Cyclooxygenase-2--specific inhibitors: are they safe?

Iatrogenic hypertension: a bioinformatic analysis

It is well known that a myriad of medications and substances can induce side effects that are related to blood pressure (BP) regulation. This study aims to investigate why certain drugs tend to cause iatrogenic hypertension (HTN) and focus on drug targets that are implicated in these conditions.Databases and resources such as SIDER, DrugBank, and Genomatix were utilized in order to bioinformatically investigate HTN-associated drug target-genes for which HTN is a side effect. A tree-like map was created, representing interactions between 198 human genes that relate to the blood pressure system. 72 HTN indicated drugs and 160 HTN-inducing drugs were investigated. HTN-associated genes affected by these drugs were identified. HTN indicated drugs, which target nearly all branches of the interaction tree, were shown to exert an effect on most functional sub-systems of the BP regulatory system; and specifically, for the adrenergic and dopaminergic receptor pathways. High prevalence (25 genes) of shared targets between the HTN indicated and HTN-inducing drug categories was demonstrated. We focus on six drug families which are not indicated for HTN treatment, yet are reported as a major cause for blood pressure side effects. We show the molecular mechanisms that may lead to this iatrogenic effect. Such an analysis may have clinical implications that could allow for the development of tailored medicine with fewer side effects.

Effect of the PGD2-DP signaling pathway on primary cultured rat hippocampal neuron injury caused by aluminum overload

In the present study, the agonists and antagonists of DP receptor were used to examine whether the PGD₂-DP signaling pathway affects neuronal function. Primary cultured hippocampal neuron was prepared and treated with aluminum maltolate (100 μM) to establish the neuronal damage model. PGD₂ and cAMP content was detected by ELISA. L-PGDS and DPs mRNA and protein expression were measured by RT-PCR and Western blotting, respectively. The aluminium-load neuron was treated with the DP₁ agonist BW245C, the DP₁ antagonist BWA868C, the DP₂ agonist DK-PGD_2, and the DP₂ antagonist CAY10471, respectively. Neuronal pathomorphology was observed using H-E staining. The cell viability and the lactate dehydrogenase leakage rates of neurons were measured with MTT and LDH kit, respectively. Ca²⁺ level was detected by Fluo-3/AM. In the model group, the MTT values obviously decreased; LDH leakage rates and PGD₂ content increased significantly; L-PGDS, DP₁ mRNA and protein expressions increased, and DP₂ level decreased. BW245C reduced the Ca²⁺ fluorescence intensity and protected the neurons. DK-PGD₂ increased the intensity of Ca²⁺ fluorescence, while CAY10471 had the opposite effect. In conclusion, contrary to the effect of DP₂, the PGD₂-DP₁ signaling pathway protects against the primary cultured rat hippocampal neuronal injury caused by aluminum overload.

NSAIDs and Cardiovascular Diseases: Role of Reactive Oxygen Species

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs worldwide. NSAIDs are used for a variety of conditions including pain, rheumatoid arthritis, and musculoskeletal disorders. The beneficial effects of NSAIDs in reducing or relieving pain are well established, and other benefits such as reducing inflammation and anticancer effects are also documented. The undesirable side effects of NSAIDs include ulcers, internal bleeding, kidney failure, and increased risk of heart attack and stroke. Some of these side effects may be due to the oxidative stress induced by NSAIDs in different tissues. NSAIDs have been shown to induce reactive oxygen species (ROS) in different cell types including cardiac and cardiovascular related cells. Increases in ROS result in increased levels of oxidized proteins which alters key intracellular signaling pathways. One of these key pathways is apoptosis which causes cell death when significantly activated. This review discusses the relationship between NSAIDs and cardiovascular diseases (CVD) and the role of NSAID-induced ROS in CVD.

