Gastro-protective agent rebamipide induces cyclooxygenease-2 (COX-2) in gastric epithelial cells

[Pharmacokinetics and pharmacodynamics of rebamipide. New possibilities of therapy: A review]

The MedLine database contains 570 publications, including 71 randomized clinical trials and 6 meta-analyses on the rebamipide molecule in 2022. Indications for the use of rebamipide are gastric ulcer, chronic gastritis with hyperacidityin the acute stage, erosive gastritis, prevention of damage to the gastrointestinal mucosa while taking non-steroidal anti-inflammatory drugs, eradication of Helicobacter pylori. Currently trials are studying the efficacy and safety of the drug in gouty and rheumatoid arthritis, osteoarthritis, Sjögren's syndrome, bronchial asthma, vitiligo, atherosclerosis, diseases of the kidneys and liver; using in traumatology to accelerate bone regeneration; in ophthalmology to improve the regeneration of corneal epithelium; in oncology to reduce inflammatory changes in the oral mucosa after chemoradiotherapy. The review article is about the main pharmacokinetic and pharmacodynamic characteristics of rebamipide. A detailed understanding of pharmacodynamics and pharmacokinetics allows for individual selection of therapy based on the characteristics of the patient's body - gender, age, comorbidities; choose the optimal route of administration and dosing regimen; predict adverse effects and drug interactions; be determined with new clinical indications.

[Rebamipide: evidence base for use in gastroenterology]

Rebamipide is a cytoprotective drug that has been used in practical gastroenterology for 30 years. This article summarizes the main results of the most relevant clinical studies of rebamipide in diseases of various parts of the gastrointestinal tract, including the esophagus, stomach, small and large intestine.

Pharmacological and clinical feature of rebamipide: new therapeutic targets

Rebamipide is a cytoprotector developed in Japan where it has been successfully used for the treatment of stomach diseases for 30 years. Initially discovered effects of the drug included the induction of prostaglandins and the elimination of free oxygen radicals. Recent studies discovered new therapeutic targets of the drug, its new forms that made possible using rebamipid for the treatment of such diseases as NSAID enteropathy, ulcerative colitis, radiation colitis, pouchitis, enteropathy with impaired membrane digestion. It is used in endoscopy, ophthalmology, chemotherapy, rheumatology. The aim of this review is to present current information about the pharmacological and clinical feature of rebamipide and to study its therapeutic potential.

Implementation of Quality by Design for Formulation of Rebamipide Gastro-retentive Tablet

The purpose of the present study was to develop a rebamipide (RBM) gastro-retentive (GR) tablet by implementing quality by design (QbD). RBM GR tablets were prepared using a sublimation method. Quality target product profile (QTPP) and critical quality attributes (CQAs) of the RBM GR tablets were defined according to the preliminary studies. Factors affecting the CQAs were prioritized using failure mode and effects analysis (FMEA). Design space and optimum formulation were established through a mixture design. The validity of the design space was confirmed using runs within the area. The QTPP of the RBM GR tablets was the orally administered GR tablet containing 300 mg of RBM taken once daily. Based on the QTPP, dissolution rate, tablet friability, and floating property were chosen as CQAs. According to the risk assessment, the amount of sustained-release agent, sublimating material, and diluent showed high-risk priority number (RPN) values above 40. Based on the RPN, these factors were further investigated using mixture design methodology. Design space of formulations was depicted as an overlaid contour plot and the optimum formulation to satisfy the desired responses was obtained by determining the expected value of each response. The similarity factor (f2) of the release profile between predicted response and experimental response was 89.463, suggesting that two release profiles are similar. The validity of the design space was also confirmed. Consequently, we were able to develop the RBM GR tablets by implementing the QbD concept. These results provide useful information for development of tablet formulations using the QbD.

