Cyclo-oxygenase isoenzymes. How recent findings affect thinking about nonsteroidal anti-inflammatory drugs

Discovery of new thymol-3,4-disubstituted thiazole hybrids as dual COX-2/5-LOX inhibitors with in vivo proof

New thymol-3,4-disubstitutedthiazole hybrids were synthesised as dual COX-2/5-LOX inhibitors. Compounds 6b, 6d, 6e, and 6f displayed in vitro inhibitory activity against COX-2 (IC50= 0.037, 0.042, 0.046, and 0.039 µM) nearly equal to celecoxib (IC50= 0.045 µM). 6b, 6d, and 6f showed SI (379, 341, and 374, respectively) higher than that of celecoxib (327). 6a-l elicited in vitro 5-LOX inhibitory activity higher than quercetin. 6a-f, 6i-l, 7a, and 7c possessed in vivo inhibition of formalin induced paw edoema higher than celecoxib. 6a, 6b, 6f, 6h-l, and 7b showed gastrointestinal safety profile as celecoxib and diclofenac sodium in the population of fasted rats. Induced fit docking and molecular dynamics simulation predicted good fitting of 6b and 6f without changing the packing and globularity of the apo protein. In conclusion, 6b and 6f achieved the target goal as multitarget inhibitors of inflammation.

Insight on novel oxindole conjugates adopting different anti-inflammatory investigations and quantitative evaluation

Background: A dual COX/5-LOX strategy was adopted to develop new oxindole derivatives with superior anti-inflammatory activity. Methods: Three series of oxindoles - esters 4a-p, 6a-l and imines 7a-o - were synthesized and evaluated for their anti-inflammatory and analgesic activities. Molecular docking and predicted pharmacokinetic parameters were done for the most active compounds. A new LC-MS/MS method was developed and validated for the quantification of 4h in rat plasma. Results: Compounds 4h, 6d, 6f, 6j and 7m revealed % edema inhibition up to 100.00%; also, 4l and 7j showed 100.00% writhing protection. Compound 4h showed dual inhibitory activity with IC50 = 0.0533 and 0.4195 μM for COX-2 and 5-LOX, respectively. Molecular docking rationalized the obtained biological activity. The pharmacokinetic parameters of 4h from rat plasma were obtained.

Seasonal expressions of COX-1, COX-2, and EP4 in the scent glands of muskrats (Ondatra zibethicus)

Prostaglandins (PGs) serve as signaling molecules that regulate various physiological processes, including inflammation, immune response, blood clotting, and reproduction. The aim of this study was to investigate the immunolocalizations and expression patterns of prostaglandin-E2 (PGE2), cyclooxygenase (COX)-1, and COX-2, as well as its receptor subtypes 4 (EP4) in the scent glands of muskrats (Ondatra zibethicus) during the breeding and nonbreeding periods. There were significant seasonal differences in the scent glandular mass, with higher values in the breeding season and relatively low in the nonbreeding season. PGE2, EP4, COX-1, and COX-2 have been immunolocalized in the scent glandular and epithelial cells in both breeding and nonbreeding seasons, whereas no immunostaining was observed in the interstitial cells. The protein and mRNA expression levels of EP4, COX-1, and COX-2 were higher in the scent glands of the breeding season than those of the nonbreeding season. The mean mRNA levels of EP4, COX-1, and COX-2 were positively correlated with the scent glandular weights. The circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), and PGE2, as well as scent glandular PGE2 and dihydrotestosterone (DHT) concentrations, were also significantly higher in the breeding season. In addition, the transcriptomic study in the scent glands identified that differentially expressed genes might be related to fatty carboxylic monocarboxylic acid, steroidogenic-related pathways, and prostanoid metabolic processes. These findings suggested that prostaglandin-E2 might play an essential autocrine or paracrine role in regulating seasonal changes in the scent glandular functions of the muskrats.

Mechanisms of Bioactivities of Fucoidan from the Brown Seaweed Fucus vesiculosus L. of the Barents Sea

The aim of this study was to elucidate some mechanisms of radical scavenging and the anti-inflammatory, anti-hyperglycemic, and anti-coagulant bioactivities of high molecular weight fucoidan from Fucus vesiculosus in several in vitro models. Fucoidan has displayed potent 1, 1-diphenyl-2-picryl hydrazil radical scavenging and reduction power activities. It significantly inhibits the cyclooxygenase-2 (COX-2) enzyme (IC50 4.3 μg mL-1) with a greater selectivity index (lg(IC80 COX-2/IC80COX-1), -1.55) than the synthetic non-steroidal anti-inflammatory drug indomethacin (lg(IC80 COX-2/IC80COX-1), -0.09). A concentration-dependent inhibition of hyaluronidase enzyme with an IC50 of 2.9 μg mL-1 was observed. Fucoidan attenuated the lipopolysaccharide-induced expression of mitogen-activated protein kinase p38. Our findings suggest that the inhibition of dipeptidyl peptidase-IV (DPP-IV) (IC50 1.11 μg mL-1) is one of the possible mechanisms involved in the anti-hyperglycemic activity of fucoidan. At a concentration of 3.2 μg mL-1, fucoidan prolongs the activated partial thromboplastin time and thrombin time by 1.5-fold and 2.5-fold compared with a control, respectively. A significant increase of prothrombin time was observed after the concentration of fucoidan was increased above 80 μg mL-1. This evidenced that fucoidan may have an effect on intrinsic/common pathways and little effect on the extrinsic mechanism. This study sheds light on the multiple pathways of the bioactivities of fucoidan. As far as we know, the inhibition of hyaluronidase and DPP-IV by high molecular fucoidan was studied for the first time in this work. Our results and literature data suggest that molecular weight, sulfate content, fucose content, and polyphenols may contribute to these activities. It seems that high molecular weight fucoidan has promising therapeutic applications in different pharmacological settings. Anti-oxidant, anti-inflammatory and anti-coagulant drugs have been used for the management of complications of COVID19. Taken as a whole, fucoidan could be considered as a prospective candidate for the treatment of patients with COVID19; however, additional research in this field is required.

