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

[Medicinal chemistry and pharmacology focused on cannabidiol, a major component of the fiber-type cannabis]

Considerable attention has focused on cannabidiol (CBD), a major non-psychotropic constituent of fiber-type cannabis plant, and it has been reported to possess diverse biological activities. Although CBD is obtained from non-enzymatic decarboxylation of its parent molecule, cannabidiolic acid (CBDA), several studies have investigated whether CBDA itself is biologically active. In the present report, the author summarizes findings indicating that; 1) CBDA is a selective cyclooxygenase-2 (COX-2) inhibitor, and ii) CBDA possesses an anti-migrative potential for highly invasive cancer cells, apparently through a mechanism involving inhibition of cAMP-dependent protein kinase A, coupled with an activation of the small GTPase, RhoA. Further, the author introduces recent findings on the medicinal chemistry and pharmacology of the CBD derivative, CBD-2',6'-dimethyl ether (CBDD), that exhibits inhibitory activity toward 15-lipoxygenase (15-LOX), an enzyme responsible for the production of oxidized low-density lipoprotein (LDL). These studies establish CBD as both an important experimental tool and as a lead compound for pharmaceutical development. In this review, the author further discusses the potential uses of CBD and its derivatives in future medicines.

Intravenous ibuprofen for postoperative pain

SUMMARY A multimodal analgesic approach involving intravenous NSAIDs in the perioperative setting has been common practice for many years outside of the USA. As an adjunct to the central analgesic effects of opioids, intravenous NSAIDs may be important for perioperative pain management due to their analgesic and peripheral anti-inflammatory effects. Together, these agents may attenuate the pain resulting from the surgical procedure better than either agent used singly. Prior to 2009, ketorolac was the only intravenous NSAID approved in the USA for the treatment of pain. However, in June 2009, intravenous ibuprofen (Caldolor(®)) was approved by the US FDA for the treatment of mild-to-moderate pain as a single agent and moderate-to-severe pain as an adjunct to opioids. A growing body of research has demonstrated the efficacy and safety of intravenous ibuprofen in the perioperative setting and is reviewed herein.

The bitter barricading of prostaglandin biosynthesis pathway: understanding the molecular mechanism of selective cyclooxygenase-2 inhibition by amarogentin, a secoiridoid glycoside from Swertia chirayita

Swertia chirayita, a medicinal herb inhabiting the challenging terrains and high altitudes of the Himalayas, is a rich source of essential phytochemical isolates. Amarogentin, a bitter secoiridoid glycoside from S. chirayita, shows varied activity in several patho-physiological conditions, predominantly in leishmaniasis and carcinogenesis. Experimental analysis has revealed that amarogentin downregulates the cyclooxygenase-2 (COX-2) activity and helps to curtail skin carcinogenesis in mouse models; however, there exists no account on selective inhibition of the inducible cyclooxygenase (COX) isoform by amarogentin. Hence the computer-aided drug discovery methods were used to unravel the COX-2 inhibitory mechanism of amarogentin and to check its selectivity for the inducible isoform over the constitutive one. The generated theoretical models of both isoforms were subjected to molecular docking analysis with amarogentin and twenty-one other Food and Drug Authority (FDA) approved lead molecules. The post-docking binding energy profile of amarogentin was comparable to the binding energy profiles of the FDA approved selective COX-2 inhibitors. Subsequent molecular dynamics simulation analysis delineated the difference in the stability of both complexes, with amarogentin-COX-2 complex being more stable after 40ns simulation. The total binding free energy calculated by MMGBSA for the amarogentin-COX-2 complex was −52.35 KCal/mol against a binding free energy of −8.57 KCal/mol for amarogentin-COX-1 complex, suggesting a possible selective inhibition of the COX-2 protein by the natural inhibitor. Amarogentin achieves this potential selectivity by small, yet significant, structural differences inherent to the binding cavities of the two isoforms. Hypothetically, it might block the entry of the natural substrates in the hydrophobic binding channel of the COX-2, inhibiting the cyclooxygenation step. To sum up briefly, this work highlights the mechanism of the possible selective COX-2 inhibition by amarogentin and endorses the possibility of obtaining efficient, futuristic and targeted therapeutic agents for relieving inflammation and malignancy from this phytochemical source.

Design, synthesis and structure-activity relationship studies of novel and diverse cyclooxygenase-2 inhibitors as anti-inflammatory drugs

Because of the pivotal role of cyclooxygenase (COX) in the inflammatory processes, non-steroidal anti-inflammatory drugs (NSAIDs) that suppress COX activities have been used clinically for the treatment of inflammatory diseases/syndromes; however, traditional NSAIDs exhibit serious side-effects such as gastrointestinal damage and hyper sensitivity owing to their COX-1 inhibition. Also, COX-2 inhibition-derived suppressive or preventive effects against initiation/proliferation/invasion/motility/recurrence/metastasis of various cancers/tumours such as colon, gastric, skin, lung, liver, pancreas, breast, prostate, cervical and ovarian cancers are significant. In this study, design, synthesis and structure-activity relationship (SAR) of various novel {2-[(2-, 3- and/or 4-substituted)-benzoyl, (bicyclic heterocycloalkanophenyl)carbonyl or cycloalkanecarbonyl]-(5- or 6-substituted)-1H-indol-3-yl}acetic acid analogues were investigated to seek and identify various chemotypes of potent and selective COX-2 inhibitors for the treatment of inflammatory diseases, resulting in the discovery of orally potent agents in the peripheral-inflammation model rats. The SARs and physicochemical properties for the analogues are described as significant findings. For graphical abstract: see Supplementary Material. ( www.informahealthcare.com/enz ).

