A randomized double-blind comparison of placebo, etodolac, and naproxen on gastrointestinal injury and prostaglandin production

Clinical Guidelines for Drug-Related Peptic Ulcer, 2020 Revised Edition

Korean guidelines for nonsteroidal anti-inflammatory drug (NSAID)-induced peptic ulcer were previously developed in 2009 with the collaboration of the Korean College of Helicobacter and Upper Gastrointestinal Research and Korean Society of Gastroenterology. However, the previous guidelines were based mainly upon a review of the relevant literature and expert opinion. Therefore, the guidelines need to be revised. We organized a guideline Development Committee for drug-related peptic ulcer under the auspices of the Korean College of Helicobacter and Upper Gastrointestinal Research in 2017 and developed nine statements, including four for NSAIDs, three for aspirin and other antiplatelet agents, and two for anticoagulants through a de novo process founded on evidence-based medicine that included a literature search and a meta-analysis, A consensus was reached through the application of the modified Delphi method. The primary target of these guidelines is adult patients undergoing long-term treatment with NSAIDs, aspirin or other antiplatelet agents and anticoagulants. The revised guidelines reflect the expert consensus and is intended to assist clinicians in the management and prevention of drug-induced peptic ulcer and associated conditions.

[Clinical Guidelines for Drug-induced Peptic Ulcer, 2020 Revised Edition]

The Korean guidelines for nonsteroidal anti-inflammatory drug (NSAID)-induced peptic ulcers were previously developed under co-work with the Korean College of Helicobacter and Upper Gastrointestinal Research and Korean Society of Gastroenterology at 2009. On the other hand, the previous guidelines were based mainly on a literature review and expert opinions. Therefore, the guidelines need to be revised. In this study, a guideline development committee for drug-induced peptic ulcers was organized under the Korean College of Helicobacter and Upper Gastrointestinal Research in 2017. Nine statements were developed, including four for NSAID, three for aspirin and other antiplatelet agents, and two for anticoagulants through de novo processes based on evidence-based medicine, such as a literature search, meta-analysis, and the consensus was established using the modified Delphi method. The primary target of this guideline was adult patients taking long-term NSAIDs, aspirin, or other antiplatelet agent and anticoagulants. The revised guidelines reflect the consensus of expert opinions and are intended to assist relevant clinicians in the management and prevention of drug-induced peptic ulcers and associated conditions.

Network Meta-Analysis Comparing Relatively Selective COX-2 Inhibitors Versus Coxibs for the Prevention of NSAID-Induced Gastrointestinal Injury

Currently 2 difference classes of cyclooxygenase (COX)-2 inhibitors, coxibs and relatively selective COX-2 inhibitors, are available for patients requiring nonsteroidal anti-inflammatory drug (NSAID) therapy; their gastroprotective effect is hardly directly compared. The aim of this study was to compare the gastroprotective effect of relatively selective COX-2 inhibitors with coxibs. MEDLINE, EMBASE, and the Cochrane Library (from their inception to March 2015) were searched for potential eligible studies. We included randomized controlled trials comparing coxibs (celecoxib, etoricoxib, parecoxib, and lumiracoxib), relatively selective COX-2 inhibitors (nabumetone, meloxicam, and etodolac), and nonselective NSAIDs with a study duration ≥ 4 weeks. Comparative effectiveness and safety data were pooled by Bayesian network meta-analysis. The primary outcomes were ulcer complications and symptomatic ulcer. Summary effect-size was calculated as risk ratio (RR), together with the 95% confidence interval (CI). This study included 36 trials with a total of 112,351 participants. Network meta-analyses indicated no significant difference between relatively selective COX-2 inhibitors and coxibs regarding ulcer complications (RR, 1.38; 95% CI, 0.47-3.27), symptomatic ulcer (RR, 1.02; 95% CI, 0.09-3.92), and endoscopic ulcer (RR, 1.18; 95% CI, 0.37-2.96). Network meta-analyses adjusting potential influential factors (age, sex, previous ulcer disease, and follow-up time), and sensitivity analyses did not reveal any major change to the main results. Network meta-analyses suggested that relatively selective COX-2 inhibitors and coxibs were associated with comparable incidences of total adverse events (AEs) (RR, 1.09; 95% CI, 0.93-1.31), gastrointestinal AEs (RR, 1.04; 95% CI, 0.87-1.25), total withdrawals (RR, 1.00; 95% CI, 0.74-1.33), and gastrointestinal AE-related withdrawals (RR, 1.02; 95% CI, 0.57-1.74). Relatively selective COX-2 inhibitors appear to be associated with similar gastroprotective effect and tolerability as coxibs. Owing to the indirectness of the comparisons, future research is required to confirm the study conclusion.

Effect of single dose pretreatment analgesia with three different analgesics on postoperative endodontic pain: A randomized clinical trial

Introduction:

One of the aims of root canal treatment is to prevent or eliminate pain. Postoperative endodontic pain control continues to be a significant challenge.

Aim:

To compare and evaluate the effect of single oral dose of 100 mg of tapentadol, 400 mg of etodolac, or 10 mg of ketorolac as a pretreatment analgesic for the prevention and control of postoperative endodontic pain in patients with symptomatic irreversible pulpitis. The incidence of side effects was recorded as secondary outcome.

Materials and Methods:

Sixty emergency patients with moderate to severe pain, diagnosed with symptomatic irreversible pulpitis were randomly allocated (1:1:1) to any of the three groups; tapentadol, etodolac, or ketorolac. Medications were administered 30 min before beginning of the endodontic treatment. Patients recorded pain intensity on 10 cm visual analog scale (VAS) after treatment, for upto 24 h.

Results:

At 24 h, mean ±standard deviation (SD) of VAS scores (in cm) for tapentadol, etodolac, and ketorolac were 0.89 ± 0.83, 2.68 ± 2.29, and 0.42 ± 0.69, respectively. Kruskal-Wallis (K-W) test showed significant difference among the three groups (P = 0.001). Mann-Whitney test showed significantly lower VAS scores in tapentadol and ketorolac than etodolac group (P = 0.013 and 0.001, respectively).

Conclusions:

Single oral dose of 10 mg of ketorolac and 100mg of tapentadol as a pretreatment analgesic significantly reduced postoperative endodontic pain in patients with symptomatic irreversible pulpitis when compared to 400 mg of etodolac.

5-Lipoxygenase metabolic contributions to NSAID-induced organ toxicity

Cyclooxygenase (COX)-1, COX-2, and 5-lipoxygenase (5-LOX) enzymes produce effectors of pain and inflammation in osteoarthritis (OA) and many other diseases. All three enzymes play a key role in the metabolism of arachidonic acid (AA) to inflammatory fatty acids, which contribute to the deterioration of cartilage. AA is derived from both phospholipase A(2) (PLA(2)) conversion of cell membrane phospholipids and dietary consumption of omega-6 fatty acids. Nonsteroidal antiinflammatory drugs (NSAIDs) inhibit the COX enzymes, but show no anti-5-LOX activity to prevent the formation of leukotrienes (LTs). Cysteinyl LTs, such as LTC(4), LTD(4), LTE(4), and leukoattractive LTB(4) accumulate in several organs of mammals in response to NSAID consumption. Elevated 5-LOX-mediated AA metabolism may contribute to the side-effect profile observed for NSAIDs in OA. Current therapeutics under development, so-called "dual inhibitors" of COX and 5-LOX, show improved side-effect profiles and may represent a new option in the management of OA.

