The effects of aspirin on gastric mucosal integrity, surface hydrophobicity, and prostaglandin metabolism in cyclooxygenase knockout mice

Cellular mechanisms of taste disturbance induced by the non-steroidal anti-inflammatory drug, diclofenac, in mice

Drug-induced taste disorders are a serious problem in an aging society. This study investigated the mechanisms underlying taste disturbances induced by diclofenac, a non-steroidal anti-inflammatory drug that reduces pain and inflammation by inhibiting the synthesis of prostaglandins by cyclooxygenase enzymes (COX-1 and COX-2). RT-PCR analyses demonstrated the expression of genes encoding arachidonic acid pathway components such as COX-1, COX-2 and prostaglandin synthases in a subset of mouse taste bud cells. Double-staining immunohistochemistry revealed that COX-1 and cytosolic prostaglandin E synthase (cPGES) were co-expressed with taste receptor type-1 member-3 (T1R3), a sweet/umami receptor component, or gustducin, a bitter/sweet/umami-related G protein, in a subset of taste bud cells. Long-term administration of diclofenac reduced the expression of genes encoding COX-1, gustducin and cPGES in mouse taste buds and suppressed both the behavioral and taste nerve responses to sweet and umami taste stimuli but not to other tastants. Furthermore, diclofenac also suppressed the responses of both mouse and human sweet taste receptors (T1R2/T1R3, expressed in HEK293 cells) to sweet taste stimuli. These results suggest that diclofenac may suppress the activation of sweet and umami taste cells acutely via a direct action on T1R2/T1R3 and chronically via inhibition of the COX/prostaglandin synthase pathway inducing down-regulated expression of sweet/umami responsive components. This dual inhibition mechanism may underlie diclofenac-induced taste alterations in humans.

Safety of surfactant excipients in oral drug formulations

Surfactants are a diverse group of compounds that share the capacity to adsorb at the boundary between distinct phases of matter. They are used as pharmaceutical excipients, food additives, emulsifiers in cosmetics, and as household/industrial detergents. This review outlines the interaction of surfactant-type excipients present in oral pharmaceutical dosage forms with the intestinal epithelium of the gastrointestinal (GI) tract. Many surfactants permitted for human consumption in oral products reduce intestinal epithelial cell viability in vitro and alter barrier integrity in epithelial cell monolayers, isolated GI tissue mucosae, and in animal models. This suggests a degree of mis-match for predicting safety issues in humans from such models. Recent controversial preclinical research also infers that some widely used emulsifiers used in oral products may be linked to ulcerative colitis, some metabolic disorders, and cancers. We review a wide range of surfactant excipients in oral dosage forms regarding their interactions with the GI tract. Safety data is reviewed across in vitro, ex vivo, pre-clinical animal, and human studies. The factors that may mitigate against some of the potentially abrasive effects of surfactants on GI epithelia observed in pre-clinical studies are summarised. We conclude with a perspective on the overall safety of surfactants in oral pharmaceutical dosage forms, which has relevance for delivery system development.

Non-steroidal anti-inflammatory drugs (NSAIDs): A current insight into its molecular mechanism eliciting organ toxicities

Non-steroidal anti-inflammatory drugs (NSAIDs) are a class of medications that are routinely been used across the world. Their analgesic, anti-inflammatory, and antipyretic effects have all been well-documented. Moreover, they are been deliberated to have a protective role against various critical diseases such as cancer and cardiovascular diseases. However, the data presented by numerous studies in past have signified the adverse effects of NSAIDs due to overdosing on various systems such as cardiovascular, gastrointestinal, hepatic, renal, neural, etc. Despite substantial studies representing the mechanism behind the clinical risk of NSAIDs, there are very few reviews that have collated comprehensive records of various toxicities caused by overdosing on NSAIDs. As a result, we have presented a comprehensive overview of existing information on NSAIDs in this review. In addition to that, we have concentrated on presenting our understanding of various organ-based toxicities caused due to NSAID's prolonged use/overdosage.

C-Phycocyanin and Lycium barbarum Polysaccharides Protect against Aspirin-Induced Inflammation and Apoptosis in Gastric RGM-1 Cells

Aspirin causes gastrotoxicity and damaged epithelial defense via cyclooxygenase inhibition. C-phycocyanin (CPC) and Lycium barbarum polysaccharides (LBP), an active ingredient of Spirulina platensis and wolfberry, respectively, exerted antioxidation, anti-inflammation, and/or immunoregulation. The actions of CPC and/or LBP on gastric damage induced by aspirin were explored in rat gastric mucosal RGM-1 cells. Gastric injury was performed by 21 mM aspirin for 3 h after the pretreatment of CPC and/or LBP (100-500 μg/mL) for 24 h in RGM-1 cells. Proinflammatory, anti-inflammatory, and apoptotic markers were examined by ELISA or gel electrophoresis and Western blotting. Cell viability and interleukin 10 (IL-10) were reduced by aspirin. Increased proinflammatory markers, caspase 3 activity, and Bax protein were observed in RGM-1 cells with aspirin treatment. Aspirin elevated nuclear factor-κB (NF-κB), extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK) activation, while CPC and/or LBP increased IL-10, and attenuated proinflammatory markers, Bax protein, NF-κB, and the activation of ERK and JNK. Therefore, CPC and/or LBP possess anti-inflammation by restraining the activation of the ERK signaling pathway, and LBP decreases apoptosis by suppressing the JNK signaling pathway activation in gastric RGM-1 cells with aspirin-induced epithelial damage.

Dehydroevodiamine ameliorates indomethacin-induced gastric injury via inhibition of ERK and p38 signaling pathway

BACKGROUND

Dehydroevodiamine (DHE), a pivotal quinazoline alkaloid isolated from Fructus Evodiae (Tetradium ruticarpum (A. Juss.) Hartley), has various pharmacological effects. However, the effect of DHE on gastric injury is still uncharted.

PURPOSE

To clarify the pharmacological effect and mechanism of DHE on gastric injury (GI) induced by indomethacin (IDO).

STUDY DESIGN

The gastric injury was induced in rat by oral administration of 5 mg/kg IDO for 7 days. Then the rats were treated with DHE (10, 20, 40 mg/kg, ig) for 7 days.

METHODS

The changes of food intake, body weight, gastric pH and general state observation were determined. And HE staining and AB-PAS staining was analyzed. Then, the inflammatory infiltration of gastric tissue was observed through MPO immunohistochemical approach, and the expression of TNF-α, IL-6 and IL-10 were measured. Furthermore, the levels of proteins ERK, p-ERK, P38, p-P38, JNK and p-JNK were determined to elucidate the molecular mechanism of DHE.

RESULTS

DHE alleviated food intake reduction, weight loss and gastric injury induced by IDO and made gastric pH and mucosal thickness return to normal. In addition, DHE could down regulate the expression of MPO, TNF-α and IL-6 and up regulate the expression of IL-10 to reduce the damage induced by inflammatory, and create a healing environment. Furthermore, DHE could significantly inhibit the phosphorylation of ERK and p38 not JNK.

