarachnoid haemorrhage (SAH). Inflammation is believed to play a role in post-haemorrhagic vasospasm. Meloxicam is a non-steroidal anti-inflammatory drug. We investigated the effect of meloxicam on a rat femoral artery vasospasm model using the radial wall thickness and cross-sectional lumen area as parameters under light, scanning and transmission electron microscopy examination. Rats were randomly separated into SAH, SAH+ meloxicam and control groups. Rats in the SAH+ meloxicam group were given meloxicam at 2 mg/kg daily for 7 days. Femoral arteries were examined by light microscopy and scanning and transmission electron microscopy, and for morphometric analysis. A statistically significant difference (p<0.001) was detected between the SAH and SAH+ meloxicam groups. Meloxicam treatment reduced ultrastructural and morphometric vasospastic changes. These findings support the hypothesis that inflammation may play a role in the pathophysiologyical pathways of post-haemorrhagic cerebral vasospasm.

Effects of the cyclooxygenase inhibitor meloxicam on recovery of ischemia-injured equine jejunum

OBJECTIVE

To determine the effect of meloxicam and flunixin meglumine on recovery of ischemia-injured equine jejunum.

ANIMALS

18 horses.

PROCEDURES

Horses received butorphanol tartrate; were treated IV with saline (0.9% NaCl) solution (SS; 12 mL; n = 6), flunixin meglumine (1.1 mg/kg; 6), or meloxicam (0.6 mg/kg; 6) 1 hour before ischemia was induced for 2 hours in a portion of jejunum; and were allowed to recover for 18 hours. Flunixin and SS treatments were repeated after 12 hours; all 3 treatments were administered immediately prior to euthanasia. Selected clinical variables, postoperative pain scores, and meloxicam pharmacokinetic data were evaluated. After euthanasia, assessment of epithelial barrier function, histologic evaluation, and western blot analysis of ischemia-injured and control jejunal mucosa samples from the 3 groups were performed.

RESULTS

Meloxicam- or flunixin-treated horses had improved postoperative pain scores and clinical variables, compared with SS-treated horses. Recovery of transepithelial barrier function in ischemia-injured jejunum was inhibited by flunixin but permitted similarly by meloxicam and SS treatments. Eighteen hours after cessation of ischemia, numbers of neutrophils in ischemia-injured tissue were higher in horses treated with meloxicam or flunixin than SS. Plasma meloxicam concentrations were similar to those reported previously, but clearance was slower. Changes in expression of proteins associated with inflammatory responses to ischemic injury and with different drug treatments occurred, suggesting cyclooxygenase-independent effects.

CONCLUSIONS AND CLINICAL RELEVANCE

Although further assessment is needed, these data have suggested that IV administration of meloxicam may be a useful alternative to flunixin meglumine for postoperative treatment of horses with colic.

Comparative plasma pharmacokinetics of meloxicam in sheep and goats following intravenous administration

Meloxicam, a novel cyclooxygenase-2 selective nonsteroidal anti-inflammatory drug (NSAID), has been used extensively in humans and recently in some domestic animal species. Although it is an attractive NSAID for use in small ruminants, meloxicam pharmacokinetics have not been investigated in sheep and goats and this information is essential for rational therapeutic use of the drug in these species. In this investigation, comparative pharmacokinetic properties of meloxicam were studied in sheep and goats after a single intravenous dose of 0.5 mg kg(-1) body mass. Blood samples were collected via jugular venepuncture into heparinised tubes at predetermined times after drug administration. Plasma concentrations of meloxicam were determined by reversed-phase high performance liquid chromatography. The plasma concentrations of meloxicam were detectable in sheep and goats up to 72 and 48 h, respectively. The plasma concentration versus time data of meloxicam in both sheep and goats were adequately described by a two-compartment open model. The values obtained for sheep and goats for distribution half-life, volume of distribution at steady state and volume of the central compartment were almost similar in sheep and goats. The elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), mean residence time (MRT) and total systemic clearance (Cl(B)) in sheep were significantly different from those of goats. The mean+/-S.E. values of t(1/2beta), MRT, AUC and Cl(B) in sheep were 10.85+/-1.21 h, 15.13+/-1.67 h, 31.88+/-2.97 microg h mL(-1) and 0.016+/-0.002 L h(-1) kg(-1), respectively whereas the respective values in goats were 6.73+/-0.58 h, 9.37+/-0.83 h, 19.23+/-2.23 microg h mL(-1) and 0.03+/-0.01 L h(-1) kg(-1). The results indicate that elimination kinetics of meloxicam differ significantly between sheep and goats and the elimination of the drug tends to be faster in goats compared to sheep.