Meta-analysis: incidence of endoscopic gastric and duodenal ulcers in placebo arms of randomized placebo-controlled NSAID trials

BACKGROUND

The safety of NSAIDs is often evaluated by comparison with placebo in clinical trials.

AIM

To investigate the incidence of gastric and duodenal ulcers (GDU) in placebo arms in NSAID trials over the last three decades.

METHODS

Randomized placebo-controlled trials of oral NSAIDs from 1975 to 2006 were systematically reviewed. The pooled incidence of GDU in placebo arms was calculated and compared. Meta-regression was used to identify risk factors related to the incidence of the placebo ulcer at the study level.

RESULTS

Thirty-six studies met inclusion criteria (duration of 6.5 days to 24 weeks). In total, 3.29% GDUs were reported in 36 placebo arms. The incidence of GDU in placebo arms was 0, 4.20% and 3.03% in the studies from 1975-1989, 1990-1999 and 2000-2006 respectively (P > 0.05). Eligible subjects with previous GI events and eligible subjects on co-therapy with low-lose aspirin/corticosteroids were associated with the increase in placebo ulcer incidence after adjusting for other factors.

CONCLUSIONS

The incidence of GDU in placebo arms has not changed significantly over the last three decades, although has decreased in the past 10 years. Studies show that previous GI events and co-therapy with low-dose aspirin/corticosteroids were associated with increasing GDU in placebo arms.

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

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

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

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

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

Effects of cyclooxygenase inhibition on the gastrointestinal tract

Cyclooxygenase (COX) is a rate-limiting enzyme that catalyzes the conversion of arachidonic acid, an essential fatty acid present in cell membrane phospholipids and liberated by phospholipase, into prostaglandins (PGs) and prostanoids. COX has two distinct membrane-anchored isoenzymes; COX-1 and COX-2. COX-1 is a constitutively expressed and found in most normal body tissues; COX-2 is expressed in normal tissues at low levels and is highly induced by pro-inflammatory mediators in the setting of inflammation, injury, and pain. Inhibitors of COX activity include: (1) conventional non-selective non-steroidal anti-inflammatory drugs (ns-NSAIDs); (2) selective COX-2 inhibitors (COXIBs); and (3) COX-1 inhibitors. Non-selective NSAIDs, at therapeutic doses, inhibit both COX-1 and COX-2. The anti-inflammatory benefits of these drugs are primarily derived from COX-2 inhibition, while inhibition of COX-1 often elicits gastrointestinal (GI) toxicity. Therefore, COXIBs were developed to provide a selective COX-2 agent, i.e., one, that at fully therapeutic doses demonstrated comparable therapeutic benefit to non-selective NSAIDs, without the attendant COX-1-mediated GI toxicities. In this review, we evaluate available literature describing the pathophysiologic role of cyclooxygenases and the effects of their inhibition in GI system in experimental and domestic animal species.

GI Risk and Risk Factors of NSAIDs

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most widely used drugs in the United States. Ulcers are found at endoscopy in 15% to 30% of patients using NSAIDs regularly. The annual incidence of upper gastrointestinal (GI) complications such as bleeding with regular NSAID use is approximately 1.0% to 1.5%, whereas the annual rate of upper GI clinical events (complicated plus symptomatic uncomplicated ulcers) is approximately 2.5% to 4.5%. Upper GI symptoms such as dyspepsia also occur in many patients taking NSAIDs--at a relative risk of about 1.5 to 2 compared with that in patients without NSAID use. Important risk factors for upper GI clinical events include older age, prior history of upper GI events, use of corticosteroids or anticoagulants, and high-dose or multiple NSAIDs (including NSAID plus low-dose aspirin). Lower GI clinical events such as bleeding may also occur with NSAIDs, although they are less common and less well studied than upper GI events. The decision to employ a protective strategy to decrease NSAID-associated GI clinical events is based on risk stratification. Strategies employed include the use of non-NSAID analgesics, use of lowest effective dose of NSAID, use of medical cotherapy (eg, proton pump inhibitor, misoprostol), or use of coxibs.

Gastrointestinal effects of COX-2 inhibitors

The developing popularity of non-steroidal anti-inflammatory drugs (NSAIDs) over the last 100 years has been paralleled by an increase in associated complications, particularly affecting the gastrointestinal (GI) tract [1]. Over this period, there have been several attempts to develop less toxic NSAIDs, most of which have been unsuccessful. Since the discovery that the enzyme cyclooxygenase (COX) exists as two isoforms, the largely constitutive COX-1 and the mainly inducible COX-2, much interest has centred on the development of drugs capable of selectively inhibiting COX-2. Early studies that investigated specific COX-2 inhibitors (with no effect on the COX-1 isoform over the whole range of concentrations achieved in clinical usage) are encouraging, as they demonstrate that these drugs have fewer effects on gastroduodenal mucosa than standard NSAIDs given at equivalent doses. Further clinical experience with these agents outside trial settings and additional studies to assess the role of COX-2 when induced in the GI tract are needed, before such agents can be safely recommended for widespread prescribing.

Risks of clinically significant upper gastrointestinal events with etodolac and naproxen: a historical cohort analysis

BACKGROUND AND AIMS

Etodolac is a generic nonsteroidal anti-inflammatory drug (NSAID). Previous in vitro studies have shown that etodolac is a selective inhibitor of cyclooxygenase (COX)-2 with selectivity in between that of other COX-2 inhibitors such as celecoxib and rofecoxib. However, there are no outcomes data assessing clinically significant upper gastrointestinal (CSUGI) events with etodolac.

METHODS

A historical cohort study was performed at the Dallas Veterans Affairs Medical Center in which 16,286 veteran patients (5596 patient-years) received etodolac or naproxen during a 3-year period without concurrent use of other ulcerogenic drugs other than low-dose aspirin. The primary outcome was the CSUGI event rate of the etodolac and naproxen groups without concomitant low-dose aspirin.

RESULTS

The incidence of CSUGI events was .78% and .24% for naproxen and etodolac, respectively. In the NSAID-naive subset, the incidence of CSUGI events was .99% and .24% for naproxen and etodolac, respectively. Compared with naproxen, etodolac was associated with a reduction in upper gastrointestinal events, corresponding to an odds ratio of .39 (95% confidence interval, .20-.76; P = .006). Concomitantly used low-dose aspirin increased event rates with naproxen 2-fold and etodolac 9-fold. Hence, there was no significant difference in gastrointestinal event rates between etodolac and naproxen when low-dose aspirin was taken concomitantly.

CONCLUSIONS

Etodolac is a generic COX-2 selective inhibitor that reduces CSUGI events compared with the nonselective NSAID naproxen. However, concomitant use of low-dose aspirin negates the gastrointestinal safety advantages of etodolac.

Time dependent risk of gastrointestinal complications induced by non-steroidal anti-inflammatory drug use: a consensus statement using a meta-analytic approach

OBJECTIVES

To provide an updated document assessing the global, NSAID-specific, and time dependent risk of gastrointestinal (GI) complications through meta-analyses of high quality studies.