Cyclooxygenase-2 and antagonists in pain management

Non-steroidal anti-inflammatory drugs are widely used for the treatment of pain and inflammation by inhibiting the formation of prostaglandins. However, their use is limited by their side-effects, including gastrointestinal, renal function, cardiovascular and platelet function. Cyclooxygenase activity is the principal target for the action of non-steroidal anti-inflammatory drugs. Two isoforms of cyclooxygenase have been characterized: (i) cyclooxygenase-1, which is found in many tissues and is generally constitutively expressed and synthesizes prostanoids that mediate homeostatic functions; and (ii) cyclooxygenase-2, the inducible isoform, which is mainly expressed at sites of injury or inflammation and synthesizes prostanoids that mediate inflammation, pain and fever. These findings led to the development of selective cyclooxygenase-2 inhibitors, with comparable anti-inflammatory and analgesic properties to traditional non-steroidal anti-inflammatory drugs, but with significantly fewer side-effects. However, these new selective cyclooxygenase-2 inhibitors are not risk free, and care should be taken when using these drugs, especially with elderly patients with multiple medical problems. Finally, the future is bright for the broader usage of these agents in the treatment of diseases other than inflammation and pain, such as Alzheimer's disease, colonic polyp and colon cancer, just to name a few.

Bifidobacterium Lactis sp. 420 up-regulates cyclooxygenase (Cox)-1 and down-regulates Cox-2 gene expression in a Caco-2 cell culture model

Cyclooxygenases (Cox) -1 and -2 play important roles in gastrointestinal health; chronic overexpression of Cox-2 is associated with inflammatory and cancerous disease, whereas Cox-1 is expressed constitutively. We studied the effects of two probiotic (Bifidobacterium lactis sp. 420 and Lactobacillus acidophilus) and two control microorganisms (Escherichia coli and Salmonella enteritidis) and four microbial metabolites (acetate, butyrate, lactate and propionate) on the expression levels of the Cox isoforms in the enterocyte-like cell line Caco-2. Butyrate, which is anticarcinogenic, resulted in an 85% down-regulation of Cox-2 and a 37-fold increase in Cox-1 transcription. Propionate gave similar results (72% reduction of Cox-2, 23-fold induction of Cox-1), but lactate and acetate had no effect on Cox expression profile. Bifidobacterium sp. 420, which produces acetate and lactate but no butyrate or propionate, shared the Cox-1-increasing and Cox-2-silencing properties of butyrate and propionate, whereas L. acidophilus was similar to E. coli and S. enteritidis in having no effect on the Cox-1/Cox-2 ratio. For the first time, we therefore demonstrate evidence for a direct relationship between a probiotic bacterial strain and host Cox expression profile, suggesting that modulation of Cox expression may be an important factor in the potential anti-inflammatory and anticarcinogenic properties of some probiotics.

Treatment costs to prevent or treat upper gastrointestinal adverse events associated with NSAIDs

The widespread use of nonselective NSAIDs and cyclo-oxygenase (COX)-2 inhibitors has a substantial impact on healthcare budgets worldwide. The cost of their gastrointestinal (GI) adverse effects is a major component of their direct cost and has received much attention in the literature. Published studies have often differed in their methodologies and results. It is important for decision makers to understand the reasons for these differences in order to make informed decisions. We conducted a literature review to summarise data that evaluate the direct costs of NSAID-related GI adverse effects worldwide. This resulted in 789 articles from which 29 studies met the inclusion criteria and were fully reviewed. Of these 29, the 9 studies that assessed the cost of COX-2 inhibitors were all based on decision economic models, compared with only 7 of the remaining 20 studies, which assessed the cost of nonselective NSAIDs. In most studies, the perspective was that of the healthcare payer and the costs assessed were reimbursement costs. Costs of GI events almost doubled between regular users and non-users of nonselective NSAIDs and were much higher in high-dose versus low-dose users. The ratio of the total cost of nonselective NSAIDs to their acquisition cost reported in all studies varied from 1.36 to 2.12. Both of these numbers were reported in one single study assessing several different NSAIDs in France. Thus, the GI adverse events attributable to nonselective NSAIDs are substantial, and their costs often exceed the cost of the nonselective NSAID itself.The acquisition cost of the COX-2 inhibitors was the main driver of their total cost. The GI adverse effects with the COX-2 inhibitors added 10-20% to their acquisition cost in North America, while this increase was about 50% in some European countries. Decision analysis models showed that the direct costs of COX-2 inhibitors were lower than those of nonselective NSAIDs in patients at risk of NSAID gastropathy but higher in patients at no to low risk of gastropathy. Thus, from an economic perspective, the healthcare system would benefit from treating patients at risk of NSAID gastropathy with COX-2 inhibitors, but not those at no to low risk.

