Lack of gastric toxicity of nitric oxide-releasing indomethacin, NCX-530, in experimental animals

Gaseous Mediators as a Key Molecular Targets for the Development of Gastrointestinal-Safe Anti-Inflammatory Pharmacology

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most widely used classes of drugs and play a pivotal role in the therapy of numerous inflammatory diseases. However, the adverse effects of these drugs, especially when applied chronically, frequently affect gastrointestinal (GI) tract, resulting in ulceration and bleeding, which constitutes a significant limitation in clinical practice. On the other hand, it has been recently discovered that gaseous mediators nitric oxide (NO), hydrogen sulfide (H₂S) and carbon monoxide (CO) contribute to many physiological processes in the GI tract, including the maintenance of GI mucosal barrier integrity. Therefore, based on the possible therapeutic properties of NO, H₂S and CO, a novel NSAIDs with ability to release one or more of those gaseous messengers have been synthesized. Until now, both preclinical and clinical studies have shown promising effects with respect to the anti-inflammatory potency as well as GI-safety of these novel NSAIDs. This review provides an overview of the gaseous mediators-based NSAIDs along with their mechanisms of action, with special emphasis on possible implications for GI mucosal defense mechanisms.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Management of NSAID-associated peptic ulcer disease

Non-steroidal anti-inflammatory drug (NSAID) use increases the risk of gastrointestinal complications such as ulcers or bleeding. The presence of factors like advanced age, history of peptic ulcer, Helicobacter pylori infection and the use of anticoagulants or antiplatelet agents increase this risk further. COX-2 inhibitors and antisecretory drugs, particularly proton pump inhibitors, help to minimize the risk of gastrointestinal complications in high-risk patients. This review presents a practical approach to the prevention and treatment of NSAID-associated peptic ulcer disease and examines the new advances in the rational use of NSAIDs.

Current perspectives in NSAID-induced gastropathy

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most highly prescribed drugs in the world. Their analgesic, anti-inflammatory, and antipyretic actions may be beneficial; however, they are associated with severe side effects including gastrointestinal injury and peptic ulceration. Though several approaches for limiting these side effects have been adopted, like the use of COX-2 specific drugs, comedication of acid suppressants like proton pump inhibitors and prostaglandin analogs, these alternatives have limitations in terms of efficacy and side effects. In this paper, the mechanism of action of NSAIDs and their critical gastrointestinal complications have been reviewed. This paper also provides the information on different preventive measures prescribed to minimize such adverse effects and analyses the new suggested strategies for development of novel drugs to maintain the anti-inflammatory functions of NSAIDs along with effective gastrointestinal protection.

Synthesis and pharmacological characterization of a novel nitric oxide-releasing diclofenac derivative containing a benzofuroxan moiety

1-oxy-benzo[1,2,5]oxadiazol-5-ylmethyl [2-(2,6-dichloro-phenylamino)-phenyl]-acetate, a new diclofenac derivative bearing a benzofuroxan heterocyclic moiety in its structure, was prepared by the reaction of sodium diclofenac and 5-bromomethyl-benzo[1,2,5]oxadiazole 1-oxide. Pharmacological characterization of this modified diclofenac maintained the anti-inflammatory activity similar to its parent compound assayed in vitro and in vivo. The ulcerogenic properties of native diclofenac were not observed with this modified compound, despite the inhibition of prostaglandin E2 gastric content. The better gastric tolerability seems to be related to nitric oxide release ability.

Risk factors for gastrointestinal complications in aspirin users: review of clinical and experimental data

This paper reviews recent clinical evidence that suggests that aspirin prophylaxis against cardiac and cerebral vascular ischemia is associated with significant gastrointestinal complications. The clinical and experimental evidence to confirm the role of risk factors of concomitant use of nonsteroidal anti-inflammatory drugs (NSAID), tobacco cigarette smoking, and alcohol consumption are discussed. The limitations of long-term acid suppression treatment for the prevention of these complications are considered. Future experimental studies to guide the clinical approach to develop novel and potentially cost-effective management strategies are discussed.