Detection and Pharmacokinetics of Etoricoxib in Thoroughbred Horses

Etoricoxib, a selective inhibitor of cyclooxygenase-2, is used in the treatment of many inflammatory diseases and dental pain in humans. The aim of this study was to determine the pharmacokinetics and metabolism of etoricoxib in horses. Six horses weighing an average of 475 ± 25 kg were administered a single oral dose of etoricoxib at 1 mg/kg body weight. The results show that the drug reached a maximum concentration of 505.2 ± 67.8 ng/mL in 48 minutes after administration. The elimination half-life was calculated to be 10.20 ± 1.30 hours. Mass spectrometric analysis confirmed that etoricoxib is metabolized in horses via the oxidation of its 6'-methyl group to form a hydroxyl methyl etoricoxib which can further be oxidized to form either an acid or be glucuronidated. In addition, the 1'-N terminal of 6'-hydroxymethyl metabolite is oxidized to form the corresponding 1'-N oxide metabolite. The present results have clearly demonstrated that etoricoxib is mainly excreted in urine as metabolites. From these data, it is also possible to postulate a detection time for the metabolites which in turn can assist in the control of illegal use of the drug in horse racing.

Seasonal expressions of prostaglandin E synthases and receptors in the prostate of the wild ground squirrel (Spermophilus dauricus)

The prostate gland is a male accessory reproductive gland, whose vitality and function are under tight regulation of different hormones. Prostaglandins E2 (PGE2) is one of the major products generated by the actions of cyclooxygenases (COX) and prostaglandin E synthase (PTGES) on arachidonic acid, and is involved in a number of physiological and pathological processes. In this study, we investigated the seasonal immunolocalizations and expressions of COX-1, COX-2 and PTGES, as well as PGE2 receptors (PTGERs) subtypes 1-4 (EP1, EP2, EP3, EP4) in the prostate of the wild ground squirrel. Histological examination observed enlarged prostatic lumens in the breeding season and significantly shrunken lumens in the nonbreeding season. COX-1, COX-2, PTGES and PTGERs were mainly localized in epithelial and stromal cells in the breeding and nonbreeding seasons. The mRNA expression levels of Cox-1, Cox-2, Ptges, Ptger2 (encoding EP2) and Ptger4 (encoding EP4) were higher in the prostate of the breeding season than in the nonbreeding season. The relative mRNA levels of Cox-1, Cox-2, Ptges, Ptger2 and Ptger4 were positively correlated with prostatic weights. In addition, both the prostatic and plasma concentrations of PGE2 were significantly higher in the breeding season compared to the nonbreeding season. These results suggested that PGE2 synthesis and signaling might play an important autocrine or paracrine role in the regulation of seasonal changes in the prostatic function of the wild ground squirrel.

Docking assisted design of novel 4-adamantanyl-2-thiazolylimino-5-arylidene-4-thiazolidinones as potent NSAIDs

Docking analysis was used to predict the effectiveness of adamantanyl insertion in improving cycloxygenase/lipoxygenase (COX/LOX) inhibitory action of previously tested 2-thiazolylimino-5-arylidene-4-thiazolidinones. The crystal structure data of human 5-LOX (3O8Y), ovine COX-1 (1EQH) and mouse COX-2 (3ln1) were used for docking analysis. All docking calculations were carried out using AutoDock 4.2 software. Following prediction results, 11 adamantanyl derivatives were synthesized and evaluated for biological action. Prediction evaluations correlated well with experimental biological results. Comparison of the novel adamantanyl derivatives with the 2-thiazolylimino-5-arylidene-4-thiazolidinones previously tested showed that insertion of the adamantanyl group led to the production of more potent COX-1 inhibitors, as well as LOX inhibitors (increased activity from 200% to 560%). Five compounds out of the 11 exhibited better activity than naproxen; while nine out of 11 showed better activity than NDGA and seven compounds possessed better anti-inflammatory activity than indomethacin.

Prediction of the potency of mammalian cyclooxygenase inhibitors with ensemble proteochemometric modeling

Cyclooxygenases (COX) are present in the body in two isoforms, namely: COX-1, constitutively expressed, and COX-2, induced in physiopathological conditions such as cancer or chronic inflammation. The inhibition of COX with non-steroideal anti-inflammatory drugs (NSAIDs) is the most widely used treatment for chronic inflammation despite the adverse effects associated to prolonged NSAIDs intake. Although selective COX-2 inhibition has been shown not to palliate all adverse effects (e.g. cardiotoxicity), there are still niche populations which can benefit from selective COX-2 inhibition. Thus, capitalizing on bioactivity data from both isoforms simultaneously would contribute to develop COX inhibitors with better safety profiles. We applied ensemble proteochemometric modeling (PCM) for the prediction of the potency of 3,228 distinct COX inhibitors on 11 mammalian cyclooxygenases. Ensemble PCM models ([Formula: see text], and RMSEtest = 0.71) outperformed models exclusively trained on compound ([Formula: see text], and RMSEtest = 1.09) or protein descriptors ([Formula: see text] and RMSEtest = 1.10) on the test set. Moreover, PCM predicted COX potency for 1,086 selective and non-selective COX inhibitors with [Formula: see text] and RMSEtest = 0.76. These values are in agreement with the maximum and minimum achievable [Formula: see text] and RMSEtest values of approximately 0.68 for both metrics. Confidence intervals for individual predictions were calculated from the standard deviation of the predictions from the individual models composing the ensembles. Finally, two substructure analysis pipelines singled out chemical substructures implicated in both potency and selectivity in agreement with the literature. Graphical AbstractPrediction of uncorrelated bioactivity profiles for mammalian COX inhibitors with Ensemble Proteochemometric Modeling.

Celecoxib analogs bearing benzofuran moiety as cyclooxygenase-2 inhibitors: design, synthesis and evaluation as potential anti-inflammatory agents

Novel series of celecoxib analogs endowed with benzofuran moiety 3a-e and 9a-d were synthesized and evaluated for COX-1/COX-2 inhibitory activity in vitro. The most potent and selective COX-2 inhibitors - compounds 3c, 3d, 3e, 9c and 9d - were assessed for their anti-inflammatory activity and ulcerogenic liability in vivo. The 3-(pyridin-3-yl)pyrazole derivatives 3c and 3e exhibited the highest anti-inflammatory activity, that is equipotent to celecoxib. Furthermore, the tested compounds proved to have better gastric safety profile compared to celecoxib. In particular, compound 3e demonstrated about 40% reduction in ulcerogenic potential relative to the reference drug. Finally, molecular docking simulation of the new compounds in COX-2 active site and drug likeness studies showed good agreement with the obtained pharmaco-biological results.

