Enteric coating of aspirin significantly decreases gastroduodenal mucosal lesions

Low-Dose Enteric-Coated and Chewable Aspirin Are Not Equally Effective in Preventing Venous Thromboembolism in Total Knee and Hip Arthroplasty

BACKGROUND

Low-dose aspirin is an effective venous thromboembolism (VTE) prophylactic medication in primary total joint arthroplasty, but the efficacy and safety of the formulations of chewable and enteric-coated aspirin have not been compared. The purpose of this study was to investigate the VTE and gastrointestinal (GI) complication rates of chewable and enteric-coated 81 mg aspirin bis in die for VTE prophylaxis in primary total joint arthroplasty.

METHODS

A retrospective, single-institution cohort study was performed on patients who underwent primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) from 2017 to 2021. Comparisons were made between 4,844 patients who received chewable, noncoated aspirin 81 mg and 4,388 patients who received enteric-coated 81 mg aspirin. Power analysis demonstrated 1,978 and 3,686 patients were needed per group to achieve a power of 80% for 90-day VTE rates (using inferiority testing) and GI complications (using superiority testing), respectively. Patients had similar baseline characteristics. Statistical analyses were done using t-tests and Chi-squared tests, with statistical significance defined as a P value < .05.

RESULTS

There were no significant differences in the incidences of postoperative VTE (0.31% versus 0.55%; P = .111) or GI complications (0.14% versus 0.14%; P = 1.000) between patients who received either chewable or enteric-coated 81 mg aspirin bis in die in the overall comparison that included both THA and TKA patients combined, or THA patients alone. However, the VTE incidence for TKA patients alone was significantly lower with chewable than enteric-coated aspirin (0.22% versus 0.62%; P = .037), with no difference in GI complications (0.13% versus 0.19%; P = .277).

CONCLUSIONS

Low-dose aspirin in enteric-coated formulation is inferior to chewable aspirin for VTE prophylaxis in primary TKA, but not inferior in THA patients. Both formulations have a similar GI complication rate. Therefore, it is reasonable to consider a transition from enteric-coated to uncoated chewable low-dose aspirin.

Pharmacological Efficacy and Gastrointestinal Safety of Different Aspirin Formulations for Cardiovascular Prevention: A Narrative Review

Aspirin inhibits platelet function by irreversibly inhibiting the synthesis of thromboxane A2 (TxA2). Aspirin, at low doses, is widely used for cardiovascular prevention. Gastrointestinal discomfort, mucosal erosions/ulcerations and bleeding are frequent complications of chronic treatment. To reduce these adverse effects, different formulations of aspirin have been developed, including enteric-coated (EC) aspirin, the most widely used aspirin formulation. However, EC aspirin is less effective than plain aspirin in inhibiting TxA2 production, especially in subjects with high body weight. The inadequate pharmacological efficacy of EC aspirin is mirrored by lower protection from cardiovascular events in subjects weighing >70 kg. Endoscopic studies showed that EC aspirin causes fewer erosions of the gastric mucosa compared to plain aspirin (which is absorbed in the stomach) but causes mucosal erosions in the small intestine, where it is absorbed. Several studies demonstrated that EC aspirin does not reduce the incidence of clinically relevant gastrointestinal ulceration and bleeding. Similar results were found for buffered aspirin. Although interesting, the results of experiments on the phospholipid-aspirin complex PL2200 are still preliminary. Considering its favorable pharmacological profile, plain aspirin should be the preferred formulation to be used for cardiovascular prevention.

Small Intestinal Perforation Caused by Enteric-coated Low-dose Aspirin

A 77-year-old man presented with abdominal pain for 1 week. He was taking enteric-coated low-dose aspirin (LDA) to prevent secondary cardiovascular events and a proton pump inhibitor (PPI). Computed tomography indicated a small intestinal perforation; thus, small intestine resection was performed. Two months after surgery, he experienced a recurrence of the perforation. Since his repeated perforation was suspected to be due to LDA, LDA was discontinued. He has experienced no further recurrence since then. This is the first case of small intestinal perforation caused by enteric-coated LDA. Enteric-coated LDA may cause small intestinal perforation in patients with severe atherosclerosis under PPI administration.

The impact of enteric coating of aspirin on aspirin responsiveness in patients with suspected or newly diagnosed ischemic stroke: prospective cohort study: results from the (ECASIS) study

Background and purpose

Uncertainty remains regarding the impact of enteric-coated aspirin (EC-ASA) on secondary prevention of ischemic stroke compared to plain aspirin (P-ASA). Hence, this study was designed to investigate the effect of EC formulation on ASA response via evaluating thromboxane B2 (TXB2) levels in patients with suspected or newly diagnosed stroke.

Methods

A prospective cohort study on suspected or newly diagnosed ischemic stroke patients who are aspirin-naive was conducted. Patients were received either EC aspirin or plain aspirin for at least 3 days. The primary outcome was the proportion of aspirin non-responsiveness between two groups (level of residual serum TXB2 associated with elevated thrombotic risk (< 99.0% inhibition or TXB2 > 3.1 ng/ml) within 72 h after three daily aspirin doses, while secondary outcomes were the incidence of early gastrointestinal tract (GIT) bleeding with the various aspirin preparations. (Trial registration: Clinicaltrials.gov NCT04330872 registered on 02 April 2020).

Results

Of 42 patients, ischemic strokes were confirmed in both P-ASA (81%) and EC-ASA (67%) arms. ASA non-responsiveness showed no significant difference between the two formulations (P-ASA vs. EC-ASA; 28.6% vs 23.8%; P = 0.726). Univariate and multivariate logistic regression analysis showed that patients treated with EC-ASA were more likely to have a lower rate of non-responders compared to P-ASA (unadjusted OR 0.78; 95% CI 0.20, 3.11); with the risk highest in type 2 diabetic patients with HBA1c > 6.5% (adjusted OR 6; 95% CI 1.02, 35.27; P = 0.047). No incidence of GIT bleeding observed throughout the study.