Effects of esomeprazole on glutathione levels and mitochondrial oxidative phosphorylation in the gastric mucosa of rats treated with indomethacin

Proton pump inhibitors exert their preventive and healing effects on gastropathy induced by nonsteroidal anti-inflammatory drug (NSAIDs) by a dual action: the antisecretory and the antioxidant effect. The latter was investigated by using esomeprazole against indomethacin-induced gastric mucosa lesions in rats and assessed by a histomorphometric analysis. Treatment by intragastric gavage were 1% methocel as vehicle; esomeprazole 10, 30, or 60 micromol/kg; indomethacin 100 micromol/kg; and esomeprazole 10, 30, or 60 micromol/kg plus indomethacin 100 micromol/kg. The evaluation of glutathione (GSH) levels and respiratory chain complex activities [nicotinamide adenine dinucleotide, reduced (NADH)-ubiquinone oxidoreductase, succinate dehydrogenase, cytochrome C reductase, cytochrome oxidase] was performed in the isolated gastric mucosa. Esomeprazole (10-60 micromol/kg) dose dependently reversed, up to complete recovery, the inhibitory effect of indomethacin on GSH levels (approximately 60% inhibition) and mitochondrial enzyme activities (inhibition ranging from 60% to 75%). Indomethacin-induced mucosal injuries were reduced by esomeprazole. Thus, in addition to inhibiting acid secretion, the gastroprotective effect of esomeprazole can be ascribed to a reduction in gastric oxidative injury.

Structure-based design, synthesis, and biological evaluation of indomethacin derivatives as cyclooxygenase-2 inhibiting nitric oxide donors

Indomethacin, a nonselective cyclooxygenase (COX) inhibitor, was modified in three distinct regions in an attempt both to increase cyclooxygenase-2 (COX-2) selectivity and to enhance drug safety by covalent attachment of an organic nitrate moiety as a nitric oxide donor. A human whole-blood COX assay shows the modifications on the 3-acetic acid part of the indomethacin yielding an amide-nitrate derivative 32 and a sulfonamide-nitrate derivative 61 conferred COX-2 selectivity. Along with their respective des-nitrate analogs, for example, 31 and 62, the nitrates 32 and 61 were effective antiinflammatory agents in the rat air-pouch model. After oral dosing, though, only 32 increased nitrate and nitrite levels in rat plasma, indicating that its nitrate tether served as a nitric oxide donor in vivo. In a rat gastric injury model, examples 31 and 32 both show a 98% reduction in gastric lesion score compared to that of indomethacin. In addition, the nitrated derivative 32 inducing 85% fewer gastric lesions when coadministered with aspirin as compared to the combination of aspirin and valdecoxib.

Involvement of alpha(2)-adrenoceptors in the gastric protective effect of nitroglycerin against acidified ethanol-induced mucosal injury

Clinical observations reveal that alcohol intake is associated with an increase in upper gastrointestinal hemorrhage requiring hospitalization and that nitroglycerin or long-acting nitrates lower this risk. Nitroglycerin, a gastric vasodilator that can increase gastric fluid volume, protects the rodent stomach against damage, including that caused by 70% ethanol. Blockade of alpha(2)-adrenoceoptors attenuates gastric protection by intragastric nicotine against 40% ethanol. We tested the hypothesis that the protective effect of nitroglycerin is mediated by an increase in gastric fluid volume and alpha(2)-adrenoceoptors. Nitroglycerin, 5 mg/kg, vehicle, or acidified ethanol was administered intragastrically. In study 1 acidified ethanol-induced mucosal injury was measured. In study 2 the effect of increasing gastric volume (1 ml/kg) on mucosal injury was assessed. In study 3 the effect of yohimbine (alpha(2)-adrenoceoptor antagonist), 5 mg/kg subcutaneously, on the nitroglycerein-mediated protective effect was determined. Results showed that nitroglycerin significantly attenuated the number and length of mucosal lesions induced by acidified ethanol. Increase in gastric fluid volume by exogenously administered saline did not alter the protective effect. Yohimbine blocked the nitroglycerin-mediated protection. These experimental data are consistent with the observation that nitrates lower the risk of ethanol-induced gastrointestinal complications. alpha(2)-Adrenoceoptors are responsible in part for the protective effect of nitroglycerin.

