Nonsteroid drug selectivities for cyclo-oxygenase-1 rather than cyclo-oxygenase-2 are associated with human gastrointestinal toxicity: a full in vitro analysis

Effect of firocoxib or flunixin meglumine on recovery of ischemic-injured equine jejunum

OBJECTIVE

To determine whether treatment of horses with firocoxib affects recovery of ischemic-injured jejunum, while providing effective analgesia.

ANIMALS

18 horses.

PROCEDURES

Horses (n = 6 horses/group) received saline (0.9% NaCl) solution (1 mL/50 kg, IV), flunixin meglumine (1.1 mg/kg, IV, q 12 h), or firocoxib (0.09 mg/kg, IV, q 24 h) before 2 hours of jejunal ischemia. Horses were monitored via pain scores and received butorphanol for analgesia. After 18 hours, ischemic-injured and control mucosa were placed in Ussing chambers for measurement of transepithelial resistance and permeability to lipopolysaccharide. Histomorphometry was used to determine denuded villus surface area. Western blots for cyclooxygenase (COX)-1 and COX-2 were performed. Plasma thromboxane B(2) and prostaglandin E(2) metabolite (PGEM) concentrations were determined.

RESULTS

Pain scores did not significantly increase after surgery in horses receiving flunixin meglumine or firocoxib. Transepithelial resistance of ischemic-injured jejunum from horses treated with flunixin meglumine was significantly lower than in saline- or firocoxib-treated horses. Lipopolysaccharide permeability across ischemic-injured mucosa was significantly increased in horses treated with flunixin meglumine. Treatment did not affect epithelial restitution. Cyclooxygenase-1 was constitutively expressed and COX-2 was upregulated after 2 hours of ischemia. Thromboxane B(2) concentration decreased with flunixin meglumine treatment but increased with firocoxib or saline treatment. Flunixin meglumine and firocoxib prevented an increase in PGEM concentration after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Flunixin meglumine retarded mucosal recovery in ischemic-injured jejunum, whereas firocoxib did not. Flunixin meglumine and firocoxib were effective visceral analgesics. Firocoxib may be advantageous in horses recovering from ischemic intestinal injury.

Anti-inflammatory effects of intravenously administered lidocaine hydrochloride on ischemia-injured jejunum in horses

OBJECTIVE

To investigate effects of lidocaine hydrochloride administered IV on mucosal inflammation in ischemia-injured jejunum of horses treated with flunixin meglumine.

ANIMALS

24 horses.

PROCEDURES

Horses received saline (0.9% NaCl) solution (SS; 1 mL/50 kg, IV [1 dose]), flunixin meglumine (1 mg/kg, IV, q 12 h), lidocaine (bolus [1.3 mg/kg] and constant rate infusion [0.05 mg/kg/min], IV, during and after recovery from surgery), or both flunixin and lidocaine (n = 6/group). During surgery, blood flow was occluded for 2 hours in 2 sections of jejunum in each horse. Uninjured and ischemia-injured jejunal specimens were collected after the ischemic period and after euthanasia 18 hours later for histologic assessment and determination of cyclooxygenase (COX) expression (via western blot procedures). Plasma samples collected prior to (baseline) and 8 hours after the ischemic period were analyzed for prostanoid concentrations.

RESULTS

Immediately after the ischemic period, COX-2 expression in horses treated with lidocaine alone was significantly less than expression in horses treated with SS or flunixin alone. Eighteen hours after the ischemic period, mucosal neutrophil counts in horses treated with flunixin alone were significantly higher than counts in other treatment groups. Compared with baseline plasma concentrations, postischemia prostaglandin E(2) metabolite and thromboxane B(2) concentrations increased in horses treated with SS and in horses treated with SS or lidocaine alone, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

In horses with ischemia-injured jejunum, lidocaine administered IV reduced plasma prostaglandin E(2) metabolite concentration and mucosal COX-2 expression. Coadministration of lidocaine with flunixin ameliorated the flunixin-induced increase in mucosal neutrophil counts.

A comparison of the effects of ibuprofen and rofecoxib on rabbit fibula osteotomy healing

BACKGROUND AND PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity, which is the rate-limiting enzyme in the synthesis of prostaglandins. Previous studies have indicated that NSAID therapy, and in particular NSAIDs that specifically target the inflammatory cyclooxygenase (COX-2), impair bone healing. We compared the effects of ibuprofen and rofecoxib on fibula osteotomy healing in rabbits to determine whether nominal, continuous inhibition of COX-2 with rofecoxib would differentially affect fracture healing more than cyclical inhibition of COX-2 using ibuprofen, which inhibits COX-1 and COX-2 and has a short half-life in vivo.

METHODS

Bilateral fibula osteotomies were done in 67 skeletally mature male New Zealand white rabbits. The rabbits were treated with placebo, rofecoxib (12.5 mg once a day), or ibuprofen (50 mg 3 times a day) for 28 days after surgery. Plasma ibuprofen levels were measured by HPLC analysis. Bone healing was assessed by histomorphometry at 3 and 6 weeks after osteotomy, and at 6 and 12 weeks by torsional mechanical testing.

RESULTS

Plasma ibuprofen levels peaked and declined between successive doses. Fracture callus morphology was abnormal in the rofecoxib-treated rabbits and torsional mechanical testing showed that fracture healing was impaired. Ibuprofen treatment caused persistence of cartilage within the fracture callus and reduced peak torque at 6 weeks after osteotomy as compared to the fibulas from the placebo-treated rabbits. In the specimens allowed to progress to possible healing, non-union was seen in 5 of the 26 fibulas from the rofecoxib-treated animals as compared to 1 of 24 in the placebo group and 1 of 30 in the ibuprofen treatment group.

INTERPRETATION

Continuous COX-2 inhibition as modeled by rofecoxib treatment appears to be more deleterious to fracture repair than cyclical cyclooxygenase inhibition as modeled by ibuprofen treatment. Ibuprofen treatment appeared to delay bone healing based upon the persistence of cartilage within the fracture callus and diminished shear modulus. Despite the ibuprofen-induced delay, rofecoxib treatment produced worse fracture (osteotomy) healing than ibuprofen treatment.

