Interaction Between Low-Dose Aspirin and Nonsteroidal Anti-Inflammatory Drugs Can Compromise Aspirin's Efficacy in Preventing Venous Thrombosis Following Total Joint Arthroplasty

Total joint arthroplasty is a rapid recovery procedure with patients optimized quickly in preparation for discharge. Two significant postoperative goals are effective pain management and prevention of postoperative venous thromboembolism (VTE). Low-risk patients receive aspirin 81 mg twice daily for VTE prophylaxis; this dosing regimen has been reduced over the past few years from 325 mg to 162 mg to 81 mg twice daily. Unless contraindications exist, all patients receive multimodal pain management that includes the use of celecoxib or meloxicam. Upon reduction of the aspirin dose to 81 mg twice daily, we rapidly identified 2 patients who developed a pulmonary embolus when celecoxib or meloxicam was administered concurrently with aspirin. The interaction between nonsteroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin varies among the different NSAIDs. It is also highly dependent on numerous factors, including time of administration, dose of aspirin, and both pharmacodynamics and dose of the NSAID. Real-world outcomes of concomitant administration of NSAIDs with low-dose aspirin led to increased incidence of VTE, possibly due to competitive inhibition of aspirin at platelet receptor sites. This interaction was mitigated by altering the administration times of both agents.

Lessons Learned: Using the Caprini Risk Assessment Model to Provide Safe and Efficacious Thromboprophylaxis Following Hip and Knee Arthroplasty

Two of the more common potential complications after arthroplasty are venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolus (PE), and excess bleeding. Appropriate chemoprophylaxis choices are essential to prevent some of these adverse events and from exacerbating others. Risk stratification to prescribe safe and effective medications in the prevention of postoperative VTE has shown benefit in this regard. The Department of Orthopaedic Surgery at Syosset Hospital/Northwell Health, which performs over 1200 arthroplasties annually, has validated and is using the 2013 version of the Caprini Risk Assessment Model (RAM) to stratify each patient for risk of postoperative VTE. This tool results in a culling of information, past and present, personal and familial, that provides a truly thorough evaluation of the patient's risk for postoperative VTE. The Caprini score then guides the medication choices for thromboprophylaxis. The Caprini score is only valuable if the data is properly collected, and we have learned numerous lessons after applying it for 18 months. Risk stratification requires practice and experience to achieve expertise in perioperative patient evaluation. Having access to pertinent patient information, while gaining proficiency in completing the Caprini RAM, is vital to its efficacy. Ongoing, real time analyses of patient outcomes, with subsequent change in process, is key to improving patient care.

Cardio-renal safety of non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used therapeutic class in clinical medicine. These are sub-divided based on their selectivity for inhibition of cyclooxygenase (COX) isoforms (COX-1 and COX-2) into: (1) non-selective (ns-NSAIDs), and (2) selective NSAIDs (s-NSAIDs) with preferential inhibition of COX-2 isozyme. The safety and pathophysiology of NSAIDs on the renal and cardiovascular systems have continued to evolve over the years following short- and long-term treatment in both preclinical models and humans. This review summarizes major learnings on cardiac and renal complications associated with pharmaceutical inhibition of COX-1 and COX-2 with focus on preclinical to clinical translatability of cardio-renal data.

The prognostic utility of tests of platelet function for the detection of 'aspirin resistance' in patients with established cardiovascular or cerebrovascular disease: a systematic review and economic evaluation

BACKGROUND

The use of aspirin is well established for secondary prevention of cardiovascular disease. However, a proportion of patients suffer repeat cardiovascular events despite being prescribed aspirin treatment. It is uncertain whether or not this is due to an inherent inability of aspirin to sufficiently modify platelet activity. This report aims to investigate whether or not insufficient platelet function inhibition by aspirin ('aspirin resistance'), as defined using platelet function tests (PFTs), is linked to the occurrence of adverse clinical outcomes, and further, whether or not patients at risk of future adverse clinical events can be identified through PFTs.

OBJECTIVES

To review systematically the clinical effectiveness and cost-effectiveness evidence regarding the association between PFT designation of 'aspirin resistance' and the risk of adverse clinical outcome(s) in patients prescribed aspirin therapy. To undertake exploratory model-based cost-effectiveness analysis on the use of PFTs.

DATA SOURCES

Bibliographic databases (e.g. MEDLINE from inception and EMBASE from 1980), conference proceedings and ongoing trial registries up to April 2012.

METHODS

Standard systematic review methods were used for identifying clinical and cost studies. A risk-of-bias assessment tool was adapted from checklists for prognostic and diagnostic studies. (Un)adjusted odds and hazard ratios for the association between 'aspirin resistance', for different PFTs, and clinical outcomes are presented; however, heterogeneity between studies precluded pooling of results. A speculative economic model of a PFT and change of therapy strategy was developed.

RESULTS

One hundred and eight relevant studies using a variety of PFTs, 58 in patients on aspirin monotherapy, were analysed in detail. Results indicated that some PFTs may have some prognostic utility, i.e. a trend for more clinical events to be associated with groups classified as 'aspirin resistant'. Methodological and clinical heterogeneity prevented a quantitative summary of prognostic effect. Study-level effect sizes were generally small and absolute outcome risk was not substantially different between 'aspirin resistant' and 'aspirin sensitive' designations. No studies on the cost-effectiveness of PFTs for 'aspirin resistance' were identified. Based on assumptions of PFTs being able to accurately identify patients at high risk of clinical events and such patients benefiting from treatment modification, the economic model found that a test-treat strategy was likely to be cost-effective. However, neither assumption is currently evidence based.