Conclusion

A significant proportion of ASA non-responsiveness was recorded regardless of ASA formulation administered. The increased risk of ASA non-responsiveness in diabetic patients needs further exploration by larger prospective studies.

Pathophysiology and therapeutic management of anemia in gastrointestinal disorders

INTRODUCTION

Anemia is a common complication of gastrointestinal (GI) disorders, with a prevalence up to 60% in celiac disease (CeD) and inflammatory bowel disease (IBD). Iron deficiency anemia (IDA) is the most prevalent form of anemia in these conditions, but chronic inflammation and vitamin B12 deficiency represent other common contributing mechanisms, especially in IBD.

AREAS COVERED

We discuss the pathogenesis of anemia in various medical GI disorders, the sometime problematic distinction between IDA, anemia of inflammation (AI) and the association of the two, and therapeutic and preventive measures that can be useful for the management of anemia in GI disorders. Unfortunately, with the exception of IDA and AI in IBD, large RCT concerning the treatment of anemia in GI disorders are lacking.

EXPERT OPINION

Anemia management strategies in GI disorders are outlined, with a focus on the main prevention, diagnostic, and therapeutic measures. Specific problems and situations such as the role of gluten-free diet for IDA treatment in CeD, the choice between oral and parenteral supplementation of iron or vitamin B12 in carential anemias, the use of endoscopic procedures to stop bleeding in intestinal angiodysplasia and preventive/treatment strategies for NSAID-associated GI bleeding are discussed.

Is There an Optimal Antiplatelet Strategy after Gastrointestinal Bleeding in Patients with Coronary Artery Disease?

Gastrointestinal bleeding after percutaneous coronary intervention (PCI) is a not too uncommon clinical situation and is associated with high morbidity and mortality. After initial treatment, a number of clinical decisions must be made weighing the risks of ischemic events and future bleeding. In particular, healthcare providers must carefully balance the effectiveness of antiplatelet therapy in the secondary prevention of coronary events, primarily future spontaneous myocardial infarction and stent thrombosis, against the risk of major, most commonly gastrointestinal bleeding. The first question is whether a dual antiplatelet therapy strategy is required or if a single antiplatelet agent will suffice. Then, if a single antiplatelet agent is adequate, which agent should be continued. Although there is some guidance to answer some of these questions, there are inadequate evidence-based data for others. Below, we review the various considerations and summarize our approach and rationale to manage patients who had gastrointestinal bleeding after PCI.

Contemporary Clinical Use of Aspirin: Mechanisms of Action, Current Concepts, Unresolved Questions, and Future Perspectives

The ability of aspirin to inhibit platelet aggregation has positioned this agent within the most frequently used drugs worldwide. The aim of this article is to review the contemporary clinical use of aspirin and also to discuss unresolved issues not yet translated into clinical practice. Results from several clinical trials have led to strong guideline recommendations for aspirin use in the acute management and secondary prevention of cardiovascular disease. On the contrary, guidelines regarding aspirin use as primary prevention of cardiovascular disease are almost conservative, supported by recent trials reporting that the bleeding risk outweighs the potential benefits in most patients. In pregnancy, aspirin has proved efficient in preventing preeclampsia and small-for-gestational-age births in women at high risk, and is hence widely recommended in clinical guidelines. Despite the vast amount of clinical data on aspirin, several unresolved questions remain. Randomized trials have reported that aspirin reduces the risk of recurrent venous thromboembolism, but the clinical relevance remains limited, because direct oral anticoagulants are more effective. Laboratory studies suggest that a twice-daily dosing regimen or evening intake may lead to more efficient platelet inhibition, and the potential clinical benefit of such strategies is currently being explored in ongoing clinical trials. Enteric-coated formulations of aspirin are frequently used, but it remains unclear if they are safer and as efficient as plain aspirin. In the future, aspirin use after percutaneous coronary interventions might not be mandatory in patients who also need anticoagulant therapy, as several trials support shorter aspirin duration strategies. On the other hand, new treatment indications for aspirin will likely arise, as there is growing evidence that aspirin may reduce the risk of colorectal cancer and other types of cancer.

Development of Duloxetine Hydrochloride Tablets for Delayed and Complete Release Using Eudragit L 100

The purpose of the research was to optimize the preparation of duloxetine hydrochloride (duloxetine HCl) delayed release tablets. Duloxetine HCl produces a toxic substance called alpha-naphthol when duloxetine HCl is in contact with gastric fluid. Thus, duloxetine HCl when given orally needed a protective enteric coating that disable the delivery of duloxetine HCl in gastric fluid while enabling the drug delivery only in small intestine. Four different core tablets were prepared by direct compression technique, and the one which displayed quick disintegration and dissolution was chosen for enteric coating. The compressed tablets were enteric coated by dip coating technique. Since subcoating is required to safeguard the enteric coating, the core tablets were subcoated by using polymer HPMC K15M and then enteric coated with Eudragit L 100. The prepared tablets were assessed for the entire precompression and postcompression characteristics. FTIR study revealed the existence of all prominent peaks signifying its compatibility and authenticity. The in vitro studies showed that enteric-coated tablets were capable of restricting release in acidic media. The formulation F8 was optimised with 5% and 15% increase in weight of seal coat and enteric coat with good dissolution profile. Stability studies revealed that the optimized formulation was intact without any deterioration for 3 months. In conclusion, the optimized formulation could resist the drug release in acidic environment of gastrointestinal region and release the drug at a time once the tablet reaches the intestine.