METHODS

An exhaustive systematic search was performed. Inclusion criteria were: RCT or controlled study, duration of 5 days at least, inactive control, assessment of minor or major NSAID adverse effects, publication range January 1985 to January 2003. The publications retrieved were assessed during a specifically dedicated WHO meeting including leading experts in all related fields. Statistics were performed conservatively. Meta-regression was performed by regressing NSAID adjusted estimates against study duration categories.

RESULTS

Among RCT data, indolic derivates provided a significantly higher risk of GI complications related to NSAID use than for non-users: RR = 2.25 (1.00; 5.08) than did other compounds: naproxen: RR = 1.83 (1.25; 2.68); diclofenac: RR = 1.73 (1.21; 2.46); piroxicam: RR = 1.66 (1.14; 2.44); tenoxicam: RR = 1.43 (0.40; 5.14); meloxicam: RR = 1.24 (0.98; 1.56), and ibuprofen: RR = 1.19 (0.93; 1.54). Indometacin users had a maximum relative risk for complication at 14 days. The other compounds presented a better profile, with a maximum risk at 50 days. Significant additional risk factors included age, dose, and underlying disease. The controlled cohort studies provided higher estimates: RR = 2.22 (1.7; 2.9). Publication bias testing was significant, towards a selective publication of deleterious effects of NSAIDs from small sized studies.

CONCLUSION

This meta-analysis characterised the "compound" and "time" aspects of the GI toxicity of non-selective NSAIDs. The risk/benefit ratio of such compounds should thus be carefully and individually evaluated at the start of long term treatment.

NSAIDs: gastroprotection or selective COX-2 inhibitor?

Conventional nonsteroidal anti-inflammatory drugs (NSAIDs) are effective adjuvant analgesics commonly encountered in palliative care. However, these drugs are associated with adverse effects that are primarily due to gastrointestinal toxicity, with resultant serious complications such as gastroduodenal perforations, ulcers and bleeds. This toxicity has been attributed to inhibition of cyclooxygenase-1 (COX-1). Factors known to increase this risk of toxicity include age above 65 years, classification of NSAID in terms of COX-1/COX-2 selectivity, previous history of complications and coadministration of aspirin, anticoagulants and corticosteroids. Selective inhibitors of cyclooxygenase-2 (COX-2) were developed in an attempt to reduce this association; trials to date confirm that these drugs do indeed have reduced incidence of gastroduodenal toxicity. Prior to the introduction of the COX-2 selective inhibitors, patients at high risk were often coprescribed a gastroprotective agent (such as misoprostol or a proton pump inhibitor) with a conventional NSAID. This review discusses the merits of both options and devises a treatment strategy for the safe and cost-effective use of these drugs in the palliative care population.

The gastrointestinal tolerability of the LOX/COX inhibitor, licofelone, is similar to placebo and superior to naproxen therapy in healthy volunteers: results from a randomized, controlled trial

OBJECTIVES

Concerns exist over the safety of conventional nonsteroidal antiinflammatory drugs (NSAIDs) and selective cyclooxygenase (COX)-2 inhibitors. In experimental models, licofelone, a competitive inhibitor of 5-lipoxygenase (5-LOX) and COX-1/-2, has been shown to have good gastrointestinal and general tolerability and analgesic and antiinflammatory properties. The aim of the present endoscopy trial was to investigate the gastroduodenal tolerability of licofelone compared to placebo and naproxen in healthy volunteers.

METHODS

In this randomized, parallel-group trial, healthy volunteers received licofelone 200 mg b.i.d. (n = 30), licofelone 400 mg b.i.d. (n = 30), naproxen 500 mg b.i.d. (n = 30), or placebo (n = 31). Tolerability was assessed by gastro/duodenoscopy following 4 wk of treatment. Laboratory parameters and the incidence of ulcers and adverse events were recorded.

RESULTS

Ulcers were observed in 20% of the naproxen-treated volunteers, compared with 0% of those receiving licofelone 200 mg, licofelone 400 mg, and placebo (p= 0.024). Posttreatment mean gastric Lanza scores were similar for volunteers who received placebo or either dose of licofelone, while Lanza scores were significantly worse following naproxen therapy (p < 0.00001). The gastric mucosa was normal in 93%, 89%, and 90% of volunteers who received licofelone 200 mg, licofelone 400 mg, or placebo, respectively, compared with 37% of volunteers receiving naproxen. The incidence of adverse events did not differ significantly between licofelone 200 mg or naproxen therapy. No clinically relevant changes in laboratory parameters were observed with licofelone or naproxen therapy.

CONCLUSIONS

The results from this trial indicate that licofelone has a potential gastrointestinal safety advantage over conventional NSAID therapy, as licofelone was associated with significantly superior gastric tolerability and a lower incidence of ulcers compared with naproxen in healthy volunteers. Further trials will be required to investigate the safety and efficacy of licofelone in the treatment of diseases such as osteoarthritis.

A randomized, controlled comparison of ibuprofen at the maximal over-the-counter dose compared with prescription-dose celecoxib on upper gastrointestinal mucosal injury

BACKGROUND & AIMS

Ibuprofen is a well-tolerated nonsteroidal anti-inflammatory drug (NSAID), particularly at over-the-counter (OTC) doses. Cyclooxygenase 2 (COX-2)-selective inhibitors cause less ulceration than prescription-dose nonselective NSAIDs. We compared endoscopic injury related to nonprescription ibuprofen doses with celecoxib, also comparing prescription doses of naproxen with placebo as a positive control.

METHODS

The study was a randomized, placebo-controlled, double blind, double-dummy endoscopic evaluation with concealed allocation. A 2-way crossover with a 4-5-week washout period was used. Participants were healthy adults with normal baseline findings from endoscopy. Ninety-five subjects were randomly assigned, and 79 subjects completed both study phases. Age distribution was reflective of the target population of the OTC agent. Twenty percent were infected with Helicobacter pylori, and 79% and 67% had a current or past medical problem, respectively. Qualifying subjects, stratified by the presence or absence of H. pylori infection (n = 20), were randomly assigned to 1 of the 4 sequences (phase I/II) as follows: ibuprofen/celecoxib; celecoxib/ibuprofen, naproxen/placebo, or placebo/naproxen. Primary end points were the frequency of endoscopic ulcers and erosions in the groups administered: (1) celecoxib vs. ibuprofen and (2) naproxen vs. placebo.

RESULTS

In celecoxib-treated subjects, 2.6% developed ulcers compared with 17.9% of those treated with ibuprofen (P = 0.056). Naproxen treatment was associated with a significantly greater ulceration rate compared with placebo.

CONCLUSIONS

Short-term use of the nonselective COX inhibitors ibuprofen and naproxen is associated with a greater risk for endoscopic mucosal injury compared with the COX-2-selective inhibitor celecoxib or placebo. A prospective analysis appropriately powered to address the incidence of clinically significant gastroduodenal ulceration associated with the short-term use of these agents would be required to further define the clinical relevance of these findings.