LIMITATIONS

Poor or incomplete reporting of studies suggests a potentially large volume of inaccessible data. Analyses were confined to studies on patients prescribed aspirin as sole antiplatelet therapy at the time of PFT. Clinical and methodological heterogeneity across studies precluded meta-analysis. Given the lack of robust data the economic modelling was speculative.

CONCLUSIONS

Although evidence indicates that some PFTs may have some prognostic value, methodological and clinical heterogeneity between studies and different approaches to analyses create confusion and inconsistency in prognostic results, and prevented a quantitative summary of their prognostic effect. Protocol-driven and adequately powered primary studies are needed, using standardised methods of measurements to evaluate the prognostic ability of each test in the same population(s), and ideally presenting individual patient data. For any PFT to inform individual risk prediction, it will likely need to be considered in combination with other prognostic factors, within a prognostic model.

STUDY REGISTRATION

This study is registered as PROSPERO 2012:CRD42012002151.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Celecoxib interferes to a limited extent with aspirin-mediated inhibition of platelets aggregation

AIMS

The aim of the study was to analyze the interaction between celecoxib and low dose aspirin for COX-1 binding and its consequences on the aspirin-mediated antiplatelet effects.

METHODS

We investigated ex vivo the interaction between celecoxib and aspirin for COX-1 binding and measured the resulting antiplatelet effects. We applied mechanism-based pharmacokinetic-pharmacodynamic (PKPD) modelling to analyze these data and to predict in vivo platelet aggregation for different doses and administration schedules of aspirin and celecoxib.

RESULTS

The predictions of the PK-PD model were consistent with results from previous studies that investigated interaction between aspirin and celecoxib. The modelling results indicate that celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. The extent of this interaction can be substantial (up to 15% increase in platelet aggregation by 200 mg day(-1) celecoxib when combined with low dose aspirin) during the first days of aspirin administration in patients who are already treated with celecoxib, and it cannot be prevented by separate administration of the interacting drugs.

CONCLUSIONS

At the recommended therapeutic doses, celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. Patients receiving a combination of low dose aspirin and the recommended doses of celecoxib were not identified to have increased risk of cardiovascular and cerebrovascular events due to competition between these drugs for COX-1 binding. Interaction between low dose aspirin and other COX-2 inhibitors and its clinical consequences requires further investigation.

Use of nonsteroidal anti-inflammatory drugs in the older adult

PURPOSE

Annually, approximately 90 million prescriptions are filled for nonsteroidal anti-inflammatory drugs (NSAIDs) with the number prescribed for older adults approximately three times higher than for younger adults. This article examines the benefits and risk of NSAID use in older adults.

DATA SOURCES

Electronic data collection of research studies, evidence-based reviews, consensus statements, and guidelines related to the purpose of this article were analyzed if published between 2000 and 2013 in English from Ovid, MEDLINE, and PubMed databases.

CONCLUSIONS

While NSAIDs are commonly used to treat pain and inflammation in older adults, strong consideration must be given to the potential adverse effects. A lack of consistency in the guidelines regarding NSAID use poses further challenges for clinicians in the selection of the best pharmacological approach. When prescribing NSAIDs, adverse events, polypharmacy, comorbidities, and treatment guidelines must be considered. NSAIDs are an appropriate option for pain management in select older adults, often after a trial of acetaminophen and if benefits outweigh risks. Alternative pharmacological and nonpharmacological therapies may be more appropriate in many older adults.

IMPLICATIONS FOR PRACTICE

The challenge for clinicians prescribing NSAIDs in the treatment of pain in older adults is to utilize safe, individualized, and evidenced-based pain management regimens.

Effects of celecoxib on hematoma and edema volumes in primary intracerebral hemorrhage: a multicenter randomized controlled trial

BACKGROUND AND PURPOSE

We investigated the effect of celecoxib, a selective inhibitor of cyclo-oxygenase 2, in patients with intracerebral hemorrhage (ICH).

METHODS

We conducted a multicenter, randomized, controlled, and open with blinded end-point trial of 44 Korean patients 18 years or older with ICH within 24 h of onset. The intervention group (n = 20) received celecoxib (400 mg twice a day) for 14 days. The control group (n = 24) received the standard medical treatment for ICH. The primary end-point was the number of patients with a change in the volume of perihematomal edema (PHE) from the 1st to the 7th ± 1 day (cut-off value, 20%).

RESULTS

The time from onset to computed tomography scan slightly differed between groups (177 ± 160 min for control vs. 297 ± 305 min for the celecoxib group; P = 0.10). In the primary end-point analysis using cut-off values, there was a significant shift to reduced expansion of PHE in the celecoxib group (P = 0.005). With respect to the secondary end-points, there was also a significant shift to reduced expansion of ICH in the celecoxib group (P = 0.046). In addition, the expansion rate of PHE at follow-up tended to be higher in the control group than in the celecoxib group (90.6 ± 91.7% vs. 44.4 ± 64.9%; P = 0.058).

CONCLUSIONS

In our small, pilot trial, administration of celecoxib in the acute stage of ICH was associated with a smaller expansion of PHE than that observed in controls.