Aspirin, cyclooxygenase inhibition and colorectal cancer

Colorectal cancer (CRC) is the third most common type of cancer worldwide. Screening measures are far from adequate and not widely available in resource-poor settings. Primary prevention strategies therefore remain necessary to reduce the risk of developing CRC. Increasing evidence from epidemiological studies, randomized clinical trials and basic science supports the effectiveness of aspirin, as well as other non-steroidal anti-inflammatory drugs, for chemoprevention of several types of cancer, including CRC. This includes the prevention of adenoma recurrence and reduction of CRC incidence and mortality. The detectable benefit of daily low-dose aspirin (at least 75 mg), as used to prevent cardiovascular disease events, strongly suggests that its antiplatelet action is central to explaining its antitumor efficacy. Daily low-dose aspirin achieves complete and persistent inhibition of cyclooxygenase (COX)-1 in platelets (in pre-systemic circulation) while causing a limited and rapidly reversible inhibitory effect on COX-2 and/or COX-1 expressed in nucleated cells. Aspirin has a short half-life in human circulation (about 20 minutes); nucleated cells have the ability to resynthesize acetylated COX isozymes within a few hours, while platelets do not. COX-independent mechanisms of aspirin have been suggested to explain its chemopreventive effects but this concept remains to be demonstrated in vivo at clinical doses.

Acetylsalicylic acid enhances tachyphylaxis of repetitive capsaicin responses in TRPV1-GFP expressing HEK293 cells

Since many years acetylsalicylic acid (ASA) is known for its antithrombotic, antiphlogistic and analgesic effects caused by irreversible acetylation of cyclooxygenase. ASA also inhibits capsaicin- and heat-induced responses in cultured dorsal root ganglia (DRG) neurons, suggesting TRPV1 (transient receptor potential channel of the vanilloid receptor family, subtype 1) to be an additional target of ASA. We now studied the effect of ASA on heterologously expressed rat TRPV1 using calcium microfluorimetry. Capsaicin dose-dependently increased intracellular calcium with an EC50 of 0.29 μM in rTRPV1 expressing HEK293 cells. During repetitive stimulation the second response to capsaicin was reduced (53.4 ± 8.3% compared to vehicle control; p<0.005; Student's unpaired t-test) by 1μM ASA, a concentration much below the one needed to inhibit cyclooxygenase (IC50 of 35 μM in thromboxane B2 production assay). In contrast, calcium transients induced by a single stimulus of 0.3 or 1 μM capsaicin were not significantly reduced by 0.3 or 1 μM ASA. These data suggest that ASA increases the tachyphylaxis of rTRPV1 channel activation. Mechanisms are unknown and may be direct by e.g. stabilization of the desensitized state or indirect via inhibition of intracellular signaling pathways e.g. of the mitogen-activated protein kinase family (MAPK/ERK).

Design and optimization of PLGA-based diclofenac loaded nanoparticles

Drug based nanoparticle (NP) formulations have gained considerable attention over the past decade for their use in various drug formulations. NPs have been shown to increase bioavailability, decrease side effects of highly toxic drugs, and prolong drug release. Nonsteroidal anti-inflammatory drugs such as diclofenac block cyclooxygenase expression and reduce prostaglandin synthesis, which can lead to several side effects such as gastrointestinal bleeding and renal insufficiency. The aim of this study was to formulate and characterize diclofenac entrapped poly(lactide-co-glycolide) (PLGA) based nanoparticles. Nanoparticles were formulated using an emulsion-diffusion-evaporation technique with varying concentrations of poly vinyl alcohol (PVA) (0.1, 0.25, 0.5, or 1%) or didodecyldimethylammonium bromide (DMAB) (0.1, 0.25, 0.5, 0.75, or 1%) stabilizers centrifuged at 8,800 rpm or 12,000 rpm. The resultant nanoparticles were evaluated based on particle size, zeta potential, and entrapment efficacy. DMAB formulated NPs showed the lowest particle size (108±2.1 nm) and highest zeta potential (−27.71±0.6 mV) at 0.1 and 0.25% respectively, after centrifugation at 12,000 rpm. Results of the PVA based NP formulation showed the smallest particle size (92.4±7.6 nm) and highest zeta potential (−11.14±0.5 mV) at 0.25% and 1% w/v, respectively, after centrifugation at 12,000 rpm. Drug entrapment reached 77.3±3.5% and 80.2±1.2% efficiency with DMAB and PVA formulations, respectively. The results of our study indicate the use of DMAB for increased nanoparticle stability during formulation. Our study supports the effective utilization of PLGA based nanoparticle formulation for diclofenac.

Valdecoxib for the management of chronic and acute pain

Cyclooxygenase-2 specific inhibitors have anti-inflammatory and analgesic properties, and are effective in managing a wide range of chronic and acute painful conditions such as adult rheumatoid arthritis, osteoarthritis, migraine, primary dysmenorrhea and postoperative pain. Valdecoxib, an orally administered cyclooxygenase-2 specific inhibitor, provides effective pain relief for both chronic and acute conditions, and reduces postoperative opioid use, with a concomitant reduction in opioid-related adverse events. Valdecoxib also has superior gastrointestinal safety compared with nonspecific nonsteroidal anti-inflammatory drugs, and at therapeutic doses, it is generally safe and well tolerated in terms of renal and cardiovascular events. This drug profile reviews the efficacy, safety and tolerability of valdecoxib for the management of chronic and acute pain.

The Concise Guide to PHARMACOLOGY 2013/14: enzymes

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Enzymes are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, nuclear hormone receptors, catalytic receptors and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.