Intragastric nitroglycerin at a vasodilatory dose attenuates acidified aspirin-induced gastric mucosal injury

Clinical studies reveal that aspirin intake to prevent myocardial and cerebral ischemia is associated with a significant increase in upper gastrointestinal hemorrhage requiring hospitalization and that nitroglycerin or long-acting nitrates significantly lower this risk. Nitroglycerin can increase gastric blood flow and slow gastric emptying. We hypothesized that both features contribute to its gastroprotective property. Fasted anesthetized rats (Study 1) and conscious mice (Studies 2 to 4) received intragastric nitroglycerin or vehicle. The effects of these two treatments on various parameters were assessed in Study 1, on blood pressure and gastric blood flow; Study 2, on acidified aspirin-induced gastric mucosal lesions; and Study 3, on the weight of gastric content. In Study 4, the effect of nitroglycerin, vehicle, or vehicle plus saline, on acidified aspirin-induced gastric mucosal lesion was assessed. Compared with vehicle, nitroglycerin decreased blood pressure and produced a mild but significant increase in gastric vascular conductance, blood flow, and volume of gastric content. The number and length of gastric mucosal lesions induced by acidified aspirin were significantly attenuated by intragastric nitroglycerin in a vasodilatory dose. Exogenous saline in a volume equivalent to the increase produced by nitroglycerin, however, did not attenuate the lesions. These experimental data are consistent with the clinical observation that nitrates lower the risk of aspirin-induced gastrointestinal complications. Confirmation of the efficacy of nitroglycerin and nitrates in preventing such aspirin-induced complications in controlled trials is worthy of consideration by clinical investigators.

Effect of aspirin, paracetamol and their nitric oxide donating derivatives on exudate cytokine and PGE2 production in zymosan-induced air pouch inflammation in rats

Effects of different doses of aspirin, compared to equimolar doses of nitric oxide (NO)-donating aspirin (NCX 4016), and of a single dose of paracetamol, compared to an equimolar dose of NO-donating paracetamol (NCX 701) were investigated in acute zymosan-induced air pouch inflammation in rats. Treatments were administered by orogastric route, and interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and prostaglandin E(2) (PGE(2)) levels in the exudates were analysed 4 h after zymosan injection by enzyme immunoassay (EIA). Aspirin, at 10, 30 and 100 mg/kg doses, increased IL-1beta levels in exudates, however, only the highest dose lead to a significant increase when compared to control, whereas a significant increase in TNF-alpha level was observed at all doses tested. NCX 4016, at equimolar doses for aspirin, i.e., 18.6, 55.8 and 186 mg/kg, respectively, did not cause any changes in exudate IL-1beta or TNF-alpha levels. These effects were significantly different, when aspirin was compared with the corresponding NCX 4016 group. Nevertheless, the ability of aspirin and NCX 4016 to inhibit PGE(2) synthesis in the exudate where comparable. Although paracetamol significantly increased exudate TNF-alpha level compared to the control group and NCX 701 group, neither paracetamol, nor NCX701 treatments changed the levels of exudate IL-1beta significantly. As expected, paracetamol and NCX 701 showed poor PGE(2) inhibition. At high doses, aspirin and NCX 4016 decreased the number of polymorphonuclear leukocytes in the exudate. However, this inhibition was not significantly different from the control group. Paracetamol and NO-paracetamol did not cause any change in the number of polymorphonuclear leukocytes in exudate. These results indicated that aspirin and NCX 4016 possessed different effects on cytokine production or release, despite the fact that both drugs inhibited the synthesis of PGE(2) in a similar way. Unlike paracetamol, which increased exudate TNF-alpha level, NCX 701 had no effect on TNF-alpha level in the exudates.