1,4-Diaryl-substituted triazoles as cyclooxygenase-2 inhibitors: Synthesis, biological evaluation and molecular modeling studies

A novel group of 1,4-diaryl-substituted triazoles was designed and synthesized by introducing the cyclooxygenase-2 (COX-2) pharmacophore SO2NH2 attached to one aryl ring and various substituents (H, F, Cl, CH3 or OCH3) attached to the other aryl ring. The effects of size and flexibility of the compounds upon COX-1/COX-2 inhibitory potency and selectivity was studied by increasing the size of an alkyl linker chain [(-CH2)n, where n=0, 1, 2]. In vitro COX-1/COX-2 inhibition studies showed that all compounds (14-18, 21-25 and 28-32) are more potent inhibitors of COX-2 isozyme (IC50=0.17-28.0μM range) compared to COX-1 isozyme (IC50=21.0 to >100μM range). Within the group of 1,4 diaryl-substituted triazoles, 4-{2-[4-(4-chloro-phenyl)-[1,2,3]triazol-1-yl]-ethyl}-benzenesulfonamide (compound 30) displayed highest COX-2 inhibitory potency and selectivity (COX-1: IC50=>100μM, COX-2: IC50=0.17μM, SI >588). Molecular docking studies using the catalytic site of COX-1 and COX-2, respectively, provided complementary theoretical support for the obtained experimental biological structure-activity relationship data. Results of molecular docking studies revealed that COX-2 pharmacophore SO2NH2 in compound 30 is positioned in the secondary pocket of COX-2 active site; with the nitrogen atom of the SO2NH2 group being hydrogen bonded to Q192 (N⋯OC=2.85Å), and one of the oxygen atoms of SO2NH2 group forming a hydrogen bond to H90 (SO⋯N=2.38Å).

An Evaluation of the Dose-Dependent Inhibition of CYP1A2 by Rofecoxib Using Theophylline as a CYP1A2 Probe

This study was undertaken to determine whether rofecoxib can interfere with CYP1A2 activity in humans using theophylline as a probe substrate. Single oral doses of theophylline were administered to each of three panels of 12 healthy subjects receiving daily doses of rofecoxib for 7 days to examine the effect of rofecoxib administration on the absorption and disposition of theophylline. Each panel was administered doses of 12.5, 25, or 50 mg of rofecoxib or a matching placebo in a two-way, randomized, crossover fashion and administered a single oral 300-mg dose of theophylline on day 7 of rofecoxib or placebo administration. Plasma concentrations of theophylline were monitored for 48 hours postdose to assess differences in pharmacokinetics. All three commercially marketed doses of rofecoxib were found to slow the clearance of theophylline with no detectable effect on absorption. CL/F values for theophylline were estimated from AUC infinity and by point estimates from the concentrations of drug in plasma at 12 and 24 hours postdose. The point estimates of CL/F were found to be in agreement with those derived from AUC.

Dual role of cyclooxygenase-2 during tissue repair induced by low level laser therapy: an intriguing issue

Tissue repair is an excellent example of pathophysiological model for studying the role of cyclooxygenase-2 (COX-2) on eukaryotic cells. It has been established that two COX isoforms are expressed in human tissues: constitutive or induced. COX-1 activity is constitutive, present in nearly all cell types at a constant level; COX-2 activity is normally absent from cells, and when induced, the protein levels increase and decrease in a matter of hours after a single stimulus. Thus, the purpose of this review was to describe the role of COX-2 during tissue repair induced by low level laser therapy (LLLT) in humans and experimental models. COX-2 expression has been implicated in the onset or the exacerbation of inflammation during tissue repair induced by LLLT in a number of studies, Many studies are conducted to investigate the role of COX-2 during tissue repair induced by LLLT using different experimental protocols and dosages. Therefore, this is an area that warrants investigation, since the estimation of COX-2 expression from using such important techniques in therapeutics with respect to tissue repair will be added to those already established in the literature as a way to improve health status and prevention of side effects.

N-1 and C-3 substituted indole Schiff bases as selective COX-2 inhibitors: synthesis and biological evaluation

A group of N-1 and C-3 disubstituted-indole Schiff bases bearing an indole N-1 (R'=H, CH(2)Ph, COPh) substituent in conjunction with a C-3 -C=HN-C(6)H(4)-4-X (X=F, Me, CF(3), Cl) substituent were synthesized and evaluated as inhibitors of cyclooxygenase (COX) isozymes (COX-1/COX-2). Within this group of Schiff bases, compounds 15 (R(1)=CH(2)Ph, X=F), 17 (R(1)=CH(2)Ph, X=CF(3)), 18 (R(1)=COPh, X=F) and 20 (R(1)=COPh, X=CF(3)) were identified as effective and selective COX-2 inhibitors (COX-2 IC(50)'s=0.32-0.84 μM range; COX-2 selectivity index (SI)=113 to >312 range). 1-Benzoyl-3-[(4-trifluoromethylphenylimino)methyl]indole (20) emerged as the most potent (COX-1 IC(50) >100 μM; COX-2 IC(50)=0.32 μM) and selective (SI >312) COX-2 inhibitor. Furthermore, compound 20 is a selective COX-2 inhibitor in contrast to the reference drug indomethacin that is a potent and selective COX-1 inhibitor (COX-1 IC(50)=0.13 μM; COX-2 IC(50)=6.9 μM, COX-2 SI=0.02). Molecular modeling studies employing compound 20 showed that the phenyl CF(3) substituent attached to the CN spacer is positioned near the secondary pocket of the COX-2 active site, the CN nitrogen atom is hydrogen bonded (N···NH=2.85 Å) to the H90 residue, and the indole N-1 benzoyl is positioned in a hydrophobic pocket of the COX-2 active site near W387.

MOLECULAR DOCKING STUDY OF THE AFFINITY OF CYP2C9 AND CYP2D6 FOR IMRECOXIB

With the aid of the automatic molecular docking, the affinity of CYP2C9 and CYP2D6 for imrecoxib was studied by InsightII/Affinity program. The results indicate that CYP2C9–imrecoxib complex has higher stability and stronger affinity because CYP2C9 has more favorable interaction energy (-62.72 kcal/mol) and higher Ludi score (610) with imrecoxib than CYP2D6 (-50.22 kcal/mol and 551) and this is consistent with the results of the kinetic experiments by Li et al. By analyzing the theoretical results combined with the experimental ones, we suggest that the affinity difference is caused by the difference of the structure between CYP2C9 and CYP2D6, and the most important residues for enzyme–substrate complexes, such as Phe476, Asn204, Phe100, Leu366 and Arg108 of CYP2C9 and Phe120, Glu216, and Phe483 of CYP2D6 were also identified.