Gastrointestinal effects of NSAIDs and coxibs

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world, but their use is limited because of their propensity to cause gastrointestinal (GI) injury. All patients are at risk of GI injury but certain risk factors increase the likelihood of adverse GI effects. The most important include a history of ulcer or GI complications, increasing age, concomitant anticoagulation, concomitant corticosteroid use, and high-dose NSAIDs or multiple NSAIDs (including an NSAID plus low-dose aspirin). Concurrent illness (e.g., severe rheumatoid arthritis, heart disease) has also been reported to increase the risk of GI events. NSAID-associated GI side effects markedly increase health care costs, with up to 31% of cost of managing arthritis patients accounted for through the management of GI side effects. The COX-2 specific inhibitors (coxibs) were developed with the aim of maintaining anti-inflammatory efficacy but improving gastrointestinal safety in comparison to non-selective NSAIDs. The use of COX-2 specific inhibitors significantly decreases the rate of endoscopic ulcers as compared to traditional NSAIDs. Prospective GI outcomes studies also indicate that these agents decrease clinical GI events as compared to non-selective NSAIDs. The number of patients needed to treat to avert one clinical event in one year is approximately 40-100. The cost-effectiveness of coxibs increases (the cost per GI event averted decreases) in patients with high-risk clinical features because they have higher rates of GI hospitalizations and greater use of expensive prophylactic co-therapy.

Pathogenesis and therapy of gastric and duodenal ulcer disease

Despite the decreasing frequency of Helicobacter pylori-induced peptic ulcers, peptic ulcer disease remains a major clinical problem partly because nonsteroidal anti-inflammatory drug ulcers have increased in frequency. The reduction in nonsteroidal anti-inflammatory drug ulcers by use of selective cyclooxygenase-2 inhibitors will not eliminate the problem because of increased use of aspirin for cardiovascular prophylaxis. This article reviews current concepts of peptic ulcer pathogenesis and therapy according to ulcer etiology; discusses potential interactions between etiologies; and considers the therapy for H pylori infection including the effects of antimicrobial resistance, and the role of bismuth quadruple therapy or furazolidone salvage therapy.

Cyclooxygenase selectivity of nonsteroidal anti-inflammatory drugs in canine blood

OBJECTIVE

To evaluate cyclooxygenase (COX) selectivity of several nonsteroidal anti-inflammatory drugs (NSAID) in canine blood in vitro.

ANIMALS

11 healthy adult male hound crosses.

PROCEDURE

9 NSAID were studied at 5 concentrations. Thromboxane B2 (TxB2) was assayed as a measure of COX-1 activity in clotted blood. Prostaglandin E2 (PGE2) was assayed as a measure of COX-2 activity in heparinized, lipopolysaccharide (LPS)-stimulated blood. All assays were competitive ELISA tests. Cyclooxygenase selectivity was expressed as a ratio of the concentration of an NSAID that inhibited 50% of the activity (IC50) of COX-1 to the IC50 of COX-2. A separate ratio of the concentration that inhibited 80% of COX activity (IC80) was also determined. A ratio of < 1.0 indicated selectivity for COX-1, whereas a ratio of > 1.0 indicated COX-2 selectivity.

RESULTS

Ketoprofen, aspirin, and etodolac were COX-1 selective. Piroxicam, meloxicam, and carprofen had COX-2 selectivity. The IC50 and IC80 values were similar for most NSAID.

CONCLUSIONS

This methodology provides repeatable data from individual dogs and is comparable to results of previous in vitro and ex vivo models. Findings are also consistent with those of canine studies performed in vivo, suggesting that this is a viable in vitro assessment of the COX selectivity of NSAID in dogs.

Physiology and organ-related pathology of the elderly: stomach ulcers

Peptic ulcer disease, particularly as a result of its complications, is a burden that is focused on the elderly through their higher Helicobacter pylori prevalence and use of non-steroidal anti-inflammatory drugs (NSAIDs). In these patients, senescence may further increase ulcer susceptibility, particularly in the stomach, by the loss of mucosal protection and repair mechanisms. Age is mainly a marker for the increased prevalence of other complicated ulcer risk factors such as previous ulcer history and use of anti-coagulants, steroids and aspirin. The development of selective cyclo-oxygenase inhibitors (coxibs) has reduced the specific risk of NSAID ulceration, but the residual incidence in high risk patients remains substantially higher than that in young patients without other risk factors. The argument for early surgery versus endoscopic therapy in high risk patients with bleeding ulcers has not been resolved, both having a high mortality. There is still potential for the development of new strategies to prevent primary and secondary ulcers, either by new drug development or by expanding existing co-prescription strategies.

Nonsteroidal anti-inflammatory drug gastrointestinal toxicity

Toxic effects in the upper gastrointestinal tract, primarily complicated gastric and intestinal ulcers, are the most common undesirable effects of the nonsteroidal anti-inflammatory drugs. During the last several years, there have been several advances, both in the laboratory and clinically, toward reducing nonsteroidal anti-inflammatory drugs' gastrointestinal toxicity. Some of these important developments are the delineation of mechanisms of nonsteroidal anti-inflammatory drug-induced gastrointestinal toxicity, identification of groups at highest risk for development of nonsteroidal anti-inflammatory drug-induced gastrointestinal complications, recognition of co-therapies that could reduce nonsteroidal anti-inflammatory drug toxicity, and, most recently, development of classes of nonsteroidal anti-inflammatory drugs with improved gastrointestinal safety profiles. Many of these advances have occurred during the last year. This review focuses on several of the important recent observations that have improved understanding and safety of nonsteroidal anti-inflammatory drugs in the gastrointestinal tract.

Inhibition of COX in ocular tissues: an in vitro model to identify selective COX-2 inhibitors

The aim of this work was to study the regulation of LPS-stimulated PGE 2 synthesis by traditional NSAIDs (piroxicam and diclofenac) and a selective COX-2 inhibitor (NS-398), in cultured bovine corneal endothelial cells and retinal pigmentary epithelial cells. The IC50 values of piroxicam and diclofenac were compared with IC50 values of NS-398, diclofenac, in both types of cells, showed higher potency than piroxicam. Diclofenac seemed to be a COX-2 inhibitor because its IC50 values were similar to the IC50 values of NS-398. We suggest that this in vitro cell assay system could be useful for identifying compounds that selectively inhibit COX-2 in ocular tissues.

Approaches to nonsteroidal anti-inflammatory drug use in the high-risk patient

Nonsteroidal anti-inflammatory drugs (NSAIDs) are probably the most common cause of gastroduodenal injury in the United States today. Approximately half of patients who regularly take NSAIDs have gastric erosions, and 15%-30% have ulcers when they are examined endoscopically. However, the incidence of clinical gastrointestinal (GI) events caused by NSAIDs is much lower. Clinical upper GI events may occur in 3%-4.5% of patients taking NSAIDs, and serious complicated events develop in approximately 1.5%. However, the risk varies widely in relationship to clinical features such as history of ulcers or GI events, age, concomitant anticoagulant or steroid use, and NSAID dose. This review discusses the risks of clinical GI disease in NSAID users, the predictors of increased risk, and strategies for prevention of NSAID-associated GI disease.