Effect of meloxicam and carprofen on renal function when administered to healthy dogs prior to anesthesia and painful stimulation

OBJECTIVE

To determine whether administration of the nonsteroidal anti-inflammatory drugs meloxicam or carprofen to healthy dogs that were subsequently anesthetized and subjected to painful electrical stimulation has adverse effects on renal function as measured by glomerular filtration rate (GFR) and evaluation of serum concentrations of urea and creatinine.

ANIMALS

6 male and 6 female healthy young-adult Beagles.

PROCEDURE

A study was conducted in accordance with a randomized crossover Latin-square design. One of 3 treatments (saline [0.9% NaCl] solution, 0.2 mg of meloxicam/kg, or 4.0 mg of carprofen/kg) was administered i.v. 1 hour before anesthesia was induced by use of drugs in accordance with a standard anesthetic protocol (butorphanol tartrate and acepromazine maleate as preanesthetic medications, ketamine hydrochloride and diazepam for induction, and maintenance with isoflurane). Anesthetized dogs were subjected to intermittent electrical stimulation for 30 minutes. Direct, mean arterial blood pressure; heart rate; and respiratory rate were monitored. End-tidal isoflurane concentration was maintained at 1.5 times the minimum alveolar concentration. The GFR, as measured by plasma clearance of 99mTc-diethylenetriaminepentaacetic acid, and serum concentrations of serum and creatinine were determined 24 hours after induction of anesthesia.

RESULTS

Neither meloxicam nor carprofen significantly affected GFR or serum concentrations of urea and creatinine, compared with values for the saline treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

When administered 1 hour before onset of anesthesia and painful electrical stimulation, meloxicam or carprofen did not cause clinically important alterations of renal function in young healthy dogs.

A mechanistic perspective on the specificity and extent of COX-2 inhibition in pregnancy

Cyclo-oxygenase (COX)-2-specific inhibitors form one of the most commonly prescribed groups of pain relief drugs. Despite the known reproductive toxicity of NSAIDs, which are nonspecific COX inhibitors, little is known about the differential role between COX-1 and COX-2 inhibition on reproduction. It has been suggested that COX-2 plays a prominent role in animals at all stages of reproduction, from ovulation to implantation to decidualisation and delivery. Both estrogen and progesterone have been shown to be involved in regulation of COX production in tissues of the reproductive tract. Similar to NSAIDs, warnings on reproduction have been included in the product labelling of marketed COX-2-specific inhibitors. Variations in the level of warnings in these labels are noted, with an order of stringency being celecoxib approximate, equals etoricoxib > rofecoxib approximate, equals valdecoxib. The specificity of etoricoxib for COX-2 has been found to be approximately 3-fold greater than that of rofecoxib and valdecoxib and approximately 14-fold more than celecoxib in human whole blood assays. There is growing evidence to suggest that the inducible COX-2, rather than the COX-1, is the main enzyme responsible for reproduction. It was demonstrated that the change in estrogen and progesterone levels during pregnancy contributes to the dramatic increase in COX-2 expression. This further strengthens the earlier findings that COX-2 activities are necessary to support pregnancy. It is also worth mentioning that although a definite correlation between the specificity of a COX-2-specific inhibitor and the level of precaution stated in the drug labels in UK was not obtained, a direct relationship between the specificity and the potential to result in teratogenicity has not been excluded. With growing interest of the pharmaceutical industry in developing more COX-2-specific inhibitors and the fact that reproductive toxicity is not tested in pregnant women before marketing, it is important for drug regulators to raise awareness of the potential reproductive adverse effects and provide guidance on the level of caution when using these drugs in pregnancy.

In vitro investigation of the effects of nonsteroidal anti-inflammatory drugs, prostaglandin E2, and prostaglandin F2alpha on contractile activity of the third compartment of the stomach of llamas

OBJECTIVE

To determine the in vitro effect of prostaglandin (PG) E2, PGF2alpha, and the nonsteroidal anti-inflammatory drugs (NSAIDs) indomethacin, ketoprofen, and nabumetone on the contractile strength of the circular smooth muscle layer of the third compartment of the stomach of llamas.