Fragment-based design, docking, synthesis, biological evaluation and structure-activity relationships of 2-benzo/benzisothiazolimino-5-aryliden-4-thiazolidinones as cycloxygenase/lipoxygenase inhibitors

Balanced modulation of several targets is one of the current strategies for the treatment of multi-factorial diseases. Based on the knowledge of inflammation mechanisms, it was inferred that the balanced inhibition of cyclooxygenase-1/cyclooxygenase-2/lipoxygenase might be a promising approach for treatment of such a multifactorial disease state as inflammation. Detection of fragments responsible for interaction with enzyme's binding site provides the basis for designing new molecules with increased affinity and selectivity. A new chemoinformatics approach was proposed and applied to create a fragment library that was used to design novel inhibitors of cycloxygenase-1/cycloxygenase-2/lipoxygenase enzymes. Potential binding sites were elucidated by docking. Synthesis of novel compounds, and the in vitro/in vivo biological testing confirmed the results of computational studies. The benzothiazolyl moiety was proved to be of great significance for developing more potent inhibitors.

Docking and Molecular Dynamics Calculations of Pyrrolidinone Analog MMK16 Bound to COX and LOX Enzymes

The new molecule 4-[(2S)-2-(1H-imidazol-1-ylmethyl)-5-oxotetrahydro-1H-pyrrol-1-yl]methylbenzenecarboxylic acid (MMK16) was found to have promising anti-inflammatory activity. This biological behavior of MMK16 triggered our interest to study its binding affinity using NMR spectroscopy in LOX and its docking and molecular dynamics (MD) properties in LOX and COX enzymes. The present NMR and docking binding studies not only rationalize the obtained biological results since in all three receptors MMK16 shows high affinity and scoring but also make it a potential dual LOX-5/COX-2 inhibitor. Thus, this class of molecules must be further investigated for discovering compounds possessing better biological activity and more lasting biological effect.

Synthesis, anti-inflammatory activity, and in vitro antitumor effect of a novel class of cyclooxygenase inhibitors: 4-(aryloyl)phenyl methyl sulfones

Following our previous research on anti-inflammatory drugs (NSAIDs), we report on the design and synthesis of 4-(aryloyl)phenyl methyl sulfones. These substances were characterized for their capacity to inhibit cyclooxygenase (COX-1 and COX-2) isoenzymes. Molecular modeling studies showed that the methylsulfone group of these compounds was inserted deep in the pocket of the human COX-2 binding site, in an orientation that precludes hydrogen bonding with Arg120, Ser353, and Tyr355 through their oxygen atoms. The N-arylindole 33 was the most potent inhibitor of COX-2 and also the most selective (COX-1/COX-2 IC(50) ratio was 262). The indole derivative 33 was further tested in vivo for its anti-inflammatory activity in rats. This compound showed greater inhibitory activity than ibuprofen. Other compounds (20, 26, 9, and 30) showed strong activity against carrageenan-induced inflammation. The latter compounds showed a weak capacity to inhibit the proliferation of human cell lines K562, NCI-H460, and HT-29 in vitro.

[Pathophysiological relevance of peroxisome proliferators activated receptors (PPAR) to joint diseases - the pro and con of agonists]

Peroxisome proliferators activated receptors (PPAR) are ligand-inducible nuclear transacting factors comprising three subtypes, PPARalpha, PPARbeta/delta and PPARgamma, which play a key role in lipids and glucose homeostasis. All PPAR subtypes have been identified in joint or inflammatory cells and their activation resulted in a transcriptional repression of pro-inflammatory cytokines (IL-1, TNFalpha), early inflammatory genes (NOS(2), COX-2, mPGES-1) or matrix metalloproteases (MMP-1, MMP-13), at least for the gamma subtype. PPAR full agonists were also shown to stimulate IL-1 receptor antagonist (IL-1Ra) production by cytokine-stimulated articular cells in a subtype-dependent manner. These anti-inflammatory and anti-catabolic properties were confirmed in animal models of joint diseases where PPAR agonists reduced synovial inflammation while preventing cartilage destruction or inflammatory bone loss, although many effects required much higher doses than needed to restore insulin sensitivity or to lower circulating lipid levels. However, these promising effects of PPAR full agonists were hampered by their ability to reduce the growth factor-dependent synthesis of extracellular matrix components or to induce chondrocyte apoptosis, by the possible contribution of immunosuppressive properties to their anti-arthritic effects, by the increased adipocyte differentiation secondary to prolonged stimulation of PPARgamma, and by a variable contribution of PPAR subtypes depending on the system. Clinical data are scarce in rheumatoid arthritis (RA) patients whereas thousands of patients worldwilde, treated with PPAR agonists for type 2 diabetes or dyslipidemia, are paradoxically prone to suffer from osteoarthritis (OA). Whereas high dosage of full agonists may expose RA patients to cardiovascular adverse effects, the proof of concept that PPAR agonists have therapeutical relevance to OA may benefit from an epidemiological follow-up of joint lesions in diabetic or hyperlipidemic patients treated for long periods of time with glitazones or fibrates. Additionally, cellular and animal studies are required to assess whether partial agonists of PPAR (SPPARMs) may preserve therapeutical properties with potentially less safety concern.

The perioperative management of pain from intracranial surgery

Analgesic therapy following intracranial procedures remains a source of concern and controversy. Although opioids are the mainstay of the "balanced" general anesthetic techniques frequently used during intracranial procedures, neurosurgeons and others have been reluctant to administer opioid analgesics to patients following such procedures. This practice is supported by the concern that the sedation and miosis associated with opioid administration could mask the early signs of intracranial catastrophe, or even exacerbate it through decreased ventilatory drive, elevated arterial carbon dioxide levels, and increased cerebral blood flow. This reluctance to use opioids following intracranial surgery is enabled by decades of training and anecdote emphasizing that pain is minimal following these procedures. However, recent data suggests otherwise, and raises the question of how to provide safe and effective analgesia for these patients. Here, this data is reviewed along with the relevant pain pathways, analgesic drugs and techniques, and the available data on their use following intracranial surgery. Although pain following intracranial surgery appears to be more intense than initially believed, it is readily treated safely and effectively with techniques that have proven useful following other types of surgery, including patient-controlled administration of opioids. The use of multimodal analgesic therapy is emphasized not only for its effectiveness, but to reduce dosages and, therefore, side effects, primarily of the opioids, that could be of legitimate concern to physicians and affect the comfort of their patients.