The effectiveness of prophylactic etodolac on postendodontic pain

To determine if prophylactic etodolac would significantly reduce postendodontic pain, when compared with ibuprofen or placebo, 36 patients consented to single blind oral administration of either 400 mg of etodolac, 600 mg of ibuprofen, or a placebo, before conventional one-appointment root canal therapy. Patient-reported visual analog scale ratings of pain intensity were conducted upon initial clinical presentation, immediately postoperative, 4, 8, 12, 24, 48, and 72 h after initiation of root canal therapy. Results showed that prophylactic ibuprofen administration significantly reduced postendodontic pain at 4 and 8 h after initiation of root canal therapy, when compared with etodolac and a placebo. Patients with a periapical diagnosis of acute apical periodontitis or with a Phoenix abscess showed a significant increased need for additional medication after completion of root canal therapy, compared with all other periapical diagnoses.

NSAID gastrointestinal toxicity

Toxic effects in the upper gastrointestinal tract, primarily complicated gastric and intestinal ulcers, are the most common undesirable effects of the nonsteroidal antiinflammatory drugs (NSAIDs). During the last several years there have been several advances, both in the laboratory and clinically, toward reducing NSAIDs' gastrointestinal toxicity. Some of these important developments have been the delineation of mechanisms of NSAID-induced GI toxicity, identification of groups at highest risk for development of NSAID-induced gastrointestinal complications, recognition of co-therapies that could reduce NSAID toxicity, and, most recently, development of classes of NSAIDs that have an improved gastrointestinal safety profile. Many of these advances occurred during the last year. This review focuses on several of the important recent observations that have improved our understanding and the safety of NSAIDs in the gastrointestinal tract.

Nonsteroidal anti-inflammatory drug gastrointestinal toxicity

Nonsteroidal anti-inflammatory drugs (NSAIDs) are currently the most widely used class of therapeutic agents. By inhibiting cyclooxygenase (COX) and reducing gastrointestinal prostaglandins, they provide effective analgesia and suppress inflammation in a variety of conditions. However, through the same mechanism of COX inhibition, they also cause significant gastrointestinal toxicity. One of the most common methods to reduce NSAID-induced gastrointestinal toxicity has been to co-prescribe prophylactic therapies such as acid-reducing agents or the synthetic prostaglandin analogue, misoprostol. More recently safer NSAIDs, such as the COX-2 specific NSAIDs or the nitric oxide-releasing NSAIDs, have been developed or are currently in development. This article reviews mechanisms of NSAID-induced gastrointestinal toxicity. Also reviewed are data on the gastrointestinal consequences of the prophylatic co-therapies, COX-2 specific NSAIDs and nitric oxide-releasing NSAIDs.

A randomized trial comparing the effect of rofecoxib, a cyclooxygenase 2-specific inhibitor, with that of ibuprofen on the gastroduodenal mucosa of patients with osteoarthritis. Rofecoxib Osteoarthritis Endoscopy Study Group

BACKGROUND & AIMS

Prostaglandin production in the normal gastrointestinal tract, believed to be critical for mucosal integrity, is mediated by cyclooxygenase (COX)-1, whereas prostaglandin production at inflammatory sites seems to occur via induction of COX-2. We hypothesized that COX-2-specific inhibition with rofecoxib (25 mg once daily) in the treatment of patients with osteoarthritis would cause fewer gastroduodenal ulcers than an equally effective dose of ibuprofen (800 mg 3 times a day), a nonspecific COX inhibitor.

METHODS

A total of 742 osteoarthritis patients without ulcers on baseline endoscopy were randomly assigned to receive rofecoxib (25 or 50 mg once daily), ibuprofen (800 mg 3 times daily), or placebo. Endoscopy was repeated at 6, 12, and 24 weeks. At 16 weeks, by study design, 95% of the placebo group and 5% of the other groups were discontinued.

RESULTS

The cumulative incidence of gastroduodenal ulcers >/=3 mm with rofecoxib (25 or 50 mg once daily) was significantly (P < 0.001) lower than with ibuprofen and was statistically equivalent to placebo at week 12 (placebo, 9.9%; 25 mg rofecoxib, 4.1%; 50 mg rofecoxib, 7.3%; and ibuprofen, 27.7%). At 24 weeks, ulcer rates were 25 mg rofecoxib, 9. 6%; 50 mg rofecoxib, 14.7%; and ibuprofen, 45.8% (P < 0.001, ibuprofen vs. 25 and 50 mg rofecoxib).

CONCLUSIONS

Rofecoxib, at doses 2-4 times the dose demonstrated to relieve symptoms of osteoarthritis, caused significantly less gastroduodenal ulceration than ibuprofen, with ulcer rates comparable to placebo.

Non-steroidal anti-inflammatory drugs (NSAIDs) and gastro-intestinal toxicity: current issues

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs and their widespread use is associated with increased gastro-intestinal toxic effects such as ulceration, haemorrhage, perforation and death. They result in these complications mainly by reducing cytoprotective prostaglandins (PGE2 and PGI2) in the stomach, through the inhibition of cyclo-oxygenase (COX) enzyme. The increased morbidity and mortality, in addition to enormous cost, associated with NSAID-associated side effects, necessitates a need for safer GI-friendly NSAID. Various approaches have been used to counteract NSAID associated side effects with varying degrees of success and acceptance. These include the use of alternative analgesia, anti-acid secretory agents like proton pump inhibitors, sucralfate and prostaglandin analogues. In addition, new types of NSAIDs are being developed, based on new understanding of their mechanism of action and the pathogenesis of inflammation. These include a new class of NSAIDs called "selective Cox-2 inhibitors". These agents preserve the COX-1 that is responsible for the production of cytoprotective prostaglandins in the stomach and selectively inhibit COX-2 induced at the sites of inflammation. Selective COX-2 inhibitors exert the same analgesic and anti-inflammatory effects as the existing NSAIDs but may be less toxic to the stomach. In this review the background development and well-structured clinical trials on this new generation NSAIDs are discussed.

Review article: nonsteroidal anti-inflammatory drug-associated gastrointestinal complications--guidelines for prevention and treatment

Chronic ingestion of NSAIDs increases the risk for gastrointestinal complications, which range from dyspepsia to gastrointestinal bleeding, obstruction, and perforation. Among patients using NSAIDs, 0.1 to 2.0% per year suffer serious gastrointestinal complications. Patients who require analgesic therapy should be carefully assessed for the lowest possible dosage and shortest duration of NSAID use and for the potential of treatment with a non-NSAID pain reliever. These patients should also be assessed for factors that increase their risk of gastrointestinal complications, including increased age, concomitant anticoagulant or corticosteroid use, and past history of NSAID-associated gastrointestinal complications. The exact association between Helicobacter pylori infection and NSAID-related ulcer disease is unclear, and the routine testing and treatment of all NSAID using patients for H. pylori infection is not recommended at this time. NSAID-using patients who suffer from dyspepsia should have NSAIDs discontinued, the dosage changed, or be changed to a different class of NSAID. If NSAIDs cannot be discontinued, then an antisecretory agent should be initiated. Misoprostol prevents NSAID-associated gastrointestinal complications. Proton pump inhibitors are the most effective at healing NSAID-associated ulcers among patients who cannot discontinue NSAID therapy.