Scintigraphic evaluation of the in vivo performance of dry-coated delayed-release tablets in humans

We characterized the gastrointestinal (GI) transit and drug release characteristics of dry-coated delayed-release tablets under both prandial states in humans using a gamma scintigraphy approach. We also estimated the onset time of drug release from the dry-coated tablets after dissolution of the outer layer in a clinical study, and compared findings with those of in vitro release testing. The dry-coated tablets used in this study were composed of a core containing radiolabeled resin (111-Indium) and a gel forming outer layer made of polyethylene oxide and polyethylene glycol. The dry-coated tablets were administered to human subjects in the fasted and fed state (30 min after ingestion of a standard breakfast radiolabeled with 99m-Technetium). Gastric emptying time, small intestinal transit time, and onset of radioactivity release in the GI tract were estimated from scintigraphic imaging. Release characteristics of the radiolabel from the dry-coated tablets were also assessed in in vitro dissolution testing using a USP apparatus 2 (paddle). Ingestion of food affected the gastric emptying time of the dry-coated tablets but not small intestinal transit. Onset timing of the release of radioactivity from the core of two different formulas of dry-coated tablets was characterized. The onset timing of drug release in the fasted subjects was markedly similar to that in the in vitro dissolution testing at a paddle rate of 200 rpm.

Differing disintegration and dissolution rates, pharmacokinetic profiles and gastrointestinal tolerability of over the counter ibuprofen formulations

OBJECTIVES

Formulations of over the counter (OTC) NSAIDs differ substantially, but information is lacking on whether this alters their gastrointestinal profiles. To assess disintegration and dissolution rates and pharmacokinetics of four preparations of OTC ibuprofen and relate these with spontaneously reported gastrointestinal adverse events.

METHODS

Disintegration and dissolution rates of ibuprofen tablets as (a) acid, (b) sodium salt, (c) lysine salt, and (d) as a liquid gelatine capsule were assessed. Pharmacokinetic data gastrointestinal and spontaneously reported adverse events arising from global sales were obtained from files from Reckitt Benckiser.

KEY FINDINGS

Disintegration at low pH was progressively shorter for the preparations from a-to-d with formation of correspondingly smaller ibuprofen crystals, while dissolution was consistently poor. Dissolution at a neutral pH was least rapid for the liquid gelatine capsule. Pharmacokinetic data showed a shorter t_max and a higher C_max for preparations b-d as compared with ibuprofen acid. Spontaneously reported abdominal symptoms were rare with the liquid gelatine preparation.

CONCLUSIONS

The formulations of OTC ibuprofen differ in their disintegration and dissolution properties, pharmacokinetic profiles and apparent gastrointestinal tolerability. Spontaneously reported abdominal symptoms were five times lower with the liquid gelatine capsule as compared with ibuprofen acid despite a 30% increase in C_max .

Non-steroidal anti-inflammatory drug-induced enteropathy

Non-steroidal anti-inflammatory drugs (NSAIDs) are well known to be associated with serious upper gastrointestinal complications, such as peptic ulcer, bleeding, perforation, and obstruction. Recently, attention has been mainly focused on the small bowel injuries caused by NSAIDs, and new endoscopic techniques such as capsule endoscopy and double balloon endoscopy can help in detecting such injuries. This article reviewed the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of small bowel injuries caused by NSAIDs. Small bowel injures by NSAIDs might occur with a similar frequency and extent as those observed in the upper gastrointestinal tract. The pathogenesis of NSAID-induced enteropathy is complex and not clearly understood. The various lesions observed in the small bowel, including petechiae, reddened folds, loss of villi, erosions, and ulcers can be detected by capsule endoscopy. A drug that could prevent or treat NSAID-induced enteropathy has not yet been developed. Therefore, further investigations should be performed to elucidate the pathogenesis of such enteropathy and develop suitable preventive and treatment strategies.

Gastroprotective [6]-Gingerol Aspirinate as a Novel Chemopreventive Prodrug of Aspirin for Colon Cancer

A growing body of research suggests daily low-dose aspirin (ASA) reduces heart diseases and colorectal cancers. However, the major limitation to the use of aspirin is its side effect to cause ulceration and bleeding in the gastrointestinal tract. Preclinical studies have shown that ginger constituents ameliorate ASA-induced gastric ulceration. We here report the design and synthesis of a novel prodrug of aspirin, [6]-gingerol aspirinate (GAS). Our data show that GAS exerts enhanced anti-cancer properties in vitro and superior gastroprotective effects in mice. GAS was also able to survive stomach acid and decomposed in intestinal linings or after absorption to simultaneously release ASA and [6]-gingerol. We further present that GAS inactivates both COX-1 and COX-2 equally. Our results demonstrate the enhanced anticancer properties along with gastroprotective effects of GAS, suggesting that GAS can be a therapeutic equivalent for ASA in inflammatory and proliferative diseases without the deleterious effects on stomach mucosa.

Which Aspirin Dose and Preparation Is Best for the Long-Term Prevention of Cardiovascular Disease and Cancer? Evidence From a Systematic Review and Network Meta-Analysis

The evidence base on aspirin in primary prevention suggests that it can reduce significantly the risk of cardiovascular disease (CVD) events and cancer, especially colorectal, albeit increasing bleeding. There is, however, uncertainty on the optimal aspirin dose and preparation for primary prevention. We thus aimed to review main sources of evidence informing on daily dosage and preparation of aspirin for primary prevention of CVD and cancer. We collected and elaborated aspirin effectiveness and safety data from U.S. Preventive Services Task Force reports on aspirin in primary prevention, distinguishing average daily dose in <100mg, 100mg, and >100mg. The following preparations were also systematically compared: enteric coated, controlled release, non-coated, or otherwise unspecified. Fixed-effect pairwise and network meta-analytic models were run in a frequentist framework. Eleven randomized trials were shortlisted, enrolling 104,101 subjects, followed for a median of 60months. At pairwise analysis, aspirin was associated with significant reductions in death and CVD events, non-significant reductions in cancer death or incidence, and significant increases in the risk of intracranial and gastrointestinal (GI) bleeding. An average daily dose of 100mg had the highest probability of reducing death, cancer death, and cancer incidence, whereas higher doses seemed superior for reducing CVD events, and 100mg or less daily proved better tolerated. Coated preparations appeared more beneficial for death, cancer death, cancer incidence, and GI bleeding, whereas controlled release preparations appeared better for CVD events and non-coated ones for intracranial bleeding. In conclusion, an average daily dose of 100mg of coated aspirin seems more likely to confer favorable preventive effects on death and cancer, with higher doses more appealing for CVD prevention and lower doses better tolerated.