Rebamipide induces the gastric mucosal protective factor, cyclooxygenase-2, via activation of 5'-AMP-activated protein kinase

Rebamipide, an amino acid derivative of 2(1H)-quinolinone, has been used for mucosal protection, healing of gastroduodenal ulcers, and treatment of gastritis. Induction of cyclooxygenase (COX)-2, a gastric mucosal protective factor, by rebamipide has been suggested as the major mechanism of the drug action. However, how rebamipide induces COX-2 at the molecular level needs further investigation. In this study, the molecular mechanism underlying the induction of COX-2 by rebamipide was investigated. In gastric carcinoma cells and macrophage cells, rebamipide induced phosphorylation of AMP-activated protein kinase (AMPK), leading to phosphorylation of acetyl-CoA carboxylase (ACC), a substrate of AMPK. The induction of COX-2 by rebamipide was dependent on AMPK activation because compound C, an AMPK inhibitor, abolished COX-2 induction by rebamipide. In a mouse ulcer model, rebamipide protected against hydrochloric acid/ethanol-induced gastric ulcer, and these protective effects were deterred by co-administration of compound C. In parallel, in the gastric tissues, rebamipide increased the phosphorylation AMPK, whereas compound C reduced the levels of COX-2 and phosphorylated ACC, which were increased by rebamipide. Taken together, the activation of AMPK by rebamipide may be a molecular mechanism that contributes to induction of COX-2, probably resulting in protection against gastric ulcers.

Benexate hydrochloride betadex modulates nitric oxide synthesis and cytokine expression in gastric ulcers

The present study investigated benexate hydrochloride betadex (BHB)-mediated ulcer healing, and changes to microcirculation modulated through nitric oxide synthase (NOS) and anti-inflammatory activity. A rat model of gastric mucosal injury was established through injection of a 60% acetic acid solution into the stomach. Following ulcer induction, the rats were administered BHB orally for 5 days at doses of 0, 100, 300 or 1,000 mg/kg. The highest dose of BHB was also administered with or without L-NG-nitroarginine methyl ester (L-NAME). The area of gastric ulcers was determined by planimetry, and expression of cyclooxygenases (COX), cytokines and NOS in stomach tissues were measured using western blotting. Compared with the control group, gastric ulcer size was significantly decreased in the 1,000 mg/kg BHB-treated group (P<0.05). Administration of BHB led to a significant increase in endothelial (e)NOS expression (P<0.05). Although acetic acid co-treatment with L-NAME induced more severe mucosal damage, BHB decreased COX expression and tumor necrosis factor-α levels when administered with the nitric oxide inhibitor, L-NAME (P<0.05). BHB exhibited protective effects in a rat model of gastric ulcers, which were associated with a decrease in pro-inflammatory cytokine levels and the activation of eNOS.

A randomized, double-blinded, placebo-controlled, multicenter trial, healing effect of rebamipide in patients with low-dose aspirin and/or non-steroidal anti-inflammatory drug induced small bowel injury

BACKGROUND

It is not clear what kind of drug is appropriate to heal NSAID-induced enteropathy. Several reports showed the preventive effect of prostaglandin analogue or inducer using healthy subjects who took NSAIDs. However there was no report for healing effect and for patients. The aim of this study was to evaluate the healing effect of rebamipide in patients with NSAIDs-induced enteropathy. In addition, we evaluated for nutritional parameter.

METHODS

This study was conducted as a randomized, double-blinded, placebo-controlled, multicenter trial. Study protocol was approved by each hospital's ethical committees. Patients with LDA and/or NSAID more than 3 months were enrolled. Patients with enteropathy were divided into the placebo and the rebamipide groups. Rebamipide 100 mg three times daily was administered during 4 weeks. Capsule endoscopies were performed at 0 and 4 week. The number of small intestinal ulcer and erosion were evaluated. Total protein was analyzed as nutritional parameter.