Contributions of cyclooxygenase-2 to neuroplasticity and neuropathology of the central nervous system

Cyclooxygenase (COX) enzymes, or prostaglandin-endoperoxide synthases (PTGS), are heme-containing bis-oxygenases that catalyze the first committed reaction in metabolism of arachidonic acid (AA) to the potent lipid mediators, prostanoids and thromboxanes. Two isozymes of COX enzymes (COX-1 and COX-2) have been identified to date. This review will focus specifically on the neurobiological and neuropathological consequences of AA metabolism via the COX-2 pathway and discuss the potential therapeutic benefit of COX-2 inhibition in the setting of neurological disease. However, given the controversy surrounding the use of COX-2 selective inhibitors with respect to cardiovascular health, it will be important to move beyond COX to identify which down-stream effectors are responsible for the deleterious and/or potentially protective effects of COX-2 activation in the setting of neurological disease. Important advances toward this goal are highlighted herein. Identification of unique effectors in AA metabolism could direct the development of new therapeutics holding significant promise for the prevention and treatment of neurological disorders.

17-β-Estradiol upregulates COX-2 in the rat oviduct

We investigated the regulation of cyclooxygenase-2 (COX-2) by 17-beta-estradiol (E2) in the rat oviduct. We observed that COX-2 is expressed mainly in proestrous and estrous stages, periods under estrogenic influence. While exogenous administration of E2 (1 microg/rat) significantly increased COX-2 protein levels, progesterone did not modify it. COX-2 was mainly localized on oviductal epithelial cells from estrogenized rat. Induction of COX-2 expression by E2 was partially reverted by tamoxifen (1 mg/rat), an E2 receptor antagonist. Estradiol treatment also increased prostaglandins (PGs) synthesis: 6-keto-PGF(1alpha) (40%), a stable metabolite of prostacyclin (PGI2), PGF(2alpha) (40%) and PGE2 (50%). Tamoxifen completely suppressed this enhancement. In order to discriminate which isoform of COX was implicated in the stimulatory effect of E2 on PGs synthesis, oviducts were preincubated with meloxicam (Melo: 10(-9)M) or NS-398 (10(-7)M), two selective COX-2 inhibitors. Both Melo and NS-398 abolished the increase of PGs synthesis stimulated by E2. All together, these data indicate that E2 could upregulate COX-2 expression and activity in the rat oviduct and that the stimulatory effect of E2 may be receptor-mediated.

Heme oxygenase-carbon monoxide (HO-CO) system in rat uterus: effect of sexual steroids and prostaglandins

Pregnancy maintenance is a very complex phenomenon, and the mechanisms that allow the survival of the fetus within the maternal uterus are still poorly understood. Our objectives were to analyze heme oxygenase (HO) activity and expression in the pregnant rat and to study its association with steroid hormones and prostaglandins. Uterine tissues were obtained from non-pregnant and from time-mated rats at days 5, 13, 18-22 of pregnancy and postpartum. HO activity was significantly higher at days 5 and 20 while HO-1 protein levels measured by Western blot, were significantly elevated from days 19 to 22. In ovariectomized rats, estrogen and progesterone in estrogenized animals increased HO activity and expression. Cyclooxygenase inhibitors augmented HO activity and HO-1 expression. Pre-incubation with prostaglandin F2alpha (PGF2alpha) diminished the enzymatic activity in ovariectomized rat uterus. Tin protoporphyrin IX, an HO inhibitor, significantly decreased uterine cGMP accumulation. Bilirubin decreased uterine thiobarbituric acid substances levels (an index of lipid peroxidation). These results demonstrate a uterine gestational pattern of HO activity and expression in the rat. In addition, these results suggest that uterine HO activity could regulate uterine quiescence in pregnancy via cGMP and it may contribute to the defense against oxidative stress.