Small bowel injury in low-dose aspirin users

The use of low-dose aspirin (LDA) is well known to be associated with an increased risk of serious upper gastrointestinal complications, such as peptic ulceration and bleeding. Until recently, attention was mainly focused on aspirin-induced damage of the stomach and duodenum. However, recently, there has been growing interest among gastroenterologists on the adverse effects of aspirin on the small bowel, especially as new endoscopic techniques, such as capsule endoscopy (CE) and balloon-assisted endoscopy, have become available for the evaluation of small bowel lesions. Preliminary CE studies conducted in healthy subjects have shown that short-term administration of LDA can induce mild mucosal inflammation of the small bowel. Furthermore, chronic use of LDA results in a variety of lesions in the small bowel, including multiple petechiae, loss of villi, erosions, and round, irregular, or punched-out ulcers. Some patients develop circumferential ulcers with stricture. In addition, to reduce the incidence of gastrointestinal lesions in LDA users, it is important for clinicians to confirm the differences in the gastrointestinal toxicity between different types of aspirin formulations in clinical use. Some studies suggest that enteric-coated aspirin may be more injurious to the small bowel mucosa than buffered aspirin. The ideal treatment for small bowel injury in patients taking LDA would be withdrawal of aspirin, however, LDA is used as an antiplatelet agent in the majority of patients, and its withdrawal could increase the risk of cardiovascular/cerebrovascular morbidity and mortality. Thus, novel means for the treatment of aspirin-induced enteropathy are urgently needed.

Gastrointestinal symptoms in low-dose aspirin users: a comparison between plain and buffered aspirin

Background

Aspirin is associated with gastrointestinal side effects such as gastric ulcers, gastric bleeding and dyspepsia. High-dose effervescent calcium carbasalate (ECC), a buffered formulation of aspirin, is associated with reduced gastric toxicity compared with plain aspirin in healthy volunteers, but at lower cardiovascular doses no beneficial effects were observed.

Aim

To compare the prevalence of self-reported gastrointestinal symptoms between low-dose plain aspirin and ECC.

Methods

A total of 51,869 questionnaires were sent to a representative sample of the Dutch adult general population in December 2008. Questions about demographics, gastrointestinal symptoms in general and specific symptoms, comorbidity, and medication use including bioequivalent doses of ECC (100 mg) and plain aspirin (80 mg) were stated. We investigated the prevalence of self-reported gastrointestinal symptoms on ECC compared with plain aspirin using univariate and multivariate logistic regression analyses.

Results

A total of 16,715 questionnaires (32 %) were returned and eligible for analysis. Of these, 911 (5 %) respondents reported the use of plain aspirin, 633 (4 %) ECC and 15,171 reported using neither form of aspirin (91 %). The prevalence of self-reported gastrointestinal symptoms in general was higher in respondents using ECC (27.5 %) compared with plain aspirin (26.3 %), but did not differ significantly with either univariate (OR 1.06, 95 %CI 0.84–1.33), or multivariate analysis (aOR 1.08, 95 %CI 0.83–1.41). Also, none of the specific types of symptoms differed between the two aspirin formulations.

Conclusions

In this large cohort representative of the general Dutch population, low-dose ECC is not associated with a reduction in self-reported gastrointestinal symptoms compared with plain aspirin.

Electronic supplementary material

The online version of this article (doi:10.1007/s12471-014-0522-3) contains supplementary material, which is available to authorized users.

Risk factor profiles, drug usage, and prevalence of aspirin-associated gastroduodenal injuries among high-risk cardiovascular Japanese patients: the results from the MAGIC study

BACKGROUND

Low-dose aspirin is widely used for the prevention of cardiovascular events. The prevalence of gastroduodenal injuries and the risk factor profile including gastroprotective drug therapy needs to be clarified in Japanese patients taking daily aspirin for cardioprotection.

METHODS

This Management of Aspirin-induced Gastro-Intestinal Complications (MAGIC) study was conducted with a prospective nationwide, multicenter, real-world registry of Japanese patients at high-risk of cardiovascular diseases who were taking regular aspirin (75-325 mg) for 1 month or more. All patients underwent endoscopic examination for detection of gastroduodenal ulcer and mucosal erosion. The risk factor profiles including the concurrent drug therapy were compared for those patients with gastroduodenal problems and those without.

RESULTS

Gastroduodenal ulcer and erosion were detected in 6.5, and 29.2% of the 1,454 patients receiving aspirin, respectively. H. pylori infection was associated with an increased risk for ulcer: OR 1.83 (1.18-2.88 p = 0.0082). Risk of erosion was lower with enteric-coated aspirin than with buffered aspirin: odds ratio (OR) 0.47 (0.32-0.70, p = 0.0002). Patients receiving proton pump inhibitors had lower risks for both gastroduodenal ulcer and erosion: OR 0.34 (0.15-0.68, p = 0.0050) and 0.32 (0.22-0.46, p < 0.0001), respectively. However, those receiving histamine 2-receptor antagonists had reduced risks for erosion but not for ulcer: OR 0.49 (0.36-0.68, p < 0.0001).

CONCLUSION

Gastroduodenal ulcer and erosion are common in Japanese patients taking low dose aspirin for cardioprotection. Proton pump inhibitors reduce the risk of gastroduodenal mucosal injury.

The role of food for the formation and prevention of gastrointestinal lesions induced by aspirin in cats

BACKGROUND/AIMS

The effects of feeding conditions (fasted or fed) and dietary fiber (DF) in the diet on gastrointestinal (GI) damage induced by aspirin (ASA) were examined in cats.