Novel 3,6-disubstituted 7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines: synthesis, characterization, and evaluation of analgesic/anti-inflammatory, antioxidant activities

In this study, the synthesis of a new series of 3,6-disubstituted-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine 1a-4c compounds derived from 4-amino-3-substituted-1,2,4-triazole-5-thiones 1-4 is described. All of the synthesized compounds were screened for their possible analgesic / anti-inflammatory, antioxidant activities and gastric toxicity. The compound 2c was found to have both significant analgesic and consistent anti-inflammatory activity without inducing any gastric lesions along with minimal lipid peroxidation. A deep insight into the structures of the active compounds revealed that the compounds carrying an electron withdrawing group (a chloride or fluoride) on the phenyl ring at 6-position of the condensed heterocyclic derivatives exhibited noticeable higher activity.

Diclofenac potassium restores objective and subjective measures of sleep quality in women with primary dysmenorrhea

STUDY OBJECTIVES

Primary dysmenorrhea is a common gynecological disorder that disrupts daytime functioning and nighttime sleep quality. We determined the effectiveness of diclofenac potassium, compared to placebo, in alleviating nighttime pain and restoring sleep architecture in women with primary dysmenorrhea.

DESIGN

Randomized, double-blind, crossover study.

SETTING

Sleep laboratory.

PARTICIPANTS

Ten healthy women (21 +/- 1 years) with a history of primary dysmenorrhea.

INTERVENTIONS

Placebo or diclofenac potassium (150 mg per day) for menstrual pain.

MEASUREMENTS AND RESULTS

We assessed objective measures of sleep (polysomnography) and subjective measures of sleep quality, mood, and intensity of menstrual pain. Compared to a pain-free phase of the menstrual cycle (mid-follicular), women receiving placebo for their menstrual pain had a poorer mood (P < 0.01), decreased sleep efficiency (P < 0.05), less REM sleep (P < 0.05), more stage 1 sleep (P < 0.01), and more sleep stage changes per hour of sleep during the night. Administration of diclofenac potassium compared to placebo not only attenuated the women's menstrual pain (P < 0.05), but also increased sleep efficiency (P < 0.05) and percentage of REM sleep (P < 0.01), decreased percentage of stage 1 sleep (P < 0.05) and number of sleep stage changes per hour of sleep (P < 0.05), and improved subjective ratings of sleep quality and morning vigilance (P < 0.05).

CONCLUSION

Diclofenac potassium effectively attenuates nighttime dysmenorrheic pain and restores subjective and objective measures of sleep quality to values recorded in a pain-free phase of the menstrual cycle.

The Reactions of Oxicam and Sulfoanilide Non Steroidal Anti-Inflammatory Drugs with Hypochlorous Acid: Determination of the Rate Constants with an Assay Based on the Competition with Para-aminobenzoic Acid Chlorination and Identification of Some Oxidation Products

Hypochlorous acid (HOCl) is an oxygen-derived species involved in physiological processes related to the defence of the organism that may cause adverse effects when its production is insufficiently controlled. In order to examine its reactivity with potential scavenging molecules from the non steroidal anti-inflammatory drugs (NSAIDs) family, a competition assay based on para-aminobenzoic acid (PABA) chlorination was developed. The original optimised in vitro fluorimetric procedure offered the possibility to determine rate constants (ks) for the reaction with HOCl in physiologically relevant conditions. The specificity of the system was improved by a liquid chromatography (LC) which allows the separation of the drugs and their oxidation products. After determination of the rate constant for PABA chlorination by HOCl (mean +/- SD in M(-1) s(-1): 4.3 +/- 0.3 x 10(3)), the applied mathematical model for a chemical competition permits to obtain linear curves from competition studies between several NSAIDs and PABA. Their slopes provided the following rate constants for the different studied drugs: tenoxicam: 4.0 +/- 0.7 x 10(3), piroxicam: 3.6 +/- 0.7 x 10(3), lornoxicam: 4.3 +/- 0.7 x 10(3), meloxicam: 1.7 +/- 0.3 x 10(4), nimesulide: 2.3 +/- 0.6 x 10(2). Meloxicam therefore reacted significantly faster than the other oxicams and nimesulide, which is the weakest scavenger of the studied series. The identification of some of the oxidation products by NMR or MS permitted to explore the reaction mechanism and to examine some aspects of the structure/activity relationships for the molecules of the same chemical family.

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

This study investigated the analgesic, anti-inflammatory and antipyretic efficacy of the new COX-2 selective inhibitor robenacoxib in the cat and established pharmacodynamic (PD) parameters for these effects. Robenacoxib, at a dosage of 2 mg/kg administered subcutaneously, was evaluated in a kaolin-induced paw inflammation model in 10 cats, using both clinically relevant endpoints (lameness scoring, locomotion tests) and other indicators of inflammation (body and skin temperature, thermal pain threshold) to establish its pharmacological profile. A pharmacokinetic/pharmacodynamic (PK/PD) modelling approach, based on indirect response models, was used to describe the time course and magnitude of the responses to robenacoxib. All endpoints demonstrated good responsiveness to robenacoxib administration and both the magnitude and time courses of responses were well described by the indirect pharmacodynamic response models. Pharmacokinetic and clinically relevant pharmacodynamic parameters were used to simulate dosage regimens that will assist the planning of clinical trials and the selection of an optimal dosage regimen for robenacoxib in the cat.

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

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

The interactions of some commonly consumed drugs with mitochondrial adaptations to exercise

The importance of mitochondrial dysfunctions in the progression of chronic disease has been well established. Patients with chronic diseases are often prescribed a variety of medications, many of which have been shown to induce mitochondrial dysfunction. Exercise is a known stimulus for mitochondrial biogenesis and also recommended to patients as a lifestyle modification to supplement drug therapy. However, the potential interference of those drugs with mitochondrial adaptations to exercise has not been thoroughly investigated. This review provides a summary and discussion of known and potential interactions of commonly consumed drugs with exercise-induced mitochondrial adaptations.