COX-2 inhibition decreases VEGF expression and alveolar bone loss during the progression of experimental periodontitis in rats

BACKGROUND

Vascular endothelial growth factor (VEGF) is a macromolecule of importance in inflammation that has been implicated in periodontitis. The aims of this study were to investigate VEGF expression during the progression of periodontal disease and to evaluate the effect of a preferential cyclooxygenase (COX)-2 inhibitor meloxicam on VEGF expression and alveolar bone loss in experimentally induced periodontitis.

METHODS

A total of 120 Wistar rats were randomly separated into groups 1 (control) and 2 (meloxicam, 3 mg/kg/day, intraperitoneally, for 3, 7, 14, or 30 days). Silk ligatures were placed at the gingival margin level of the lower right first molar of all rats. VEGF expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR), Western blot (WB), and immunohistochemical (IHC) analyses. The hemiarcades were processed for histopathologic analysis. RT-PCR and WB results were submitted to analysis of variance, the Tukey test, and Pearson correlation analysis (P <0.05).

RESULTS

A reduction in alveolar bone resorption was observed in the meloxicam-treated group compared to the control group at all periods studied. There was a positive correlation between COX-2 mRNA and VEGF mRNA in the gingival tissues and periodontal disease (R = 0.80; P = 0.026). Meloxicam significantly reduced the increased mRNA VEGF expression in diseased tissues after 14 days of treatment (P = 0.023). Some alterations in VEGF receptor 1 mRNA expression were observed, but these were not statistically significant. VEGF protein expression in WB experiments was significantly higher in diseased sites compared to healthy sites (P <0.05). After 14 days of treatment with meloxicam, an important decrease in VEGF protein expression was detected in diseased tissues (P = 0.08). Qualitative IHC analysis revealed that VEGF protein expression was higher in diseased tissues and decreased in tissues from rats treated with meloxicam.

CONCLUSIONS

The present data suggest an important role for VEGF in the progression of periodontal disease. Systemic therapy with meloxicam can modify the progression of experimentally induced periodontitis in rats by reducing VEGF expression and alveolar bone loss.

Acetaminophen, phenacetin and dipyrone do not modulate pressor responses to arachidonic Acid or to pressor agents

In contrast to nonsteroidal anti-inflammatory drugs (NSAIDs), the nonopioid analgesics phenacetin, acetaminophen and dipyrone exhibit weak anti-inflammatory properties. An explanation for this difference in pharmacologic activity was provided by the recent discovery of a new cyclooxygenase isoform, cyclooxygenase (COX)-3, that is reported to be inhibited by phenacetin, acetaminophen and dipyrone. However, COX-3 was found to be a spliced variant of COX-1 and renamed COX-1b. Although recent studies provide evidence for the existence of this new COX isoform, it is uncertain whether this COX-3 (COX-1b) isoform, or putative acetaminophen-sensitive pathway, plays a role in the generation of vasoactive prostaglandins. NSAIDs increase systemic blood pressure by inhibiting the formation of vasodilator prostanoids. Angiotensin II, norepinephrine and other vasoconstrictor agents have been reported to release prostaglandins. It is possible that this acetaminophen-sensitive pathway also modulates pressor responses to these vasoconstrictor agents. Therefore, the purpose of the present study was to determine whether this acetaminophen-sensitive pathway plays a role in the generation of vasoactive products of arachidonic acid or in the modulation of vasoconstrictor responses in the pulmonary and systemic vascular bed of the intact-chest rat. In the present study, the nonopioid analgesics did not attenuate changes in pulmonary or systemic arterial pressure in response to injections of the prostanoid precursor, arachidonic acid, to the thromboxane A(2) mimic, U46619, or to angiotensin II or norepinephrine. The results of the present study do not provide evidence in support of a role of a functional COX-3 (COX-1b) isoform, or an acetaminophen-sensitive pathway, in the generation of vasoactive prostanoids or in the modulation of responses to vasoconstrictor hormones in the intact-chest rat.

Simultaneous determination of ZLR-8 and its active metabolite diclofenac in dog plasma by high-performance liquid chromatography

ZLR-8 is a nitric oxide releasing derivative of diclofenac for the treatment of inflammation. In this paper, a sensitive and reliable high-performance liquid chromatography method for simultaneous determination of ZLR-8 and its active metabolite diclofenac in the plasma of beagle dogs has been developed and validated. After the addition of ketoprofen as the internal standard (IS), plasma samples were extracted with n-hexane-isopropanol (95:5, v/v) mixture solution and separated by HPLC on a reversed-phase C(18) column with a mobile phase of gradient procedure. Analytes were determined by the UV detector which was set at 280 nm. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of ZLR-8 and diclofenac were linear over the range 0.05-4.0 microg/mL. The within- and between-batch precisions (RSD%) were lower than 10% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.05 microg/mL. The proposed method has been readily implemented in preclinical pharmacokinetics studies of ZLR-8 and its active metabolite diclofeance. Representative plasma concentration vs time profiles resulting from administration of ZLR-8 to beagle dogs are presented in this communication.

An ELISA method to measure inhibition of the COX enzymes

The cyclooxygenase (COX) reaction can be monitored by measurement of oxygen consumption, peroxidase co-substrate oxidation or prostaglandin (PG) detection. This protocol describes a procedure measuring cyclooxygenase activity by quantifying PGE2 produced by enzymatic conversion of arachidonic acid, in the presence or absence of potential inhibitors. This high-throughput method has the advantage that it directly measures cyclooxygenase activity and requires little enzyme. The first part of the assay consists of incubating arachidonic acid, cyclooxygenase and the test samples to generate prostaglandins. The second part uses an ELISA method to quantify the amount of PGE2 produced by the enzymatic reaction. The isolation of COX-1 and COX-2 enzymes is also described. This protocol can be completed in approximately 23 h, including 16-h and 4-h incubation phases. This does not include enzyme preparation (3 h for COX-1 and 24 h for COX-2) or preparation of ELISA plates (23 h, including incubation).