Impact of hematopoietic cyclooxygenase-1 deficiency on obesity-linked adipose tissue inflammation and metabolic disorders in mice

OBJECTIVE

Adipose tissue (AT)-specific inflammation is considered to mediate the pathological consequences of obesity and macrophages are known to activate inflammatory pathways in obese AT. Because cyclooxygenases play a central role in regulating the inflammatory processes, we sought to determine the role of hematopoietic cyclooxygenase-1 (COX-1) in modulating AT inflammation in obesity.

MATERIALS/METHODS

Bone marrow transplantation was performed to delete COX-1 in hematopoietic cells. Briefly, female wild type (wt) mice were lethally irradiated and injected with bone marrow (BM) cells collected from wild type (COX-1+/+) or COX-1 knock-out (COX-1-/-) donor mice. The mice were fed a high fat diet for 16 weeks.

RESULTS

The mice that received COX-1-/- bone marrow (BM-COX-1-/-) exhibited a significant increase in fasting glucose, total cholesterol and triglycerides in the circulation compared to control (BM-COX-1+/+) mice. Markers of AT-inflammation were increased and were associated with increased leptin and decreased adiponectin in plasma. Hepatic inflammation was reduced with a concomitant reduction in TXB2 levels. The hepatic mRNA expression of genes involved in lipogenesis and lipid transport was increased while expression of genes involved in regulating hepatic glucose output was reduced in BM-COX-1-/- mice. Finally, renal inflammation and markers of renal glucose release were increased in BM-COX-1-/- mice.

CONCLUSION

Hematopoietic COX-1 deletion results in impairments in metabolic homeostasis which may be partly due to increased AT inflammation and dysregulated adipokine profile. An increase in renal glucose release and hepatic lipogenesis/lipid transport may also play a role, at least in part, in mediating hyperglycemia and dyslipidemia, respectively.

The COX-2 selective blocker etodolac inhibits TNFα-induced apoptosis in isolated rabbit articular chondrocytes

Chondrocyte apoptosis contributes to the disruption of cartilage integrity in osteoarthritis (OA). Recently, we reported that activation of volume-sensitive Cl⁻ current (I_Cl,vol) mediates cell shrinkage, triggering apoptosis in rabbit articular chondrocytes. A cyclooxygenase (COX) blocker is frequently used for the treatment of OA. In the present study, we examined in vitro effects of selective blockers of COX on the TNFα-induced activation of I_Cl,vol in rabbit chondrocytes using the patch-clamp technique. Exposure of isolated chondrocytes to TNFα resulted in an obvious increase in membrane Cl⁻ conductance. The TNFα-evoked Cl⁻ current exhibited electrophysiological and pharmacological properties similar to those of I_Cl,vol. Pretreatment of cells with selective COX-2 blocker etodolac markedly inhibited I_Cl,vol activation by TNFα as well as subsequent apoptotic events such as apoptotic cell volume decrease (AVD) and elevation of caspase-3/7 activity. In contrast, a COX-1 blocker had no effect on the decrease in cell volume or the increase in caspase-3/7 activity induced by TNFα. Thus, the COX-2-selective blocker had an inhibitory effect on TNFα-induced apoptotic events, which suggests that this drug would have efficacy for the treatment of OA.

Exploring the molecular determinants of substrate-selective inhibition of cyclooxygenase-2 by lumiracoxib

Lumiracoxib is a substrate-selective inhibitor of endocannabinoid oxygenation by cyclooxygenase-2 (COX-2). We assayed a series of lumiracoxib derivatives to identify the structural determinants of substrate-selective inhibition. The hydrogen-bonding potential of the substituents at the ortho positions of the aniline ring dictated the potency and substrate selectivity of the inhibitors. The presence of a 5'-methyl group on the phenylacetic acid ring increased the potency of molecules with a single ortho substituent. Des-fluorolumiracoxib (2) was the most potent and selective inhibitor of endocannabinoid oxygenation. The positioning of critical substituents in the binding site was identified from a 2.35Å crystal structure of lumiracoxib bound to COX-2.

Mechanisms of action of non-steroidal anti-inflammatory drugs (NSAIDs) and mesalazine in the chemoprevention of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. Although conclusive evidence is still lacking, epidemiologic studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has chemopreventive properties against CRC. Similarly, regular consumption of mesalazine, a drug structurally related to NSAIDs, seems to reduce the risk of CRC in patients with ulcerative colitis. These observations are supported by a large body of experimental data showing the ability of such drugs to inhibit multiple pathways that sustain colon carcinogenesis. This review summarizes the current information on the molecular mechanisms by which NSAIDs and mesalazine could interfere with CRC cell growth and survival.

Mechanisms of action of non-steroidal anti-inflammatory drugs (NSAIDs) and mesalazine in the chemoprevention of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. Although conclusive evidence is still lacking, epidemiologic studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has chemopreventive properties against CRC. Similarly, regular consumption of mesalazine, a drug structurally related to NSAIDs, seems to reduce the risk of CRC in patients with ulcerative colitis. These observations are supported by a large body of experimental data showing the ability of such drugs to inhibit multiple pathways that sustain colon carcinogenesis. This review summarizes the current information on the molecular mechanisms by which NSAIDs and mesalazine could interfere with CRC cell growth and survival.