CONCLUSION

DHE ameliorated dyspepsia, inflammatory infiltration and tissue damage induced by IDO through ERK and p38 signaling pathways rather than JNK pathway.

Antithrombotic Effect of the Ethanol Extract of Angelica gigas Nakai (AGE 232)

Cardiovascular diseases, such as stroke, are the most common causes of death in developed countries. Ischemic stroke accounts for 85% of the total cases and is caused by abnormal thrombus formation in the vessels, causing deficient blood and oxygen supply to the brain. Prophylactic treatments include the prevention of thrombus formation, of which the most used is acetylsalicylic acid (ASA); however, it is associated with a high incidence of side effects. Angelica gigas Nakai (AG) is a natural herb used to improve blood circulation via anti-platelet aggregation, one of the key processes involved in thrombus formation. We examined the antithrombotic effects of AGE 232, the ethanol extract of A. gigas Nakai. AGE 232 showed a significant reduction in death or paralysis in mice caused by collagen/epinephrine-induced thromboembolism in a dose-dependent manner and inhibition of collagen-induced human platelet aggregation in a concentration-dependent manner. Additionally, AGE 232-treated mice did not show severe bleeding in the gut compared to ASA-treated mice. AGE 232 resulted in a decrease in the number of neutrophils attached to the human umbilical vein endothelial cells (HUVECs) and lower inhibition of COX-1 in response to bleeding and damage to blood vessels, a major side effect of ASA. Therefore, AGE 232 can prevent thrombus formation and stroke.

Zuojin Pill ameliorates inflammation in indomethacin-induced gastric injury via inhibition of MAPK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zuojin Pill (ZJP) has been a classic prescription for the treatment of gastrointestinal diseases in China since ancient times. But its effect on non-steroidal anti-inflammatory drugs (NSAIDs) induced gastric injury (GI) is still uncharted.

AIM OF THE STUDY

This study aims to investigate the therapeutic effect and molecular mechanism of ZJP on indomethacin (IDO) induced gastric injury.

MATERIALS AND METHODS

GI was induced in rat by oral administration of 5 mg/kg IDO. Then the rats were treated with ZJP (1.26, 2.52, 5.04 g/kg, ig). The changes of food intake, body weight, gastric pH and general state observation were carried out to determine the improvement of ZJP in IDO-induced GI: HE staining and AB-PAS staining was analyzed to characterize the thickness of gastric mucosa and micro mucosal injury; in order to elucidate the effect of ZJP on IDO-induced inflammatory injury, the inflammatory infiltration of gastric tissue was observed by MPO immunohistochemical method, and the contents of TNF-α, IL-6 and IL-10 were measured. Furthermore, the regulatory mechanism of ZJP in treating IDO-induced GI was predicted with the help of network pharmacology, and the expression levels of key proteins ERK, p-ERK, P38, p-P38, JNK, p-JNK were determined to elucidate the molecular mechanism of ZJP.

RESULTS

Current data strongly demonstrated that ZJP alleviated food intake reduction, weight loss and gastric injury caused by IDO and made gastric pH and mucosal thickness return to normal. In addition, ZJP could reduce the level of MPO to alleviate the inflammatory infiltration of gastric tissue. Simultaneously, ZJP could down regulate the expression of TNF-α and IL-6 and up regulate the expression of IL-10 to reduce the damage caused by inflammatory, and create a healing environment. Furthermore, ZJP could significantly inhibit the phosphorylation of ERK, p38 and JNK, which leaded to the increase of inflammatory factors and the damage of gastric mucosa.

CONCLUSION

ZJP improved local inflammation by inhibiting MAPK signaling pathway, and had a good therapeutic effect on IDO-induced GI. This study has reference significance for the study of ZJP in the prevention and treatment of NSAID induced gastric injury. In addition, ZJP may be a new treatment option for the prevention and treatment of NSAID induced gastric disease.

In-vitro and in-vivo metabolism of different aspirin formulations studied by a validated liquid chromatography tandem mass spectrometry method

Low-dose aspirin (ASA) is used to prevent cardiovascular events. The most commonly used formulation is enteric-coated ASA (EC-ASA) that may be absorbed more slowly and less efficiently in some patients. To uncover these "non-responders" patients, the availability of proper analytical methods is pivotal in order to study the pharmacodynamics, the pharmacokinetics and the metabolic fate of ASA. We validated a high-throughput, isocratic reversed-phase, negative MRM, LC-MS/MS method useful for measuring circulating ASA and salicylic acid (SA) in blood and plasma. ASA-d4 and SA-d4 were used as internal standards. The method was applied to evaluate: (a) the "in vitro" ASA degradation by esterases in whole blood and plasma, as a function of time and concentration; (b) the "in vivo" kinetics of ASA and SA after 7 days of oral administration of EC-ASA or plain-ASA (100 mg) in healthy volunteers (three men and three women, 37-63 years). Parameters of esterases activity were Vmax 6.5 ± 1.9 and Km 147.5 ± 64.4 in plasma, and Vmax 108.1 ± 20.8 and Km 803.2 ± 170.7 in whole blood. After oral administration of the two formulations, tmax varied between 3 and 6 h for EC-ASA and between 0.5 and 1.0 h for plain-ASA. Higher between-subjects variability was seen after EC-ASA, and one subject had a delayed absorption over eight hours. Plasma AUC was 725.5 (89.8-1222) for EC-ASA, and 823.1(624-1196) ng h/mL (median, 25-75% CI) for plain ASA. After the weekly treatment, serum levels of TxB2 were very low (< 10 ng/mL at 24 h from the drug intake) in all the studied subjects, regardless of the formulation or the tmax. This method proved to be suitable for studies on aspirin responsiveness.

Effect of frequently prescribed drugs on gastric cancer risk

Gastric cancer is the fifth leading cancer worldwide. Infection with Helicobacter pylori represents the major risk factor, but only a small fraction of infected individuals will develop neoplasia. The progression of advanced gastric lesions to cancer is influenced by characteristics of the bacterial strain, host genetic and environmental factors. Recently, the effect of medications on gastric cancer risk has gained interest, because many commonly prescribed drugs affect gastric homeostasis. While non-steroidal anti-inflammatory drugs (NSAIDs) are a frequent cause of gastric ulcer disease, low-dose aspirin has been propagated for chemoprevention of various tumour entities. Beneficial effects of cyclooxygenase-inhibition for gastric cancer prevention is plausible, but its clinical relevance remains unclear. Furthermore, anti-tumorous effects have been postulated for statins and metformin. On the contrary, proton pump inhibitors (PPIs), which are commonly used for prevention of gastric ulcers and bleeding, have been associated with an increased gastric cancer risk in large observational studies. Most of these observations still require confirmation in prospective controlled trials. NSAIDs, statins and metformin have also been investigated as concomitant cancer treatment, but studies did not show convincing results to date. Here, we review the available evidence and possible mechanisms for the role of PPIs, NSAIDs, statins and metformin in gastric carcinogenesis, and discuss possible implications for clinical practice.