Prostaglandin E2 derived from cyclooxygenases 1 and 2 mediates intestinal epithelial ion transport stimulated by the activation of protease-activated receptor 2

Proteinase-activated receptor (PAR)(2) is activated by trypsin-like serine proteinases and has been implicated in intestinal inflammation. However, its role in the regulation of intestinal mucosal function remains unclear. Using the intestinal epithelial cell line, SCBN, we have studied the stimulus-secretion coupling mechanisms of PAR(2)-induced epithelial chloride transport, focusing on cyclooxygenase (COX)-1 and COX-2 activities and prostaglandin (PG) E(2) secretion. SCBN monolayers were grown on Snapwell supports, mounted in modified Ussing chambers, and exposed to the activating peptide, SLIGRL-NH(2) (50 microM), to activate PAR(2). Pretreatment with inhibitors of cytosolic PLA(2) (cPLA(2)) (AACOCF3, arachidonyltrifluoromethyl ketone), COX-1 [SC560, 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole], and COX-2 (celecoxib) resulted in a significant concentration-dependent attenuation of PAR(2)-induced changes in short-circuit current. Immunoblot analysis showed a PAR(2)-induced increase in cPLA(2) phosphorylation that was blocked by the mitogen-activated protein kinase kinase inhibitor, PD98059 [2-(2-amino-3methoxyphenyl)-4H-1benzopyran-4-one, C(16)H(13)NO(3)], and the pan-protein kinase C inhibitor, GFX (bisindolylmaleimide). PAR(2) stimulation also resulted in a large increase in the production of PGE(2) as determined by enzyme-linked immunosorbent assay and was also blocked by PD98059 and GFX. Immunofluorescence and immunoblot analysis determined that EP2 and EP4 are expressed at the basolateral membrane of SCBN cells. Through the use of selective inhibitors (EP2, AH6809 [6-isopropoxy-9-oxoxanthene-2-carboxylic acid]; EP4, GW627368X [N-[2[4,9-diethoxy-1-oxo-1,3-dihydro-2H-benzo[f]isoindol-2-yl)phenyl] acetyl]benzene sulphonamide]), it was found that both EP2 and EP4 were involved in mediating the PAR(2)-induced chloride secretory response. We conclude that basolateral PAR(2) activation induces epithelial chloride secretion that is mediated by cPLA(2), COX-1, COX-2, and the subsequent release of PGE(2). The production of PGE(2) results in an autocrine secretory response that is dependent on basolateral EP2 and EP4 receptors.

Preferential uptake of the non steroid anti-inflammatory drug diclofenac into inflamed tissues after a single oral dose in rats

Background

Diclofenac is a nonsteroidal anti-inflammatory drug which is available as prescription (RX) and over-the-counter (OTC) medication for the systemic and topical treatment of painful and inflammatory conditions such as arthritis and back pain. This study was undertaken to investigate the distribution and retention of diclofenac and/or its metabolites in inflamed tissues, using the carrageenan-induced inflammation model and quantitative whole body autoradiography in rats.

Methods

[¹⁴C]diclofenac sodium was administrated as a single 2 mg/kg oral dose 1 h after injection of carrageenan into one front and one hind footpads and subcutaneously into the dorsum of the neck of rats. A control animal received saline injections. Three carrageenan-treated rats and one control rat were sacrificed at 1, 4, 8, and 24 h after [¹⁴C]diclofenac sodium administration (total of 4 rats/time point). The carcasses were immediately snap-frozen and prepared for cryosectioning. Lengthwise whole-body sections (40 μm thick), including all major tissues, were obtained from different levels across the body. The tissue concentrations of total radiolabeled components were determined using quantitative autoradioluminography.

Results

The radioactivity patterns demonstrated that diclofenac and/or its metabolites preferentially distributed into the inflamed tissues. In unharmed tissues the distribution was similar in control and treated animals. The exposure, based on the areas under the tissue concentration versus time (AUC_0-tlast), was 26 and 53 fold higher in the inflamed neck and inflamed footpads of treated animals than in control rats; the exposures in unharmed tissues were similar in the treated and control rats, and the AUC_0-tlast was 17 fold higher in the inflamed paws than in the non inflamed footpads of the carrageenan-treated rats. The higher exposure in the inflamed tissues may be explained partly to the fact that the elimination of total radiolabeled components from inflamed tissues (t_1/2 = 6 h) appeared lower than from the corresponding unharmed tissues (t_1/2 = 2 h).

Conclusion

This animal study demonstrated that diclofenac and/or its metabolites were rapidly and preferentially taken up and retained in inflamed tissues. Although there were theoretical considerations that mildly acidic NSAID may show some preferential distribution in inflamed tissues there was no clear experimental proof for diclofenac until the present study.

Cyclooxygenase-2 inhibitors, nonsteroidal anti-inflammatory drugs, and cardiovascular risk

Cyclooxygenase-2 (cox-2) inhibitors, also known as coxibs, were introduced with the promise that they would provide pain relief similar to that of traditional nonsteroidal anti-inflammatory drugs (NSAIDs) but would be better tolerated with lower risk of gastrointestinal (GI) side effects. Although coxibs were associated with lower GI risk, experimental and observational data raised the specter of increased cardiovascular risk associated with this class of drugs. This article describes the pharmacologic and biologic basis of cardiovascular risk associated with coxibs, summarizes the evidence for cardiovascular risk associated with cox-2 inhibitors, and weighs the risks and potential benefits of pain management with these agents.