Prevention of upper gastrointestinal haemorrhage: current controversies and clinical guidance

Acute upper gastrointestinal (GI) bleeding is a common medical emergency and associated with significant morbidly and mortality. The risk of bleeding from peptic ulceration and oesophagogastric varices can be reduced by appropriate primary and secondary preventative strategies. Helicobacter pylori eradication and risk stratification with appropriate gastroprotection strategies when used with antiplatelet drugs and nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in preventing peptic ulcer bleeding, whilst endoscopic screening and either nonselective beta blockade or endoscopic variceal ligation are effective at reducing the risk of variceal haemorrhage. For secondary prevention of variceal haemorrhage, the combination of beta blockade and endoscopic variceal ligation is more effective. Recent data on the possible interactions of aspirin and NSAIDs, clopidogrel and proton pump inhibitors (PPIs), and the increased risk of cardiovascular adverse events associated with all nonaspirin cyclo-oxygenase (COX) inhibitors have increased the complexity of choices for preventing peptic ulcer bleeding. Such choices should consider both the GI and cardiovascular risk profiles. In patients with a moderately increased risk of GI bleeding, a NSAID plus a PPI or a COX-2 selective agent alone appear equivalent but for those at highest risk of bleeding (especially those with previous ulcer or haemorrhage) the COX-2 inhibitor plus PPI combination is superior. However naproxen seems the safest NSAID for those at increased cardiovascular risk. Clopidogrel is associated with a significant risk of GI haemorrhage and the most recent data concerning the potential clinical interaction of clopidogrel and PPIs are reassuring. In clopidogrel-treated patients at highest risk of GI bleeding, some form of GI prevention is indicated.

Photoelectron spectroscopy of non-steroidal anti-inflammatory drugs

The electronic structures of eight non-steroidal anti-inflammatory drugs (NSAIDs) had been studied by UV photoelectron spectroscopy (UPS) and high-level Green's function (GF) calculations. Our UPS data show that the electronic structure influences the measured biological activity of NSAID, but that it is not the dominating factor. The role of electronic structure needs to be considered in conjunction with other factors like steric properties of the COX active site and orientation of relevant residues in the same site.

NSAID therapy effects on healing of bone, tendon, and the enthesis

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for the treatment of skeletal injuries. The ability of NSAIDs to reduce pain and inflammation is well-established. However, the effects of NSAID therapy on healing of skeletal injuries is less defined. NSAIDs inhibit cyclooxygenase activity to reduce synthesis of prostaglandins, which are proinflammatory, lipid-signaling molecules. Inhibition of cyclooxygenase activity can impact many physiological processes. The effects of NSAID therapy on healing of bone, tendon, and the tendon-to-bone junction (enthesis) have been studied in animal and cell culture models, but human studies are few. Use of different NSAIDs with different pharmacological properties, differences in dosing regimens, and differences in study models and outcome measures have complicated comparisons between studies. In this review, we summarize the mechanisms by which bone, tendon, and enthesis healing occurs, and describe the effects of NSAID therapy on each of these processes. Determining the impact of NSAID therapy on healing of skeletal tissues will enable clinicians to appropriately manage the patient's condition and improve healing outcomes.

Are there any differences among non-steroidal anti-inflammatory drugs? Focus on nimesulide

Although the efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) as anti-inflammatory, analgesic and antipyretic agents is well established, there is still an open question as to whether their different pharmacokinetic and pharmacodynamic characteristics do have a different clinical impact in treating rheumatology patients. The mechanism related to the anti-inflammatory activity of these drugs is mainly related to the inhibition of the cyclo-oxygenase (COX)-2 isoform, whereas inhibition of COX-1 is associated with the side effects of these drugs. However, some NSAIDs exert their anti-inflammatory and analgesic action by additional mechanisms. The NSAID nimesulide, along with its preferential activity on COX-2 and a short half-life that correlates with a rapid onset of analgesic action, acts also through a variety of COX-independent pathways that contributes to its potent antiinflammatory and analgesic activity. The pathways affected by nimesulide include inhibition of tumour necrosis factor alpha (TNF-α) release, histamine release, reactive oxygen species production and chondrocyte death. Furthermore, the use of nimesulide has been associated with reduced levels of matrix metalloproteases and other biomarkers of joint destruction, suggesting it may have a protective effect against disease progression. Due to its multifactorial mechanism as well as to rapid onset of the analgesic action, nimesulide represents an appealing therapeutic choice for the treatment of rheumatology patients.

LC-MS/MS confirms that COX-1 drives vascular prostacyclin whilst gene expression pattern reveals non-vascular sites of COX-2 expression

There are two schools of thought regarding the cyclooxygenase (COX) isoform active in the vasculature. Using urinary prostacyclin markers some groups have proposed that vascular COX-2 drives prostacyclin release. In contrast, we and others have found that COX-1, not COX-2, is responsible for vascular prostacyclin production. Our experiments have relied on immunoassays to detect the prostacyclin breakdown product, 6-keto-PGF_1α and antibodies to detect COX-2 protein. Whilst these are standard approaches, used by many laboratories, antibody-based techniques are inherently indirect and have been criticized as limiting the conclusions that can be drawn. To address this question, we measured production of prostanoids, including 6-keto-PGF_1α, by isolated vessels and in the circulation in vivo using liquid chromatography tandem mass spectrometry and found values essentially identical to those obtained by immunoassay. In addition, we determined expression from the Cox2 gene using a knockin reporter mouse in which luciferase activity reflects Cox2 gene expression. Using this we confirm the aorta to be essentially devoid of Cox2 driven expression. In contrast, thymus, renal medulla, and regions of the brain and gut expressed substantial levels of luciferase activity, which correlated well with COX-2-dependent prostanoid production. These data are consistent with the conclusion that COX-1 drives vascular prostacyclin release and puts the sparse expression of Cox2 in the vasculature in the context of the rest of the body. In doing so, we have identified the thymus, gut, brain and other tissues as target organs for consideration in developing a new understanding of how COX-2 protects the cardiovascular system.