Role of rat liver cytochrome P450 3A and 2D in metabolism of imrecoxib

AIM

To investigate the in vitro metabolism of imrecoxib in rat liver microsomes and to identify the cytochrome P450 (CYP) forms involved in its metabolism.

METHODS

Liver microsomes of Wistar rats were prepared using an ultracentrifuge. The in vitro metabolism of imrecoxib was studied by incubation with rat liver microsomes. To characterize the CYP forms involved in the 4 '-methyl hydroxylation of imrecoxib, the effects of typical CYP inducers (such as dexamethasone, isoniazid and beta-naphthoflavone) and of CYP inhibitors (such as ketoconazole, quinine, alpha-naphthoflavone, methylpyrazole, and cimetidine) on the formation rate of 4 '-hydroxymethyl imrecoxib were investigated.

RESULTS

Imrecoxib was metabolized to 3 metabolites by rat liver microsomes: 4'-hydroxymethyl imrecoxib (M4), 4'-hydroxymethyl-5-hydoxyl imrecoxib (M3), and 4 '-hydroxymethyl-5-carbonyl imrecoxib (M5). Over the imrecoxib concentration range studied (5-600 micromol/L), the rate of 4'-methyl hydroxylation conformed to monophasic Michaelis-Menten kinetics. Dexamethasone significantly induced the formation of M4. Ketoconazole markedly lowered the metabolic rate of imrecoxib in a concentration-dependent manner. Moreover, a significant inhibitory effect of quinine on the formation of M4 was observed in microsomes obtained from control rats, isoniazid-induced rats, and b-naphthoflavone-induced rats. In contrast, a-naphthoflavone, cimetidine, and methylpyrazole had no inhibitory effects on this metabolic pathway.

CONCLUSION

Imrecoxib is metabolized via 4'-methyl hydroxylation in rat liver microsomes. The reaction is mainly catalyzed by CYP 3A. CYP 2D also played a role in control rats, in isoniazid-induced rats and in beta-naphthoflavone-induced rats.

Clinical implications of cyclo-oxygenase-2 inhibitors for acute dental pain management: benefits and risks

BACKGROUND; Cyclo-oxygenase-2 inhibitors (COX-2i) demonstrate analgesic efficacy for patients who require gastrointestinal safety. The authors discuss the potential benefits and risks of these novel, but expensive, analgesics when used in dentistry.

METHODS

The authors conducted a MEDLINE search focused on the subject headings of common analgesic drugs and COX-2i, using peer-reviewed journals limited to the English language. They selected for review 127 articles that met the criteria. They also tried to identify any randomized controlled trials pertinent to dentistry and indicative of evidence-based medicine. RESULTS. When comparing COX isoforms (COX-1 and COX-2), the authors found that overlapping and mutually exclusively properties coexist. COX-2i originally were developed to minimize interference with the gastroprotective properties of the COX-1 isoform, while selectively preventing prostanoid synthesis expressed solely at sites of bodily trauma or other inflammation. COX-2i were found to provide pain relief equal to or slightly exceeding that offered by many mild narcotics. They may avoid some of the serious side effects that can occur with even short-term use of nonselective nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

The pharmacodynamics of COX-2i reveal an agent that includes analgesic, anti-inflammatory and gastroprotective properties but also allows for an undesirable disruption of the delicate hemodynamic balance.

CLINICAL IMPLICATIONS

Symptomatic and asymptomatic gastroparietic patients who do not have severe cardiovascular, cerebral or renal ischemic disease benefit from use of COX-2i. Long-term use of these agents in medically compromised patients may prove disastrous.

10t,12c-conjugated linoleic acid inhibits lipopolysaccharide-induced cyclooxygenase expression in vitro and in vivo

Previous data demonstrated that conjugated linoleic acid (CLA) reduced eicosanoid release from select organs. We hypothesized that one active CLA isomer was responsible for the reduced prostaglandin release and that the mechanism was through the inhibition of inducible cyclooxygenase-2 (COX-2). Here, we examined the effects of 10t,12c-CLA and 9c,11t-CLA on COX-2 protein/mRNA expression, prostaglandin E(2) (PGE(2)) production, and the mechanism by which CLA affects COX-2 expression and prostaglandin release. The COX-2 protein expression level was inhibited 80% by 10t, 12c-CLA and 26% by 9c,11t-CLA at 100 microM in vitro. PGE(2) production was decreased from 5.39 to 1.12 ng/2 x 10(6) cells by 10t,12c-CLA and from 5.7 to 4.5 ng/2 x 10(6) cells by 9c,11t-CLA at 100 microM. Mice fed 10t,12c-CLA but not 9c,11t-CLA were found to have a 34% decrease in COX-2 protein and a 43% reduction of PGE(2) release in the lung. 10t,12c-CLA reduced COX-2 mRNA expression level by 30% at 100 microM in vitro and by 30% in mouse lung in vivo. Reduced COX-2 mRNA was attributable to an inhibition of the nuclear factor kappaB (NF-kappaB) pathway by 10t,12c-CLA. These data suggested that the inhibition of NF-kappaB was one of the mechanisms for the reduced COX-2 expression and PGE(2) release by 10t,12c-CLA.

Lumiracoxib is effective in the treatment of osteoarthritis of the knee: a prospective randomized 13-week study versus placebo and celecoxib

The objective of this study was to evaluate the efficacy, safety and tolerability of lumiracoxib compared with placebo and celecoxib in patients with osteoarthritis (OA). Following a 3- to 7-day washout period for previous non-steroidal anti-inflammatory drugs, 1,600 patients aged >or=18 years with primary knee OA were randomized to receive lumiracoxib 200 or 400 mg once daily (o.d.), celecoxib 200 mg o.d. or placebo for 13 weeks. Primary efficacy variables were OA pain intensity in the target knee, patient's global assessment of disease activity and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and total scores at week 13. Secondary variables included OA pain intensity in the target knee and physician's and patient's global assessments of disease activity by visit. Exploratory analysis of responder rates using the Outcomes Measures in Rheumatology Clinical Trials-Osteoarthritis Research Society International (OMERACT-OARSI) criteria was performed. Safety and tolerability were assessed. Lumiracoxib was superior to placebo in all primary and secondary variables and was generally similar to celecoxib. There were no statistically significant differences between the two doses of lumiracoxib. All active treatments were significantly more effective than placebo at weeks 2 and 13 in terms of response to treatment assessed using OMERACT-OARSI criteria. The incidence of adverse events was similar across the groups. Lumiracoxib 200 mg o.d. is a well-tolerated and effective treatment option for OA of the knee, providing pain relief and improved functional status with efficacy superior to placebo and similar to celecoxib. Lumiracoxib demonstrated a tolerability profile similar to placebo and celecoxib.