Lumiracoxib Does Not Affect the Ex Vivo Antiplatelet Aggregation Activity of Low-Dose Aspirin in Healthy Subjects

This randomized, double-blind, placebo-controlled study evaluated the pharmacodynamic effects of concomitant low-dose aspirin and lumiracoxib in healthy subjects. Participants received lumiracoxib 400 mg once daily (n = 14) or placebo (n = 14) for 11 days, with concomitant low-dose aspirin (75 mg once daily) from days 5 to 11. Ex vivo pharmacodynamic assessments included assays of platelet aggregation and urinary thromboxane and prostacyclin metabolite profile. Arachidonic acid-stimulated platelet aggregation was reduced from 76.3% on day 4 to 4.8% on day 11 in the placebo group and from 75.8% on day 4 to 5.1% on day 11 in the lumiracoxib group. Collagen-induced platelet aggregation was reduced from 77.5% on day 4 to 52.8% on day 11 in the placebo group and from 79.5% on day 4 to 55.9% on day 11 in the lumiracoxib group. Urinary thromboxane and prostacyclin were unaffected by lumiracoxib. In conclusion, concomitant lumiracoxib did not interfere with the cyclooxygenase-1-mediated antiplatelet effects of low-dose aspirin.

American College of Rheumatology 2012 recommendations for the use of nonpharmacologic and pharmacologic therapies in osteoarthritis of the hand, hip, and knee

OBJECTIVE

To update the American College of Rheumatology (ACR) 2000 recommendations for hip and knee osteoarthritis (OA) and develop new recommendations for hand OA.

METHODS

A list of pharmacologic and nonpharmacologic modalities commonly used to manage knee, hip, and hand OA as well as clinical scenarios representing patients with symptomatic hand, hip, and knee OA were generated. Systematic evidence-based literature reviews were conducted by a working group at the Institute of Population Health, University of Ottawa, and updated by ACR staff to include additions to bibliographic databases through December 31, 2010. The Grading of Recommendations Assessment, Development and Evaluation approach, a formal process to rate scientific evidence and to develop recommendations that are as evidence based as possible, was used by a Technical Expert Panel comprised of various stakeholders to formulate the recommendations for the use of nonpharmacologic and pharmacologic modalities for OA of the hand, hip, and knee.

RESULTS

Both “strong” and “conditional” recommendations were made for OA management. Modalities conditionally recommended for the management of hand OA include instruction in joint protection techniques, provision of assistive devices, use of thermal modalities and trapeziometacarpal joint splints, and use of oral and topical nonsteroidal antiinflammatory drugs (NSAIDs), tramadol, and topical capsaicin. Nonpharmacologic modalities strongly recommended for the management of knee OA were aerobic, aquatic, and/or resistance exercises as well as weight loss for overweight patients. Nonpharmacologic modalities conditionally recommended for knee OA included medial wedge insoles for valgus knee OA, subtalar strapped lateral insoles for varus knee OA, medially directed patellar taping, manual therapy, walking aids, thermal agents, tai chi, self management programs, and psychosocial interventions. Pharmacologic modalities conditionally recommended for the initial management of patients with knee OA included acetaminophen, oral and topical NSAIDs, tramadol, and intraarticular corticosteroid injections; intraarticular hyaluronate injections, duloxetine, and opioids were conditionally recommended in patients who had an inadequate response to initial therapy. Opioid analgesics were strongly recommended in patients who were either not willing to undergo or had contraindications for total joint arthroplasty after having failed medical therapy. Recommendations for hip OA were similar to those for the management of knee OA.

CONCLUSION

These recommendations are based on the consensus judgment of clinical experts from a wide range of disciplines, informed by available evidence, balancing the benefits and harms of both nonpharmacologic and pharmacologic modalities, and incorporating their preferences and values. It is hoped that these recommendations will be utilized by health care providers involved in the management of patients with OA.

Human cyclooxygenase-1 activity and its responses to COX inhibitors are allosterically regulated by nonsubstrate fatty acids

Recombinant human prostaglandin endoperoxide H synthase-1 (huPGHS-1) was characterized. huPGHS-1 has a single high-affinity heme binding site per dimer and exhibits maximal cyclooxygenase (COX) activity with one heme per dimer. Thus, huPGHS-1 functions as a conformational heterodimer having a catalytic monomer (E(cat)) with a bound heme and an allosteric monomer (E(allo)) lacking heme. The enzyme is modestly inhibited by common FAs including palmitic, stearic, and oleic acids that are not COX substrates. Studies of arachidonic acid (AA) substrate turnover at high enzyme-to-substrate ratios indicate that nonsubstrate FAs bind the COX site of E(allo) to modulate the properties of E(cat). Nonsubstrate FAs slightly inhibit huPGHS-1 but stimulate huPGHS-2, thereby augmenting AA oxygenation by PGHS-2 relative to PGHS-1. Nonsubstrate FAs potentiate the inhibition of huPGHS-1 activity by time-dependent COX inhibitors, including aspirin, all of which bind E(cat). Surprisingly, preincubating huPGHS-1 with nonsubstrate FAs in combination with ibuprofen, which by itself is a time-independent inhibitor, causes a short-lived, time-dependent inhibition of huPGHS-1. Thus, in general, having a FA bound to E(allo) stabilizes time-dependently inhibited conformations of E(cat). We speculate that having an FA bound to E(allo) also stabilizes E(cat) conformers during catalysis, enabling half of sites of COX activity.