RESULTS

Sixty one participants were completed this study. Change in number of small intestinal erosion in the rebamipide group was -2.5 ± 3.4, and 2.1 ± 3.9 in the placebo group (P < 0.0001). Change in number of small intestinal ulcer in the rebamipide group was -0.5 ± 1.6, and 0.1 ± 0.7 in the placebo group (P = 0.024). Change in serum total protein levels in the rebamipide group was 0.06 ± 0.36, and -0.27 ± 0.34 in the placebo group (P = 0.0005).

CONCLUSIONS

Rebamipide has not only the healing effect for NSAIDs-induced enteropathy compared with placebo, but the improvement of nutritional condition. These results showed a tentative therapeutical strategy for chronic NSAIDs users.

Effects of rebamipide on nephrotoxicity associated with selected NSAIDs in rats

Use of nonsteroidal anti-inflammatory drugs (NSAIDs) is primarily limited by renal and gastrointestinal adverse effects. Rebamipide suppresses gastric mucosal injury when administered with NSAIDs. This study aimed to determine rebamipide's influence upon renal effects following concomitant use with celecoxib or diclofenac. On day 0, rats were randomly divided into 6 groups (n≥6). On days 1 and 2, three groups received placebo and three groups were administered rebamipide (30 mg/kg) twice daily. On day 3, the rats treated with placebo received another dose of placebo and ten minutes later a single dose of celecoxib (40 mg/kg), diclofenac (10mg/kg), or placebo, respectively. The rats treated with rebamipide received one more dose of rebamipide and ten minutes later one single dose of celecoxib, diclofenac, or placebo, respectively. Urine and blood samples were collected on days 0, 2, and 3. Sodium and potassium excretion rates decreased significantly in the rats treated with celecoxib, diclofenac, rebamipide plus celecoxib, or rebamipide plus diclofenac on day 3. Blood urea nitrogen (BUN) levels significantly increased in placebo plus diclofenac and rebamipide plus diclofenac groups on day 3. Comparing the two groups, the levels of BUN was significantly higher in the rebamipide plus diclofenac group compared to that of placebo plus diclofenac group. Concomitant administration of rebamipide with either NSAID caused a rise in concentrations of urinary kidney injury molecule-1. Histopathological evaluations revealed an intensified NSAID-induced tubular necrosis by rebamipide. Based upon the results obtained, concomitant administration of rebamipide with NSAIDs enhances the effect of NSAIDs on tubular injury.

Rebamipide, a mucoprotective drug, inhibits NSAIDs-induced gastric mucosal injury: possible involvement of the downregulation of 15-hydroxyprostaglandin dehydrogenase

Prostaglandin E₂ plays an important role in the maintenance of gastric mucosal integrity. The level of biologically active prostaglandin E₂ in the tissue is regulated by the balanced expression of its synthetic enzymes, such as cyclooxygenase, and its catabolic enzyme, 15-hydroxyprostaglandin dehydrogenase. We examined the effect of rebamipide, a mucoprotective drug, on prostaglandin E₂ production and metabolism in the gastric tissue and its effect on indomethacin-induced gastric mucosal injury in mice. Rebamipide suppressed indomethacin-induced gastric mucosal injury. Suppressive effect of rebamipide on indomethacin-induced gastric mucosal injury was also observed in cyclooxygenase-2-knockout mice. The mice that were treated with rebamipide showed a 2-fold increase in cyclooxygenase-2 mRNA expression in the gastric tissue, whereas 15-hydroxyprostaglandin dehydrogenase mRNA expression markedly decreased as compared to vehicle-treated control mice. Rebamipide did not affect the expression of cyclooxygenase-1 in the gastric tissue. Rebamipide did not increase prostaglandin E₂ production in the gastric tissue; however, it induced a 1.4-fold increase in the concentration of prostaglandin E₂ in the gastric tissue as compared to vehicle-treated control mice. These results suggest that the suppressive effect of rebamipide on non-steroidal anti-inflammatory drugs-induced gastric mucosal injury can be attributed to reduced 15-hydroxyprostaglandin dehydrogenase expression, which increases the prostaglandin E₂ concentration in the gastric tissue.