Prostaglandins modulate nitric oxide synthase activity early in time in the uterus of estrogenized rat challenged with lipopolysaccharide

The aim of our study was to investigate if the lipopolysaccharide (LPS) differentially modulates throughout time the nitric oxide synthase (NOS) and cyclooxygenase (COX) enzymes in the estrogenized rat uterus. To study the effect of LPS throughout time on nitric oxide and prostaglandins production and on NOS and COX expression in the estrogenized rat uterus, females received 5 mg/kg intraperitoneally (i.p.) of LPS and were sacrificed 0.5, 1, 2, 3, 4 and 5 h post-administration. NO production was measured by arginine-citrulline conversion assay and prostaglandin E2/prostaglandin F2alpha by radioconversion. Enzyme expression was evaluated by Western blot analysis. The present work shows that LPS augmented NOS activity 3 h post-treatment and iNOS expression earlier, 2 h post-administration. On the other hand, the administration of LPS stimulated the production of prostaglandin E2/prostaglandin F2alpha and augmented the expression of COX-I 1 h after the treatment and of COX-II 2 h post-treatment. Meloxicam, a COX-II inhibitor, stimulated NO production in a group of rats injected i.p. with both LPS and the inhibitor and sacrificed 2 h after the treatment. These results indicate that, in the estrogenized rat uterus challenged with LPS, the early stimulation in the production of prostaglandins inhibited NOS activity, until the expression of the NOS isoforms is sufficient to overpass the inhibitory effect of the prostaglandins. The above findings suggest that the interaction between NOS and COX might be important in the regulation of physiopathologic events during pregnancy.

Comparative study of anti-inflammatory and ulcerogenic activities of different cyclo-oxygenase inhibitors

The aim of the present work was to study the in vivo anti-inflammatory activity of six NSAIDs, ibuprofen, diclofenac, nimesulide, meloxicam, celecoxib and rofecoxib, using the rat air-pouch model of inflammation to characterize the ability of these drugs to induce gastric damage and PGE(2) inhibition. Selective compounds were observed to have no ulcerogenic properties at anti-inflammatory doses; however, these drugs were weaker inhibitors of several inflammatory aspects such as cell influx and exudate formation. In contrast, the non-selective and preferential compounds present anti-inflammatory properties at lower doses than presented by selective drugs. At anti-inflammatory doses, only meloxicam and ibuprofen produced gastric damage and inhibition of PGE(2) synthesis, suggesting that ulcerogenic properties of NSAIDs cannot be predicted by their selectivity index, since meloxicam demonstrates ulcerogenic properties despite its preferential profile.

Effects of meloxicam on renal function in dogs with hypotension during anaesthesia

OBJECTIVE

To evaluate the effects of meloxicam on renal function in dogs anaesthetized and rendered hypotensive with acepromazine-thiopental-isoflurane.

ANIMALS

Eight healthy beagles, four males and four females, 25.6 +/- 19.3 months old and weighing 12.8 +/- 2.0 kg.

MATERIALS AND METHODS

Either meloxicam suspension at a dose of 0.133 mL kg(-1) (0.2 mg kg(-1)) or 0.133 mL kg(-1) saline solution (control), were given by mouth (PO) in a randomized, cross-over fashion. The treatment or control was given 3 hours before anaesthesia. Dogs were sedated with intramuscular acepromazine 0.1 mg kg(-1). Anaesthesia was induced with intravenous thiopental, followed by tracheal intubation and maintenance with isoflurane in oxygen and air, delivered using a semi-closed breathing system. Renal function was quantified using serum biochemistry, urinalysis and glomerular filtration rate measured by scintigraphy. Analysis of variance or Friedman anova were used for statistical analysis.