Signal transduction underlying carbachol-induced PGE2 generation and cox-1 mRNA expression of rat brain

In this paper we have determined the different signal pathways involved in M(1) and M(3) muscarinic acetylcholine receptor (mAChR) dependent stimulation of cyclo-oxygenase 1 (cox-1) mRNA gene expression and PGE(2) production on rat cerebral frontal cortex. Carbachol stimulation of M(1) and M(3) mAChR exerts an increase in cox-1 mRNA gene expression without affecting cox-2 mRNA expression and increased PGE(2) generation. Besides, increased phosphoinositide (PI) turnover and stimulation of nitric oxide synthase (NOS) and cyclic GMP (cGMP) production. Inhibitors of phospholipase A(2) (PLA(2)), COX and phospholipase C (PLC), calcium/calmodulin (CaM), NOS and soluble guanylate cyclase prevent the carbachol effect. These results suggest that carbachol-activation of M(1) and M(3) mAChR increased PGE(2) release associated with an increased expression of cox-1 and NO-cGMP production. The mechanism appears to occur directly to PLC stimulation and indirectly to PLA(2) activation. These results may contribute to understand the effects and side effect of non-steroidal anti-inflammatory drugs in patients with cerebral degenerative diseases.

Nabumetone: therapeutic use and safety profile in the management of osteoarthritis and rheumatoid arthritis

Nabumetone is a nonsteroidal anti-inflammatory prodrug, which exerts its pharmacological effects via the metabolite 6-methoxy-2-naphthylacetic acid (6-MNA). Nabumetone itself is non-acidic and, following absorption, it undergoes extensive first-pass metabolism to form the main circulating active metabolite (6-MNA) which is a much more potent inhibitor of preferentially cyclo-oxygenase (COX)-2. The three major metabolic pathways of nabumetone are O-demethylation, reduction of the ketone to an alcohol, and an oxidative cleavage of the side-chain occurs to yield acetic acid derivatives. Essentially no unchanged nabumetone and < 1% of the major 6-MNA metabolite are excreted unchanged in the urine from which 80% of the dose can be recovered and another 10% in faeces. Nabumetone is clinically used mainly for the management of patients with osteoarthritis (OA) or rheumatoid arthritis (RA) to reduce pain and inflammation. The clinical efficacy of nabumetone has also been evaluated in patients with ankylosing spondylitis, soft tissue injuries and juvenile RA. The optimum oral dosage of nabumetone for OA patients is 1 g once daily, which is well tolerated. The therapeutic response is superior to placebo and similar to nonselective COX inhibitors. In RA patients, nabumetone 1 g at bedtime is optimal, but an additional 0.5-1 g can be administered in the morning for patients with persistent symptoms. In RA, nabumetone has shown a comparable clinical efficacy to aspirin (acetylsalicylic acid), diclofenac, piroxicam, ibuprofen and naproxen. Clinical trials and a decade of worldwide safety data and long-term postmarketing surveillance studies show that nabumetone is generally well tolerated. The most frequent adverse effects are those commonly seen with COX inhibitors, which include diarrhoea, dyspepsia, headache, abdominal pain and nausea. In common with other COX inhibitors, nabumetone may increase the risk of GI perforations, ulcerations and bleedings (PUBs). However, several studies show a low incidence of PUBs, and on a par with the numbers reported from studies with COX-2 selective inhibitors and considerably lower than for nonselective COX inhibitors. This has been attributed mainly to the non-acidic chemical properties of nabumetone but also to its COX-1/COX-2 inhibitor profile. Through its metabolite 6-MNA, nabumetone has a dose-related effect on platelet aggregation, but no effect on bleeding time in clinical studies. Furthermore, several short-term studies have shown little to no effect on renal function. Compared with COX-2 selective inhibitors, nabumetone exhibits similar anti-inflammatory and analgesic properties in patients with arthritis and there is no evidence of excess GI or other forms of complications to date.

The effects of modifying in vivo cytochrome P450 3A (CYP3A) activity on etoricoxib pharmacokinetics and of etoricoxib administration on CYP3A activity

To investigate the influence of modifying in vivo cytochrome P450 3A (CYP3A) activity on the pharmacokinetics of etoricoxib, a selective inhibitor of cyclooxygenase-2, and of etoricoxib administration on CYP3A activity, a 3-part, randomized, crossover study was conducted in 3 panels of healthy volunteers. In part I, 8 subjects were administered a single dose of 60 mg etoricoxib alone and following daily doses of 400 mg ketoconazole, a known strong inhibitor of CYP3A. In part II, 8 different subjects were administered a single dose of 60 mg etoricoxib alone and following daily doses of 600 mg rifampin, a known strong inducer of CYP3A. In parts I and II, plasma samples were collected following each etoricoxib dose and analyzed for etoricoxib. In part III, 8 different subjects were administered 120 mg etoricoxib or placebo once daily for 11 days, and the erythromycin breath test was administered on day 11 of each period. Coadministration of etoricoxib with daily doses of ketoconazole resulted in an average 43% increase in etoricoxib AUC; based on previous studies, this increase would not be expected to have any clinically meaningful effect. In contrast, coadministration of etoricoxib with daily doses of rifampin had a potentially clinically important effect on etoricoxib pharmacokinetics (average 65% decrease in etoricoxib AUC). Etoricoxib had no effect on hepatic CYP3A activity, as assessed by the erythromycin breath test.