The Influence of Lipid Excipients on Platelet Function and the Pharmacodynamic Effects of Aspirin

ABSTRACT

The combination of pharmaceutical lipid excipients with aspirin in a novel liquid oral formulation (Vazalore) limits gastrointestinal toxicity of aspirin. This study was performed to determine whether the lipid excipients influence the pharmacodynamic effects of aspirin and determine whether the excipients directly affect platelet function. The pharmacodynamic effects of aspirin were assessed over a range of concentrations designed to exert limited to maximal inhibition of cyclooxygenase-1 (COX1) necessary for thromboxane A2 production. Platelet aggregation induced by arachidonic acid and assessed with the use of light transmission aggregometry (LTA) was used as a direct measure of the inhibition of COX1 by aspirin. Flow cytometry was used to assess the direct effect of excipients on platelet function. Twice the ratio of lipid excipient to aspirin used in the formulation of the novel oral agent was used. Blood was taken from 20 healthy subjects and anticoagulated with trisodium citrate (3.2%, 1:10 v/v). Aspirin and excipients were added in vitro and incubated for 10 minutes before performance of LTA and flow cytometry. The excipients did not limit the pharmacodynamic effects of aspirin. When the extent of inhibition of platelet aggregation was limited, the excipients tended to enhance pharmacodynamic effects. The excipients did not activate platelets in the absence of agonist and did not alter activation of platelets in response to adenosine diphosphate, arachidonic acid, thrombin, or convulxin (a collagen mimetic). Lipid excipients used in an oral formulation of aspirin do not impair the pharmacodynamic effects of aspirin and do not alter platelet function.

Bioavailability of aspirin in fasted and fed states of a novel pharmaceutical lipid aspirin complex formulation

Dyspeptic symptoms are common with aspirin and clinicians frequently recommend that it be taken with food to reduce these side effects. However, food can interfere with absorption, especially with enteric-coated aspirin formulations. We evaluated whether food interferes with the bioavailability of a new, pharmaceutical lipid-aspirin complex (PL-ASA) liquid-filled capsule formulation. In this randomized, open label, crossover study, 20 healthy volunteers fasted for ≥ 10 h and then randomized as either "fasted", receiving 650 mg of PL-ASA, or as "fed", with a standard high-fat meal and 650 mg of PL-ASA 30 min later. After a washout of 7 days, participants crossed over to the other arm. The primary outcome was comparison of PK parameters of the stable aspirin metabolite salicylic acid (SA) between fasted and fed states. Mean age of participants was 36.8 years and 55% were male. The ratios for the fed to fasted states of the primary SA PK parameters of AUC_0-t and AUC_0-∞ were 88.7% and 88.8% respectively, with 90% confidence intervals between 80 and 125%, which is consistent with FDA bioequivalence guidance. Mean peak SA concentration was about 22% lower and occurred about 1.5 h later in the fed state. Food had a modest effect on peak SA levels and the time required to reach them after PL-ASA administration, but did not impact the extent of exposure (AUC) compared with intake in a fasted state. These data demonstrate that PL-ASA may be co-administered with food without significant impact on aspirin bioavailability.Clinical Trial Registration:http://www.clinicaltrials.gov Unique Identifier: NCT01244100.

Non-steroidal anti-inflammatory drugs (NSAIDs) and organ damage: A current perspective

Owing to the efficacy in reducing pain and inflammation, non-steroidal anti-inflammatory drugs (NSAIDs) are amongst the most popularly used medicines confirming their position in the WHO's Model List of Essential Medicines. With escalating musculoskeletal complications, as evident from 2016 Global Burden of Disease data, NSAID usage is evidently unavoidable. Apart from analgesic, anti-inflammatory and antipyretic efficacies, NSAIDs are further documented to offer protection against diverse critical disorders including cancer and heart attacks. However, data from multiple placebo-controlled trials and meta-analyses studies alarmingly signify the adverse effects of NSAIDs in gastrointestinal, cardiovascular, hepatic, renal, cerebral and pulmonary complications. Although extensive research has elucidated the mechanisms underlying the clinical hazards of NSAIDs, no review has extensively collated the outcomes on various multiorgan toxicities of these drugs together. In this regard, the present review provides a comprehensive insight of the existing knowledge and recent developments on NSAID-induced organ damage. It precisely encompasses the current understanding of structure, classification and mode of action of NSAIDs while reiterating on the emerging instances of NSAID drug repurposing along with pharmacophore modification aimed at safer usage of NSAIDs where toxic effects are tamed without compromising the clinical benefits. The review does not intend to vilify these 'wonder drugs'; rather provides a careful understanding of their side-effects which would be beneficial in evaluating the risk-benefit threshold while rationally using NSAIDs at safer dose and duration.

Pharmacokinetic/pharmacodynamic assessment of a novel, pharmaceutical lipid-aspirin complex: results of a randomized, crossover, bioequivalence study

Aspirin (acetylsalicylic acid, ASA) can lead to gastrointestinal mucosal injury through disruption of its protective phospholipid bilayer. A liquid formulation of a novel pharmaceutical lipid-aspirin complex (PL-ASA) was designed to prevent this disruption. We sought to determine the pharmacokinetic (PK)/pharmacodynamic (PD) characteristics of PL-ASA compared with immediate release aspirin (IR-ASA). In this active-control crossover study, 32 healthy volunteers were randomized to receive 1 of 2 dose levels (a single dose of 325 mg or 650 mg) of either PL-ASA or IR-ASA. After a 2-week washout period between treatment assignments, subjects received a single dose of the alternative treatment, at the same dose level. The primary objectives of the study were to assess, for PL-ASA and IR-ASA at 325 mg and 650 mg dose levels, PK and PD bioequivalence, and safety, over a 24-h period after administration of both drugs. PK parameters were similar for PL-ASA and IR-ASA, and met FDA-criteria for bioequivalence. Regarding PD, both drugs also showed C_min TxB2 values below 3.1 ng/mL (cut-off associated with decreased cardiovascular events) and > 99% inhibition of serum TxB2 ( ≥ 95% inhibition represents the cut-off for aspirin responders) along with similar results in several secondary PK/PD parameters. There were no serious adverse events or changes from baseline in vital signs or laboratory values in either of the 2 treatment groups. PL-ASA's novel liquid formulation has similar PK and PD performance compared with IR-ASA, supporting functional and clinical equivalence. These data coupled with the improved gastric safety of PL-ASA suggest that this novel formulation may exhibit an improved benefit-risk profile, warranting evaluation in future trials.Clinical trial registration: http://www.clinicaltrials.gov . Unique Identifier: NCT04008979.

Highlights from the 2019 International Aspirin Foundation Scientific Conference, Rome, 28 June 2019: benefits and risks of antithrombotic therapy for cardiovascular disease prevention

At the 2019 International Aspirin Foundation Scientific Conference 'Benefits and Risks of Antithrombotic Therapy for Cardiovascular Disease Prevention', held in Rome, Italy, international experts sought to discuss and debate the optimal antithrombotic strategy for the secondary prevention of cardiovascular disease (CVD) and to seek agreement around dosing and target populations for aspirin use in primary disease prevention. Getting the best evidence to support real-life decisions in the clinic can be complex, and individualising management in order to balance both the risks and benefits of different disease prevention strategies appears to be the best approach. It is hoped that future decision-making tools and biomarkers will help direct treatments at those most likely to benefit.