Celecoxib: a review of its use for symptomatic relief in the treatment of osteoarthritis, rheumatoid arthritis and ankylosing spondylitis

Celecoxib (Celebrex®) was the first cyclo-oxygenase (COX)-2 selective inhibitor (coxib) to be introduced into clinical practice. Coxibs were developed to provide anti-inflammatory/analgesic activity similar to that of nonselective NSAIDs, but without their upper gastrointestinal (GI) toxicity, which is thought to result largely from COX-1 inhibition. Celecoxib is indicated in the EU for the symptomatic treatment of osteoarthritis, rheumatoid arthritis and ankylosing spondylitis in adults. This article reviews the clinical efficacy and tolerability of celecoxib in these EU-approved indications, as well as overviewing its pharmacological properties. In randomized controlled trials, celecoxib, at the recommended dosages of 200 or 400 mg/day, was significantly more effective than placebo, at least as effective as or more effective than paracetamol (acetaminophen) and as effective as nonselective NSAIDs and the coxibs etoricoxib and lumiracoxib for the symptomatic treatment of patients with active osteoarthritis, rheumatoid arthritis or ankylosing spondylitis. Celecoxib was generally well tolerated, with mild to moderate upper GI complaints being the most common body system adverse events. In meta-analyses and large safety studies, the incidence of upper GI ulcer complications with recommended dosages of celecoxib was significantly lower than that with nonselective NSAIDs and similar to that with paracetamol and other coxibs. However, concomitant administration of celecoxib with low-dose cardioprotective aspirin often appeared to negate the GI-sparing advantages of celecoxib over NSAIDs. Although one polyp prevention trial noted a dose-related increase in cardiovascular risk with celecoxib 400 and 800 mg/day, other trials have not found any significant difference in cardiovascular risk between celecoxib and placebo or nonselective NSAIDs. Meta-analyses and database-derived analyses are inconsistent regarding cardiovascular risk. At recommended dosages, the risks of increased thrombotic cardiovascular events, or renovascular, hepatic or hypersensitivity reactions with celecoxib would appear to be small and similar to those with NSAIDs. Celecoxib would appear to be a useful option for therapy in patients at high risk for NSAID-induced GI toxicity, or in those responding suboptimally to or intolerant of NSAIDs. To minimize any risk, particularly the cardiovascular risk, celecoxib, like all coxibs and NSAIDs, should be used at the lowest effective dosage for the shortest possible duration after a careful evaluation of the GI, cardiovascular and renal risks of the individual patient.

Use of nonsteroidal anti-inflammatory drugs in patients with cardiovascular disease: a cautionary tale

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit production of prostaglandins by acting on cyclooxygenase (COX) isoenzymes 1 and 2. Nonselective NSAIDs inhibit both COX 1 and 2 isoenzymes (eg, ibuprofen and naproxen). Selective NSAIDs act on COX-1 (eg, aspirin) or COX-2 (eg, celecoxib) isoenzymes, respectively. Prostaglandins are produced in platelets and gastric mucosal cells through constitutively expressed COX-1 isoenzyme. They are involved in the regulation of hemostasis, functional integrity of the gastrointestinal and renal tracts, platelet function, and macrophage differentiation. Inhibition of COX-1 isoenzymes impedes platelet aggregation, impairs maintenance of protective gastric mucosal barrier, and affects renal function. Prostaglandin production in inflamed tissue results from de novo induction of COX-2 expression by inflammatory cytokines and other noxious stimuli. Thus, COX-2 isoenzyme inhibition either selectively or nonselectively helps in reducing inflammation in the setting of musculoskeletal disorders. Safety and efficacy of NSAIDs are related to their relative actions on COX-1 or COX-2 inhibition. Given the multisystem (gastrointestinal, hematopoietic, and renal) adverse effect profile of COX-1 inhibition, formulation of NSAIDs with relative COX-2 selectivity became a highly desirable target during the 90's. However, studies in the first half of this decade revealed adverse effects of COX-2 inhibition on the cardiovascular system, including increased risks of myocardial infarction, exacerbation of stable congestive heart failure, and worsening high blood pressure. Randomized trials and meta-analyses confirmed these findings, which led to withdrawal of some of the COX-2 inhibitors from the market by the federal Food and Drug Administration a few years ago. Here, we review the effects of COX-2 isoenzyme inhibitors on the cardiovascular system to provide a safe strategy for prescribing these agents in patients with existing cardiovascular disease. We did not find adequate long-term randomized controlled trials appropriately powered to evaluate cardiovascular outcomes. Potentially, all NSAIDs possess a fair risk of adverse effects on gastrointestinal, cardiovascular, and renal systems. Until more evidence for safety via randomized trials is available, we recommend caution in prescribing COX-1 and 2 inhibitors for musculoskeletal disorders in patients with existing gastrointestinal or cardiovascular conditions.

Using pharmacokinetic principles to optimize pain therapy

Cyclo-oxygenase (COX) inhibitors are widely used to relieve musculoskeletal pain. These agents block the production of prostaglandins (PGs) at sites of inflammation by inhibiting the activity of two COX enzymes necessary for PG production and normal organ homeostasis. Inhibition of PG production at sites unrelated to pain is associated with adverse drug reactions (ADRs). The degree of analgesic efficacy, as well as the incidence and the localization of ADRs, are critically influenced by the pharmacokinetics (absorption, distribution and elimination) of these drugs. Ideally, sufficient and permanent inhibition of COX enzymes should be achieved in target tissues, with minimal ADRs. To minimize underdosing or overdosing, which result in therapeutic failure or ADRs, the COX inhibitor with the most appropriate pharmacokinetic properties should be selected on the basis of a thorough pharmacokinetic-pharmacodynamic analysis. In this Review, the pharmacokinetics of the prevailing COX inhibitors will be discussed and enigmatic aspects of these intensively used drugs will be considered.