METHODS

Plain ASA (P-ASA, 20 mg/kg) or one enteric-coated ASA tablet (EC-ASA, containing 100 mg ASA) was administered p.o. once daily for 3 or 7 days just after morning meal, 3 h after the evening meal, or in the morning without a morning meal (fasted). Several types of diet, dry food (DRY, DF: 2.8 %), canned food (CAN, DF: 0.4 %), and diets with added cellulose or pectin were provided twice daily.

RESULTS

P-ASA or EC-ASA administered just after feeding of DRY caused marked lesions in the GI tract, although EC-ASA did not produce any lesions in the stomach. GI damage was markedly decreased when ASA was administered 3 h after the evening meal. The induction of lesions by EC-ASA was markedly decreased in cats that ate CAN, but lesions were induced in cats fed CAN with added cellulose (6 %). The addition of pectin (6 %) to the DRY markedly decreased the induction of lesions by EC-ASA.

CONCLUSIONS

The results indicate that the induction of GI lesions by ASA was highly dependent on the feeding conditions and DF. To minimize the induction of GI damage, it would be better to take ASA 3 h after the evening meal, or after consuming diets that contain low amounts of insoluble DF and high amounts of soluble DF.

Differences in the severity of small bowel mucosal injury based on the type of aspirin as evaluated by capsule endoscopy

BACKGROUND

The differences in the small intestinal toxicity of low-dose aspirin based on the type of aspirin used remains unclear. The purpose of this study was to evaluate the differences in the small bowel mucosal injury between buffered and enteric-coated aspirin users by capsule endoscopy.

METHODS

We retrospectively reviewed the findings in chronic low-dose aspirin users (>3 months) who underwent capsule endoscopy for the investigation of obscure gastrointestinal bleeding. The patients were classified into two groups based on the type of low-dose aspirin that they had been prescribed (enteric-coated aspirin group or buffered aspirin group), and evaluated the numbers of small bowel lesions and the Lewis score.

RESULTS

Capsule-endoscopic findings of a total of 70 patients taking low-dose aspirin were reviewed. Significant differences in the number of erosions and ulcers were observed between the buffered and enteric-coated aspirin groups (P=0.017 and P=0.037, respectively). The median Lewis score for the small bowel mucosal inflammatory change was significantly higher in the enteric-coated aspirin group than in the buffered aspirin group (P=0.035).

CONCLUSIONS

The results of this study suggested that enteric-coated aspirin might be more injurious to the small bowel mucosa than buffered aspirin.

Gastroduodenal toxicity of low-dose acetylsalicylic acid: a comparison with non-steroidal anti-inflammatory drugs

BACKGROUND

Low-dose acetylsalicylic acid (ASA; aspirin; 75-325 mg/day) is effective for the prevention of cardiovascular events, and its use in this indication is rapidly increasing. However, the use of ASA and, indeed, other non-steroidal anti-inflammatory drugs (NSAIDs) is limited by the incidence of adverse gastroduodenal events. OBJECTIVES AND SCOPE: To review the clinical evidence for, and the pharmacodynamic basis of, ASA-induced gastroduodenal toxicity in comparison with NSAIDs, and address the question of whether low-dose ASA is 'safe' from a gastroduodenal perspective. This was a narrative, descriptive review, rather than a formal systematic review.

FINDINGS

Adverse gastroduodenal effects, which are well known to occur with NSAIDs, are also prevalent in patients receiving low-dose ASA for cardiovascular protection even at doses as low as 75 mg/day. The risk of gastroduodenal toxicity is particularly high among 'at-risk' low-dose ASA patients (aged >70 years, previous ulcer or upper gastrointestinal bleeding and users of antiplatelets or NSAIDs). There are important differences in the mechanism of ASA-induced gastroduodenal toxicity, relative to NSAIDs. These differences include the effects on the cyclooxygenase (COX)-1 isoenzyme, local effects on the gastroduodenal mucosa specific to ASA and a reduction in platelet aggregation.

CONCLUSION

Data suggest that ASA causes significant gastroduodenal damage even at the low doses used for cardiovascular protection. These effects (both systemic and possibly local) may be pharmacodynamically distinct from the gastroduodenal toxicity seen with NSAIDs. Studies are required to establish strategies for improving the tolerability of low-dose ASA, allowing patients to continue to benefit from the cardiovascular protection associated with such therapy.

Preliminary trial of rebamipide for prevention of low-dose aspirin-induced gastric injury in healthy subjects: a randomized, double-blind, placebo-controlled, cross-over study

Although low-dose aspirin is widely used, since it is a cheap and effective means of prevention of cardiovascular events, it can cause hemorrhagic gastrointestinal complications. The aim of this study was to evaluate the efficacy of rebamipide in preventing low-dose aspirin-induced gastric injury. A randomized, double-blind, placebo-controlled, crossover trial was performed in twenty healthy volunteers. Aspirin 81 mg was administered with placebo or rebamipide 300 mg three times daily for 7 consecutive days. The rebamipide group exhibited significant prevention of erythema in the antrum compared with the placebo group (p = 0.0393, respectively). Results for the body and fornix did not differ significantly between the placebo and rebamipide groups. In conclusion, short-term administration of low-dose aspirin induced slight gastric mucosal injury in the antrum, but not in the body or fornix. Rebamipide may be useful for preventing low-dose aspirin-induced gastric mucosal injury, especially which confined to the antrum.

Characteristics of small bowel injury in symptomatic chronic low-dose aspirin users: the experience of two medical centers in capsule endoscopy

BACKGROUND

The antithrombotic effects of low-dose aspirin (LDA) are well established, and it is used for primary and secondary prevention of cardiovascular events. However, the small intestinal toxicity of LDA remains unclear. The aim of this study was to review the characteristics of small bowel injury in long-term LDA users with capsule endoscopy (CE).