Roles of Hepatic Drug Transporters in Drug Disposition and Liver Toxicity

Hepatic drug transporters are mainly distributed in parenchymal liver cells (hepatocytes), contributing to drug's liver disposition and elimination. According to their functions, hepatic transporters can be roughly divided into influx and efflux transporters, translocating specific molecules from blood into hepatic cytosol and mediating the excretion of drugs and metabolites from hepatic cytosol to blood or bile, respectively. The function of hepatic transport systems can be affected by interspecies differences and inter-individual variability (polymorphism). In addition, some drugs and disease can redistribute transporters from the cell surface to the intracellular compartments, leading to the changes in the expression and function of transporters. Hepatic drug transporters have been associated with the hepatic toxicity of drugs. Gene polymorphism of transporters and altered transporter expressions and functions due to diseases are found to be susceptible factors for drug-induced liver injury (DILI). In this chapter, the localization of hepatic drug transporters, their regulatory factors, physiological roles, and their roles in drug's liver disposition and DILI are reviewed.

Protective effects of Aronia melanocarpa juices either alone or combined with extracts from Rosa canina or Alchemilla vulgaris in a rat model of indomethacin-induced gastric ulcers

The aim of the study was to investigate the effects of four Aronia melanocarpa-based juices in a rat model of indomethacin-induced gastric ulceration. THE JUICES WERE: AM1 and AM2 (produced from aronia fruits at 20 °C and 60 °C, respectively), AMRC (a mixture of AM2 with Rosa canina extract) and AMAV (aronia juice with Alchemilla vulgaris). Male Wistar rats were used. Each of the juices (10 ml/kg) was administered for 10 days. Indomethacin (30 mg/kg) was injected subcutaneously and after 4 h, the effects were estimated. Indomethacin caused heavy destructions of the gastric mucosa, increased the expression of Bax and decreased the expression of Bcl-2, induced a certain increase in lipid peroxidation and a slight decrease in gastric PGE2 content. The pretreatment with the juices reduced the severity of indomethacin-induced gastric lesions and antagonized the effects of indomethacin on apoptosis and lipid peroxidation. The highest was the protective effect of AMAV, the juice with the highest polyphenolic content. The protective effect of Aronia melanocarpa-based juices against indomethacin-induced gastric lesions could be attributed to their polyphenolic contents. The mechanism involved to the highest extent in the protective effect of the juices was the inhibition of apoptosis.

Cytoprotective, antioxidant and anti-inflammatory mechanism related to antiulcer activity of Cissampelos sympodialis Eichl. in animal models

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves and roots of Cissampelos sympodialis (Menispermaceae) are used by indian tribes and in folk medicine to treat genitourinary infections, inflammation, asthma and gastrointestinal disorders.

MATERIAL AND METHODS

The standardized ethanolic extract (Cs-EtOHE) and alkaloids total fraction (Cs-TAF) obtained from aerial parts of C. sympodialis were evaluated in several models of acute gastric ulcers. The antisecretory and/or neutralizing mechanisms of the gastric acid secretion, cytoprotective, antioxidant and immunoregulatory mechanisms were also evaluated.

RESULTS

Cs-EtOHE and Cs-TAF presented a reduction in gastric mucosa lesions against ethanol, NSAIDs, hypothermic restraint-stress and gastric juice containment induced ulcer models. This activity is related to alkaloids present in the extract, and involves the participation of sulfhydryl compounds, nitric oxide, K_ATP channels, prostaglandins, decreased levels of IL-1β and TNF-α and increased levels of GSH and IL-10.

CONCLUSION

The data indicate gastroprotective activity, due to the participation of the cytoprotective, antioxidant and immunoregulatory mechanisms.

Beyond COX-1: the effects of aspirin on platelet biology and potential mechanisms of chemoprevention

After more than a century, aspirin remains one of the most commonly used drugs in western medicine. Although mainly used for its anti-thrombotic, anti-pyretic, and analgesic properties, a multitude of clinical studies have provided convincing evidence that regular, low-dose aspirin use dramatically lowers the risk of cancer. These observations coincide with recent studies showing a functional relationship between platelets and tumors, suggesting that aspirin's chemopreventive properties may result, in part, from direct modulation of platelet biology and biochemistry. Here, we present a review of the biochemistry and pharmacology of aspirin with particular emphasis on its cyclooxygenase-dependent and cyclooxygenase-independent effects in platelets. We also correlate the results of proteomic-based studies of aspirin acetylation in eukaryotic cells with recent developments in platelet proteomics to identify non-cyclooxygenase targets of aspirin-mediated acetylation in platelets that may play a role in its chemopreventive mechanism.

Chemoprevention with phosphatidylcholine non-steroidal anti-inflammatory drugs in vivo and in vitro

The chemopreventive activity of non-steroidal anti-inflammatory drugs (NSAIDs), particularly aspirin, has been well demonstrated in preclinical and clinical studies. However, the primary side effect from this class of drug is gastrointestinal (GI) bleeding, which has limited the widespread use of NSAIDs for the prevention of cancer. The development of GI-safer NSAIDs, which are associated with phosphatidylcholine (PC) may provide a solution to this therapeutic problem. In the present study, the efficacy of two NSAIDs, aspirin and indomethacin, were compared using murine colon cancer cell line MC-26. Each NSAID was assessed alone and in combination with PC, using in vitro and in vivo systems. The results reveal that the PC-associated NSAIDs had a significantly higher degree of protection against cancer cell growth compared with the unmodified NSAIDs. It was also observed that Aspirin-PC and Indomethacin-PC prevented the metastatic spread of cancer cells in a syngeneic mouse model. These results support the potential use of PC-NSAIDs for the chemoprevention of colorectal cancer.

Aspirin and omeprazole for secondary prevention of cardiovascular disease in patients at risk for aspirin-associated gastric ulcers

INTRODUCTION

Cardiovascular disease is the most important cause of morbidity and mortality in the world and low-dose aspirin is considered the cornerstone of the cardiovascular disease prevention. However, low-dose aspirin use is associated with gastrointestinal adverse effects in the whole gastrointestinal tract. In this setting, co-therapy with a proton pump inhibitor is the most accepted strategy to reduce aspirin related upper gastrointestinal damage. In addition, some adverse effects have been described with proton pump inhibitors long term use. Areas covered: Low-dose aspirin related beneficial and adverse effects in cardiovascular system and gastrointestinal tract are reviewed. In addition, this manuscript summarizes current data on upper gastrointestinal damage prevention and adverse events with proton pump inhibition. Finally, we discuss the benefit/risk ratio of proton pump inhibitor use in patients at risk of gastrointestinal damage taking low-dose aspirin. Expert commentary: Nowadays, with the current available evidence, the combination of low-dose aspirin with proton pump inhibitor is the most effective therapy for cardiovascular prevention in patients at high gastrointestinal risk. However, further studies are needed to discover new effective strategies with less related adverse events.