Protective effect of rebamipide against celecoxib-induced gastric mucosal cell apoptosis

A major clinical problem encountered with the use of non-steroidal anti-inflammatory drugs (NSAIDs) is gastrointestinal complications. We have previously suggested that both decreases in prostaglandin E(2) (PGE(2)) levels and mucosal apoptosis are involved in the development of NSAID-produced gastric lesions and that this apoptosis is mediated by an increase in the intracellular Ca(2+) concentration and the resulting endoplasmic reticulum (ER) stress response and mitochondrial dysfunction. Celecoxib and rebamipide are being used clinically as a safer NSAID and an anti-ulcer drug, respectively. In this study, we have examined the effect of rebamipide on celecoxib-induced production of gastric lesions. In mice pre-administered with a low dose of indomethacin, orally administered rebamipide suppressed celecoxib-induced mucosal apoptosis and lesion production but did not decrease in PGE(2) levels in the stomach. Rebamipide also suppressed celecoxib-induced increases in intracellular Ca(2+) concentration, the ER stress response, mitochondrial dysfunction and apoptosis in vitro. We also found that rebamipide suppresses the increases in intracellular Ca(2+) concentration induced by an activator of voltage-dependent L-type Ca(2+) channels and that another blocker of this channel suppresses celecoxib-induced increases in intracellular Ca(2+) concentration. These results suggest that celecoxib activates voltage-dependent L-type Ca(2+) channels and that rebamipide blocks this activation, resulting in suppression of celecoxib-induced apoptosis. We believe that this novel activity of rebamipide may play an important role in the protection of gastric mucosa against the formation of celecoxib-induced lesions.

Effect of rebamipide on quality of peptic ulcer healing in rat

The aim of this study is to elucidate the effects and the mechanism of rebamipide, omeprazole, and their combination treatment on quality of peptic ulcer healing (QOUH). Peptic ulcer models were induced by acetic acid exposure of the serosa of rat stomach. Forty Sprague-Dawley (SD) rats were divided randomly into four groups of ten rats each. Saline 2 ml/d (group 1), rebamipide 60 mg/kg/d (group 2), omeprazole 10 mg/kg/d (group 3) as well as its combination regimen (group 4) were administrated for 7 days. After sacrifice, size of the ulcer and focal layer structures were measured in vitro by miniature ultrasonic probe, and the mucosal sections were stained with hematoxylin and eosin (HE) for histological examination; the levels of interleukin (IL)-8/prostaglandin E(2) (PGE(2)) were evaluated by enzyme-linked immunosorbent assay (ELISA) and malondialdehyde (MDA) level was evaluated by thiobarbituric acid (TBA) method. Macroscopically, compared with the control group, the maximal diameters of the ulcers in the medication groups were significantly reduced (P < 0.05), and the layer echo structures of gastric wall were partially rebuilt. Histologically, ulcer range and inflammatory infiltration were less severe compared with the control group. In addition, mucosal MDA and IL-8 levels were significantly decreased, while PGE(2) level was significantly increased in the medication groups. Between the two monotherapy groups, there was no statistical difference in terms of PGE(2) and MDA levels. However, PGE(2) level was significantly increased, while MDA and IL-8 levels were significantly decreased in the combination group. Rebamipide as well as omeprazole and the combination regimen may improve QOUH through increasing the level of PGE(2), decreasing the levels of IL-8 and MDA in gastric mucosa, and this may potentially result in reduced recurrence of ulcer; moreover, the combination regimen was identified as having more antiulcer effects than monotherapy.

