Carlos Sostres

Adverse effects of non-steroidal anti-inflammatory drugs (NSAIDs, aspirin and coxibs) on upper gastrointestinal tract.

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most widely prescribed medication in the world. Their main benefit derives from their anti-inflammatory and analgesic effect, but the use of these agents is not innocuous since they mainly increase the risk of gastrointestinal (GI) and cardiovascular complications compared with non-NSAID users. NSAIDs injures the upper and lower gut by depleting COX-1 derived prostaglandins and causing topical injury to the mucosa. The risk of upper GI complications varies, depending on the presence of one or more risk factors. Among them, the three main risk factors are prior history of peptic ulcer, the single most important risk factor, age, the most common, and concomitant aspirin use, due to their GI and cardiovascular implications. Those individuals at-risk should be considered for alternatives to NSAID therapy and modifications of risk factors. If NSAID therapy is required, patients at risk will need prevention strategies including co-therapy of NSAID with gastroprotectants (PPI or misoprostol) or the prescription of COX-2 selective inhibitors. The probable introduction of NO-NSAIDs in the market in the near future may open a new therapeutic option for patients with hypertension who need NSAIDs.

Nonsteroidal anti-inflammatory drugs and upper and lower gastrointestinal mucosal damage

NSAIDs are among the most commonly used drugs worldwide and their beneficial therapeutic properties are thoroughly accepted. However, they are also associated with gastrointestinal (GI) adverse events. NSAIDs can damage the whole GI tract including a wide spectrum of lesions. About 1 to 2% of NSAID users experienced a serious GI complication during treatment. The relative risk of upper GI complications among NSAID users depends on the presence of different risk factors, including older age (>65 years), history of complicated peptic ulcer, and concomitant aspirin or anticoagulant use, in addition to the type and dose of NSAID. Some authors recently reported a decreasing trend in hospitalizations due to upper GI complications and a significant increase in those from the lower GI tract, causing the rates of these two types of GI complications to converge. NSAID-induced enteropathy has gained much attention in the last few years and an increasing number of reports have been published on this issue. Current evidence suggests that NSAIDs increase the risk of lower GI bleeding and perforation to a similar extent as that seen in the upper GI tract. Selective cyclooxygenase-2 inhibitors have the same beneficial effects as nonselective NSAIDs but with less GI toxicity in the upper GI tract and probably in the lower GI tract. Overall, mortality due to these complications has also decreased, but the in-hospital case fatality for upper and lower GI complication events has remained constant despite the new therapeutic and prevention strategies.

Risk of Upper and Lower Gastrointestinal Bleeding in Patients Taking Nonsteroidal Anti-inflammatory Drugs, Antiplatelet Agents, or Anticoagulants

BACKGROUND & AIMS Treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) or low-dose aspirin is associated with increased risk of upper gastrointestinal bleeding. There is little evidence on the risk of lower gastrointestinal bleeding with NSAIDs, antiplatelet agents (APAs), or anticoagulants. We aimed to quantify the relative risk (RR) of upper and lower gastrointestinal bleeding associated with use of NSAIDs, APAs, or anticoagulants. METHODS We performed a case-control study that used data collected from consecutive patients hospitalized for gastrointestinal bleeding (563 upper, mean age, 63.6 ± 16.7 years and 415 lower, mean age, 70.8 ± 13.8 years), confirmed by endoscopy or other diagnostic procedures. Unhospitalized patients were used as controls (n = 1008) and matched for age, hospital, and month of admission. Drug use was considered current when taken within 7 days or less before hospitalization. RRs and 95% confidence intervals (CIs) were estimated by unconditional logistic regression analysis. RESULTS Use of anticoagulants, low-dose aspirin, and other drugs (non-aspirin-APA, 82.3% thienopiridines) was associated with upper and lower gastrointestinal bleeding; the risk was 2-fold higher for anticoagulants (RR, 4.2; 95% CI, 2.9-6.2) than for low-dose aspirin (RR, 2.1; 95% CI, 1.4-3.3) or other non-aspirin-APA drugs (RR, 2.0; 95% CI, 1.6-2.6). NSAID use was also associated with increased risk of gastrointestinal bleeding and greater for upper (RR, 2.6; 95% CI, 2.0-3.5) than lower gastrointestinal bleeding (RR, 1.4; 95% CI, 1.0-1.9). Use of proton pump inhibitors was associated with reduced risk of upper, but not lower, gastrointestinal bleeding. CONCLUSIONS Anticoagulants, low-dose aspirin, NSAIDs, and other non-aspirin-APA drugs are associated with increased risk of upper and lower gastrointestinal bleeding. Use of anticoagulants appears to be the strongest risk factor for gastrointestinal bleeding.