Human Intestinal Barrier Function in Health and Disease

The gastrointestinal tract consists of an enormous surface area that is optimized to efficiently absorb nutrients, water, and electrolytes from food. At the same time, it needs to provide a tight barrier against the ingress of harmful substances, and protect against a reaction to omnipresent harmless compounds. A dysfunctional intestinal barrier is associated with various diseases and disorders. In this review, the role of intestinal permeability in common disorders such as infections with intestinal pathogens, inflammatory bowel disease, irritable bowel syndrome, obesity, celiac disease, non-celiac gluten sensitivity, and food allergies will be discussed. In addition, the effect of the frequently prescribed drugs proton pump inhibitors and non-steroidal anti-inflammatory drugs on intestinal permeability, as well as commonly used methods to assess barrier function will be reviewed.

Colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome

The inflammasome is a large, multiprotein complex that consists of a nucleotide-binding oligomerization domain-like receptor (NLR), an apoptosis-associated speck-like protein containing a caspase recruitment domain, and pro-caspase-1. Activation of the inflammasome results in cleavage of pro-caspase-1 into cleaved caspase-1, which promotes the processing of pro-interleukin (IL)-1β into mature IL-1β. We investigated the effects of colchicine on non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal injury and activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. Colchicine treatment inhibited indomethacin-induced small intestinal injury by 86% (1 mg/kg) and 94% (3 mg/kg) as indicated by the lesion index 24 h after indomethacin administration. Colchicine inhibited the protein expression of cleaved caspase-1 and mature IL-1β, without affecting the mRNA expression of NLRP3 and IL-1β. Although treatment with recombinant IL-1β (0.1 μg/kg) did not change the severity of small intestinal damage, the preventive effects of colchicine were abolished by supplementation with the same dose of recombinant IL-1β. Indomethacin-induced small intestinal damage was reduced by 77%, as determined by the lesion index in NLRP3^−/− mice, and colchicine treatment failed to inhibit small intestinal damage in NLRP3^−/− mice. These results demonstrate that colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome.

Protective role of hydrogen-rich water on aspirin-induced gastric mucosal damage in rats

AIM: To investigate the role of the hydrogen-rich water (HRW) in the prevention of aspirin-induced gastric mucosal injury in rats.

METHODS: Forty male rats were allocated into four groups: normal control group, HRW group, aspirin group, and HRW plus aspirin group. The protective efficacy was tested by determining the gastric mucosal damage score. Malondialdehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO), interleukin (IL)-06 and tumor necrosis factor (TNF)-α in gastric tissues were evaluated. The serum levels of IL-1β and TNF-α were also detected. Histopathology of gastric tissues and localization of Cyclooxygenase 2 (COX-2) were detected using hematoxylin and eosin staining and immunohistochemistry, respectively.

RESULTS: Pretreatment with HRW obviously reduced aspirin-induced gastric damage scores (4.04 ± 0.492 vs 2.10 ± 0.437, P < 0.05). The oxidative stress levels of MDA and MPO in the gastric tissues increased significantly in the aspirin-treated group compared with the HRW group (2.43 ± 0.145 vs 1.79 ± 0.116 nmol/mg prot, P < 0.05 and 2.53 ± 0.238 vs 1.40 ± 0.208 U/g tissue, P < 0.05, respectively). HRW could obviously elevated the SOD levels in the gastric tissues (37.94 ± 8.44 vs 59.55 ± 9.02 nmol/mg prot, P < 0.05). Pretreatment with HRW significantly reduced IL-06 and TNF-α in the gastric tissues (46.65 ± 5.50 vs 32.15 ± 4.83 pg/mg, P < 0.05 and 1305.08 ± 101.23 vs 855.96 ± 93.22 pg/mg, P < 0.05), and IL-1β and TNF-α in the serum (505.38 ± 32.97 vs 343.37 ± 25.09 pg/mL, P < 0.05 and 264.53 ± 28.63 vs 114.96 ± 21.79 pg/mL, P < 0.05) compared to treatment with aspirin alone. HRW could significantly decrease the COX-2 expression in the gastric tissues (staining score: 8.4 ± 2.1 vs 2.9 ± 1.5, P < 0.05).

CONCLUSION: HRW pretreatment alleviated the aspirin-induced gastric lesions by inhibiting the oxidative stress, inflammatory reaction and reducing the COX-2 in the gastric tissues.

Nonsteroidal anti-inflammatory drug induces proinflammatory damage in gastric mucosa through NF-κB activation and neutrophil infiltration: anti-inflammatory role of heme oxygenase-1 against nonsteroidal anti-inflammatory drug

Nonsteroidal anti-inflammatory drug (NSAID)-induced mitochondrial oxidative stress (MOS) is an important prostaglandin (PG)-independent pathway of the induction of gastric mucosal injury. However, the molecular mechanism behind MOS-mediated gastric pathology is still obscure. In various pathological conditions of tissue injury oxidative stress is often linked with inflammation. Here we report that MOS induced by indomethacin (an NSAID) induces gastric mucosal inflammation leading to proinflammatory damage. Indomethacin, time dependently stimulated the expression of proinflammatory molecules such as intercellular adhesion molecule 1(ICAM-1), vascular cell adhesion molecule 1(VCAM-1), interleukin1β (IL-1β), and monocyte chemotactic protein-1 (MCP-1) in gastric mucosa in parallel with the increase of neutrophil infiltration and injury of gastric mucosa in rat. Western immunoblotting and confocal microscopic studies revealed that indomethacin induced nuclear translocation of nuclear factor kappa-B (NF-κB) in gastric mucosal cells, which resulted in proinflammatory signaling. The prevention of MOS by antioxidant tryptamine-gallic acid hybrid (SEGA) inhibited indomethacin-induced expression of ICAM-1, VCAM-1, IL-1β, and MCP-1. SEGA also prevented indomethacin-induced NF-κB activation and neutrophil infiltration as documented by chromatin immunoprecipitation studies and neutrophil migration assay, respectively. Heme oxygenase-1 (HO-1), a cytoprotective enzyme associated with tissue repair mechanisms is stimulated in response to oxidative stress. We have investigated the role of HO-1 against MOS and MOS-mediated inflammation in recovering from gastropathy. Indomethacin stimulated the expression of HO-1 and indomethacin-stimulated HO-1 expression was reduced by SEGA, an antioxidant, which could prevent MOS. Thus, the data suggested that the induction of HO-1 was a protective response against MOS developed by indomethacin. Moreover, the induction of HO-1 by cobalt protoporphyrin inhibited inflammation and chemical silencing of HO-1 by zinc protoporphyrin aggravated the inflammation by indomethacin. Thus, NSAID by promoting MOS-induced proinflammatory response damaged gastric mucosa and HO-1 protected NSAID-induced gastric mucosal damage by preventing NF-κB activation and proinflammatory activity.