Celecoxib does not attenuate the antiplatelet effects of aspirin and clopidogrel in healthy volunteers

BACKGROUND AND OBJECTIVES

The prevalence of arthritis, which is often treated with celecoxib, is high in patients with coronary artery disease. Furthermore, celecoxib has been reported to reduce restenosis after coronary stenting by inhibiting expression of the proto-oncogene Akt. A concern is that celecoxib increases thrombogenicity by inhibiting the synthesis of prostacyclin in endothelial cells. However, it is not known whether the administration of celecoxib will attenuate the antiplatelet effects of aspirin and clopidogrel, which are used after stenting. We addressed this gap in our knowledge.

SUBJECTS AND METHODS

We recruited healthy volunteers (n=40) and randomized them into five subgroups (n=8 for each group: aspirin, celecoxib, aspirin+celecoxib, aspirin+clopidogrel, and aspirin+clopidogrel+celecoxib). Each subject received their medications for 6 days and blood samples were taken on day 0 and day 7. Celecoxib (200 mg twice a day), and/or aspirin (100 mg daily), and/or clopidogrel (75 mg daily) were administered. We compared platelet function among subgroups using light transmittance aggregometry and arachidonic acid metabolite assays.

RESULTS

Celecoxib treatment alone did not significantly affect platelet aggregation. The reduction in adenosine diphosphase (ADP)-induced platelet aggregation by aspirin+clopidogrel was not affected by addition of celecoxib (31.3+/-6.9% vs. 32.4+/-12.2%, p=0.83). Inhibition of collagen-induced platelet aggregation by aspirin+clopidogrel was not affected by addition of celecoxib (47.6+/-13.4% vs. 51.6+/-3.7%, p=0.69). Drug-induced changes in prostacyclin and thromboxane levels did not differ among treatment groups.

CONCLUSION

Celecoxib treatment does not interfere with the antiplatelet effects of aspirin or clopidogrel, suggesting that celecoxib can be safely administered in combination with dual antiplatelet therapy in patients with coronary stenting without increased thrombogenicity.

Coxibs interfere with the action of aspirin by binding tightly to one monomer of cyclooxygenase-1

Pain associated with inflammation involves prostaglandins synthesized from arachidonic acid (AA) through cyclooxygenase-2 (COX-2) pathways while thromboxane A(2) formed by platelets from AA via cyclooxygenase-1 (COX-1) mediates thrombosis. COX-1 and COX-2 are both targets of nonselective nonsteroidal antiinflammatory drugs (nsNSAIDs) including aspirin whereas COX-2 activity is preferentially blocked by COX-2 inhibitors called coxibs. COXs are homodimers composed of identical subunits, but we have shown that only one subunit is active at a time during catalysis; moreover, many nsNSAIDS bind to a single subunit of a COX dimer to inhibit the COX activity of the entire dimer. Here, we report the surprising observation that celecoxib and other coxibs bind tightly to a subunit of COX-1. Although celecoxib binding to one monomer of COX-1 does not affect the normal catalytic processing of AA by the second, partner subunit, celecoxib does interfere with the inhibition of COX-1 by aspirin in vitro. X-ray crystallographic results obtained with a celecoxib/COX-1 complex show how celecoxib can bind to one of the two available COX sites of the COX-1 dimer. Finally, we find that administration of celecoxib to dogs interferes with the ability of a low dose of aspirin to inhibit AA-induced ex vivo platelet aggregation. COX-2 inhibitors such as celecoxib are widely used for pain relief. Because coxibs exhibit cardiovascular side effects, they are often prescribed in combination with low-dose aspirin to prevent thrombosis. Our studies predict that the cardioprotective effect of low-dose aspirin on COX-1 may be blunted when taken with coxibs.

[Are the NSAIDs able to compromising the cardio-preventive efficacy of aspirin?]

OBJECTIVES

Some studies have recently suggested a potential pharmacodynamic interaction between aspirin and some non-selective non-steroidal anti-inflammatory drugs (NSAIDs). We have evaluated the reality of this pharmacodynamic interaction and analyse its clinical pertinence.

METHODS

Literature review (Medline search - December 2005).

RESULTS

Several ex vivo studies show that some non-selective NSAIDs can block the active site of Cox1 thus preventing aspirin from exerting its platelet anti-aggregating cardio-preventive action. Cox2 selective molecules do not act at this site. The few studies, mainly case reports, have analysed the potential loss of the cardiovascular preventive benefit of aspirin in patients receiving concomitantly non-selective anti-inflammatory drugs with controversial results.

IN PRACTICE

It seems necessary to know the existence of this pharmacodynamic interaction between aspirin at a low dose and some non-selective anti-inflammatory drugs notably ibuprofen and naproxen. In the absence of a clear clinical demonstration, it is advisable to avoid the non-selective NSAIDs in patients treated with a low dose of aspirin. It might be advisable to switch to an anti-aggregating treatment other than aspirin (clopidrogel, etc.) in these cases. At the present time, however, there are no data on which to base such a recommendation.