Prescriptions of NSAIDs to patients undergoing third molar surgery : an observational, prospective, multicentre survey

BACKGROUND AND OBJECTIVES

Surgical extraction of an impacted third molar is generally followed by acute post-operative pain that has been shown to be primarily inflammatory. Thus, use of NSAIDs in this context is appropriate and has been shown to be effective. Several drugs are employed for this purpose, but no information exists on the reasons why preference is given to one rather than another. The principal objective of this study was to evaluate the pattern of administration of NSAIDs in patients undergoing surgery for impacted third molar extraction. The study also aimed to collect information on the efficacy, onset and duration of the analgesic effect of routinely prescribed NSAIDs and to assess the duration of treatment with these drugs and their tolerability.

METHODS

This was an observational, multicentre, prospective survey. A total of 616 patients (38% male and 62% female) from the Italian Stomatology Clinics of the Universities of Bologna, Brescia, Cagliari, Chieti, Pavia, Pisa, Siena and Varese and from the Department of Oral and Maxillo-Facial Surgery of Semmelweis University, Budapest, were eligible for the study. Patients were evaluated over the 7 days following surgical extraction. NSAIDs were prescribed according to the normal prescribing habits of the centre and physician involved. The main outcomes of interest in the survey were the efficacy, onset and duration of analgesic effect, duration of therapy, and tolerability of the NSAIDs prescribed.

RESULTS

Nimesulide was the most prescribed NSAID (68%), followed by diclofenac, ketoprofen and ibuprofen. Because of the low proportion of patients receiving other NSAIDs, these patients were considered a single treatment group for evaluation purposes. Nimesulide, especially when given before patients started experiencing pain after surgery, was more effective than other NSAIDs in reducing the severity of pain on the day of surgery, in delaying the time to maximum intensity of pain, in providing complete pain relief and in prolonging the duration of analgesic effect on the day of surgery. These results are consistent with the known anti-inflammatory and analgesic actions of nimesulide and with the important role of inflammation in the onset of pain after this type of surgery.

CONCLUSION

These results confirm nimesulide as an effective reference drug for the treatment of post-operative dental pain and show that it has a positive benefit/risk profile in this setting.

COX-1 vs. COX-2 as a determinant of basal tone in the internal anal sphincter

Prostanoids, produced endogenously via cyclooxygenases (COXs), have been implicated in the sustained contraction of different smooth muscles. The two major types of COXs are COX-1 and COX-2. The COX subtype involved in the basal state of the internal anal sphincter (IAS) smooth muscle tone is not known. To identify the COX subtype, we examined the effect of COX-1- and COX-2-selective inhibitors, SC-560 and rofecoxib, respectively, on basal tone in the rat IAS. We also determined the effect of selective deletion of COX-1 and COX-2 genes (COX-1(-/-) and COX-2(-/-) mice) on basal tone in murine IAS. Our data show that SC-560 causes significantly more efficacious and potent concentration-dependent decreases in IAS tone than rofecoxib. In support of these data, significantly higher levels of COX-1 than COX-2 mRNA were found in the IAS. In addition, higher levels of COX-1 mRNA and protein were expressed in rat IAS than rectal smooth muscle. In wild-type mice, IAS tone was decreased 41.4 +/- 3.4% (mean +/- SE) by SC-560 (1 x 10(-5) M) and 5.4 +/- 2.2% by rofecoxib (P < 0.05, n = 5). Basal tone was 0.172 +/- 0.021 mN//mg in the IAS from wild-type mice and significantly less (0.080 +/- 0.015 mN/mg) in the IAS from COX-1(-/-) mice (P < 0.05, n = 5). However, basal tone in COX-2(-/-) mice was not significantly different from that in wild-type mice. We conclude that COX-1-related products contribute significantly to IAS tone.

n3 and n6 polyunsaturated fatty acids differentially modulate prostaglandin E secretion but not markers of lipogenesis in adipocytes

A dramatic rise in the incidence of obesity in the U.S. has accelerated the search for interventions that may impact this epidemic. One recently recognized target for such intervention is adipose tissue, which secretes a variety of bioactive substances including prostaglandins. Prostaglandin E₂ (PGE₂) has been shown to decrease lipolysis in adipocytes, but limited studies have explored alternative mechanisms by which PGE₂ might impact obesity, such as adipogenesis or lipogenesis. Studies conducted on Apc^Min/+ mice indicated that selective inhibition of the cyclooxygenase (COX)-2 enzyme led to significant reductions in fatty acid synthase (FAS) activity in adipose tissue suggesting lipogenic effects of PGE₂. To further investigate whether these lipid mediators directly regulate lipogenesis, we used 3T3-L1 adipocytes to determine the impact of eicosapentaenoic acid (EPA) and celecoxib on PGE₂ formation and FAS used as a lipogenic marker. Both arachidonic acid (AA) and EPA dose-dependently increased PGE secretion from adipocytes. AA was expectedly more potent and exhibiting at 150 uM dose a 5-fold increase in PGE₂ secretion over EPA. Despite higher secretion of PGE by EPA and AA compared to control, neither PUFA significantly altered FAS activity. By contrast both AA and EPA significantly decreased FAS mRNA levels. Addition of celecoxib, a selective COX-2 inhibitor, significantly decreased PGE₂ secretion (p < 0.05) versus control, and also significantly decreased FAS activity (p < 0.05). Unexpectedly, the combination of exogenous PGE₂ and celecoxib further decreased the FAS activity compared to PGE₂ alone or untreated controls. In conclusion, EPA-mediated inhibition of AA metabolism did not significantly alter FAS activity while both AA and EPA significantly decreased FAS mRNA expression. COX-2 inhibition significantly decreased PGE₂ production resulting in a decrease in FAS activity and expression that was not reversed with the addition of exogenous PGE₂, suggesting an additional mechanism that is independent of COX-2.