Conventional and extended-release etodolac for postsurgical dental pain

This double-masked, parallel-group, randomized study compared the analgesic efficacy and tolerability of a single investigational 1200-mg dose of extended-release etodolac with those of a single 400-mg dose of extended-release etodolac and twice-daily doses of conventional etodolac 200 and 400 mg and placebo given 8 hours apart in 237 patients with moderate or severe postoperative pain following surgical removal of > or = 2 impacted third molars. Both doses of conventional etodolac and the 1200-mg dose of extended-release etodolac were significantly more effective on all summary analgesic measures than placebo (P < 0.05). Conventional etodolac had an onset of analgesic activity within 45 (400 mg) to 60 (200 mg) minutes and an analgesic duration of 5 to 6 hours. Extended-release etodolac 1200 mg had an onset of action within 60 minutes and an analgesic duration of 12 to 24 hours. At hours 2 and 3, conventional etodolac 400 mg was significantly more effective than the other treatments; from hours 6 through 12, extended-release etodolac 1200 mg was significantly more effective than the other treatments (both, P < 0.05). No serious adverse events were observed in this study, with an incidence of side effects in the active etodolac groups no different than that with placebo. Extended-release etodolac 1200 mg has a prolonged analgesic duration and an acceptable side-effect profile in the oral surgery pain model.

Arthrotec: the evidence speaks for itself

This article examines the most recently published scientific literature on arthritis therapy options and available mucosal-protective agents. Emphasis is placed on the risks of current nonsteroidal anti-inflammatory drug (NSAID) therapy, the options for reducing such risks, and the published information that either supports or refutes current thinking in these areas. A comprehensive evaluation is made of clinical data related to the use of Arthrotec (diclofenac/misoprostol) in the treatment of arthritis. A recent meta-analysis of the prophylaxis of NSAID-associated upper gastrointestinal complications is reviewed. The results of this meta-analysis should help to consolidate much of the current scientific literature on the safe and effective treatment of arthritis.

Preventing NSAID Toxicity to the Upper Gastrointestinal Tract

Prevention of gastrointestinal toxicity begins with the selection of an appropriate analgesic or anti-inflammatory agent. For conditions without inflammation, such as some cases of osteoarthritis, an analgesic with no risk for gastrointestinal toxicity is appropriate. Risk factors for nonsteroidal anti-inflammatory drug (NSAID)-related complications include advanced age; history of ulcer disease or gastrointestinal bleeding; concomitant corticosteroid or anticoagulant use; use of high-dose or multiple NSAIDs; and certain chronic diseases, such as cardiovascular disease. If an NSAID must be used in a patient with risk factors, the patient should receive the lowest-risk NSAID and, in most cases, co-therapy to reduce the risk for NSAID-associated ulcers and their complications. The PGE1 prostaglandin analogue misoprostol is highly efficacious for the prevention of both gastric and duodenal ulcers and has also been shown to reduce the incidence of NSAID-induced ulcer complications. Side effects, such as diarrhea, may limit patient acceptance of the drug. Acid suppression with traditional ulcer-healing doses of H2-blockers significantly reduces rates of duodenal ulcer but is ineffective in reducing gastric ulceration. More potent acid inhibition with double-dose H2-blockers reduces rates of both gastric and duodenal ulcers. Proton-pump inhibitors, such as omeprazole, have been shown to prevent gastric and duodenal ulcers with an efficacy equal to that of misoprostol. They also reduce NSAID-related dyspepsia. Specific cyclooxygenase-2 (COX-2) inhibitors are associated with a markedly reduced rate of endoscopic ulcers. Very high-risk patients who receive these agents may still require co-therapy to prevent complications or reduce dyspepsia. This protocol may be changed by the results of long-term gastrointestinal outcome studies now underway.

Pathogenesis of nonsteroidal anti-inflammatory drug-related upper gastrointestinal toxicity

The mechanisms involved in the pathogenesis of ulcers associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) have not been fully elucidated. Although studies using acute mucosal injury as a surrogate for clinically relevant outcomes have provided useful information, in practice, acute mucosal injury does not necessarily provide a reliable predictor of clinical ulcers or complications. Several factors that increase the risk of NSAID-associated gastroenteropathy have been identified, and there are data to support or provide speculation for other physiologic factors that might predispose specific subsets of patients to increased mucosal injury. Since clinically significant events occur less frequently than does ulceration, it is the latter determinant, i.e., the identification of the traits that distinguish patients who develop serious NSAID-associated gastrointestinal (GI) toxicity from those who can tolerate these drugs, that may provide the clues necessary to understand the events underlying ulcer pathogenesis.

Safety profiles of leading nonsteroidal anti-inflammatory drugs

Recently introduced nonsteroidal anti-inflammatory drugs (NSAIDs) have capitalized on new formulations or unique physical and pharmacologic properties in an attempt to provide a greater margin of gastrointestinal (GI) safety. The use of enteric coatings and nonoral or pro-drug formulations have not necessarily provided the expected safety, but other properties have been identified that appear to be more promising. However, as demonstrated by oxaprozin, considered to be one of the least safe NSAIDs but one of the leading drugs on the US market, success may not be dependent on safety. In contrast, the improved tolerability of 2 other new NSAIDs, nabumetone and etodolac, has been established in clinical trials and limited postmarketing surveillance. This improved tolerability is probably associated with several pharmacologic properties that have been suggested to contribute to GI safety: (1) nonacidic pro-drug formulation; (2) lack of enterohepatic recirculation; (3) a short plasma half-life; and (4) preferential inhibition of cyclo-oxygenase-2 (COX-2). Although these factors may not improve efficacy, their incorporation into the design of drugs suggests that safer NSAIDs may be a clinical reality. However, the safety and clinical value of any new drug for the general population will be validated only through extensive postmarketing surveillance.

Future trends in the development of safer nonsteroidal anti-inflammatory drugs

Gastrointestinal (GI) adverse events, ranging from mild to life-threatening, are well-recognized sequelae to nonsteroidal anti-inflammatory drug (NSAID) use. Recent improvements in our knowledge of the mechanisms responsible for NSAID-associated gastropathy have enabled several experimental approaches to decreasing the risk of these events. Whereas such strategies as preassociation of NSAIDs to zwitterionic phospholipids to prevent NSAID-mucosal interactions and concomitant administration of trefoil peptides to stimulate mucosal defense pathways represent novel approaches, their clinical feasibility remains to be determined. Other strategies that appear more immediately promising in the reduction of NSAID-associated GI toxicity are the coupling of NSAIDs to nitric oxide (NO)-releasing compounds and the introduction of NSAIDs that are preferential or specific for cyclo-oxygenase-2 (COX-2), the isoform implicated in the inflammatory response. Clinical trials of several specific COX-2 inhibitors, as well as European clinical data for a preferential COX-2 inhibitor, meloxicam, suggest that COX-2 inhibitors provide an advantage over standard NSAIDs in terms of GI tolerability. However, as recent observations have implicated COX-2 as an integral component in the maintenance of physiologic homeostasis, careful scrutiny of both the beneficial and the deleterious effects of the selective COX-2 inhibitors is requisite before their approval and widespread use. Furthermore, based on the physiologic importance of COX-2, the preferential inhibitors may ultimately prove to represent the optimal compromise for the treatment of various arthritides.