The antiplatelet effect of six non-steroidal anti-inflammatory drugs and their pharmacodynamic interaction with aspirin in healthy volunteers

Patients with cardiovascular disease taking aspirin and some nonsteroidal anti-inflammatory drugs (NSAIDs) appear to have increased vascular events. This study was conducted to compare the ex vivo antiplatelet effects of 6 commonly used NSAIDs and to determine whether these agents antagonize the effect of aspirin. Platelet function was assessed by Platelet Function Analyzer 100 closure time in normal subjects in a randomized, blinded, multiple-crossover study. Platelet function was measured 12 hours after the administration of each NSAID. The NSAID was then given 2 hours before aspirin 300 mg, and platelet function was reassessed 24 hours later. At 12 hours after the administration of naproxen and tiaprofenic acid, closure time was significantly prolonged, whereas the other NSAIDs did not cause significant prolongations. Compared with placebo plus aspirin, closure time was significantly reduced when ibuprofen, indomethacin, naproxen, or tiaprofenic acid was given before aspirin. In conclusion, ibuprofen, indomethacin, naproxen, and tiaprofenic acid all block the antiplatelet effect of aspirin. Sulindac and celecoxib did not demonstrate any significant antiplatelet effect or reduce the antiplatelet of aspirin and, therefore, of the NSAIDs evaluated may be the drugs of choice for patients requiring aspirin and NSAIDs.

Hyperexpression of cyclooxygenase 2 in the lupus immune system and effect of cyclooxygenase 2 inhibitor diet therapy in a murine model of systemic lupus erythematosus

OBJECTIVE

To investigate the role of cyclooxygenase 2 (COX-2) in the functioning of different cell types involved in the lupus autoimmune response, and to examine the therapeutic effect of COX-2 inhibitors in mice prone to spontaneously develop systemic lupus erythematosus (SLE).

METHODS

Lupus-prone (SWR x NZB)F(1) mice were fed with a diet containing different doses of the COX-2-specific inhibitor celecoxib or the nonspecific inhibitor aspirin, or a combination of both, and the effects of the therapy on autoantibody production, development of lupus nephritis, and mortality were determined. Expression of COX-2 by different cells of the lupus immune system and the effect of COX-2 inhibitors on the function of these cells in vitro and in vivo were assessed.

RESULTS

The immune cells of mice with SLE spontaneously hyperexpressed COX-2, and COX-2 inhibitors could cause cell apoptosis. Treatment with COX-2 inhibitors resulted in decreased autoantibody production and inhibition of the T cell response to the major lupus autoantigen, nucleosome, and its presentation by antigen-presenting cells. Surprisingly, a significant increase in survival occurred only in mice receiving intermittent therapy with the lowest dose of celecoxib (500 parts per million), approximating <100 mg of celecoxib/day in humans. A continuous diet, but not intermittent feeding, with the combination of celecoxib and aspirin delayed development of nephritis temporarily, but failed to prolong survival. Indeed, treatment with aspirin alone increased mortality.

CONCLUSION

The contributions of the major players in the pathogenic autoimmune response, namely, T cells, B cells, dendritic cells, and macrophages that are abnormally hyperactive in lupus, depend on the increased expression and activity of COX-2, similar to inflammatory cells in target organs. Intermittent pulse therapy with low doses of select COX-2 inhibitors would be of value in the treatment of lupus.

Adverse drug interactions involving common prescription and over-the-counter analgesic agents

BACKGROUND

Eight analgesic preparations with approved indications for acute pain were among the top 200 drugs prescribed in the United States in 2006. In addition, an estimated 36 million Americans use over-the-counter (OTC) analgesics daily. Given this volume of use, it is not surprising that a number of drug interactions involving analgesic drugs have been reported.

OBJECTIVES

This article examines the pharmacologic factors that enhance the clinical relevance of potential drug interactions and reviews the literature on drug interactions involving the most commonly used analgesic preparations in the United States.

METHODS

A PubMed search was conducted for English-language articles published between January 1967 and July 2007. Among the search terms were drug interactions, acetaminophen, aspirin, ibuprofen, naproxen, celecoxib, NSAIDs, hydrocodone, oxycodone, codeine, tramadol, OTC analgesics, alcohol, ethanol, antihypertensive drugs, methotrexate, warfarin, SSRIs, paroxetine, fluoxetine, sertraline, citalopram, serotonin syndrome, MAOIs, and overdose. Controlled clinical trials, case-control studies, and case reports were included in the review.

RESULTS

A number of case reports and well-controlled clinical trials were identified that provided evidence of the relatively well known drug-drug interactions between prescription/OTC NSAIDs and alcohol, antihypertensive drugs, high-dose methotrexate, and lithium, as well as between frequently prescribed narcotics and other central nervous system depressants. In contrast, the ability of recent alcohol ingestion to exacerbate the hepatotoxic potential of therapeutic doses of acetaminophen is not supported by either case reports or clinical research. Use of ibuprofen according to OTC guidelines in patients taking cardioprotective doses of aspirin does not appear to interfere with aspirin's antiplatelet activity, whereas chronic prescription use of ibuprofen and other NSAIDs may interfere. Low-dose aspirin intake appears to abolish the gastroprotective effects of cyclooxygenase-2-selective inhibitors, including celecoxib. There is evidence of other less well known and potentially clinically significant drug-drug interactions, including the ability of selective serotonin reuptake inhibitors to inhibit the analgesic activity of tramadol and codeine through inhibition of their metabolic activation, to induce serotonin syndrome when used chronically in the presence of high doses of tramadol through synergistic serotonergic action, and to increase the potential for gastrointestinal bleeding associated with NSAID therapy through additive or supra-additive antiplatelet activity.