RESULTS

Values (mean +/- SD) for mean arterial blood pressure did not differ significantly between treatments but was low (54 +/- 7 mmHg) during anaesthesia. Glomerular filtration rate did not differ significantly between treatments or over time, and results of urine and serum analysis were within reference ranges after meloxicam treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Meloxicam caused no adverse effects on renal function when given to healthy dogs anaesthetized and rendered hypotensive with acepromazine, thiopental and isoflurane.

Differential Effects of Selective Cyclooxygenase (COX)-1 and COX-2 Inhibitors on Anorexic Response and Prostaglandin Generation in Various Tissues Induced by Zymosan

We have shown that anorexic response is induced by intraperitoneal injection of zymosan in mice, although the role of prostaglandins in this response is relatively unknown as compared with lipopolysaccharide (LPS)-induced anorexic response. Indomethacin (0.5 and 2.0 mg/kg), a non-selective cyclooxygenase (COX) inhibitor, as well as meloxicam (0.5 mg/kg), a selective COX-2 inhibitor, but not FR122047 (2.0 mg/kg), a selective COX-1 inhibitor, attenuated zymosan-induced anorexia. Zymosan injection elevated COX-2 expression in brain and liver but not in small intestine and colon. Meloxicam (0.5 mg/kg) and FR122047 treatment (2.0 mg/kg) similarly suppressed the generation of brain prostaglandin E(2) (PGE(2)) and peritoneal prostacyclin (PGI(2)) upon zymosan injection. PGE(2) generation in liver upon zymosan injection was suppressed by meloxicam (0.5 mg/kg) but not by FR122047 treatment (2.0 mg/kg). Our observations suggest that COX-2 plays an important role in zymosan-induced anorexia, which is a similar feature in LPS-induced anorexic response. However, non-selective inhibition by selective COX-1 and COX-2 inhibitors of brain PGE(2) generation upon zymosan injection does not support the role of COX-2 expressed in brain in zymosan-induced anorexic response. PGE(2) generation in liver may account for peripheral role of COX-2 in zymosan-induced anorexic response.

Post-training intrahippocampal infusion of nicotine prevents spatial memory retention deficits induced by the cyclo-oxygenase-2-specific inhibitor celecoxib in rats

Recently, we demonstrated that intrahippocampal infusion of the cyclo-oxygenase (COX)-2-specific inhibitor celecoxib impaired spatial memory retention in the Morris water maze. In the present work, we investigated the effects of nicotine, infused in the rat dorsal hippocampus several minutes after infusion of celecoxib, on memory retention in the Morris water maze. Rats were trained for 3 days; each day included two blocks, and each block contained four trials. Test trials were conducted 48 h after surgery. As expected, bilateral intrahippocampal infusion of celecoxib (19 microg/side; 0.1 m) increased escape latency and travel distance in rats, indicating significant impairment of spatial memory retention. We also examined the effects of bilateral infusion of nicotine (0.5, 1.0 and 2.0 microg/side) on memory retention. Infusion of 1 microg nicotine significantly decreased escape latency and travel distance but not swimming speed, compared with controls, suggesting memory retention enhancement by nicotine at this concentration. In separate experiments, bilateral infusion of nicotine, infused 5 min after 0.1 m (19 microg/side) celecoxib infusion, was associated with escape latency, travel distance and swimming speed profiles very similar to those in control animals. Brain tissue sections from several of these animals were subjected to immunohistochemical staining analysis with anti-COX-2 antibodies. Quantification analysis by optical density measurements showed that the celecoxib infusion reduced the immunoreactivity of COX-2-containing neurons in the CA1 area of the hippocampus compared with controls, although this reduction was not significant. However, infusion of a combination of celecoxib and nicotine significantly increased this immunoreactivity compared with levels in control and celecoxib-infused groups. These results suggest that nicotine prevented or reversed the adverse effects of celecoxib on spatial memory retention and protected or restored the immunostaining pattern of COX-2 neurons in the rat dorsal hippocampus.