Cyclooxygenase-1 inhibition prolongs postnatal ovarian follicle lifespan in mice

Menopause is the permanent cessation of menstruation that results from depletion of ovarian germ cells and follicles. Although most animals experience reproductive senescence, the mechanisms differ from that in women, who may live more than one-third of their lives after menopause and consequently face the risk of a number of menopause-associated health problems. Understanding factors that influence ovarian aging may provide strategies to delay or alleviate physiological alterations that take place in postmenopausal women. The germ cell-deficient Wv mice recapitulate follicle loss, prolong postreproductive lifespan, and model many physiological changes that take place in postmenopausal women. Here, using genetic and pharmacological approaches, we found that inhibition of cyclooxygenase-1 but not cyclooxygenase-2 in Wv mice delays germ cell depletion and preserves ovarian follicles. Cyclooxygenase-1 inhibition slows down follicle maturation at the conversion of primary to secondary follicles and prolongs postnatal ovarian follicle lifespan. The current study suggests that inhibition of cyclooxygenase-1 may be able to delay ovarian aging and modulate menopausal timing.

Effect of menthol in experimentally induced ulcers: pathways of gastroprotection

Based on ethnopharmacological indications that Mentha species may be used in the treatment of gastrointestinal diseases, this study aimed to characterize the gastroprotective mechanisms of menthol (ME), the major compound of the essential oil from species of the genus Mentha. The gastroprotective action of ME was analyzed in gastric ulcers that were induced by ethanol or indomethacin in Wistar male rats. The mechanisms responsible for the gastroprotective effect were assessed by analyzing the amount of mucus secreted, involvement of non-protein sulfhydryl (NP-SH) compounds, involvement of calcium ion channels and NO/cGMP/K(+)ATP pathway, gastric antisecretory activity and the prostaglandin E2 (PGE2) production. The anti-diarrheal activity and acute toxicity of ME were also evaluated. Oral treatment with ME (50mg/kg) offered 88.62% and 72.62% of gastroprotection against ethanol and indomethacin, respectively. There was an increased amount of mucus and PGE2 production. The gastroprotective activity of ME involved NP-SH compounds and the stimulation of K(+)ATP channels, but not the activation of calcium ion channels or the production of NO. The oral administration of ME induced an antisecretory effect as it decreased the H(+) concentration in gastric juice. ME displayed anti-diarrheal and antiperistaltic activity. There were no signs of toxicity in the biochemical analyses performed in the rats' serum. These results demonstrated that ME provides gastroprotective and anti-diarrheal activities with no toxicity in rats.

Effect of NSAIDs on Na⁺/H⁺ exchanger activity in rat colonic crypts

Nonsteroidal anti-inflammatory drugs (NSAIDs; 1) are widely recommended for several acute and chronic conditions. For example, both indomethacin and aspirin are taken for pain relief. Aspirin is also used for prevention of myocardial infarction, and indomethacin can be administered orally or as a suppository for patients with rheumatoid disease and other chronic inflammatory states. However, use of NSAIDs can cause damage to the mucosal barrier surrounding the gastrointestinal (GI) tract, increasing the risk of ulcer formation. While microencapsulation of NSAIDs has been shown to reduce upper GI injury, sustained release in the lower GI tract and colon may cause epithelial erosion due to increased acidification. The use of suppositories has also been linked to rectal and lower GI bleeding. In this study, we investigated the role of NSAIDs aspirin and indomethacin on Na⁺/H⁺ exchanger (NHE) activity in rat colonic crypts. By comparing average rates of pH recovery between control and NSAID perfusion runs, we were able to determine that both aspirin and indomethacin increase hydrogen extrusion into the colonic lumen. Through treatment with 5-ethylisopropyl amiloride (EIPA), amiloride, and zoniporide dihydrochloride, we further demonstrated that indomethacin specifically enhances proton excretion through regulation of apical NHE-3 and NHE-2 and to a lesser extent on basolateral NHE-1 and NHE-4. Our results suggest that clinical exposure to NSAIDs may affect colonic tissue at the site of selected NHE isoforms, resulting in modulation of transport and barrier function.

Advent of novel phosphatidylcholine-associated nonsteroidal anti-inflammatory drugs with improved gastrointestinal safety

The mucosa of the gastrointestinal (GI) tract exhibits hydrophobic, nonwettable properties that protect the underlying epithelium from gastric acid and other luminal toxins. These biophysical characteristics appear to be attributable to the presence of an extracellular lining of surfactant-like phospholipids on the luminal aspects of the mucus gel layer. Phosphatidylcholine (PC) represents the most abundant and surface-active form of gastric phospholipids. PC protected experimental rats from a number of ulcerogenic agents and/or conditions including nonsteroidal anti-inflammatory drugs (NSAIDs), which are chemically associated with PC. Moreover, preassociating a number of the NSAIDs with exogenous PC prevented a decrease in the hydrophobic characteristics of the mucus gel layer and protected rats against the injurious GI side effects of NSAIDs while enhancing and/or maintaining their therapeutic activity. Bile plays an important role in the ability of NSAIDs to induce small intestinal injury. NSAIDs are rapidly absorbed from the GI tract and, in many cases, undergo enterohepatic circulation. Thus, NSAIDs with extensive enterohepatic cycling are more toxic to the GI tract and are capable of attenuating the surface hydrophobic properties of the mucosa of the lower GI tract. Biliary PC plays an essential role in the detoxification of bile salt micelles. NSAIDs that are secreted into the bile injure the intestinal mucosa via their ability to chemically associate with PC, which forms toxic mixed micelles and limits the concentration of biliary PC available to interact with and detoxify bile salts. We have worked to develop a family of PC-associated NSAIDs that appear to have improved GI safety profiles with equivalent or better therapeutic efficacy in both rodent model systems and pilot clinical trials.

The effect of nonsteroidal anti-inflammatory drug administration on acute phase fracture-healing: a review

BACKGROUND

The analgesic efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) is well established, and these agents often form an integral part of posttraumatic pain management. However, potentially deleterious effects of resulting prostaglandin suppression on fracture-healing have been suggested.

METHODS

A systematic literature review involving searches of electronic databases and online sources was performed to identify articles exploring the influence of NSAIDs on fracture-healing.

RESULTS

A structured search approach identified 316 papers as potentially relevant to the topic, and these were manually reviewed. The majority described small-scale studies that were retrospective or observational in nature, with limited control of potentially confounding variables, or presented little key information that was not also present in other studies.

CONCLUSIONS

Although increasing evidence from animal studies suggests that cyclooxygenase-2 (COX-2) inhibition suppresses early fracture-healing, in vivo studies involving human subjects have not provided convincing evidence to substantiate this concern. We found no robust evidence to attest to a significant and appreciable patient detriment resulting from the short-term use of NSAIDs following a fracture. The balance of evidence in the available literature appears to suggest that a short-duration NSAID regimen is a safe and effective supplement to other modes of post-fracture pain control, without a significantly increased risk of sequelae related to disrupted healing.

Gastrointestinal lesions and complications of low-dose aspirin in the gastrointestinal tract

Low dose aspirin (ASA) use has been associated with a wide range of adverse side effects in the upper gastrointestinal (GI) tract, which range from troublesome symptoms without mucosal lesions to more serious toxicity, including ulcers, GI bleeding, perforation and even death. Upper GI symptoms in low dose ASA users are common but often careless or misinterpreted and they are not always related to the presence of mucosal injury. Usually, low dose ASA related ulcers are reasonably small and asymptomatic, and probably heal over a period of weeks to a few months. But, the real clinical problem occurs when the ulcer results in a GI complication (mostly bleeding). The estimated average excess risk of symptomatic or complicated ulcer related to low dose ASA is five cases per 1000 ASA users per year. Death is the worst outcome of GI complications in low dose ASA users, but data about this aspect are scarce. Current evidence indicates that low dose ASA can damage the lower GI tract also, but the real size of the problem is still unknown.