Anti-inflammatory effects of rebamipide according to Helicobacter pylori status in patients with chronic erosive gastritis: a randomized sucralfate-controlled multicenter trial in China-STARS study

The aim of the study was to investigate the effects of rebamipide on symptom, histology, endogenous prostaglandin, and mucosal oxygen free radicals in chronic erosive gastritis (CEG) patients by using sucralfate as a control. The trial also examined whether Helicobacter pylori infection would affect rebamipide-induced protection. A total of 453 endoscopy-confirmed CEG patients from 11 hospitals in China were enrolled in the study. They randomly received either rebamipide (100 mg t.i.d) or sucralfate (1.0 t.i.d) for 8 weeks with a ratio of 3:1. Per-protocol analysis (n = 415) showed the accumulated symptom score in the rebamipide group dropped from 5.54 +/- 0.97 to 0.80 +/- 0.47 after 8 weeks (P < 0.001 versus control). The endoscopic inflammation score in rebamipide group also decreased from 2.65 +/- 0.09 to 0.60 +/- 0.10, which showed better effects than sucralfate. It was shown a significant improvement (P < 0.01) in prostaglandin E2 (PGE(2)) contents in rebamipide-treated subjects mucosa (225.4 +/- 18.3 pg/g versus 266.7 +/- 14.7 pg/g) compared with that in sucralfate group after 8 weeks of treatment. Malondialdehyde (MDA) contents were significantly depressed both in the trial and control group. When Helicobacter pylori infection was considered, no statistically difference was found in the effect of rebamipide on either symptom or inflammation scores. In conclusion, Rebamipide demonstrated a stronger suppressive effect on the mucosal inflammation in chronic erosive gastritis than sucralfate. The gastroprotection induced by rebamipide is not influenced by H. pylori infection, which indicates its usage in the treatment of H. pylori-associated CEG.

Rebamipide enema therapy for left-sided ischemic colitis patients accompanied by ulcers: Open label study

AIM: To attempt rectal administration of rebamipide in the treatment of ischemic colitis patients with ulcers, and evaluate its effects.

METHODS: We compared 9 ischemic colitis patients (2 men, 7 women) with ulcers treated by bowel rest only from 2000 to 2005 (conventional therapy group), with 6 patients (2 men, 4 women) treated by rebamipide enema therapy in 2006 (rebamipide enema therapy group) and analyzed the mean duration of fasting and hospitalization, degree of ulcer healing, and decrease in WBC count for the two groups.

RESULTS: The mean duration of fasting and hospitalization were 2.7 ± 1.8 d and 9.2 ± 1.5 d in the rebamipide group and 7.9 ± 4.1 d and 17.9 ± 6.8 d in the control group, respectively, and significantly reduced in the rebamipide group (t = -2.915; P = 0.0121 and t = -3.054; P = 0.0092). As for the degree of ulcer healing at 7 d after admission, the ulcer score was reduced by 3.5 ± 0.5 (points) in the rebamipide group and 2.8 ± 0.5 (points) in the control group (t = 1.975; P = 0.0797), while the decrease in WBC count was 120.0 ± 55.8 (× 10²/&mgr;L) in the rebamipide group and 85.9 ± 56.8 (× 10²/&mgr;L) in the control group (t = 1.006; P = 0.3360).

CONCLUSION: In left-sided ischemic colitis patients with ulcers, rebamipide enema therapy significantly reduced the duration of fasting and hospitalization, recommending its use as a new and effective therapeutic alternative.

Prophylactic effect of rebamipide on aspirin-induced gastric lesions and disruption of tight junctional protein zonula occludens-1 distribution