CONCLUSIONS

Considering the widespread use of analgesic agents, the overall incidence of serious drug-drug interactions involving these agents has been relatively low. The most serious interactions usually involved other interacting drugs with low therapeutic indices or chronic and/or high-dose use of an analgesic and the interacting drug.

Effect of celecoxib on restenosis after coronary angioplasty with a Taxus stent (COREA-TAXUS trial): an open-label randomised controlled study

BACKGROUND

In-vitro and animal experiments have shown that the cyclo-oxygenase 2 inhibitor celecoxib can reduce formation of neointima within stents. We aimed to test whether celecoxib has similar effects in a clinical setting.

METHODS

In a randomised two-centre trial, we enrolled 274 patients who had angina pectoris or a positive stress test and who had native coronary artery lesions for which implantation of paclitaxel-eluting stents was feasible. All patients were given aspirin (100 mg daily) and clopidogrel (75 mg daily). 136 patients were randomly assigned to receive celecoxib (400 mg before the intervention, and 200 mg twice daily for 6 months after the procedure). The primary endpoint was late luminal loss on quantitative coronary angiography at 6 months after the intervention. Secondary endpoints were cardiac death, non-fatal myocardial infarction, and revascularisation of the target lesion. Analysis was done on a modified intention-to-treat basis. This study is registered with ClinicalTrials.gov, number NCT00292721.

FINDINGS

At 6 months, mean in-stent late luminal loss was lower in the celecoxib group (0.49 mm, SD 0.47) than in the control group (0.75 mm, 0.60) (absolute difference 0.26 mm; 95% CI 0.12-0.40). Frequency of secondary outcomes at 6 months was also lower in the celecoxib group, mainly because of a reduced need for revascularisation of the target lesion.

INTERPRETATION

These data suggest that the adjunctive use of celecoxib for 6 months after stent implantation in patients with coronary artery disease is safe and can reduce the need for revascularisation of the target lesion.

Cyclooxygenase-2 inhibition and coagulation

Selective inhibitors of cyclooxygenase-2 (COX-2) have come under scrutiny because of a possibly increased thrombotic risk observed in retrospective studies and comparatively small cancer trials. Indeed, inhibition of COX-2 may favor a prothrombotic environment by suppressing endothelial prostacyclin synthesis while leaving COX-1-dependent platelet thromboxane (TX) A2 synthesis unopposed. However, in vitro studies have shown that the effect of coxibs on coagulation is dependent on several variables; for example, the coxib celecoxib reduces endothelial tissue factor expression, a key initiator of the coagulation cascade. Furthermore, animal studies are inconclusive as some studies investigating the effect of COX-2 inhibition in atherosclerosis imply a detrimental effect of coxibs, whereas others suggest a beneficial effect on plaque progression and stability. In healthy human subjects and in patients with atherosclerotic vascular diseases, the effect of COX-2 inhibition on coagulation is equally unclear as no prospective, randomized, double-blinded studies sufficiently powered to investigate cardiovascular endpoints have been performed to directly investigate a potentially cardiotoxic effect of coxibs. Here, we review the effect of COX-2 inhibition on the coagulation system; we discuss the molecular mechanisms involved and summarize important clinical trials in which an increased frequency of thrombotic complications coxibs was observed.

Risks versus benefits of cyclooxygenase-2-selective nonsteroidal antiinflammatory drugs

PURPOSE

A summary of the basic science underlying the current controversies regarding cyclooxygenase-2 (COX-2)-selective nonsteroidal antiinflammatory drugs (NSAIDs), including data on their cardiovascular safety, their gastrointestinal (GI) benefits, cost-effectiveness, physician-prescribing trends, and recommendations for prescribing these agents is presented.

SUMMARY

A number of randomized controlled trials (RCTs) have reported that COX-2-selective NSAIDs increase cardiovascular events, although there appear to be gradations of risks among the COX-2-selective NSAIDs. In addition, traditional NSAIDs may increase the risk for cardiovascular events, complicating the interpretation of RCTs that use traditional NSAIDs as comparators. Selective inhibitors of COX-2-selective NSAIDs are effective antiinflammatory and analgesic drugs with improved upper-GI safety compared to traditional NSAIDs. Data on the cost-effectiveness of COX-2-selective NSAIDs indicate that they should be limited to patients at high risk for upper-GI adverse effects. However, they had been increasingly used in patients with lower GI risks until recent events reversed that trend. Circumstances under which COX-2-selective NSAIDs may be appropriate are in patients at high GI risk and in patients who did not respond to multiple traditional NSAIDs. The national spotlight in the United States on NSAID-related adverse events and recent lawsuits against health care providers prescribing COX-2-selective NSAIDs further highlights the need for provider-patient communication and risk disclosure. The relative cardiovascular risks of NSAIDs are similar in magnitude to other currently prescribed therapies.

CONCLUSION

Health care providers must consider the efficacy, GI and cardiovascular risks, concomitant medications, and costs when determining the appropriateness of COX-2-selective NSAID therapy.