SAMPLE POPULATION

Specimens of the third compartment obtained from 5 healthy adult llamas.

PROCEDURE

Full-thickness tissue samples were collected from the third compartment immediately after euthanasia. Specimens were cut into strips oriented along the circular muscle layer and mounted in a tissue bath system. Incremental amounts of ketoprofen, nabumetone, indomethacin, PGE2, and PGF2alpha were added, and contractile strength (amplitude of contractions) was recorded.

RESULTS

Generally, PGE2 reduced contractile strength of the circular smooth layer of the third compartment, whereas PGF2alpha, increased the strength of contractions. The activity of the NSAIDs was generally excitatory in a concentration-dependent manner, although significant changes were induced only by administration of indomethacin.

CONCLUSIONS AND CLINICAL RELEVANCE

On isolated smooth muscle strips of the third compartment of llamas, exogenous PGE2 and PGF2alpha had a variable effect on contractile strength. Administration of the NSAIDs did not inhibit contractility and would not be likely to induce stasis of the third compartment in the absence of an underlying disease process.

Meloxicam, a specific COX-2 inhibitor, does not enhance the isoflurane minimum alveolar concentration reduction produced by morphine in the rat

A synergistic effect of nonselective cyclooxygenase (COX) inhibitors on morphine-induced decrease of isoflurane minimum alveolar concentration (MAC(ISO)) has been observed in the rat. We studied the influence of specific COX-2 inhibitors on this decrease of MAC. Sixty-four female rats were anesthetized with isoflurane in oxygen. The animals were grouped into saline solution, aspirin (30 mg/kg), morphine (1 mg/kg), morphine (1 mg/kg) + aspirin (30 mg/kg), meloxicam (1 and 3 mg/kg), and morphine (1 mg/kg) + meloxicam (1 and 3 mg/kg). Then the MAC(ISO) was determined from alveolar gas samples at the time of tail clamp. The groups treated with saline solution, aspirin, and 1 and 3 mg/kg meloxicam did not express any statistically relevant changes among them. The administration of morphine + meloxicam 1 or 3 mg/kg significantly reduced the MAC(ISO) just as in the group where only morphine was administered (morphine 1.35% +/- 0.07%, morphine + 1 mg/kg meloxicam 1.36% +/- 0.04%, and morphine + 3 mg/kg meloxicam 1.37% +/- 0.08%). The greatest reduction of MAC(ISO) was after administration of morphine + aspirin (1.19% +/- 0.05%). The administration of meloxicam does not potentiate the morphine-induced decrease of MAC(ISO) in the rat.

IMPLICATIONS

A synergistic effect between morphine and aspirin on isoflurane minimum alveolar concentration has been observed in the rat--an effect that does not occur between morphine and meloxicam.

Prostaglandin endoperoxide H synthase inhibitors and other tocolytics in preterm labour

Preterm delivery (<37 weeks of gestation) is the major obstetrical complication in developed countries, yet attempts to delay labour and prolong pregnancy have largely been unsuccessful. One of the many reasons it is so difficult to prevent preterm birth is that the nature of preterm labour changes as a function of gestational age, maternal lifestyle factors or infection, to list a few of the reasons. The inhibitors of prostaglandin endoperoxide H synthase (PGHS), known as the Non-steroidal Antiinflammatory Drugs, have been viewed with interest as tocolytics with promising effectiveness under most conditions of preterm labour. Three isoforms of PGHS exist; the first two, PGHS-1 and -2, have been studied for their catalytic activity, X-ray crystallographic structure, and physiological roles in the adult and the foetus. Mixed inhibitors and isoform-specific inhibitors of PGHS have been developed, and their roles in delaying preterm labour are examined and compared to other tocolytics.