Aspirin and nonsteroidal anti-inflammatory agents are known to induce gastroduodenal complications such as ulcer, bleeding, and dyspepsia. In this study, we examined the prophylactic effect of rebamipide, an anti-ulcer agent with free-radical scavenging and anti-inflammatory effect, on acidified aspirin-induced gastric mucosal injury in rats. In addition, we investigated the mucosal barrier functions disrupted by aspirin. Oral administration of acidified aspirin resulted in linear hemorrhagic erosions with increasing myeloperoxidase activity and thiobarbituric acid-reactive substance concentrations in the gastric mucosa. Rebamipide suppressed these acidified aspirin-induced gastric lesions and inflammatory changes significantly, and its protective effect was more potent in the case of repeated (twice daily for 3 days) treatment than single treatment before aspirin administration. Immunostaining of zonula occludens (ZO)-1, one of the tight junctional proteins, was strengthened in rat gastric mucosa after repeated administration of rebamipide. In addition, aspirin induced the increasing transport of fluorescine isothiocyanate-labeled dextrans with localized disruption and decreased expression of ZO-1 protein on rat gastric mucosal cell line RGM-1. Rebamipide effectively prevented aspirin-induced permeability changes and disruption of ZO-1 distribution. These results suggest that rebamipide protects against aspirin-induced gastric mucosal lesions by preserving gastric epithelial cell-to cell integrity in addition to the anti-inflammatory effects.

Effect of OPC-12759 on EGF receptor activation, p44/p42 MAPK activity, and secretion in conjunctival goblet cells

The purpose of the study was to determine if OPC-12759 stimulates secretion from conjunctival goblet cells in culture and if it activates the EGF receptor (EGFR) and p44/p42 mitogen-activated protein kinase (MAPK) to cause mucin secretion. Conjunctival goblet cells were cultured from pieces of male rat conjunctiva. OPC-12759 was added at increasing concentrations and for varying times to the cultured cells. The cholinergic agonist carbachol was used as a positive control. In selected experiments an inhibitor of the EGFR, AG1478, or an inhibitor of the kinase that activates MAPK, U0126, were added before OPC-12759. Goblet cell secretion of high molecular weight glycoconjugates was measured by an enzyme-linked lectin assay using the lectin UEA-1. Activation of the EGFR and MAPK were determined with Western blotting analysis using antibodies specific to the phosphorylated and the total amounts of these proteins. We found that OPC-12759 induced goblet cell secretion in a time- and concentration-dependent manner. Inhibition of the EGFR with AG1478 blocked secretion stimulated by OPC-12759. Inhibition of MAPK with U0126 also blocked secretion stimulated by OPC-12759. OPC-12759 increased the phosphorylation of the EGFR and MAPK in a time-dependent manner. We concluded that OPC-12759 stimulates secretion from cultured conjunctival goblet cells by activating the EGFR, which then induces MAPK activity.

Gastroprotective effects of DA-6034, a new flavonoid derivative, in various gastric mucosal damage models

This study evaluated the gastroprotective activity of DA-6034 against various ulcerogens including ethanol, aspirin, indomethacin, stress, and acetic acid. The basic mechanisms of DA-6034 as a defensive factor such as mucus secretion and endogenous prostaglandin E(2) synthesis were determined. Rats with gastric lesions induced by ethanol-HCl, aspirin, indomethacin, and stress that had been pretreated with DA-6034 orally showed a statistically significant decrease or decreasing tendency of the gastric lesion. In acetic acid-induced gastric lesions, repeated oral administration of DA-6034 exhibited a U-shape activity in ulcer healing, with the maximum and minimum inhibition being observed at 30 and 10 mg/kg/day, respectively. DA-6034 also increased the mucus content in the gel layer as well as endogenous prostaglandin E(2) synthesis. These results suggest that DA-6034 prevents gastric mucosal injury, and these gastroprotective activities appear to be due to the increase in the gastric defensive systems.

Geranylgeranylacetone induces cyclooxygenase-2 expression in cultured rat gastric epithelial cells through NF-kappaB

Geranylgeranylacetone (GGA) effectively protects the gastric mucosa against noxious agents. The precise mechanisms underlying the gastroprotective actions of GGA are not known. To elucidate the precise mechanism of GGA, the effect of GGA treatment on COX-2 expression in rat gastric epithelial (RGM1) cells was investigated. We used a prostaglandin E2 (PGE2) enzyme-linked immunoassay kit and Western blot analysis to measure PGE2 production and COX-2 induction by GGA treatment in serum-starved RGM1 cells. Gel-shift assay, Western blot analysis, and a reporter assay were performed to determine which COX-2 promoter was involved in GGA-induced COX-2 expression. GGA treatment dose dependently increased COX-2 expression and PGE2 production. The nuclear factor (NF)-kappaB sites of the COX-2 gene promoter were critical for GGA-mediated COX-2 expression. GGA induces COX-2 expression and increases PGE2 production in serum-starved RGM1 cells via activation of the NF-kappaB sites of COX-2 gene promoters.