Low direct cytotoxicity and cytoprotective effects of nitric oxide releasing indomethacin

Nitric oxide (NO) releasing non-steroidal anti-inflammatory drugs (NSAIDs) have shown a marked reduction of gastrointestinal side effects and we here examined the cytotoxicity of NCX 530 (NO-indomethacin). Under conditions where indomethacin clearly induced both necrosis and apoptosis, NCX 530 induced neither. NCX 530 protected cells from celecoxib-induced necrosis and apoptosis. NCX 530 partially suppressed celecoxib-dependent membrane permeabilization and an inhibitor for guanylate cyclase suppressed the cytoprotective effect of NCX 530 against celecoxib. In vivo, NCX 530 alone produced fewer gastric lesions in rats than did indomethacin. A combination of the oral administration of celecoxib together with the intraperitoneal administration of indomethacin, but not of NCX 530, clearly resulted in the production of gastric lesions. The low direct cytotoxicity and the cytoprotective effect of NCX 530 observed in vitro may also act in vivo, thus ensuring that NCX 530 is safe for use on the gastric mucosa.

Mechanisms of protection by pantoprazole against NSAID-induced gastric mucosal damage

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. In clinical settings, proton pump inhibitors have proven to be effective in preventing and healing NSAID-induced gastroduodenal lesions. The present study investigates the mechanisms of protection afforded by pantoprazole against gastric injury induced by different NSAIDs in rats. Animals were orally treated with indomethacin (100 micromol/kg), diclofenac (60 micromol/kg), piroxicam (150 micromol/kg) or ketoprofen (150 micromol/kg). Thirty minutes before NSAIDs, animals received pantoprazole 6 or 60 micromol/kg orally. Four hours after NSAIDs, the following parameters were assessed: histomorphometric evaluation of gastric mucosal damage; gastric mucosal levels of myeloperoxidase (MPO), malondialdehyde (MDA), reduced glutathione as an index of non-proteic sulfhydryl compounds (GSH), and prostaglandin E2 (PGE2); mucosal cyclooxygenase-1 and -2 (COX-1, COX-2) mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). Separate experiments were carried out to assay the effects of pantoprazole on gastric acid secretion in pylorus-ligated rats. The in vitro influence of pantoprazole (1-10 microM) on the oxidation of low density lipoproteins (LDLs) induced by copper sulphate was also examined. All NSAIDs elicited mucosal necrotic lesions associated with neutrophil infiltration and reduction of PGE2 levels. Increments of MPO and MDA contents, as well as a decrease in GSH levels, were detected in the gastric mucosa of indomethacin-, piroxicam- or ketoprofen-treated animals. Indomethacin enhanced mucosal COX-2 expression, while not affecting COX-1. At the oral dose of 6 micromol/kg pantoprazole did not affect NSAID-induced mucosal damage, whereas at 60 micromol/kg it markedly reduced injuries provoked by all test NSAIDs. Pantoprazole 60 micromol/kg also reversed the effects of NSAIDs on MPO, MDA, and GSH mucosal contents, without interfering with the decrease in PGE2 levels or indomethacin-induced COX-2 expression. However, at both doses, pantoprazole inhibited acid secretion in pylorus-ligated rats. Furthermore, pantoprazole concentration dependently reduced the in vitro oxidation of LDLs. Our results suggest that besides inhibiting acid secretion, the protection afforded by pantoprazole against NSAID-induced gastric damage depends on a reduction in mucosal oxidative injury, which may also account for an increment of sulfhydryl radical mucosal bioavailability. It is also suggested that pantoprazole does not influence the down-regulation of gastric prostaglandin production associated with NSAID treatment.

Lansoprazole prevents experimental gastric injury induced by non-steroidal anti-inflammatory drugs through a reduction of mucosal oxidative damage

AIM: This study investigated the mechanisms of protection afforded by the proton pump inhibitor lansoprazole against gastric injury induced by different non-steroidal anti-inflammatory drugs (NSAIDs) in rats.