METHODS

We retrospectively reviewed all chronic LDA users (>3 months) who underwent CE for suspected small bowel diseases from May 2004 to May 2008 at two medical centers.

RESULTS

At our institutions, a total of 22 patients (13 males and 9 females, mean age 66.3 years) taking LDA underwent a CE examination. The indications for CE were obscure gastrointestinal bleeding in 21 patients and 1 patient who had abdominal pain. Twenty-one patients (95.5%) had some small bowel mucosal injury. Small bowel erosions were identified in 14 patients (63.6%). This enteropathy was characterized by multiple petechiae, loss of villi, erosions, and ulcers with round, irregular, and punched-out shapes. Two patients had circumferential ulcers with stricture. In most patients, small bowel lesions were multifocal and were evenly distributed in the small bowel. No patients failed to pass the capsule.

CONCLUSIONS

This is the first CE report that has studied the characteristics of small bowel injury in chronic LDA users. CE is useful to diagnose small bowel enteropathy associated with LDA.

Aspirin in cardiology--benefits and risks

AIMS

To review the current knowledge of the benefits and risks of long-term aspirin therapy for the prevention of cardiovascular disease.

METHODS

Relevant articles published in English between 1996 and 2006 were obtained from the Current Contents Science Edition, EMBASE and MEDLINE databases.

RESULTS

Secondary aspirin prophylaxis is effective in reducing the risk of ischaemic events in patients with cardiovascular disease. However, its utility in reducing primary ischaemic events is more controversial; it appears to reduce the incidence of ischaemic stroke, but increase the incidence of haemorrhagic stroke. Aspirin therapy can also lead to an increased risk of gastrointestinal ulcers, upper gastrointestinal bleeding and other haemorrhagic complications. Lower doses of aspirin are associated with a reduced risk of gastrointestinal side effects and are equally effective in reducing cardiovascular risk. Co-therapy with non-steroidal anti-inflammatory drugs, clopidogrel or warfarin increases the risk of gastrointestinal side effects, while co-therapy with proton pump inhibitors reduces it.

CONCLUSIONS

Both the benefits and risks need to be considered carefully when prescribing aspirin, particularly in primary prevention. Patients should be prescribed lower doses rather than higher doses of aspirin in line with prescribing guidelines. Co-prescription of a proton pump inhibitors may be necessary in patients at high risk for upper gastrointestinal complications.

Endoscopic survey of low-dose-aspirin-induced gastroduodenal mucosal injuries in patients with ischemic heart disease

BACKGROUND AND AIM

Low-dose aspirin is effective for the prevention of cardiovascular and cerebrovascular events, but the frequency of gastrointestinal injuries among users of low-dose aspirin in Japan is currently unknown. In the present study endoscopic examination was performed to investigate the frequency of gastroduodenal injuries associated with low-dose aspirin in patients with ischemic heart disease (IHD).

METHODS

Screening upper endoscopic examinations were prospectively performed on 131 patients with IHD who were not receiving antiulcer treatment. Endoscopic findings such as ulcers and flat erosions were assessed as mucosal injuries.

RESULTS

Mucosal injuries were found in 62 of 101 (61.4%) low-dose aspirin users and three of 30 (10%) nonaspirin users. There were significantly more mucosal injuries among low-dose aspirin users than among the non-users (P<0.0001). Gastroduodenal ulcers were found in 19 of 101 (18.8%) low-dose aspirin users compared with one of 30 (3.3%) nonaspirin users. The frequency of mucosal injuries was not associated with the duration of aspirin treatment.

CONCLUSION

Endoscopy frequently reveals low-dose aspirin-induced gastroduodenal injuries in patients with IHD.

Small bowel injury by low-dose enteric-coated aspirin and treatment with misoprostol: a pilot study

BACKGROUND & AIMS

With capsule endoscopy, the ulcerogenic effect of low-dose enteric-coated aspirin on the small bowel and the therapeutic effect of misoprostol on intestinal injury were evaluated.

METHODS

Eleven patients who developed gastric ulcers while undergoing low-dose enteric-coated aspirin therapy were enrolled. They continued aspirin therapy while taking proton pump inhibitors (PPIs) for 8 weeks to heal the gastric ulcers. Then misoprostol 200 microg 4 times a day was administered instead of PPIs for 8 weeks. When the patients could not tolerate misoprostol as a result of side effects, they received another 8 weeks of PPI therapy.

RESULTS

Capsule endoscopy performed after 8 weeks of PPI treatment identified red spots and mucosal breaks in 100% (11/11) and 90.9% (10/11) of patients, respectively. In 7 patients who completed the study protocol, misoprostol significantly decreased the median number of red spots and mucosal breaks, with complete disappearance of mucosal breaks in 4 patients. Intestinal lesions tended not to heal in 3 patients who discontinued misoprostol.

CONCLUSIONS

Low-dose enteric-coated aspirin frequently damages the small intestine, and misoprostol is effective in the treatment of aspirin-induced enteropathy.

Determinants of the short-term gastric damage caused by NSAIDs in man

BACKGROUND

The short-term gastric damage seen with non-steroidal anti-inflammatory drugs (NSAIDs) in man may involve inhibition of cyclooxygenase (COX-1) and COX-2 as well as the topical irritancy, which is dependant on the acidity (pKa) and/or lipophilicity (log P(7.4)).

AIM

To study the quantitative relationship between NSAID-induced short-term gastric damage, their physicochemical properties and contrasting roles of COX-1 and COX-2 inhibition.

METHODS

We identified studies that allowed a qualitative comparison of the gastric injury (Lanza scores) induced by NSAIDs with their pKa and log P(7.4). Damage was correlated with gastric COX inhibition and potency to inhibit COX-1 and 2 and their COX-2/COX-1 selectivity ratio.

RESULTS

The gastric damage correlates significantly with pKa (r = -0.69; P < 0.01), log P (r = -0.58, P < 0.05) and potency of the NSAIDs to inhibit COX-1 (r = -0.61, P < 0.02), but not with COX-2 inhibition or COX-2/COX-1 selectivity.