Valdecoxib: assessment of cyclooxygenase-2 potency and selectivity

The discovery of a second isoform of cyclooxygenase (COX) led to the search for compounds that could selectively inhibit COX-2 in humans while sparing prostaglandin formation from COX-1. Celecoxib and rofecoxib were among the molecules developed from these efforts. We report here the pharmacological properties of a third selective COX-2 inhibitor, valdecoxib, which is the most potent and in vitro selective of the marketed COX-2 inhibitors that we have studied. Recombinant human COX-1 and COX-2 were used to screen for new highly potent and in vitro selective COX-2 inhibitors and compare kinetic mechanisms of binding and enzyme inhibition with other COX inhibitors. Valdecoxib potently inhibits recombinant COX-2, with an IC(50) of 0.005 microM; this compares with IC values of 0.05 microM for celecoxib, 0.5 microM for rofecoxib, and 5 microM for etoricoxib. Unique binding interactions of valdecoxib with COX-2 translate into a fast rate of inactivation of COX-2 (110,000 M/s compared with 7000 M/s for rofecoxib and 80 M/s for etoricoxib). The overall saturation binding affinity for COX-2 of valdecoxib is 2.6 nM (compared with 1.6 nM for celecoxib, 51 nM for rofecoxib, and 260 nM for etoricoxib), with a slow off-rate (t(1/2) approximately 98 min). Valdecoxib inhibits COX-1 in a competitive fashion only at very high concentrations (IC(50) = 150 microM). Collectively, these data provide a mechanistic basis for the potency and in vitro selectivity of valdecoxib for COX-2. Valdecoxib showed similar activity in the human whole-blood COX assay (COX-2 IC(50) = 0.24 microM; COX-1 IC(50) = 21.9 microM). We also determined whether this in vitro potency and selectivity translated to significant potency in vivo. In rats, valdecoxib demonstrated marked potency in acute and chronic models of inflammation (air pouch ED(50) = 0.06 mg/kg; paw edema ED(50) = 5.9 mg/kg; adjuvant arthritis ED(50) = 0.03 mg/kg). In these same animals, COX-1 was spared at doses greater than 200 mg/kg. These data provide a basis for the observed potent anti-inflammatory activity of valdecoxib in humans.

Participation of cyclooxygenase-1 in prostaglandin E2 release from synovitis tissue in primary osteoarthritis in vitro

OBJECTIVES

To investigate the relative contribution of the cyclooxygenase (COX) isoenzymes COX-1 and COX-2 to prostaglandin E2 (PGE2) release from inflamed synovial tissue in N=10 patients with primary osteoarthritis (OA) in vitro and to determine possible effects of COX inhibitors on the gene expression of synovial COX-1 and COX-2.

DESIGN

The effects of a COX-unspecific nonsteroidal anti-inflammatory drug (NSAID; diclofenac), a selective COX-1 inhibitor (SC-560) and a selective COX-2 inhibitor (SC-58125) on PGE2 release from inflamed synovial tissue (0.1-10 microM, 3 and 6 h incubation time) were compared. Release of PGE2 into the incubation media was measured by means of the enzyme-linked immunosorbent assay. Expression of synovial COX-1/-2 was quantified by means of real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

All agents inhibited synovial PGE2 release dose-dependently. Compared to short-term incubations, the inhibitory potency of diclofenac, SC-58125 and SC-560 was increased (0.1-10 microM) and decreased (0.1-1 microM), respectively, during 6 h: At 10 microM, SC-560 and SC-58125 had obviously lost their specificity for COX-1 and COX-2, respectively, indicated by a comparable inhibitory potency of the selective COX-1 inhibitor (86.6%) and the selective COX-2 inhibitor (96.6%) within identical tissue specimens. In contrast, at 1 microM, 83% and 62.8% inhibition was seen for diclofenac and SC-58125, respectively. SC-560 showed 30.6% inhibition (P<0.05). In contrast to synovial COX-1, RT-PCR revealed a significant induction of COX-2 through PGE2.

CONCLUSIONS

With respect to the concentrations studied, the data suggest that in inflamed synovial tissue in OA, up to 30% of PGE2 might be generated via the COX-1 pathway. In therapy of OA, the relative contribution of COX-1 in synovial inflammation should be considered, weighing the potency of COX-unspecific NSAID against the assumed superior gastrointestinal safety profile of selective COX-2 inhibitors.

Pharmacokinetics of etoricoxib in patients with renal impairment

The effect of renal insufficiency on the pharmacokinetics of etoricoxib, a selective inhibitor of cyclooxygenase-2, was examined in 23 patients with varying degrees of renal impairment (12 moderate [creatinine clearance between 30 and 50 mL/min/1.73 m2], 5 severe [creatinine clearance below 30 mL/min/1.73 m2], and 6 with end-stage renal disease requiring hemodialysis) following administration of single 120-mg oral doses of etoricoxib. Even the most severe renal impairment was found to have little effect on etoricoxib pharmacokinetics. The low recovery of etoricoxib in dialysate (less than 6% of the dose) supports that hemodialysis also has little effect on etoricoxib pharmacokinetics, and binding of etoricoxib to plasma proteins was generally unaffected by renal disease. Single doses of etoricoxib were generally well tolerated by patients with renal impairment. Based on pharmacokinetic considerations, dosing adjustments are not necessary for patients with any degree of renal impairment. However, because patients with advanced renal disease (creatinine clearance below 30 mL/min/1.73 m2) are likely to be very sensitive to any further compromise of renal function, and there is no long-term clinical experience in these patients, the use of etoricoxib is not recommended in patients with advanced renal disease.

[Pharmacology and classification of cyclooxygenase inhibitors]

The discovery of at least two cyclooxygenase (COX) isoenzymes had two major consequences: i) to give a new impetus to the research on lipid metabolism, giving rise to the crystallization of these peculiar membrane enzymes, the characterization of their active sites and their gene regulation, and the identification of new metabolic pathways; ii) the development of new NSAIDs aimed to have an improved safety profile, the coxibs. These drugs are defined by their COX-2 selectivity which is supported by a negligible inhibitory potency on platelet COX-1 in vitro and ex vivo after oral intake of maximal therapeutic doses. However, the coxibs marketed in France (celecoxib, rofecoxib, parecoxib) are not equivalent in terms of selectivity and some drugs developed by pharmaceutical companies (etoricoxib, lumiracoxib) will be even more selective for COX-2. These "new" coxibs are the final step in the theory of COX-2 selectivity and they will probably be helpful to better define the limitations of the therapeutic concept based on a selective inhibition of this iso-enzyme.