METHODS: Male Sprague-Dawley rats were orally treated with indomethacin (100 µmol/kg), diclofenac (60 µmol/kg), piroxicam (150 µmol/kg) or ketoprofen (150 µmol/kg). Thirty minutes before NSAIDs, animals were orally treated with lansoprazole 18 or 90 µmol/kg. Four hours after the end of treatments, the following parameters were assessed: gastric mucosal PGE2, malondialdehyde (MDA), myeloperoxidase (MPO) or non-proteic sulfhydryl compounds (GSH) levels; reverse transcription-polymerase chain reaction (RT-PCR) of mucosal COX-2 mRNA; gastric acid secretion in pylorus-ligated animals; in vitro effects of lansoprazole (1-300 µmol/L) on the oxidation of low density lipoproteins (LDLs) induced by copper sulphate.

RESULTS: All NSAIDs elicited mucosal necrotic lesions which were associated with neutrophil infiltration and reduction of PGE2 levels. Increments of MPO and MDA contents, as well as a decrease in GSH levels were detected in the gastric mucosa of indomethacin- or piroxicam-treated animals. Indomethacin enhanced mucosal cyclooxygenase-2 expression, while not affecting cyclooxygenase-1. At the oral dose of 18 µmol/kg lansoprazole partly counteracted diclofenac-induced mucosal damage, whereas at 90 µmol/kg it markedly prevented injuries evoked by all test NSAIDs. Lansoprazole at 90 µmol/kg reversed also the effects of NSAIDs on MPO, MDA and GSH mucosal contents, without interfering with the decrease in PGE2 levels or indomethacin-induced cyclooxygenase-2 expression. However, both lansoprazole doses markedly inhibited acid secretion in pylorus-ligated rats. Lansoprazole concentration-dependently reduced the oxidation of LDLs in vitro.

CONCLUSION: These results suggest that, besides the inhibition of acid secretion, lansoprazole protection against NSAID-induced gastric damage depends on a reduction in mucosal oxidative injury, which is also responsible for an increment of sulfhydryl radical bioavailability. It is also suggested that lansoprazole does not influence the down-regulation of gastric prostaglandin production associated with NSAID treatment.

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

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

Involvement of nitric oxide in the gastroprotective effects of an aqueous extract of Pfaffia glomerata (Spreng) Pedersen, Amaranthaceae, in rats

The plants belonging to Pfaffia genus are used in folk medicine to treat gastric disturbances. This study examined the effects of an aqueous extract of Pfaffia glomerata (Spreng) Pedersen (AEP) on the gastrointestinal tract. Wistar rats were pretreated orally (p.o.) with the AEP (125, 250, 500 and 1000 mg.kg(-1)) before induction of ulcers by hypothermic restraint stress (HRS, 3 h restraint stress at 4 degrees C), ethanol (ET, 70%; 0.5 ml/animal; p.o.) or indomethacin (IND, 20 mg.kg(-1); s.c.). Control animals received water (C) or ranitidine (60 mg.kg(-1)) p.o. The AEP protected rats against HRS and ET-induced ulcers, but was not able to protect the gastric mucosa against IND-induced ulcers. When injected into the duodenal lumen, the AEP reduced total acidity and both basal and histamine-stimulated acid secretion in pylorus-ligated rats. In addition, gastric secretion from AEP-treated animals exhibited increased concentrations of nitrite and nitrate. Treatment of animals with L-NAME (120 mg.kg(-1), p.o.) prevented both the reduction of total acidity and the increase in NOx levels promoted by AEP treatment. In conclusion, AEP effectively protected the gastric mucosa and inhibited gastric acid secretion in rats, probably by involving the histaminergic pathway and an enhanced production of nitric oxide in the stomach.