Mast cells are critical for protection against peptic ulcers induced by the NSAID piroxicam

Many commonly used non-steroidal anti-inflammatory drugs (NSAIDs) also cause gastrointestinal toxicity, including the development of life-threatening peptic ulcers. We report that mast cell-deficient mice have an extremely high incidence of severe peptic ulceration when exposed to the NSAID piroxicam. This enhanced ulcer susceptibility can be reversed by reconstitution with mast cells. Furthermore, wild type mice treated with diphenhydramine hydrochloride, a commonly used antihistamine that blocks histamine H1 receptors, develop a similarly high incidence of peptic ulcers following piroxicam exposure. The protective effect of mast cells is independent of TNF, blockade of H2 receptors, or acid secretion. These data indicate a critical role for mast cells and the histamine that they produce in prevention and/or repair of piroxicam-induced gastric mucosal injury. Additional studies will be required to determine whether this represents a NSAID class effect that can be exploited to develop novel therapeutic strategies to limit the incidence of NSAID-induced side effects in humans.

[Antiplatelet agents and proton pump inhibitors. How can the risk-benefit balance be optimized in patients at risk for cardiovascular disease and gastrointestinal bleeding?]

Antiplatelet agents are routinely used in both primary and secondary prevention of cardiovascular events. The development of new antiplatelet agents and the strong growth of interventional cardiology have led to this therapy being more widely prescribed and for longer periods. The most important secondary effect is the rise in the incidence of hemorrhagic complications, the most prevalent being gastrointestinal bleeding. In this context, the balance between the cardiovascular benefits and bleeding risk of these agents must be optimized. This review provides specific management recommendations and highlights important practical aspects related to antiplatelet therapy, including the interaction between clopidogrel and proton pump inhibitors. The benefits and hazards in distinct clinical settings are outlined within the context of optimizing the balance between the cardiovascular benefits and bleeding risk of antiplatelet therapy.

Comparative model studies of gastric toxicity of nonsteroidal anti-inflammatory drugs

A high percentage of people treated with a long-term nonsteroidal anti-inflammatory drug (NSAID) therapy suffer NSAID-induced gastrointestinal-tract-related side effects. A current hypothesis states that the side effects are related to the topical action of NSAID molecules on gastric mucus that lowers its resistance to luminal acid. The main lipids in human mucus are palmitoyloleoylphosphatidylcholine (POPC) and cholesterol (Chol). In this study, both X-ray diffraction and molecular dynamics (MD) simulation methods were employed to investigate the effects of selected NSAIDs in protonated and deprotonated states on the structural parameters of a POPC-Chol bilayer. The drugs were three commonly used NSAIDs with apparently different gastric toxicity: ketoprofen (KET), aspirin (ASP), and piroxicam (PXM). Both methods revealed that the effects of the NSAIDs on the POPC-Chol bilayer parameters were moderate and only slightly differentiated among the drugs. Much larger differences among the drugs were noticed in their interactions with interfacial water and Na(+) as well as with the polar groups of POPC and Chol, mainly via H-bonds. Of the three NSAIDs, KET interacted with POPC and water the most extensively, whereas ASP interacted with Chol and Na(+) more than did the other two. Interactions of PXM with POPC and Chol polar groups as well as with water and Na(+) were limited.

Gastrointestinal effects of aspirin

Aspirin is being used as an effective analgesic and anti-inflammatory agent at doses >325 mg daily. At low doses (75-325 mg daily), aspirin is the key antiplatelet drug in the pharmacological prevention of cardiovascular diseases. Topical and systemic effects of aspirin in the gastrointestinal mucosa are associated with mucosal damage in the upper and lower gastrointestinal tract. The risk of upper gastrointestinal bleeding with aspirin is increased with old age, male sex, ulcer history and concomitant medication with NSAIDs, cyclooxygenase 2 selective inhibitors, corticosteroids or other antithrombotic agents. In some patients, the cardiovascular benefits of low-dose aspirin might be overcome by the risk of gastrointestinal complications, but withdrawal of aspirin therapy can precipitate a cardiovascular event. These patients will need concomitant therapy with antisecretory agents, especially PPIs, to reduce the gastrointestinal risk. Eradication of Helicobacter pylori infection might be an additional option in patients with a history of ulcer. Furthermore, there is growing evidence that long-term use of aspirin decreases the risk of colorectal cancer, even at low doses. As aspirin is one of the most prescribed drugs worldwide and its clinical impact is huge, physicians need to consider the benefits and harms for each individual patient in order to maximize the benefits of aspirin.

Involvement of glutathione, sulfhydryl compounds, nitric oxide, vasoactive intestinal peptide, and heat-shock protein-70 in the gastroprotective mechanism of Croton cajucara Benth. (Euphorbiaceae) essential oil

This study aimed to evaluate the gastroprotective mechanism of action of the essential oil of Croton cajucara Benth. (Euphorbiaceae) stem bark in ethanol-induced gastric ulcers and its in vitro anti-Helicobacter pylori activity. The involvement of heat-shock protein-70, vasoactive intestinal peptide, glutathione, nitric oxide, and nonprotein sulfhydryl compounds in the gastroprotective effect was determined in male Wistar rats. The minimum inhibitory concentration against H. pylori was determined in vitro. The results were analyzed by analysis of variance followed by the Dunnett test, and a P value less than 0.05 was considered to represent a statistically significant difference. C. cajucara decreased ethanol-induced ulcer area in 100% of ulcers and decreased the histologic lesions. In the C. cajucara group, the area marked by heat-shock protein-70 was significantly higher than the area in the control group; this finding was not seen for vasoactive intestinal peptide. C. cajucara could not maintain glutathione levels close to those in the sham group. The gastric ulcer area of rats treated with the sulfhydryl compound blocker was decreased, but the ulcer area of rats treated with nitric oxide synthase inhibitor showed no alteration. The minimum inhibitory concentration obtained for C. cajucara was 125 μg/mL. These findings suggest that sulfhydryl compounds and heat-shock protein-70, but not nitric oxide, glutathione, or vasoactive intestinal peptide, are involved in the C. cajucara gastroprotective effect against ethanol-induced gastric ulcers.

Clinical trial: endoscopic evaluation of naproxen etemesil, a naproxen prodrug, vs. naproxen - a proof-of-concept, randomized, double-blind, active-comparator study

BACKGROUND

Nonsteroidal anti-inflammatory drugs are associated with upper gastrointestinal mucosal injury. Naproxen etemesil is a lipophilic, non-acidic, inactive prodrug of naproxen that is hydrolysed to pharmacologically active naproxen once absorbed. We hypothesized that with lesser topical exposure to naproxen from the prodrug, there would be reduced gastroduodenal mucosal injury compared with naproxen.