Standardized ginger (Zingiber officinale) extract reduces bacterial load and suppresses acute and chronic inflammation in Mongolian gerbils infected with cagAHelicobacter pylori

Previous investigations demonstrated that a standardized extract of ginger rhizome inhibited the growth of Helicobacter pylori in vitro with a minimum inhibitory concentration in the range 0.78 to 12.5 mug/mL. In the present work, the extract was tested in a rodent model of H. pylori-induced disease, the Mongolian gerbil, to examine the effects of the extract on both prevention and eradication of infection. The extract was administered to Mongolian gerbils at a daily dose of 100 mg/kg body weight in rations either 3 weeks prior to infection or 6 weeks post-infection. Treatment with the standardized ginger extract reduced H. pylori load as compared with controls and significantly (P<0.05) reduced both acute and chronic muscosal and submucosal inflammation, cryptitis, as well as epithelial cell degeneration and erosion induced by H. pylori. Importantly, the extract did not increase morbidity or mortality. Further investigations of the mechanism demonstrated that the ginger extract inhibited the activity of cyclooxygenase-2, with 50% inhibitory concentration (IC(50)) of 8.5 mug/mL in vitro, inhibited the nuclear factor-kappaB transcriptional response in kBZ Jurkat cells (human T lymphocytes) with an IC(50) of 24.6 mug/mL, and significantly inhibited the release of interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor-alpha from lipopolysaccharide-stimulated human peripheral blood mononuclear cells with IC(50) values of 3.89, 7.7, 8.5, and 8.37 mug/mL, respectively. These results suggest ginger extracts may be useful for development as agents to reduce H. pylori-induced inflammation and as for gastric cancer chemoprevention.

Effects of cranberry extracts and ursolic acid derivatives on P-fimbriated Escherichia coli, COX-2 activity, pro-inflammatory cytokine release and the NF-kappabeta transcriptional response in vitro

Cranberry, the fresh or dried ripe fruit of Vaccinium macrocarpon Ait. (Ericaceae), is currently used as adjunct therapy for the prevention and symptomatic treatment of urinary tract infections. Data from clinical trials suggest that extracts of cranberry or cranberry juice reduce the bacterial load of E. coli and also suppress the inflammatory symptoms induced by E. coli infections. A methanol extract prepared from 10 kg of dehydrated cranberries did not directly inhibit the growth of E coli strains ATCC 700336 or ATCC 25922 in concentrations up to 256 mug/mL in vitro. However, the methanol extract (CR-ME) inhibited the activity of cyclooxygenase-2, with an IC(50) of 12.8 mug/mL. Moreover, CR-ME also inhibited the NF-kappabeta transcriptional activation in human T lymphocytes with an IC(50) of 19.4 mug/mL, and significantly (p < 0.01) inhibited the release of interleukin (IL)-1beta, IL-6, IL-8 and tumor necrosis factor-alpha from E. coli lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells in vitro, at a concentration of 50 mug/mL. The extract had no effect on inducible nitric oxide synthase activity in the murine macrophage cell line RAW 264.7. The compounds responsible for this activity were identified using a novel LC-MS based assay as ursolic acid and ursolic acid derivatives. Taken together, these data suggest CR-ME and its constituent chemical compounds target specific pathways involved in E. coli-induced inflammation.

Effect of the oral absorption of benzenesulfonanilide-type cyclooxygenase-1 inhibitors on analgesic action and gastric ulcer formation

A benzensulfonanilide-type cyclooxygenase-1 (COX-1)-selective inhibitor, ZXX2-77: 4-amino-4'-chloro-N-methylbenzenesulfonanilide (4a), has been reported as a novel analgesic that does not cause gastric damage. This compound has a weak analgesic effect but has potent in vitro COX-1 inhibitory activity. Since the reason for the weak analgesic effect in vivo was thought to be the low rate of oral absorption, the blood concentration of ZXX2-77 (4a) was measured in rats. It was found that the C(max) value (1.2 microM) of ZXX2-77 (4a) at a dose of 30 mg/kg did not reach the COX-1 IC(50) value (3.2 microM). On the other hand, ZXX2-79 (4b) (SO(2)NH derivative of ZXX2-77 (4a); 4-amino-4'-chlorobenzenesulfonanilide), which shows less potent COX inhibitory activities (COX-1 IC(50) = 12 microM, COX-2 IC(50) = 150 microM) than those of ZXX2-77 (4a) in vitro, was found to be more absorbable (C(max) = 16 microM at a dose of 30 mg/kg in rats) than ZXX2-77 (4a). Furthermore, ZXX2-79 (4b) not only showed a potent analgesic effect in a formalin test but also caused little gastric damage. These findings indicate that demethylated sulfonamide compounds are more easily absorbed than are N-methylated sulfonamide compounds and suggest that COX-1-selective inhibitors will be useful as analgesics that do not cause gastric damage.

Role of coxibs in the strategies for gastrointestinal protection in patients requiring chronic non-steroidal anti-inflammatory therapy

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed drugs due to their high efficacy in the treatment of pain, fever, inflammation and rheumatic disorders. However, their use is associated with the occurrence of adverse effects at the level of digestive tract, ranging from dyspeptic symptoms, gastrointestinal erosions and peptic ulcers to more serious complications, such as overt bleeding or perforation. To overcome problems related to NSAID-induced digestive toxicity, different therapeutic strategies can presently be considered, including the co-administration of drugs endowed with protective activity on the upper gastrointestinal tract, such as the proton pump inhibitors, or the prescription of coxibs, which have been clinically developed as anti-inflammatory/analgesic drugs characterized by reduced damaging activity on gastrointestinal mucosa. The availability of different treatment options, to reduce the risk of NSAID-induced adverse digestive effects, has fostered intensive preclinical and clinical research aimed at addressing a number of unresolved issues and to establish rational criteria for an appropriate use of coxibs in the medical practice. Particular attention is being paid to the management of patients with high degrees of digestive risk, resulting by concomitant treatment with low-dose aspirin for anti-thrombotic prophylaxis or ongoing symptomatic gastroduodenal ulcers. The present review discusses the most relevant lines of evidence concerning the position of coxibs in the therapeutic strategies for gastrointestinal protection in patients who require NSAID therapy and hold different levels of risk of developing adverse effects at the level of digestive tract.