The relation between Helicobacter pylori and nonsteroidal anti-inflammatory drugs

Both infection with Helicobacter pylori and use of nonsteroidal anti-inflammatory drugs (NSAIDs) can result in gastritis and ulcers. H. pylori has been identified as a major etiologic factor in the development of peptic ulcer disease; however, its relationship to NSAID-associated toxicity is less well characterized. Several studies have suggested that NSAID use does not increase susceptibility to H. pylori, and the converse has also been suggested, namely, that H. pylori does not exacerbate NSAID-associated injury. H. pylori itself may stimulate production of gastric prostaglandins, which may have a role in ulcer healing. More carefully controlled studies may be better able to elucidate the individual and synergistic mechanisms involved in ulceration induced by H. pylori and NSAIDs. Recent studies have suggested that elimination of H. pylori before NSAID treatment decreases ulcer occurrence. Therefore, at this time, eradication of H. pylori should be considered only in certain high-risk patients, i.e., those with a history of gastroduodenal ulcers.

Preliminary study of the safety and efficacy of SC-58635, a novel cyclooxygenase 2 inhibitor: efficacy and safety in two placebo-controlled trials in osteoarthritis and rheumatoid arthritis, and studies of gastrointestinal and platelet effects

OBJECTIVE

To investigate the efficacy and safety of SC-58635 (celecoxib), an antiinflammatory and analgesic agent that acts by selective cyclooxygenase 2 (COX-2) inhibition and is not expected to cause the typical gastrointestinal (GI), renal, and platelet-related side effects associated with inhibition of the COX-1 enzyme.

METHODS

Four phase II trials were performed: a 2-week osteoarthritis efficacy trial, a 4-week rheumatoid arthritis efficacy trial, a 1-week endoscopic study of GI mucosal effects, and a 1-week study of effects on platelet function.

RESULTS

The 2 arthritis trials identified SC-58635 dosage levels that were consistently effective in treating the signs and symptoms of arthritis and were distinguished from placebo on standard arthritis scales. In the upper GI endoscopy study, 19% of subjects receiving naproxen (6 of 32) developed gastric ulcers, whereas no ulcers occurred in subjects receiving SC-58635 or placebo. The study of platelet effects revealed no meaningful effect of SC-58635 on platelet aggregation or thromboxane B2 levels, whereas aspirin caused significant decreases in 2 of 3 platelet aggregation measures and thromboxane B2 levels. In all 4 trials, SC-58635 was well tolerated, with a safety profile similar to that of placebo.

CONCLUSION

SC-58635 achieves analgesic and antiinflammatory efficacy in arthritis through selective COX-2 inhibition, without showing any evidence of 2 of the toxic effects of COX-1 inhibition associated with nonsteroidal antiinflammatory drugs.

The effect of aspirin and nonsteroidal anti-inflammatory drugs on prostaglandins

Cyclic prostanoids play important physiologic roles in inflammation and maintaining normal function of several organ systems. Prostaglandin production requires the conversion of arachidonate to the intermediate prostaglandin H2, by the 2-step cyclo-oxygenation and peroxidation catalyzed by the enzyme cyclo-oxygenase (also called prostaglandin H synthase). Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) block the production of cyclic prostanoids by binding in different ways to this enzyme and blocking the active site. This results in decreased inflammation, but it can also produce side effects in the gastrointestinal tract, kidney, and platelets. Recent data demonstrate that there are 2 isoforms of the cyclo-oxygenase enzyme, called COX-1 and COX-2. These isoforms are similar in size, substrate specificity, and kinetics, but vary in their expression and distribution. Normal physiologic functions appear to be maintained by COX-1, while COX-2 appears to mediate the inflammatory response. Nonsteroidal drugs with selective inhibitory activity on the COX-2 isoform should theoretically decrease inflammation while maintaining normal physiologic prostaglandin levels. Current NSAIDs are not selective enough to confirm this, but newer, more selective inhibitors of COX-2 may answer this important question.

Gastrointestinal side effects of nonsteroidal anti-inflammatory drugs

The gastrointestinal (GI) tract is the most common location for side effects of nonsteroidal anti-inflammatory drugs (NSAIDs). These drugs may cause problems in any part of the GI tract, from the esophagus to the rectum. The severity of these side effects ranges from nuisance symptoms such as dyspepsia to life-threatening ulcer complications. The diagnosis, treatment, and prevention of the various GI side effects of these commonly prescribed drugs are reviewed in this article.

Comparison of cyclooxygenase-1 and -2 inhibitory activities of various nonsteroidal anti-inflammatory drugs using human platelets and synovial cells

Recent studies have shown that cyclooxygenase exists in two isozyme forms. Since differences in the pharmacological profiles of nonsteroidal anti-inflammatory drugs (NSAIDs) might be accounted for by varying degrees of selectivity for these isozymes, cyclooxygenase-1 and -2, the relative potency of various NSAIDs in inhibiting their activities was examined in intact human cells. We used human platelets cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell cyclooxygenase-2 for measuring cyclooxygenase selectivity. The presence of the enzymes was confirmed by immunoblotting and immunoprecipitation analysis, and by the reverse transcriptase-polymerase chain reaction. Mean IC50 values (microM) for human platelet cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell cyclooxygenase-2 and cyclooxygenase-1/-2 IC50 ratio of various NSAIDs were as follows: aspirin, 3.2, 26, 0.12; diclofenac, 0.037, 0.00097, 38; etodolac, 122, 0.68, 179; ibuprofen, 3.0, 3.5, 0.86; indomethacin, 0.013, 0.044, 0.30; loxoprofen (active metabolite), 0.38, 0.12, 3.2; NS-398, 12, 0.0095, 1263; oxaprozin, 2.2, 36, 0.061; zaltoprofen, 1.3, 0.34, 3.8; respectively. Our bioassay system employing intact human cells to assess the cyclooxygenase selectivity of NSAIDs may provide clinically useful information.

Clinical endoscopic evaluation of the gastroduodenal tolerance to (R)- ketoprofen, (R)- flurbiprofen, racemic ketoprofen, and paracetamol: a randomized, single-blind, placebo-controlled trial

Ketoprofen, a nonsteroidal anti-inflammatory drug (NSAID) of the 2-arylpropionic acid class, causes gastroduodenal hemorrhages and erosions in 10-15% of patients. The (S)- enantiomer exhibits most of the anti-inflammatory properties, with concomitant gastrointestinal toxicity. The (R)- enantiomer, however, was recently found to have analgesic properties independent of prostaglandin inhibition. Seventy-two healthy male volunteers not receiving NSAIDs, alcohol, or anti-ulcer drugs, were enrolled in a randomized, investigator-blind, placebo-controlled trial to evaluate the gastroduodenal tolerance of (R)- ketoprofen 100 mg b.i.d., (R)- flurbiprofen 100 mg b.i.d., racemic ketoprofen 100 mg b.i.d., and paracetamol 1,000 mg b.i.d. Gastroduodenal endoscopies at baseline and after 2.5 days of dosing were used to detect newly occurring hemorrhages and erosions. Adverse events were also recorded. The incidence of submucosal hemorrhages was 4/16 in the (R)- ketoprofen group, 5/16 in the (R)- flurbiprofen group, 12/16 in the racemic ketoprofen group, 1/16 in the paracetamol group, and 1/8 in the placebo group. The incidence of erosions was 2/16 in the (R)- ketoprofen group, 4/16 in the (R)- flurbiprofen group, 10/16 in the racemic ketoprofen group, 0/16 in the paracetamol group, and 2/8 in the placebo group. The differences in hemorrhages and erosions among treatments were statistically significant (gastric hemorrhages P = 0.0008; duodenal hemorrhages P = 0.00062; gastric erosions P = 0.0004; duodenal erosions P = 0.0062, Kruskal-Wallis test). At 100 mg b.i.d., (R)- ketoprofen caused fewer gastroduodenal hemorrhages and erosions than racemic ketoprofen (P = 0.019, P = 0.0112, P = 0.0097, P = 0.0139 for gastric, duodenal hemorrhages and gastric, duodenal erosions, respectively). The difference between 100 mg b.i.d. (R)- ketoprofen and 100 mg b.i.d. (R)- flurbiprofen was not statistically significant. The dissociation between analgesic and anti-inflammatory properties for (R)- ketoprofen suggests that it may represent a unique analgesic with a favorable safety profile.