AIM

To compare the degree of endoscopic mucosal damage of naproxen etemesil vs. naproxen.

METHODS

This multicentre, randomized, double-blind, double-dummy trial compared oral naproxen etemesil 1200 mg twice daily (n = 61) with naproxen 500 mg twice daily (n = 59) for 7.5 days in 120 healthy subjects (45-70 years; mean 51 years; 58% female) with baseline total modified gastroduodenal Lanza score ≤ 2 (no erosions/ulcers) on endoscopy. The primary endpoint was mean total modified gastroduodenal Lanza score on day 7. A secondary endpoint was incidence of gastric ulcers.

RESULTS

The day 7 mean total modified gastroduodenal Lanza score was 2.8 ± 1.7 for naproxen etemesil vs. 3.5 ± 2.0 for naproxen (P = 0.03), and significantly fewer naproxen etemesil-treated subjects (3.3%) developed gastric ulcers compared with naproxen-treated subjects (15.8%) (P = 0.02).

CONCLUSION

In this first proof-of-concept study, naproxen etemesil was associated with significantly lower gastroduodenal mucosal injury compared with naproxen after 7 days of exposure (

CLINICAL TRIAL NUMBER

NCT00750243).

Effect of indomethacin on bile acid-phospholipid interactions: implication for small intestinal injury induced by nonsteroidal anti-inflammatory drugs

The injurious effect of nonsteroidal anti-inflammatory drugs (NSAIDs) in the small intestine was not appreciated until the widespread use of capsule endoscopy. Animal studies found that NSAID-induced small intestinal injury depends on the ability of these drugs to be secreted into the bile. Because the individual toxicity of amphiphilic bile acids and NSAIDs directly correlates with their interactions with phospholipid membranes, we propose that the presence of both NSAIDs and bile acids alters their individual physicochemical properties and enhances the disruptive effect on cell membranes and overall cytotoxicity. We utilized in vitro gastric AGS and intestinal IEC-6 cells and found that combinations of bile acid, deoxycholic acid (DC), taurodeoxycholic acid, glycodeoxycholic acid, and the NSAID indomethacin (Indo) significantly increased cell plasma membrane permeability and became more cytotoxic than these agents alone. We confirmed this finding by measuring liposome permeability and intramembrane packing in synthetic model membranes exposed to DC, Indo, or combinations of both agents. By measuring physicochemical parameters, such as fluorescence resonance energy transfer and membrane surface charge, we found that Indo associated with phosphatidylcholine and promoted the molecular aggregation of DC and potential formation of larger and isolated bile acid complexes within either biomembranes or bile acid-lipid mixed micelles, which leads to membrane disruption. In this study, we demonstrated increased cytotoxicity of combinations of bile acid and NSAID and provided a molecular mechanism for the observed toxicity. This mechanism potentially contributes to the NSAID-induced injury in the small bowel.

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.

Exacerbation of inflammatory bowel diseases associated with the use of nonsteroidal anti-inflammatory drugs: myth or reality?

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs), conventional and selective cyclooxygenase-2 (COX-2) inhibitors, are among the most widely used medications for the treatment of various inflammatory conditions. There is strong evidence of a possible association between the use of these drugs and the relapse of inflammatory bowel diseases (IBD).

OBJECTIVE

Our objective was to examine the literature regarding the exacerbation of IBD associated with the use of conventional NSAIDs and selective COX-2 inhibitors and the underlying pathogenetic mechanisms.

STUDY DESIGN

We reviewed articles, including original papers, controlled trials, case reports, reviews, and editorials published in English at the PubMed, Scopus Database, and Science Direct database, searching with the following keywords: nonsteroidal anti-inflammatory drugs (NSAIDs), COX-2 inhibitors, Coxibs, inflammatory bowel diseases (IBD), ulcerative colitis (UC), Crohn's disease (CD).

RESULTS

There is substantial evidence that exacerbation of IBD happens after treatment with NSAIDs, but the available data remain conflicting, and it is not clear whether selective COX-2 inhibitors are safer than traditional NSAIDs. However, there is some evidence that selective COX-2 inhibition and COX-1 inhibition (with low-dose aspirin) appear to be well-tolerated in the short term. Regarding the mechanisms of relapse, the reduction of prostaglandins appears to be the hallmark of the NSAIDs adverse effects.

CONCLUSIONS

Further randomized, double-blind, controlled trials should be performed to address this issue, and more in vitro studies to identify the pathways involved are required.

Review article: cellular and molecular mechanisms of NSAID-induced peptic ulcers

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are some of the most prescribed drugs worldwide and have now probably overtaken Helicobacter pylori as the most common cause of gastrointestinal injury in Western countries. Further understanding of the pathogenesis of NSAID-induced ulcers is important to enable the development of novel and effective preventive strategies.

AIMS

To provide an update on recent advances in our understanding of the cellular and molecular mechanisms involved in the development of NSAID-induced ulcers.

METHODS

A Medline search was performed to identify relevant literature using search terms including 'nonsteroidal anti-inflammatory drugs, aspirin, gastric ulcer, duodenal ulcer, pathogenesis, pharmacogenetics'.

RESULTS

The mechanisms of NSAID-induced ulcers can be divided into topical and systemic effects and the latter may be prostaglandin-dependent (through COX inhibition) or prostaglandin-independent. Genetic factors may play an important role in determining individual predisposition.

CONCLUSIONS

The pathogenesis of NSAID-induced peptic ulcers is complex and multifactorial. Recent advances in cellular and molecular biology have highlighted the importance of various prostaglandin-independent mechanisms. Pharmacogenetic studies may provide further insights into the pathogenetic mechanisms of NSAID-induced ulcers and help identify patients at increased risk.

Intestinal permeability in the pathogenesis of NSAID-induced enteropathy

BACKGROUND

The pathogenesis of nonsteroidal antiinflammatory drug (NSAID)-induced small bowel disease suggests that increased intestinal permeability is the central mechanism that translates biochemical damage to tissue damage. The purpose of this review is to summarize studies on the effect of NSAIDs to increase intestinal permeability in humans and methods for limiting this effect.

METHODS

A Medline search was made for papers that described measurements of increased intestinal permeability in humans.

RESULTS

Virtually all studies agree that all conventional NSAIDs increase intestinal permeability in the human within 24 h of ingestion and that this is equally evident when they are taken long term. Various methods have been tried to limit the damage. The most promising agents are coadministration of synthetic prostaglandins, micronutrients, pre-NSAIDs, and COX-2 selective agents. However, their efficacy in preventing the development of NSAID enteropathy in the long term has not been studied in detail, and, in the case of COX-2 selective agents, small bowel damage is comparable to that which is seen with conventional NSAIDs.

CONCLUSIONS

NSAID enteropathy is associated with significant morbidity and occasionally mortality. There are no proven effective ways of preventing this damage. Because increased intestinal permeability appears to be a central mechanism in the pathogenesis of NSAID enteropathy, it becomes a potential therapeutic target for prevention. At present there are a number of ways to limit the increased permeability, but additional studies are required to assess if this approach reduces the prevalence and severity of NSAID enteropathy.