Aspirin resistance: truth or dare

Acetylsalicylic acid, or aspirin (ASA), is widely used in patients with cardiovascular disease to prevent acute ischemic events. However, platelet response to ASA is not equal in all individuals, and a high variability in the prevalence of ASA resistance is reported in the literature (0.4-83%). Actually, ASA resistance is poorly understood; this stems from the fact that its definition is unclear, its presence can be evaluated by a number of assays that are not equivalent, and its prevalence may vary widely based on the population studied. This article (1) exposes the difficulties in defining ASA resistance; (2) discusses the mechanisms by which ASA resistance may occur; (3) presents the characteristics that may put patients at greater risk of exhibiting ASA resistance; and (4) discusses the clinical impact of ASA resistance in patients requiring chronic therapy.

Aspirin, NSAIDs, and COX-2 inhibitors in cardiovascular disease: Possible interactions and implications for treatment of rheumatoid arthritis

Aspirin, nonsteroidal antiinflammatory drugs (NSAIDs), and cyclooxygenase-2 (COX-2) inhibitors are widely used in patients with rheumatoid arthritis. Aspirin has the largest and most persuasive body of randomized trial evidence to support its use in secondary prevention for cardiovascular disease (CVD) and primary prevention for myocardial infarction. There is, however, a possible deleterious interaction between aspirin and NSAIDs on CVD that requires further research. Aspirin, NSAIDs, and to a lesser extent COX-2 inhibitors are associated with increased gastrointestinal side effects and bleeding, alone and in combination. The more widespread and appropriate use of aspirin in patients with rheumatoid arthritis will avoid many premature deaths in secondary prevention for CVD and first myocardial infarctions in primary prevention.

Do some inhibitors of COX-2 increase the risk of thromboembolic events?: Linking pharmacology with pharmacoepidemiology

Inhibitors of the cyclo-oxygenase (COX)-2 isoenzyme were developed with the expectation that their use would be accompanied by a reduction in adverse reactions thought to be mediated through COX-1 compared with conventional nonselective NSAIDs. However, the results of some clinical studies and other evidence have led to the hypothesis that use of COX-2 inhibitors may contribute to an increased risk of adverse thromboembolic (TE) events. In this review, we have evaluated the evidence from small-scale in vitro and in vivo pharmacological studies, clinical trials and large-scale pharmacoepidemiological studies and commented on the relationship between the pharmacological characteristics related to thromboembolic events and the clinical effects in large-scale clinical trials and pharmacoepidemiological studies. Overall, the pharmacological evidence suggests that a prothrombotic effect of COX-2 selective inhibitors is plausible. To date, despite the results from the Vioxx Gastrointestinal Outcome Research (VIGOR) study from which the clinical concern regarding cardiovascular TE risk arose, the published data from other randomised controlled trials (RCTs), retrospective observational studies and spontaneous reporting schemes provide a conflicting body of evidence on the TE risk with COX-2 inhibitors. Concerns that COX-2 inhibitors may be associated with prothrombotic effects remain and these need to be addressed in large scale, RCTs designed specifically to investigate the possibility of an excess of adverse cardiovascular outcomes in users of some or all selective COX-2 inhibitors, both with and without concomitant low-dose aspirin (acetylsalicylic acid). Consideration must also be given to other pathophysiological mechanisms for potential cardiovascular risk linked with inhibition of COX-2. In view of the evidence reviewed, it is recommended that selective COX-2 inhibitors should be prescribed with caution, only in patients with conditions for which these drugs have proven efficacy and with careful monitoring of outcomes and adverse events. This is particularly important in the elderly, in patients with cardiovascular/renal disease and in patients with other risk factors that might predispose them to adverse events.

Effets rénaux et cardiovasculaires des anti-inflammatoires non stéroïdiens et des coxibs

HYPERKALIEMIA AND RENAL FAILURE: Nonsteroidal anti-inflammatory drugs (NSAIs) may induce hyperkaliemia and renal failure. With regard to these complications, the notion of a risk factor is fundamental. Selective cyclooxygenase-2 inhibitors (Cox-2) do not provide any notable advantages with regard to the incidence of hyperkaliemia and renal failure. OEDEMA AND BLOOD PRESSURE: The NSAIs provoke salt-water retention which is responsible for oedema in 2 to 5% of patients (here again the notion of a risk factor is important). The salt-water retention is implied in the increase in blood pressure and the decompensation of heart failure. It has been shown that the incidence of oedema and the increase in blood pressure was significantly reduced with celecoxib compared with rofecoxib. This might have a crucial impact on the mean and long term follow-up of cardiovascular risk in these patients.

CARDIOVASCULAR RISK

The results of the VIGOR study that demonstrated an increase in risk of myocardial infarction with rofecoxib, can probably be explained by an anti-thrombotic effect of naproxene, the high dose of rofecoxib used, the type of patients included or the fact that aspirin had been contraindicated. A recent study suggested that the cardiovascular risk was greater with rofecoxib than with celecoxib and with NSAIs when the dose of rofecoxib used was greater than 25mg/day. In this case control study, the cardiovascular risk was identical with celecoxib and NSAIs, whatever the dose used, but increased with a relative risk rate of 1.7 with the doses of rofecoxib greater than 50mg/day. In cases treated with aspirin Some NSAIs can reduce the anti-aggregant effects of aspirin whereas this effect is not observed with Cox-2 selective inhibitors. Hence, the latter should be the pharmacological agents of choice in patients treated with aspirin.