CONCLUSION

Against a background of COX-1 and COX-2 inhibition, the physicochemical properties of NSAID appear to play an important role in short-term gastric damage.

Review article: gastrointestinal bleeding with low-dose aspirin - what's the risk?

This review examines ulcers and gastrointestinal bleeding with low-dose aspirin, focusing on randomized placebo-controlled trials. The single endoscopic trial assessing ulcers showed no significant difference in 12-week ulcer incidence: 6% of 381 given placebo vs. 7% of 387 given 81 mg enteric-coated aspirin. The relative risk of major gastrointestinal bleeding with low-dose aspirin in a meta-analysis of placebo-controlled trials of vascular protection was 2.07 (95% CI: 1.61-2.66). The absolute rate increase with aspirin above placebo was 0.12% per year (95% CI: 0.07-0.19%) with a number-needed-to-harm of 833 patients (95% CI: 526-1429). A meta-analysis of aspirin 50-1500 mg daily reported an odds ratio for any gastrointestinal bleeding of 1.68 (95% CI: 1.51-1.88) with an number-needed-to-harm at 1 year of 247. The relative risk of hospitalization for upper gastrointestinal bleeding with low-dose aspirin in a large Danish cohort study was 2.6 (95% CI: 2.2-2.9) with an absolute annual incidence of 0.6%. Factors that may increase the risk of gastrointestinal bleeding include prior history of ulcers or gastrointestinal bleeding, corticosteroid use, anticoagulant therapy and addition of a non-aspirin non-steroidal anti-inflammatory drug. When determining whether low-dose aspirin is appropriate for an individual patient, the cardiovascular benefit must be weighed against the potential for clinical events such as gastrointestinal bleeding.

Lack of effect of enteric coating on aspirin-induced inhibition of platelet aggregation in healthy volunteers

BACKGROUND

Aspirin inhibits platelet aggregation and is widely used in the treatment of cardiovascular disease. Some individuals are less responsive to aspirin's antiplatelet effect, a phenomenon termed aspirin resistance. It is not known whether the antiplatelet effect is fully preserved with the enteric-coated (EC) formulation.

METHODS

We performed a prospective randomized trial of 50 healthy volunteers using a crossover design to compare the EC with the standard aspirin formulations. The subjects received a 7-day course of each aspirin formulation (81-mg) (Bayer Corporation, Morristown, NJ) separated by a 3-week washout period. Platelet function was measured before and after each course using optical aggregometry (with arachidonic acid and adenosine diphosphate as agonists) and a point-of-care platelet assay.

RESULTS

The assays were reproducible, and the variation in baseline platelet function was small to moderate between the subjects. There was no difference in the extent of platelet inhibition between the EC and standard formulations with any of the 3 assays. With the point-of-care platelet assay, the mean aspirin effect favoring the standard formulation (more aggregation inhibition) compared with the EC formulation was 1.6% +/- 15.8% (P = .60 for difference between the formulations). The corresponding optical aggregometry values were -3.4% +/- 39.5% (P = .97) and -1.4% +/- 16.6% (P = .75) for arachidonic acid and adenosine diphosphate, respectively.

CONCLUSIONS

Compared with standard aspirin, EC aspirin appears to exhibit similar inhibition of platelet aggregation in healthy volunteers. Furthermore, point-of-care platelet assessment correlated well with the gold standard of laboratory-based optical platelet aggregometry.

Effects of NSAIDs on bladder function in normal and cystitis rats: a comparison study of aspirin, indomethacin, and ketoprofen

To clarify the potential usefulness of non-steroidal anti-inflammatory drugs, NSAIDs, for patients with overactive bladder, we examined the effect of NSAIDs on urodynamic parameters in normal and cystitis rats and compared their ulcerogenic activity in the gastrointestinal mucosa. Cystometry was performed after administration of the conventional NSAIDs, aspirin, indomethacin, or ketoprofen. Prostaglandin levels were measured in the bladder of cystitis rats pretreated with NSAIDs. Furthermore, the ulcerogenic responses were examined. NSAIDs increased bladder capacity without any effect on micturition pressure in normal rats in the following rank order of potency: ketoprofen > or = indomethacin > or = aspirin. In cystitis rats, bladder capacity was increased and micturition frequency was decreased. The levels of prostaglandin were significantly increased in cystitis rats. All NSAIDs inhibited the increment of prostaglandin levels at doses equal to that effective in the improvement of bladder functions. When administered intraduodenally, both ketoprofen and indomethacin induced lesions in the gastrointestinal mucosa. However, aspirin had no significant effect. We demonstrate that NSAIDs are effective in animal models of disease, most likely by suppressing by prostaglandin synthesis. Since aspirin, in contrast to ketoprofen or indomethacin, did not cause any gastrointestinal lesions, aspirin might be the NSAIDs treatment of choice for overactive bladder.

[Epidemiology of digestive complications associated with use of low-dose aspirin]

Low-dose aspirin (< 330 mg/d) is recommended for the prevention of myocardial infarction or ischemic stroke. Six to 12% of the general population is exposed to low-dose aspirin. The most frequently studied digestive complications are bleeding peptic ulcers, whose risk is increased twofold by low-dose aspirin treatment, and non-complicated peptic ulcers. History of bleeding or non-complicated peptic ulcer, alcohol intake, concomitant treatment with NSAID or calcic inhibitors are demonstrated risk factors of bleeding ulcer associated with low-dose aspirin. The role of enteric coating, of low-dose aspirin dose, of delay since low-dose aspirin treatment onset, and of Helicobacter pylori infection, remains controversial. Antisecretory drugs (H2 inhibitors, proton pump inhibitors), and nitroglycerin are associated with a decreased risk of bleeding ulcer. The protective effect of COX-2 inhibitors on the risk of bleeding ulcer is suppressed by concomitant treatment with low-dose aspirin. The risk of no- complicated peptic ulcer was increased by low-dose aspirin intake by a factor 2.9 in one study. Low-dose aspirin dose, infection by Helicobacter pylori, NSAID intake, and absence of enteric coating, are possible risk factors for non-complicated peptic ulcer. No association was retrieved with alcohol intake and peptic ulcer history.