Calcitonin delays the progress of early-stage mechanically induced osteoarthritis. In vivo, prospective study

BACKGROUND/RATIONALE

Introducing new or testing existing drugs in an attempt to modify the progress of osteoarthritis (OA) is of paramount importance.

QUESTIONS/PURPOSES

This study aims to determine the effect exerted by Calcitonin on the progress of early-stage osteoarthritic lesions.

METHODS

We used 18, skeletally mature, white, female, New Zealand rabbits. OA was operatively induced in the right knee of each animal by the complete dissection of the anterior cruciate ligament, complete medial meniscectomy and partial dissection of the medial collateral ligament. Postoperatively, animals were divided into two groups. Starting on the ninth postoperative day and daily thereafter, group A animals (n = 9) received 10 IU oculus dexter (o.d.) of synthetic Calcitonin IntraMuscularly (I.M.); group B animals (n = 9) received equal volume of saline o.d. Three animals from each group were sacrificed at 1, 2 and 3 months following treatment's initiation. The extent and the grade of OA were assessed macroscopically, histologically and by radiographs, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)-scans. The Osteoarthritis Research Society International (OARSI) score, incorporating histological and macroscopic information, was calculated for each knee.

RESULTS

Osteoarthritic changes in group A animals were less severe and progressed less rapidly when compared with those of group B animals (sham). This difference was statistically significant in the first and second month (P = 0.05), but not in the third month (P = 0.513).

CONCLUSIONS

I.M. administration of Calcitonin seems to delay the progress of early-stage osteoarthritic lesions induced by mechanical instability in a rabbit experimental model.

Aspirin-triggered 15-epi-lipoxin A4 predicts cyclooxygenase-2 in the lungs of LPS-treated mice but not in the circulation: implications for a clinical test

Inhibition of cyclooxygenase (COX)-2 increases cardiovascular deaths. Identifying a biomarker of COX-2 is desirable but difficult, since COX-1 and COX-2 ordinarily catalyze formation of an identical product, prostaglandin H₂. When acetylated by aspirin, however, COX-2 (but not COX-1) can form 15(R)-HETE, which is metabolized to aspirin-triggered lipoxin (ATL), 15-epi-lipoxin A₄. Here we have used COX-1- and COX-2-knockout mice to establish whether plasma ATL could be used as a biomarker of vascular COX-2 in vivo. Vascular COX-2 was low but increased by LPS (10 mg/kg; i.p). Aspirin (10 mg/kg; i.v.) inhibited COX-1, measured as blood thromboxane and COX-2, measured as lung PGE₂. Aspirin also increased the levels of ATL in the lungs of LPS-treated wild-type C57Bl6 mice (vehicle: 25.5±9.3 ng/ml; 100 mg/kg: 112.0±7.4 ng/ml; P<0.05). Despite this, ATL was unchanged in plasma after LPS and aspirin. This was true in wild-type as well as COX-1^−/− and COX-2^−/− mice. Thus, in mice in which COX-2 has been induced by LPS treatment, aspirin triggers detectable 15-epi-lipoxin A₄ in lung tissue, but not in plasma. This important study is the first to demonstrate that while ATL can be measured in tissue, plasma ATL is not a biomarker of vascular COX-2 expression.—Kirkby, N. S., Chan, M. V., Lundberg, M. H., Massey, K. A., Edmands, W. M. B., MacKenzie, L. S., Holmes, E., Nicolaou, A., Warner, T. D., Mitchell, J. A. Aspirin-triggered 15-epi-lipoxin A₄ predicts cyclooxygenase-2 in the lungs of LPS-treated mice but not in the circulation: implications for a clinical test.

Radiolabeled COX-2 inhibitors for non-invasive visualization of COX-2 expression and activity--a critical update

Cyclooxygenase-2 (COX-2) is a key player in inflammation. Its overexpression is directly associated with various inflammatory diseases and, additionally, with several processes of carcinogenesis. The development of new selective COX-2 inhibitors (COXIBs) for use in cancer treatment is in the focus of the medicinal chemistry research field. For this purpose, a set of methods is available to determine COX-2 expression and activity in vitro and ex vivo but it is still a problem to functionally characterize COX-2 in vivo. This review focusses on imaging agents targeting COX-2 which have been developed for positron emission tomography (PET) and single photon emission computed tomography (SPECT) since 2005. The literature reveals that different radiochemical methods are available to synthesize COXIBs radiolabeled with fluorine-18, carbon-11, and isotopes of radioiodine. Unfortunately, most of the compounds tested did not show sufficient stability in vivo due to de[¹⁸F]fluorination or de[¹¹C]methylation or they failed to bind specifically in the target region. So, suitable stability in vivo, matching lipophilicity for the target compartment and both high affinity and selectivity for COX-2 were identified as prominent criteria for radiotracer development. Up to now, it is not clear what approach and which model is the most suited to evaluate COX-2 targeting imaging agents in vivo. However, for proof of principle it has been shown that some radiolabeled compounds can bind specifically in COX-2 overexpressing tissue which gives hope for future work in this field.