Prescription of nonsteroidal anti-inflammatory drugs and co-prescribed drugs for mucosal protection: analysis of the present status based on questionnaires obtained from orthopedists in Japan

OBJECTIVE

Recently guidelines for the treatment and prevention of ulcers induced by nonsteroidal anti-inflammatory drugs (NSAIDs) have been established. The aim of the present study was to examine factors influencing orthopedists in Japan in the use of cytoprotective drugs to prevent NSAID-associated gastrointestinal adverse events.

METHODS

We sent a questionnaire to 402 orthopedists in Hyogo Prefecture. A standardized 10-item questionnaire was used to collect information on NSAID prescriptions (drug name, pharmaceutical form, doses, and duration of use) and associated drugs, especially gastroprotective drugs.

RESULTS

Two hundred eight (51.7%) orthopedists returned the questionnaire. The most frequently used NSAIDs, in descending order, were loxoprofen sodium, diclofenac sodium, and etodolac. Most doctors (80%) reported patients with abdominal symptoms associated with NSAIDs. Of these doctors, 59% treated the symptoms by themselves, and prescribed gastroprotective agents (32.2%), histamine H2-receptor antagonists (H2RAs) (26.4%), prostaglandin analogues (PAs) (17.0%), or proton pump inhibitors (PPIs) (16.2%). Sixty-seven percent of doctors reported that those drugs reduced the symptoms. Most orthopedists (96%) prescribed some type of drug to prevent NSAID-associated gastrointestinal events, including gastroprotective drugs (44.6%), H2RAs (19.5%), PAs (17.4%), and PPIs (10.8%). The doctors reported that they prescribed medicines for NSAID-associated gastrointestinal events on the basis of their experience (23%), by considering medical insurance restrictions (17%), and by referring to information provided by pharmaceutical company representatives (16%).

CONCLUSION

Most orthopedists prescribe some type of drug to prevent NSAID-induced ulcers but do not refer to the guidelines. We therefore strongly recommend that the guidelines be made more widely known to gastroenterologists and to physicians in every field of clinical practice, including orthopedics.

Gastroduodenal mucosal defense

PURPOSE OF REVIEW

The duodenum absorbs nearly all secreted gastric acid. Carbonic anhydrases facilitate transmucosal acid movement. The upper gastrointestinal tract must resist a variety of injuries, including those caused by ingested noxious substances, acid, ischemia/reperfusion, and infections such as Helicobacter pylori. The results are similar, however, regardless of insult: inflammation, ulceration, or metaplasia/dysplasia. In the past year, there have been prominent findings suggesting that oxidative stress and the formation of reactive oxygen species may play a pivotal role in all forms of injury, and that antioxidants may be the key to injury prevention and healing.

RECENT FINDINGS

Oxidative injury may be a common mechanism by which the upper gastrointestinal mucosa responds to noxious insults. Endogenous antioxidants, such as ghrelin, L-carnitine, and annexin-1 attenuate the oxidative-stress response. Similarly, exogenous antioxidants have also been shown to decrease inflammation, upregulate free radical scavengers, and prevent the formation of reactive oxygen species.

SUMMARY

Many studies published in the past year have linked oxidative stress to a variety of upper gastrointestinal insults. Exogenous and endogenous antioxidant compounds prevent the oxidative stress response. The future holds great promise for the development of pharmaceuticals with antioxidant properties that are safe, efficacious, and inexpensive.