Prostaglandins, NSAIDs, and gastric mucosal protection: why doesn't the stomach digest itself?

Except in rare cases, the stomach can withstand exposure to highly concentrated hydrochloric acid, refluxed bile salts, alcohol, and foodstuffs with a wide range of temperatures and osmolarity. This is attributed to a number of physiological responses by the mucosal lining to potentially harmful luminal agents, and to an ability to rapidly repair damage when it does occur. Since the discovery in 1971 that prostaglandin synthesis could be blocked by aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), there has been great interest in the contribution of prostaglandins to gastric mucosal defense. Prostaglandins modulate virtually every aspect of mucosal defense, and the importance of this contribution is evident by the increased susceptibility of the stomach to injury following ingestion of an NSAID. With chronic ingestion of these drugs, the development of ulcers in the stomach is a significant clinical concern. Research over the past two decades has helped to identify some of the key events triggered by NSAIDs that contribute to ulcer formation and/or impair ulcer healing. Recent research has also highlighted the fact that the protective functions of prostaglandins in the stomach can be carried out by other mediators, in particular the gaseous mediators nitric oxide and hydrogen sulfide. Better understanding of the mechanisms through which the stomach is able to resist injury in the presence of luminal irritants is helping to drive the development of safer anti-inflammatory drugs, and therapies to accelerate and improve the quality of ulcer healing.

Antitumor enhancement of celecoxib, a selective Cyclooxygenase-2 inhibitor, in a Lewis lung carcinoma expressing Cyclooxygenase-2

Background

The goal of this study was to determine the effects of a selective Cyclooxygenase (COX)-2 inhibitor on the inhibition of tumor growth and pulmonary metastasis in a Lewis Lung Carcinoma (LLC) animal model.

Methods

For immunoblot analysis of COX-2 and PGE2, cells were treated with irradiation in the presence or absence of celecoxib. The right thighs of male, 6-week old C57/BL mice were subcutaneously injected with 1 × 10⁶ LLC cells. The animals were randomized into one of six groups: (1) no treatment, (2) 25 mg/kg celecoxib daily, (3) 75 mg/kg celecoxib daily, (4) 10 Gy irradiation, (5) 10 Gy irradiation plus 25 mg/kg celecoxib daily, and (6) 10 Gy irradiation plus 75 mg/kg celecoxib daily. Mice were irradiated only once, and celecoxib was administered orally. Mice were irradiated with 4-MV photons once the tumor volume of the control group reached 500 mm³. All mice were sacrificed when the mean tumor volume of control animals grew to 4000 mm³. The left lobes of the lungs were extracted for the measurement of metastatic nodules.

Results

Irradiation resulted in a dose-dependent increase in PGE2 production. PGE2 synthesis decreased markedly after treatment with celecoxib alone or in combination with irradiation. Compared to mice treated with low dose celecoxib, mean tumor volume decreased significantly in mice treated with a high dose of celecoxib with or without irradiation. Mice treated with a high dose celecoxib alone, with irradiation alone, or with irradiation plus celecoxib had markedly fewer metastatic lung nodules than controls. The mean metastatic area was the smallest for mice treated with irradiation plus a high dose celecoxib.

Conclusion

Oral administration of high dose celecoxib significantly inhibited tumor growth, as compared to a low dose treatment. Radiotherapy in combination with high dose celecoxib delayed tumor growth and reduced the number of pulmonary metastases to a greater extent than celecoxib or radiotherapy alone.

Kinetic modelling of NSAID action on COX-1: focus on in vitro/in vivo aspects and drug combinations

The detailed kinetic model of Prostaglandin H Synthase-1 (COX-1) was developed to in silico test and predict inhibition effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on target. The model takes into account key features of the complex catalytic mechanism of cyclooxygenase-1, converting arachidonic acid to prostaglandin PGH(2), and includes the description of the enzyme interaction with various types of NSAIDs (reversible/irreversible, non-selective and selective to COX-1/COX-2). Two different versions of the model were designed to simulate the inhibition of COX-1 by NSAIDs in two most popular experimental settings - in vitro studies with purified enzyme, and the experiments with platelets. The developed models were applied to calculate the dose-dependence of aspirin and celecoxib action on COX- 1 in vitro and in vivo conditions. The mechanism of the enhancement of aspirin efficiency in platelet as compared to its action on purified COX-1 was elucidated. The dose-dependence of celecoxib simulated with the use of the "in vivo" version of the model predicted potentially strong inhibitory effect of celecoxib on thromboxan production in platelets. Simulation of the combined effect of two NSAIDs, aspirin and celecoxib, on COX-1 allowed us to reveal the mechanism underlying the suppression of aspirin-mediated COX-1 inhibition by celecoxib. We discuss our modelling results in the context of the on-going debates on the potential cardio-vascular risks associated with co-administration of various types of NSAIDs.

Aspirin and the in vitro linear relationship between thromboxane A2-mediated platelet aggregation and platelet production of thromboxane A2

BACKGROUND

Currently, 'aspirin resistance', the anti-platelet effects of non-steroid anti-inflammatory drugs (NSAIDs) and NSAID-aspirin interactions are hot topics of debate. It is often held in this debate that the relationship between platelet activation and thromboxane (TX) A(2) formation is non-linear and TXA(2) generation must be inhibited by at least 95% to inhibit TXA(2)-dependent aggregation. This relationship, however, has never been rigorously tested.

OBJECTIVES

To characterize, in vitro and ex vivo, the concentration-dependent relationships between TXA(2) generation and platelet activity.

METHOD

Platelet aggregation, thrombi adhesion and TXA(2) production in response to arachidonic acid (0.03-1 mmol L(-1)), collagen (0.1-30 microg mL(-1)), epinephrine (0.001-100 micromol L(-1)), ADP, TRAP-6 amide and U46619 (all 0.1-30 micromol L(-1)), in the presence of aspirin or vehicle, were determined in 96-well plates using blood taken from naïve individuals or those that had taken aspirin (75 mg, o.d.) for 7 days.