Pharmacodynamics, Chiral Pharmacokinetics, and Pharmacokinetic-Pharmacodynamic Modeling of Fenoprofen in Patients With Diabetes Mellitus

The objective of the present study was to assess the influence of type 1 and type 2 diabetes mellitus on the enantioselective pharmacodynamics and pharmacokinetics of fenoprofen. Patients with diabetes mellitus type 1 (n = 7) or type 2 (n = 7) and healthy volunteers (n = 13) received orally a single 600-mg dose of racemic fenoprofen. Monocompartmental analysis of (+)-(S)-fenoprofen showed a significant difference (P < .05, Kruskal-Wallis test) in area under the curve (AUC) values (153.68 vs 243.50 microg x h/mL) and oral clearance (1.95 vs 1.23 L/h) only between patients with diabetes mellitus type 2 and healthy volunteers. The inhibitory activity of cyclooxygenases was evaluated indirectly by the determination of prostaglandin E2 (COX-2) and thromboxane B2 (COX-1) using the sigmoidal inhibitory Emax model. The patients with type 2 diabetes mellitus presented lower IC50 (3.29 vs 6.0 microg/mL) and g (0.73 vs 2.01) values for COX-1 activity compared to healthy volunteers (P < .05, Kruskal-Wallis test). These results show that diabetes mellitus type 2, but not type 1, influences the pharmacokinetics and pharmacodynamics of (+)-(S)-fenoprofen.

Concomitant Administration of Lumiracoxib and a Triphasic Oral Contraceptive Does Not Affect Contraceptive Activity or Pharmacokinetic Profile

This study evaluated the effect of lumiracoxib on the pharmacokinetics and pharmacodynamics of ethinyl estradiol (EE) and levonorgestrel (LN) in Triphasil-28 (a triphasic oral contraceptive). Females stabilized on Triphasil-28 continued on Triphasil-28 alone for another month (Treatment Period 1), then also received lumiracoxib (400 mg daily) or placebo for 28 days each (Periods 2 and 3) in a double-blind crossover design. Plasma pharmacokinetic profiles were assessed on Day 21 of Periods 2 and 3. Progesterone and plasma sex hormone binding globulin (SHBG) concentrations were measured before and 2 hours after Triphasil-28 administration on Day 21 of all three treatment periods. Lumiracoxib had no significant effect on EE or LN pharmacokinetics or on progesterone or SHBG concentrations, indicating that anovulation and Triphasil-28 effectiveness was maintained. Adverse events were similar for lumiracoxib and placebo. Therefore, no clinically important consequences are anticipated if lumiracoxib is coadministered with oral contraceptives containing EE or LN.

Effects of NSAIDs and paracetamol (acetaminophen) on protein kinase C epsilon translocation and on substance P synthesis and release in cultured sensory neurons

Celecoxib, diclofenac, ibuprofen, and nimesulide are nonsteroidal anti-inflammatory drugs (NSAIDs) very commonly used for the treatment of moderate to mild pain, together with paracetamol (acetaminophen), a very widely used analgesic with a lesser anti-inflammatory effect. In the study reported here, we tested the efficacy of celecoxib, diclofenac, and ibuprofen on preprotachykinin mRNA synthesis, substance P (SP) release, prostaglandin E₂ (PGE₂) release, and protein kinase C epsilon (PKCɛ) translocation in rat cultured sensory neurons from dorsal root ganglia (DRGs). The efficacy of these NSAIDs was compared with the efficacy of paracetamol and nimesulide in in vitro models of hyperalgesia (investigated previously). While nimesulide and paracetamol, as in previous experiments, decreased the percentage of cultured DRG neurons showing translocation of PKCɛ caused by 100 nM thrombin or 1 μM bradykinin in a dose-dependent manner, the other NSAIDs tested did not have a significant effect. The amount of SP released by peptidergic neurons and the expression level of preprotachykinin mRNA were assessed in basal conditions and after 70 minutes or 36 hours of stimulation with an inflammatory soup (IS) containing potassium chloride, thrombin, bradykinin, and endothelin-1. The release of SP at 70 minutes was inhibited only by nimesulide, while celecoxib and diclofenac were effective at 36 hours. The mRNA basal level of the SP precursor preprotachykinin expressed in DRG neurons was reduced only by nimesulide, while the increased levels expressed during treatment with the IS were significantly reduced by all drugs tested, with the exception of ibuprofen. All drugs were able to decrease basal and IS-stimulated PGE₂ release. Our study demonstrates novel mechanisms of action of commonly used NSAIDS.

Synthesis and structure-activity relationships for 1-(4-(piperidin-1-ylsulfonyl)phenyl)pyrrolidin-2-ones as novel non-carboxylate inhibitors of the aldo-keto reductase enzyme AKR1C3

High expression of the aldo-keto reductase enzyme AKR1C3 in the human prostate and breast has implicated it in the development and progression of leukemias and of prostate and breast cancers. Inhibitors are thus of interest as potential drugs. Most inhibitors of AKR1C3 are carboxylic acids, whose transport into cells is likely dominated by carrier-mediated processes. We describe here a series of (piperidinosulfonamidophenyl)pyrrolidin-2-ones as potent (<100 nM) and isoform-selective non-carboxylate inhibitors of AKR1C3. Structure-activity relationships identified the sulfonamide was critical, and a crystal structure showed the 2-pyrrolidinone does not interact directly with residues in the oxyanion hole. Variations in the position, co-planarity or electronic nature of the pyrrolidinone ring severely diminished activity, as did altering the size or polarity of the piperidino ring. There was a broad correlation between the enzyme potencies of the compounds and their effectiveness at inhibiting AKR1C3 activity in cells.