Managing the adverse effects of nonsteroidal anti-inflammatory drugs

Conventional medical treatment for rheumatoid arthritis and osteoarthritis includes the use of NSAIDs (traditional and selective inhibitors of cyclooxygenase [COX]-2), because they provide unmistakable and significant health benefits in the treatment of pain and inflammation. However, they are associated with an increased risk of serious gastrointestinal (GI) and cardiovascular (CV) adverse events. Both beneficial and adverse effects are due to the same mechanism of action, which is inhibition of COX-dependent prostanoids. Since CV and GI risk are related to drug exposure, a reduction in the administered dose is recommended. However, this strategy will not eliminate the hazard owing to a possible contribution of individual genetic background. Further studies will be necessary to develop genetic and/or biochemical markers predictive of the CV and GI risk of NSAIDs.

Reappraisal of the clinical pharmacology of low-dose aspirin by comparing novel direct and traditional indirect biomarkers of drug action

Even though the acetylation of platelet cyclooxygenase (COX)‐1 at serine‐529 is the direct mechanism of action of low‐dose aspirin, its antiplatelet effect has been characterized using indirect indexes of COX‐1 activity.

Aspirin, cyclooxygenase inhibition and colorectal cancer

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

Mechanistic and Pharmacological Issues of Aspirin as an Anticancer Agent

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

Epidemiology and demographics of upper gastrointestinal bleeding: prevalence, incidence, and mortality.

Despite major advances in diagnosis, prevention, and treatment, nonvariceal upper gastrointestinal bleeding still is a serious problem in clinical practice. Current evidence indicates that most peptic ulcer bleeding-linked deaths are not a direct sequela of the bleeding ulcer itself. Instead, mortality derives from multiorgan failure, cardiopulmonary conditions, or terminal malignancy, suggesting that improving further current treatments for the bleeding ulcer may have a limited impact on mortality unless supportive therapies are developed for the global management of these patients.

Interaction between Helicobacter pylori infection, nonsteroidal anti-inflammatory drugs and/or low-dose aspirin use: Old question new insights

Previous reports clearly demonstrated that Helicobacter pylori (H. pylori) infection, nonsteroidal anti-inflammatory drugs (NSAID) or low dose aspirin (ASA) use significantly and independently increased the risk for the development of peptic ulcer disease. Today, the presence of H. pylori infection associated with low dose ASA and/or NSAID use in the same patient is becoming more frequent and therefore the potential interaction between these factors and the consequences of it has important implications. Whether NSAID intake in the presence of H. pylori infection may further increase the risk of peptic ulcer carried by the presence of only one risk factor is still a matter of debate. Studies on the interaction between the two risk factors yielded conflicting data and no consensus has been reached in the last years. In addition, the interaction between H. pylori infection and low-dose ASA remains even more controversial. In real clinical practice, we can find different clinical scenarios involving these three factors associated with the presence of different gastrointestinal and cardiovascular risk factors. These huge variety of possible combinations greatly hinder the decision making process of physicians.

Should Prophylactic Low-dose Aspirin Therapy be Continued in Peptic Ulcer Bleeding?

Patients taking low-dose aspirin for cardiovascular prevention who develop an acute peptic ulcer bleeding event represent a serious challenge in clinical practice. Aspirin discontinuation is associated with increased risk of developing a new cardiovascular event, but there is little evidence on the outcomes and best management strategy in the setting of an acute ulcer bleeding event. In this clinical scenario, it is common clinical practice to interrupt aspirin treatment for various, sometimes long, periods of time. A recent study suggests that patients with bleeding ulcers who keep taking aspirin after successful endoscopic therapy followed by high-dose intravenous pantoprazole, bolus of 80 mg followed by 8 mg/h for 3 days, have a small increase in the risk of rebleeding but a lower overall and cardiovascular 30-day mortality rate than those who stop taking aspirin treatment. Based on current, although limited, data, we propose that these patients should undergo early endoscopic therapy to control bleeding followed by a high-dose intravenous PPI, with early reintroduction of aspirin treatment within a 5-day window after the last dose. However, in patients taking aspirin for the primary prevention of cardiovascular events, it seems reasonable to stop aspirin treatment, re-evaluate the indication and, if needed, reintroduce aspirin after the risk of ulcer rebleeding decreases, usually after hospital discharge. In the presence of an acute ulcer bleeding event soon after the placement of coronary stents, the risk of stent thrombosis with removal of antiplatelet therapy is very high. We believe that early therapeutic endoscopy and a high-dose intravenous PPI is advisable in order to maintain patients on dual antiplatelet therapy. Until more evidence becomes available, clinicians will have to rely on actual data and the use of common sense to select the best option for the patient.