RESULTS

Platelet aggregation, adhesion and TXA(2) production induced by either arachidonic acid or collagen were inhibited in concentration-dependent manners by aspirin, with logIC(50) values that did not differ. A linear relationship existed between aggregation and TXA(2) production for all combinations of arachidonic acid or collagen and aspirin (P < 0.01; R(2) 0.92; n = 224). The same relationships were seen in combinations of aspirin-treated and naïve platelets, and in blood from individuals taking an anti-thrombotic dose of aspirin.

CONCLUSIONS

These studies demonstrate a linear relationship between inhibition of platelet TXA(2) generation and TXA(2)-mediated aggregation. This finding is important for our understanding of the anti-platelet effects of aspirin and NSAIDs, NSAID-aspirin interactions and 'aspirin resistance'.

Bradykinin stimulates prostaglandin E2 production and cyclooxygenase activity in equine nonglandular and glandular gastric mucosa in vitro

REASONS FOR PERFORMING STUDY

There are few data available regarding regulation of prostaglandin (PG) generation by equine gastric mucosae and the role of the cyclooxygenase (COX) isoforms in their production.

OBJECTIVES

To: 1) characterise and quantify PGE2 output in vitro; 2) examine the sensitivity of PGE2 production to exogenous bradykinin (BK) exposure; 3) determine the contribution of the COX-1 and COX-2 pathways to basal and BK-stimulated PGE2 production; and 4) measure if BK influences electrogenic ion transport in equine gastric mucosae in vitro.

METHODS

Full thickness gastric sheets were obtained from horses at post mortem, stripped of muscle layers and mounted in Ussing chambers. Tissues were exposed to bradykinin (BK, 0.1 micromol/l) either alone, or following pretreatment with a selective COX-2 inhibitor (NS-398, 1 micromol/l) or a nonselective COX inhibitor (piroxicam, 1 micromol/l), or were untreated.

RESULTS

BK administration increased PGE2 output from the basolateral but not the apical faces of both tissue types. Piroxicam, but not NS-398, reduced basolateral PGE2 release below control levels in both tissue types. Both piroxicam and NS-398 pretreatment inhibited BK-stimulated PGE2 release. In separate experiments, BK was without effect upon electrophysiological parameters of tissues mounted in Ussing chambers.

CONCLUSIONS

PGE2 is produced by the nonglandular and glandular equine gastric mucosae in vitro. Significantly more PGE2 is released basolaterally than apically. BK stimulated the production of PGE2 from the basolateral side of both tissue types. These findings suggest that COX-1 is a significant pathway for basal PGE2 production from the basolateral faces of both nonglandular and glandular equine gastric mucosae in vitro.

Site specific chemical delivery of NSAIDs to inflamed joints: synthesis, biological activity and gamma-imaging studies of quaternary ammonium salts of tropinol esters of some NSAIDs or their active metabolites

Quaternized tropinol ester derivatives of some commonly used non-steroidal anti-inflammatory drugs (NSAIDs) or their active metabolites, were prepared and studied for their anti-inflammatory activity in a chronic inflammation model and for inflamed tissue tropism. The quaternized esters were radiolabeled with 99mTechnetium (99mTc) and their selective localization in the inflamed tissue was traced using scintigraphy. In the chronic arthritis rodent model, most of the quaternized esters exhibited anti-inflammatory effect comparable to their respective parent drugs. In the gamma-imaging studies only the quaternary derivatives exhibited selective accumulation into the inflamed tissue unlike the parent NSAIDs or the unquaternized tropinol esters. This work is a step ahead in the direction of use of quaternary ammonium ester derivatives for site specific chemical delivery of commonly used NSAIDs to the inflamed tissues to minimize their GIT side effect or other systemic toxicities.

Cannabidiolic acid as a selective cyclooxygenase-2 inhibitory component in cannabis

In the present study it was revealed that cannabidiolic acid (CBDA) selectively inhibited cyclooxygenase (COX)-2 activity with an IC(50) value (50% inhibition concentration) around 2 microM, having 9-fold higher selectivity than COX-1 inhibition. In contrast, Delta(9)-tetrahydrocannabinolic acid (Delta(9)-THCA) was a much less potent inhibitor of COX-2 (IC(50) > 100 microM). Nonsteroidal anti-inflammatory drugs containing a carboxyl group in their chemical structures such as salicylic acid are known to inhibit nonselectively both COX-1 and COX-2. CBDA and Delta(9)-THCA have a salicylic acid moiety in their structures. Thus, the structural requirements for the CBDA-mediated COX-2 inhibition were next studied. There is a structural difference between CBDA and Delta(9)-THCA; phenolic hydroxyl groups of CBDA are freed from the ring formation with the terpene moiety, although Delta(9)-THCA has dibenzopyran ring structure. It was assumed that the whole structure of CBDA is important for COX-2 selective inhibition because beta-resorcylic acid itself did not inhibit COX-2 activity. Methylation of the carboxylic acid moiety of CBDA led to disappearance of COX-2 selectivity. Thus, it was suggested that the carboxylic acid moiety in CBDA is a key determinant for the inhibition. Furthermore, the crude extract of cannabis containing mainly CBDA was shown to have a selective inhibitory effect on COX-2. Taken together, these lines of evidence in this study suggest that naturally occurring CBDA in cannabis is a selective inhibitor for COX-2.

The Risk of Acute Myocardial Infarction with Etodolac Is not Increased Compared to Naproxen: A Historical Cohort Analysis of a Generic COX-2 Selective Inhibitor

Background: This study compares the risk of acute myocardial infarction among patients exposed to etodolac, naproxen, celecoxib, and rofecoxib.

Methods: A retrospective cohort study in 38 258 veteran patients (26 376 patient-years) measured the adjusted odds ratios of acute myocardial infarction during exposure to etodolac, naproxen, celecoxib, or rofecoxib.