The anticancer effect of phospho-tyrosol-indomethacin (MPI-621), a novel phosphoderivative of indomethacin: in vitro and in vivo studies

We have synthesized a novel derivative of indomethacin, phospho-tyrosol-indomethacin (PTI; MPI-621), and evaluated its anticancer efficacy in vitro and in vivo. PTI inhibited the growth of human colon, breast and lung cancer cell lines 6-30-fold more potently than indomethacin. In vivo, in contrast to indomethacin that was unable to inhibit colon cancer xenograft growth, PTI inhibited the growth of colon (69% at 10mg/kg/day, P < 0.01) and lung (91% at 15mg/kg/day, P < 0.01) subcutaneous cancer xenografts in immunodeficient mice, suppressing cell proliferation by 33% and inducing apoptosis by 75% (P < 0.05, for both). Regarding its pharmacokinetics in mice, after a single intraperitoneal injection of PTI, its plasma levels reached the maximum concentration (Cmax = 46 μM) at 2h (Tmax) and became undetectable at 4h. Indomethacin is the major metabolite of PTI, with plasma Cmax = 378 μM and Tmax = 2.5h; it became undetectable 24h postadministration. The cellular uptake of PTI (50-200 μM) at 6h was about 200-fold greater than that of indomethacin. Regarding its safety, PTI had no significant genotoxicity, showed less gastrointestinal toxicity than indomethacin and presented no cardiac toxicity. Mechanistically, PTI suppressed prostaglandin E2 production in A549 human lung cancer cells and strongly inhibited nuclear factor-κB activation in A549 xenografts. These findings indicate that PTI merits further evaluation as an anticancer agent.

A novel phenotype of nonsteroidal anti-inflammatory drug hypersensitivity: the high-risk patient

Background

Some nonsteroidal anti-inflammatory drug (NSAID)-hypersensitive patients develop adverse reactions when challenged with weak cyclooxygenase 1 (COX-1) inhibitors.

Objectives

To investigate the prevalence and clinical features of this high-risk population.

Materials and methods

Patients from 2 outpatient allergy clinics consulting between October 2005 and October 2007 because of adverse reactions to classic NSAIDs were submitted to confirmatory double-blind oral challenges with the suspected NSAID and with acetaminophen, preferential and/or specific COX-2 inhibitors. Patients were then classified as low-risk and high-risk groups according to the results of provocation tests.

Results

Three hundred three patients were studied: 179 (59.0%) were tolerant to acetaminophen and the selective COX-2 inhibitors (low-risk group), whereas 124 (40.9%) developed reactions to at least one of the ''low COX-1 inhibitors'' (high-risk group). No distinctive demographic or clinical characteristics were present when both groups of patients were compared.

Conclusions

A large proportion of patients sensitive to classic NSAIDs cannot tolerate the weak COX-1 inhibitors. Oral challenges should be performed by trained specialists to advise these patients about the use of NSAIDs.

Long-term Morphine-treated Rats are more Sensitive to Antinociceptive Effect of Diclofenac than the Morphine-naive rats

This study investigates the effectiveness of the antinociceptive effects of diclofenac, an NSAID, on the nociceptive behavior of morphine-treated rats on formalin test. Rats were treated with morphine-containing drinking water for twenty one days, which induced morphine dependence. The antinociceptive effects of 8, 16, and 32 mg/kg doses of diclofenac were then evaluated and compared with distilled water in a formalin-based model of pain. Diclofenac potentiated pain suppression in morphine-dependent rats during the interphase of the formalin test and reduced the pain score during phase II. The post-test analysis revealed that both 16 mg/kg (p < 0.0001) and 32 mg/kg (p < 0.0001) doses of diclofenac had a significant effect on the interphase, while 8 mg/kg (p < 0.05), 16 mg/kg (p < 0.05), and 32 mg/kg (p < 0.01) doses of diclofenac significantly affected phase II. In contrast, the antinociceptive effects of diclofenac on morphine-naïve rats were observed during phase II only with the a 32 mg/kg dose (p < 0.05). In general, these results suggest that the long-term use of morphine in rats increases their sensitivity to the antinociceptive effects of diclofenac. Furthermore, the results support the existence of a non-opioid-dependent mechanism of pain suppression during the interphase of formalin test.

In vitro cytotoxic evaluation of some synthesized COX-2 inhibitor derivatives against a panel of human cancer cell lines

Celecoxib is a non-steroidal anti-inflammatory drug (NSAID) developed as a selective inhibitor of cyclooxygenase-2 (COX-2) for the treatment of rheumatoid arthritis disease. Recently some other mechanisms have been identified for anti cancer activity of these agents including induction of apoptosis, inhibition of tumor vascularization, stimulation of antitumor immune responses and inhibition of cellular protein synthesis. The cytotoxic effects of four synthesisized analogues of celecoxib (coded as D, E, F and G) were evaluated against Hela, MDA-MB-231, A-2780-s and HT-29 cancer cells, using MTT assay; Also their induction of apoptosis using DNA fragmentation analysis were studied. MTT assay showed that cell survival percent of COX-2 positive cell lines (HT-29, MDA-MB-231 and Hela; p≤0.05) were decreased significantly after exposure to the tested COX-2 inhibitors while little effect was observed on the COX-2 negative cell line (A-2780-s). Results also showed that A-2780-s and Hela were the most resistant and the most sensitive cell lines to these compounds, respectively. Moreover, in DNA fragmentation assay, induction of apoptosis was confirmed by electrophoretic pattern of separated DNA fragments in Hela cell line. Compounds E and G in comparison with D and F exerted more cytotoxic effect on COX-2 positive cell lines (Hela, HT-29 and MDA-MB-231). This could be due to the hydrophobic substituent (Cl, CH3) located at the para position of phenyl ring leading to more lipophilicity and cell uptake. In addition, these COX-2 inhibitors induced apoptosis on Hela cell-line, which could be considered as one of the cytotoxic mechanisms of these compounds as potential anti cancer agents.