Release of prostaglandin E-2 in bovine brain endothelial cells after exposure to three unique forms of the antifungal drug amphotericin-B: role of COX-2 in amphotericin-B induced fever

Common formulations of amphotericin-B include a deoxycholate colloidal suspension (d-Amph), an amphotericin-B lipid complex (Ablc), and a liposomal product (l-Amph). The clinical incidence of infusion related fever is highest with d-Amph, intermediate with Ablc, and lowest with l-Amph. In the present study, we measured the activation of cyclooxygenase-2 (COX-2) and subsequent release of prostaglandin E-2 (PgE-2) from brain microvessel endothelium treated with these three formulations of amphotericin-B. Primary cultured bovine brain microvessel endothelial cells (BBMEC) were exposed to d-Amph, Ablc and l-Amph at concentrations that can be achieved in the plasma of patients receiving the drug. Media samples from the cells were collected and analyzed for PgE-2. Release of PgE-2 from BBMEC monolayers treated with l-Amph was similar to cells receiving culture media alone. In contrast, Ablc and d-Amph caused significantly greater release of PgE-2 from BBMEC monolayers compared to controls receiving culture media alone. PgE-2 release after d-Amph treatment was similar in magnitude to that observed with bacterial lipopolysaccharide (LPS). Western blot analysis indicated significant induction of COX-2 expression in BBMEC following LPS, Ablc or d-Amph treatment. Furthermore, PgE-2 release following exposure of BBMEC monolayers to either LPS or the various amphotericin-B formulations was reduced by the addition of the selective COX-2 inhibitor, NS-398. These studies indicate that amphotericin-B induces COX-2 expression in brain microvessel endothelium resulting in release of fever producing PgE-2. The magnitude of PgE-2 release from BBMEC following exposure to various amphotericin-B formulations mirrors the clinical observations regarding amphotericin-B induced fever and serves as initial support for the clinical use of COX-2 inhibitors to reduce amphotericin-B fever.

Non steroidal anti-inflammatory drugs and COX-2 inhibitors as anti-cancer therapeutics: hypes, hopes and reality

Non-steroidal anti-inflammatory drugs (NSAIDs) and specific inhibitors of cyclooxygenase (COX)-2, are therapeutic groups widely used for the treatment of pain, inflammation and fever. There is growing experimental and clinical evidence indicating NSAIDs and COX-2 inhibitors also have anti-cancer activity. Epidemiological studies have shown that regular use of Aspirin and other NSAIDs reduces the risk of developing cancer, in particular of the colon. Molecular pathology studies have revealed that COX-2 is expressed by cancer cells and cells of the tumor stroma during tumor progression and in response to chemotherapy or radiotherapy. Experimental studies have demonstrated that COX-2 over expression promotes tumorigenesis, and that NSAIDs and COX-2 inhibitors suppress tumorigenesis and tumor progression. Clinical trials have shown that NSAIDs and COX-2 inhibitors suppress colon polyp formation and malignant progression in patients with familial adenomatous polyposis (FAP) syndrome. Recent advances in the understanding of the cellular and molecular mechanisms of the anti-cancer effects of NSAIDs and COX-2 inhibitors have demonstrated that these drugs target both tumor cells and the tumor vasculature. The therapeutic benefits of COX-2 inhibitors in the treatment of human cancer in combination with chemotherapy or radiotherapy are currently being tested in clinical trials. In this article we will review recent advances in the understanding of the anti-tumor mechanisms of these drugs and discuss their potential application in clinical oncology.

Use of NSAIDs, COX-2 inhibitors, and acetaminophen and associated coprescriptions of gastroprotective agents in an elderly population

OBJECTIVES

To identify determinants of cyclooxygenase 2 (COX-2) inhibitor versus nonsteroidal antiinflammatory drug (NSAIDs) or acetaminophen prescription in seniors; and to compare gastroprotective agent coprescriptions.

METHODS

Administrative medical records were obtained from the government of Quebec health insurance agency. Three cohorts were formed based on prescriptions at study entry: COX-2 inhibitors, NSAIDs, or acetaminophen. Logistic regressions were used to adjust for potential confounders.

RESULTS

We identified 42,267 patients taking COX-2 inhibitors, 8,235 taking NSAIDs, and 19,716 taking acetaminophen. Determinants of utilizing COX-2 inhibitors versus NSAIDs and versus acetaminophen, respectively, include: female gender (odds ratio [OR] 1.47; 95% confidence interval [95% CI] 1.39-1.55 and OR 1.17; 95% CI 1.12-1.22); musculoskeletal diseases (OR 1.87; 95% CI 1.76-2.00 and OR 2.20; 95% CI 2.10-2.31); and prior gastrointestinal hospitalization (OR 1.82; 95% CI 1.19-2.78 and OR 0.77; 95% CI 0.64-0.92). Gastroprotective agent coprescriptions were lower with COX-2 inhibitors than NSAIDs: OR 0.53; 95% CI 0.48-0.58.