Results: Diagnosis of acute myocardial infarction was confirmed in 100 patients who were exposed to a study nonsteroidal anti-inflammatory drug. Compared to naproxen, the increased risk of acute myocardial infarction was not significant for etodolac (OR = 1.32, P = .27), whereas celecoxib (OR = 2.18, 95% CI 1.09-4.35, P = .03) and rofecoxib (OR = 2.16, 95 CI 1.04-4.46, P = .04) were significant. A post hoc analysis indicates that patients with a prior history of acute myocardial infarction had a significant, 4.26-fold risk for another acute myocardial infarction if taking celecoxib or rofecoxib.

Conclusion: Etodolac is not associated with a statistically increased risk of acute myocardial infarction compared to naproxen.

Possible glutamatergic and lipid signalling mechanisms in ECT-induced retrograde amnesia: experimental evidence for involvement of COX-2, and review of literature

We sought to explore nonselective vs. selective COX mechanisms in ECS-induced retrograde amnesia using indomethacin and celecoxib as in vivo probes. Adult Wistar rats (n=72) which showed adequate learning on a passive avoidance task received 5 once-daily 30 mC true or sham ECS. During the learning and ECS periods, indomethacin (4 mg/kg/day), celecoxib (15 mg/kg/day), or vehicle were orally administered. One day after the fifth ECS, recall of pre-ECS learning was tested. There were no baseline or pre-ECS differences in learning between groups. ECS seizure duration did not differ across groups. ECS-treated rats showed impaired recall in the vehicle but not indomethacin and celecoxib groups. Celecoxib but not indomethacin significantly protected against ECS-induced retrograde amnesia. We interpret these results as follows: ECS may impair cognition by pathologically upregulating glutmatergic signalling, thereby causing cation and water influx, oxidative stress, and saturation of hippocampal LTP. These may result from glutamatergic disinhibition through COX-2-mediated removal of endogenous cannabinoids, and by ECS-activated, NMDA-mediated upregulation of platelet activating factor and COX-2 signalling pathways. Thus, indomethacin and celecoxib, by inhibiting COX-2, may protect against ECS-induced amnesia. Furthermore, COX-2 mediated increase in hippocampal kynurenic acid may impair glutamate-dependent learning and memory processes at ionotropic glutamatergic receptor sites; the inhibition of kynurenic acid synthesis by celecoxib and its induction by indomethacin may explain the greater benefits with celecoxib. These findings suggest new avenues for the study of the neurobiology of ECT-induced amnesia and the attenuation thereof.

Pro-apoptotic effect of nonsteroidal anti-inflammatory drugs on synovial fibroblasts

Rheumatoid arthritis (RA) is a systemic inflammatory disease that mainly affects the articular synovial tissues. Although the etiology of RA has not yet been elucidated, physical and biochemical inhibition of synovial hyperplasia, which is the origin of articular destruction, may be an effective treatment for RA. Nonsteroidal anti-inflammatory drugs (NSAIDs) have long been used for the treatment of RA. The mechanism of action of NSAIDs generally involves the inhibition of cyclooxygenase (COX) at sites of inflammation. Thus, NSAIDs were not generally considered to have a so-called anti-rheumatic effect, including inhibition of progressive joint destruction and induction of remission. However, certain conventional NSAIDs and celecoxib, a selective COX-2 inhibitor, have been reported to inhibit synovial hyperplasia by inducing the apoptosis of human synovial fibroblasts. Therefore, it has been suggested that such NSAIDs may not only have an anti-inflammatory effect but also an anti-rheumatic effect. In this review, we summarize findings about the pro-apoptotic effect, in other words, anti-proliferative effect of NSAIDs on synovial fibroblasts from patients with RA.

Prostanoid function and cardiovascular disease

Prostanoids, including prostaglandins (PGs) and thromboxanes (TXs) are synthesized from arachidonic acid by the combined action of cyclooxygenases (COXs) and PG and TX synthases. Finally after their synthesis, prostanoids are quickly released to the extracellular medium exerting their effects upon interaction with prostanoid receptors present in the neighbouring cells. These agents exert important actions in the cardiovascular system, modulating vascular homeostasis and participating in the pathogenesis of vascular diseases as thrombosis and atherosclerosis. Among prostanoids, Tromboxane (TX)A(2), a potent platelet activator and vasoconstrictor and prostacyclin (PGI2), a platelet inhibitor and vasodilator, are the most important in controlling vascular homeostasis. Although multiple studies using pharmacological inhibitors and genetically deficient mice have demonstrated the importance of prostanoid-mediated actions on cardiovascular physiology, further analysis on the prostanoid mediated actions in the vascular system are required to better understand the benefits and risks for the use of COX inhibitors in cardiovascular diseases.

Mechanisms of non-steroid anti-inflammatory drugs action on ASICs expressed in hippocampal interneurons

The inhibitory action of non-steroid anti-inflammatory drugs was investigated on acid-sensing ionic channels (ASIC) in isolated hippocampal interneurons and on recombinant ASICs expressed in Chinese hamster ovary (CHO) cells. Diclofenac and ibuprofen inhibited proton-induced currents in hippocampal interneurons (IC(50) were 622 +/- 34 muM and 3.42 +/- 0.50 mM, respectively). This non-competitive effect was fast and fully reversible for both drugs. Aspirin and salicylic acid at 500 muM were ineffective. Diclofenac and ibuprofen decreased the amplitude of proton-evoked currents and slowed the rates of current decay with a good correlation between these effects. Simultaneous application of acid solution and diclofenac was required for its inhibitory effect. Unlike amiloride, the action of diclofenac was voltage-independent and no competition between two drugs was found. Analysis of the action of diclofenac and ibuprofen on activation and desensitization of ASICs showed that diclofenac but not ibuprofen shifted the steady-state desensitization curve to more alkaline pH values. The reason for this shift was slowing down the recovery from desensitization of ASICs. Thus, diclofenac may serve as a neuroprotective agent during pathological conditions associated with acidification.