Cyclooxygenase (COX)-1 and COX-2 both play an important role in the protection of the duodenal mucosa in cats

Although nonsteroidal anti-inflammatory drugs often cause ulcers in the duodenum in humans, the role of cyclooxygenase (COX) isoforms in the pathogenesis of duodenal ulcers has not been fully elucidated. We examined in cats the 1) ulcerogenic effects of selective COX-1 (SC-560, ketorolac) and COX-2 (celecoxib, meloxicam) inhibitors on the gastrointestinal mucosa, 2) effect of feeding and cimetidine on the expression of COX isoforms and prostaglandin E(2) (PGE(2)) level in the duodenum, and 3) localization of COX isoforms in the duodenum. COX inhibitors were administered after the morning meal in cats once daily for 3 days. Gastrointestinal lesions were examined on day 4. Localization and expression of COX isoforms (by immunohistochemistry, Western blot) and PGE(2) level (by enzyme immunoassay) were examined. Results were as follows. First, selective COX-1 or COX-2 inhibitors alone produced marked ulcers in the duodenum but did not cause obvious lesions in the small intestine. Coadministration of SC-560 and celecoxib produced marked lesions in the small intestine. Second, feeding increased both the expression of COX isoforms and PGE(2) level in the duodenum, and the effects were markedly inhibited by pretreatment with cimetidine. Third, COX-1 was localized in goblet and Brunner's gland cells, Meissner's and Auerbach's plexus, smooth muscle cells, and arterioles; and COX-2 was observed in capillaries, venules, and basal granulated cells. The expression of COX isoforms in the duodenum is up-regulated by feeding, and inhibition of either COX-1 or COX-2 causes ulcers in the duodenum, suggesting that both isoforms play an important role in the protection of the duodenal mucosa.

New NSAID targets and derivatives for colorectal cancer chemoprevention

Clinical and preclinical studies provide strong evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) can prevent numerous types of cancers, especially colorectal cancer. Unfortunately, the depletion of physiologically important prostaglandins due to cyclooxygenase (COX) inhibition results in potentially fatal toxicities that preclude the long-term use of NSAIDs for cancer chemoprevention. While studies have shown an involvement of COX-2 in colorectal tumorigenesis, other studies suggest that a COX-independent target may be at least partially responsible for the antineoplastic activity of NSAIDs. For example, certain NSAID derivatives have been identified that do not inhibit COX-2 but have demonstrated efficacy to suppress carcinogenesis with potential for reduced toxicity. A number of alternative targets have also been reported to account for the tumor cell growth inhibitory activity of NSAIDs, including the inhibition of cyclic guanosine monophosphate phosphodiesterases (cGMP PDEs), generation of reactive oxygen species (ROS), the suppression of the apoptosis inhibitor protein, survivin, and others. Here, we review several promising mechanisms that are being targeted to develop safer and more efficacious NSAID derivatives for colon cancer chemoprevention.

Mechanistic and pharmacological issues of aspirin as an anticancer agent

Recent findings have shown that aspirin, taken for several years, reduces the long-term risk of some cancers, particularly colorectal cancer. The result that aspirin benefit is detectable at daily low-doses (at least 75mg), the same used for the prevention of cardiovascular disease, positions the antiplatelet action of aspirin at the center of its antitumor efficacy. At low-doses given every 24 h, aspirin is acting by a complete and persistent inhibition of cyclooxygenase (COX)-1 in platelets (in the pre-systemic circulation) while causing a limited and rapidly reversible inhibitory effect on COX-2 and/or COX-1 expressed in nucleated cells. Aspirin has a short half-life in human circulation (approximately 20 min); nucleated cells have the ability to resynthesize the acetylated COX-isozymes within a few hours, while platelets do not. COX-independent mechanisms of aspirin, such as the inhibition of Wnt/ β-catenin and NF-kB signaling and the acetylation of extra-COX proteins, have been suggested to play a role in its chemo-preventive effects, but their relevance remains to be demonstrated in vivo at clinical doses. In conclusion, the results of clinical pharmacology and the analysis of randomized and epidemiological studies suggest that colorectal cancer and atherothrombosis share a common mechanism of disease, i.e. enhanced platelet activation in response to injury at distinct sites.

Semi-mechanistic modeling of the interaction between the central and peripheral effects in the antinociceptive response to lumiracoxib in rats

The model-based approach was undertaken to characterize the interaction between the peripheral and central antinociceptive effects exerted by lumiracoxib. The effects of intraplantar and intrathecal administrations and of fixed ratio combinations of lumiracoxib simultaneously administered by these two routes were evaluated using the formalin test in rats. Pain-related behavior data, quantified as the number of flinches of the injected paw, were analyzed using a population approach with NONMEM 7. The pain response during the first phase of the formalin test, which was insensitive to lumiracoxib, was modeled using a monoexponential decay. The second phase, which was sensitive to lumiracoxib, was described incorporating synthesis and degradation processes of pain mediators that were recruited locally after tissue injury. Upregulation at the local level and in the central nervous system (CNS) was set to be proportional to the predicted levels of pain mediators in the local (injured) compartment. Results suggest a greater role of upregulated COX-2(Local) in generating the pain response compared to COX-2(CNS). Drug effects were described as inhibition of upregulated COX-2. The model adequately described the time course of nociception after formalin injection in the absence or presence of lumiracoxib administered locally and/or spinally. Data suggest that the overall response is the additive outcome of drug effects at the peripheral and central compartments, with predominance of peripheral mechanisms. Application of modeling opens new perspectives for understanding the overall mechanism of action of analgesic drugs.