CONCLUSIONS

COX-2 inhibitors were more commonly used than NSAIDs in patients with musculoskeletal diseases and those with prior gastrointestinal hospitalizations. Adjusted odds ratios showed a 47% decrease in gastroprotective agent coprescriptions with COX-2 inhibitors compared with NSAIDs.

In vitro investigation of the effects of cyclooxygenase-2 inhibitors on contractile activity of the equine dorsal and ventral colon

OBJECTIVE

To evaluate the effect of 2 cyclooxygenase (COX)-2 inhibitors on contractile activity of the circular smooth muscle layer of the equine dorsal and ventral colon.

SAMPLE POPULATION

Samples of the dorsal and ventral colon obtained from 10 healthy horses.

PROCEDURE

Full-thickness tissue samples were collected from the dorsal colon in the area of the diaphragmatic flexure and the ventral colon in the area of the sternal flexure. Samples were cut into strips oriented along the fibers of the circular muscle layer and mounted in a tissue bath system for determination of contractile strength. Incremental amounts of etodolac, nabumetone, and indomethacin were added, and contractile activity was recorded.

RESULTS

Response of the dorsal and ventral colon to nonsteroidal anti-inflammatory drugs (NSAIDs) was variable. Indomethacin induced the greatest reduction in contractile activity, followed by nabumetone. For etodolac, the difference from baseline values was only significantly reduced at the highest concentration used (1 X 10(5)M) for the ventral colon.

CONCLUSIONS AND CLINICAL RELEVANCE

The NSAIDs that are designed to target the COX-2 isoform appeared to have variable effects on the contractile activity of the equine dorsal and ventral colon. Etodolac appeared to have the least effect on contractile activity, compared with the effects attributable to nabumetone, and would potentially have the fewest adverse effects relative to motility of the dorsal and ventral colon.

Cardiovascular risk profile of antirheumatic agents in patients with osteoarthritis and rheumatoid arthritis

Several new drugs have become available for the treatment of patients with osteoarthritis and rheumatoid arthritis (RA). These agents include selective cyclooxygenase (COX)-2 inhibitors, leflunomide and anti-tumour necrosis factor (TNF)-alpha antagonists. COX-2 inhibitors have a more favourable gastrointestinal adverse effect profile than conventional non-steroidal anti-inflammatory drugs (NSAIDs). However, the COX-2 inhibitors are also associated with hypertension, oedema and congestive heart failure, the well-known adverse effects of conventional NSAIDs. Patients with treated hypertension should be monitored regularly when conventional NSAIDs or COX-2 inhibitors are administered. At present, there is a considerable debate regarding the risk of cardiovascular events with the COX-2 inhibitors. The available literature gives no unequivocal answers. This matter can only be solved by an appropriate trial assessing the cardiovascular risk of these agents. Patients with RA appear to have an enhanced cardiovascular risk which might be related to an unfavourable lipid profile. Corticosteroids induce hypercholesterolaemia in patients other than those with RA. It was recently shown that total and high-density lipoprotein (HDL) cholesterol were low in patients with RA who had a high disease activity. Contrary to the expectation, combination therapy with prednisolone rapidly improved the atherogenic index (total/HDL cholesterol). Ongoing studies investigating this topic are underway. It is not known to what extent corticosteroids induce hypertension in patients with RA. Hence, we advocate blood pressure control for these patients. A small percentage of patients with RA develop hypertension when taking leflunomide, and no other serious cardiovascular adverse effects have been reported in the literature. Blood pressure monitoring is recommended especially in the first months of treatment. TNFalpha antagonists are contraindicated in patients with RA who have congestive heart failure. No specific cardiovascular adverse effects have been reported with the use of these agents in the non-cardiovascular compromised patient. TNFalpha antagonists are the most powerful anti-inflammatory drugs presently available. As inflammation plays an important role in RA as well as in cardiovascular disease and, in view of the increased cardiovascular risk in RA, it is tempting to expect that suppression of inflammation ultimately will lower the cardiovascular morbidity and mortality in patients with RA.