Current approaches to prevent NSAID-induced gastropathy--COX selectivity and beyond

Gastrointestinal (GI) toxicity associated with nonsteroidal anti-inflammatory drugs (NSAIDs) is still an important medical and socio-economic problem--despite recent pharmaceutical advances. To prevent NSAID-induced gastropathy, three strategies are followed in clinical routine: (i) coprescription of a gastroprotective drug, (ii) use of selective COX-2 inhibitors, and (iii) eradication of Helicobacter pylori. Proton pump inhibitors are the comedication of choice as they effectively reduce gastrointestinal adverse events of NSAIDs and are safe even in long-term use. Co-medication with vitamin C has only been little studied in the prevention of NSAID-induced gastropathy. Apart from scavenging free radicals it is able to induce haeme-oxgenase 1 in gastric cells, a protective enzyme with antioxidant and vasodilative properties. Final results of the celecoxib outcome study (CLASS study) attenuated the initial enthusiasm about the GI safety of selective COX-2 inhibitors, especially in patients concomitantly taking aspirin for cardiovascular prophylaxis. Helicobacter pylori increases the risk for ulcers particularly in NSAID-naive patients and therefore eradication is recommended prior to long-term NSAID therapy at least in patients at high risk. New classes of COX-inhibitors are currently evaluated in clinical studies with very promising results: NSAIDs combined with a nitric oxide releasing moiety (NO-NSAID) and dual inhibitors of COX and 5-LOX. These drugs offer extended anti-inflammatory potency while sparing gastric mucosa.

Stable renal transplant recipients can be safely converted from MMF to enteric-coated mycophenolate sodium tablets: Interim results of a multicenter Latin American study

Enteric-coated mycophenolate sodium (EC-MPS) is designed to reduce mycophenolate acid (MPA)-related upper gastrointestinal (GI) adverse events (AEs). A multicenter, open-label, Latin American study in stable renal transplant patients is ongoing to assess the safety of the conversion from mycophenolate mofetil (MMF) to EC-MPS. An interim analysis was performed when 93 patients had completed 3 months. Prior to conversion, they had received MMF at a dose of 2 g/d, with the exception of eight adult patients who were receiving an average daily dose of 1.25 g. All adult patients were converted to EC-MPS (1.44 g/d; 0.450 g/m(2) bid for children). After conversion, the reported total incidence of AEs was 40.9%, including 28% infections, 1.1% hematologic, 19.4% GI, including 10.8% upper-GI AE (all mild) and 5.4% diarrhea. No patient discontinued the study medication due to adverse events. Only six patients (6%) required a dose adjustment. There were no episodes of acute rejection, death, or graft loss. During the period of analysis, the conversion from MMF to EC-MPS was safe, the enteric-coated tablet formulation prevented release of MPA in the upper GI tract, and only one patient had to reduce the dose due to an upper GI AE, concomitant with diarrhea. EC-MPS offers transplant physicians and their patients an alternative MPA therapy that is as effective and safe as MMF, but in a formulation that may provide GI tolerability benefits.

[Prevention of gastroduodenal complications in patients taking low-dose aspirin]

Use of low-dose aspirin is associated with an increased risk of gastroduodenal ulcers and upper gastrointestinal bleeding. The risk is increased by the old age and by cardiovascular and cerebrovascular diseases of the patients receiving low-dose aspirin. Combination with nonsteroidal anti-inflammatory drugs, corticosteroids or anticoagulant increases the risk of complications and should be avoided. Proton-pump inhibitor and eradication of Helicobacter pylori are not efficient in primary prevention of ulcer complications related to low-dose aspirin use. Patients at high risk of gastroduodenal complications due to age, morbidity or concomitant use of gastrotoxic therapy should be given prophylactic treatment. Assessment of what constitutes the most effective therapy (misoprostol, proton-pump inhibitor) should be defined in controlled trials. Among patients with Helicobacter pylori infection and a history of upper gastrointestinal bleeding who are taking low-dose aspirin, the eradication of Helicobacter pylori is equivalent to treatment with proton-pump inhibitor in preventing recurrent bleeding. Long term treatment with proton-pump inhibitor in addition to the eradication of Helicobacter pylori should be considered in patients who had ulcer complications related to the use of low-dose aspirin.

Aspirin in the prophylaxis of coronary artery disease

Aspirin has been used for more than 100 years, but its mechanisms of action have only been understood in the past 20 years. Aspirin interferes with arachidonic acid metabolism in platelets and endothelial cells and thereby reduces thromboxane A2 and prostacyclin. It also has other mechanisms of action, including anti-inflammatory roles, protection from oxidative stress, enhancement of fibrinolysis, and suppression of plasma coagulation and platelet-dependent inhibition of thrombin generation. It has been used for primary and secondary prevention of myocardial ischemia, and for primary and secondary prevention of cerebrovascular ischemia. We review the 5 pivotal studies relating to primary prevention for cardiovascular risk and the many studies relating to secondary prevention of myocardial ischemia. We also review the utility of aspirin in primary prevention of myocardial infarction and stroke. We conclude that aspirin is one of the most potent drugs ever discovered and that its effects extend well beyond those of cycloxoxygenase enzyme inhibition. Aspirin treatment does not preclude control of underlying and comorbid conditions such as diabetes mellitus, hypertension, and dyslipidemia. For most patients, a daily dose of 325 mg is optimal. Patients must understand the potential for gastrointestinal upset and hemorrhagic complications. The utility of aspirin is greater in coronary artery disease prevention than in cerebrovascular prevention.

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.