Biochemical and pharmacological profile of a tetrasubstituted furanone as a highly selective COX-2 inhibitor

1. DFU (5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furan one) was identified as a novel orally active and highly selective cyclo-oxygenase-2 (COX-2) inhibitor. 2. In CHO cells stably transfected with human COX isozymes, DFU inhibited the arachidonic acid-dependent production of prostaglandin E2 (PGE2) with at least a 1,000 fold selectivity for COX-2 (IC50 = 41 +/- 14 nM) over COX-1 (IC50 > 50 microM). Indomethacin was a potent inhibitor of both COX-1 (IC50 = 18 +/- 3 nM) and COX-2 (IC50 = 26 +/- 6 nM) under the same assay conditions. The large increase in selectivity of DFU over indomethacin was also observed in COX-1 mediated production of thromboxane B2 (TXB2) by Ca2+ ionophore-challenged human platelets (IC50 > 50 microM and 4.1 +/- 1.7 nM, respectively). 3. DFU caused a time-dependent inhibition of purified recombinant human COX-2 with a Ki, value of 140 +/- 68 microM for the initial reversible binding to enzyme and a kappa 2 value of 0.11 +/- 0.06 s-1 for the first order rate constant for formation of a tightly bound enzyme-inhibitor complex. Comparable values of 62 +/- 26 microM and 0.06 +/- 0.01 s-1, respectively, were obtained for indomethacin. The enzyme-inhibitor complex was found to have a 1:1 stoichiometry and to dissociate only very slowly (t1/2 = 1-3 h) with recovery of intact inhibitor and active enzyme. The time-dependent inhibition by DFU was decreased by co-incubation with arachidonic acid under non-turnover conditions, consistent with reversible competitive inhibition at the COX active site. 4. Inhibition of purified recombinant human COX-1 by DFU was very weak and observed only at low concentrations of substrate (IC50 = 63 +/- 5 microM at 0.1 microM arachidonic acid). In contrast to COX-2, inhibition was time-independent and rapidly reversible. These data are consistent with a reversible competitive inhibition of COX-1. 5. DFU inhibited lipopolysaccharide (LPS)-induced PGE2 production (COX-2) in a human whole blood assay with a potency (IC50 = 0.28 +/- 0.04 microM) similar to indomethacin (IC50 = 0.68 +/- 0.17 microM). In contrast, DFU was at least 500 times less potent (IC50 > 97 microM) than indomethacin at inhibiting coagulation-induced TXB2 production (COX-1) (IC50 = 0.19 +/- 0.02 microM). 6. In a sensitive assay with U937 cell microsomes at a low arachidonic acid concentration (0.1 microM), DFU inhibited COX-1 with an IC50 value of 13 +/- 2 microM as compared to 20 +/- 1 nM for indomethacin. CGP 28238, etodolac and SC-58125 were about 10 times more potent inhibitors of COX-1 than DFU. The order of potency of various inhibitors was diclofenac > indomethacin approximately naproxen > nimesulide approximately meloxicam approximately piroxicam > NS-398 approximately SC-57666 > SC-58125 > CGP 28238 approximately etodolac > L-745,337 > DFU. 7. DFU inhibited dose-dependently both the carrageenan-induced rat paw oedema (ED50 of 1.1 mg kg-1 vs 2.0 mg kg-1 for indomethacin) and hyperalgesia (ED50 of 0.95 mg kg-1 vs 1.5 mg kg-1 for indomethacin). The compound was also effective at reversing LPS-induced pyrexia in rats (ED50 = 0.76 mg kg-1 vs 1.1 mg kg-1 for indomethacin). 8. In a sensitive model in which 51Cr faecal excretion was used to assess the integrity of the gastrointestinal tract in rats, no significant effect was detected after oral administration of DFU (100 mg kg-1, b.i.d.) for 5 days, whereas chromium leakage was observed with lower doses of diclofenac (3 mg kg-1), meloxicam (3 mg kg-1) or etodolac (10-30 mg kg-1). A 5 day administration of DFU in squirrel monkeys (100 mg kg-1) did not affect chromium leakage in contrast to diclofenac (1 mg kg-1) or naproxen (5 mg kg-1). 9. The results indicate that COX-1 inhibitory effects can be detected for all selective COX-2 inhibitors tested by use of a sensitive assay at low substrate concentration. The novel inhibitor DFU shows the lowest inhibitory potency against COX-1, a consistent high selectivity of inhibition of COX-2 over COX-1 (>300 fold) with enzyme, whole cell and whole blood assays, with no detectable loss of integrity of the gastrointestinal tract at doses >200 fold higher than efficacious doses in models of inflammation, pyresis and hyperalgesia. These results provide further evidence that prostanoids derived from COX-1 activity are not important in acute inflammatory responses and that a high therapeutic index of anti-inflammatory effect to gastropathy can be achieved with a selective COX-2 inhibitor.

Nonsteroidal anti-inflammatory drug-induced gastrointestinal injury

Nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, are the most commonly used medications worldwide. They are effective analgesic and anti-inflammatory agents. A major drawback to their use is a high frequency of adverse gastrointestinal (GI) effects that cause significant morbidity, occasional mortality, and substantial increases in cost of therapy. In this review, mechanisms of NSAID-induced GI injury are presented, and a clinical approach to diagnosis, treatment, and prevention of these adverse GI effects is provided.

Etodolac selectively inhibits human prostaglandin G/H synthase 2 (PGHS-2) versus human PGHS-1

The isozymes of prostaglandin G/H synthase (PGHS) are shown to be differentially inhibited in vitro by currently marketed nonsteroidal anti-inflammatory drugs (NSAIDs) using microsomal rhPGHS-1 and rhPGHS-2. Comparison of selectivity ratios (IC50 rhPGHS-1/IC50 rhPGHS-2) demonstrated a 10-fold selectivity of etodolac (Lodine) for rhPGHS-2, whereas the other NSAIDs evaluated demonstrated no preference or a slight preference for inhibition of rhPGHS-1. In vitro enzyme results were supported by a human whole blood assay where etodolac also demonstrated a 10-fold selectivity for inhibition of PGHS-2 mediated TxB2 production. Taken together, these data may be key to explaining the clinically observed gastrointestinal safety of etodolac versus other marketed NSAIDs.