Differential binding mode of diverse cyclooxygenase inhibitors

Non-steroidal anti-inflammatory drugs (NSAIDs) are competitive inhibitors of cyclooxygenase (COX), the enzyme that mediates biosynthesis of prostaglandins and thromboxanes from arachidonic acid. There are at least two different isoforms of the enzyme known as COX-1 and -2. Site directed mutagenesis studies suggest that non-selective COX inhibitors of diverse chemical families exhibit differential binding modes to the two isozymes. These results cannot clearly be explained from the sole analysis of the crystal structures of COX available from X-ray diffraction studies. With the aim to elucidate the structural features governing the differential inhibitory binding behavior of these inhibitors, molecular modeling studies were undertaken to generate atomic models compatible with the experimental data available. Accordingly, docking of different COX inhibitors, including selective and non-selective ligands: rofecoxib, ketoprofen, suprofen, carprofen, zomepirac, indomethacin, diclofenac and meclofenamic acid were undertaken using the AMBER program. The results of the present study provide new insights into a better understanding of the differential binding mode of diverse families of COX inhibitors, and are expected to contribute to the design of new selective compounds.

Prostaglandin H synthase and vascular function

Prostaglandin H synthase (PGHS) is a rate-limiting enzyme in the production of prostaglandins and thromboxane, which are important regulators of vascular function. Under normal physiological conditions, PGHS-dependent vasodilators (such as prostacyclin) modulate vascular tone. However, PGHS-dependent vasoconstriction (mediated by thromboxane and/or its immediate precursor, PGH(2)) predominates in some vascular pathologies (eg, systemic hypertension, diabetes, cerebral ischemia, and aging). This review will discuss the role of PGHS-dependent modulation of vascular function in a number of vascular beds (systemic, pulmonary, cerebral, and uterine) with an emphasis on vascular pathophysiology. Moreover, the specific contributions of the different isoforms (PGHS-1 and PGHS-2) are discussed. Understanding the role of PGHS in vascular function is of particular importance because they are the targets of the commonly used nonsteroidal antiinflammatory drugs (NSAIDs), which include aspirin and ibuprofen. Importantly, with the advent of specific PGHS-2 inhibitors for treatment of conditions such as chronic inflammatory disease, it is an opportune time to review the data regarding PGHS-dependent modulation of vascular function.

Inhibition of tumor angiogenesis by non-steroidal anti-inflammatory drugs: emerging mechanisms and therapeutic perspectives

Chronic intake of non steroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced risk of developing gastrointestinal tumors, in particular colon cancer. Increasing evidence indicates that NSAID exert tumor-suppressive activity on pre-malignant lesions (polyps) in humans and on established experimental tumors in mice. Some of the tumor-suppressive effects of NSAIDs depend on the inhibition of cyclooxygenase-2 (COX-2), a key enzyme in the synthesis of prostaglandins and thromboxane, which is highly expressed in inflammation and cancer. Recent findings indicate that NSAIDs exert their anti-tumor effects by suppressing tumor angiogenesis. The availability of COX-2-specific NSAIDs opens the possibility of using this drug class as anti-angiogenic agents in combination with chemotheapy or radiotherapy for the treatment of human cancer. Here we will briefly review recent advances in the understanding of the mechanism by which NSAIDs suppress tumor angiogenesis and discuss their potential clinical application as anti-cancer agents.

Approaches to healing and prophylaxis of nonsteroidal anti-inflammatory drug-associated ulcers

Treating and preventing peptic ulcers associated with nonsteroidal anti-inflammatory drugs (NSAIDs) calls for clinical judgment. Physicians must weigh their patients' need for anti-inflammatory therapy against their individual risks for ulcer development; their likelihood of coping with an ulcer complication if it should develop; and the economics, efficacy, and tolerability of various treatment and prevention options. This article considers some general strategies common to both treatment and prevention. Data from randomized trials that can guide clinicians and their patients as they attempt to heal an established NSAID ulcer or prevent one occurring in the future are also reviewed.