Activity of the non-steroidal anti-inflammatory drug indomethacin against colorectal cancer

A substantial body of evidence from rodent colon carcinogenesis models, in vitro experiments with human colorectal cancer cells and limited clinical observations in humans suggest that the non-steroidal anti-inflammatory drug indomethacin has anti-colorectal cancer activity. However, although many mechanisms of the anti-neoplastic activity of indomethacin have been suggested, e.g., cyclooxygenase inhibition and peroxisome proliferator-activated receptor gamma activation, the precise relevance of the majority of in vitro pharmacological observations to the in vivo anti-neoplastic activity of indomethacin remains unclear. Herein, we review the existing literature describing the chemopreventative and chemotherapeutic efficacy of indomethacin against colorectal cancer, and draw together the disparate literature describing potential mechanisms of action of indomethacin in human colorectal cancer cells in vitro. Although indomethacin itself has significant adverse effects, including serious upper gastrointestinal toxicity, the development of novel derivatives that may have an improved safety profile means that further investigation of the anti-colorectal cancer activity of indomethacin is warranted.

Gastric mucosal blood flow changes in Helicobacter pylori infection and NSAID-induced gastric injury

BACKGROUND

The impact of H. pylori infection on gastric mucosal blood flow and NSAID-induced gastric damage is unclear.

AIM

To study the effects of H. pylori infection on gastric mucosal blood flow, both at basal conditions and after NSAID exposure, and its relation with mucosal damage and nitric oxide production.

METHODS

Gastric mucosal blood flow, nitric oxide production and gastric damage were assessed in time after H. pylori SS1 or E. coli inoculation in mice. Experiments were conducted in basal conditions or after oral exposure to indomethacin (20 mg/kg).

RESULTS

H. pylori infected mice exhibited a significant increase in gastric blood flow and gastric nitric oxide production 1 week after infection, but those parameters returned to basal levels by 4 weeks. NSAID challenge elicited a similar reduction in gastric blood flow [25-35%] in H. pylori-infected and control animals. However, only 1 week H. pylori-infected mice, which exhibited a significant baseline hyperemia, were able to maintain gastric blood flow values within the normal range after NSAID exposure. NSAID-induced gastric damage was increased in H. pylori-infected mice by 4 weeks, but not 1 week after infection.

CONCLUSIONS

Underlying H. pylori infection aggravates acute NSAID-induced gastric damage. However, at early phases, gastric hyperemia associated with increased nitric oxide production may exert some protective role.

Inhibition of nuclear factor-kappaB by a nitro-derivative of flurbiprofen: a possible mechanism for antiinflammatory and antiproliferative effect

Nonsteroidal antiinflammatory drugs (NSAIDs) are widely used in the treatment of chronic inflammatory states. In addition, they show promise for the prevention and therapy of colon cancers and of Alzheimer's disease, although their gastrointestinal toxicity is of concern for these indications. Nitric oxide-releasing NSAIDs are reported to be safer than their parent compounds. We report here that flurbiprofen nitroxybutyl ester inhibits nuclear factor-kappaB (NF-kappaB) activity and cell growth in L929 cells at a concentration of 100 microM, whereas flurbiprofen is inactive. Inhibition of cell growth is not due to the induction of apoptosis, but to a retardation of all phases of the cell cycle. NF-kappaB is implicated both in the control of immune and inflammatory response and in the control of cell proliferation and apoptosis. Therefore, its inhibition at low concentrations by an NSAID with low gastrointestinal toxicity could be important for all the above-mentioned therapeutic indications.

Gastroduodenal mucosal defense: an integrated protective response

The mechanisms by which the gastroduodenal mucosa maintains viability and normal functioning despite its intensely caustic environment have puzzled clinicians and investigators alike for at least 150 years. Protective mechanisms have been divided into three main categories: preepithelial (mucus and bicarbonate secretion), epithelial (cellular buffering, mucosal architecture and permeability), and postepithelial mechanisms (mucosal blood flow). Within each category are many other factors that bear on the ability of the mucosa to withstand constant changes of luminal pH. We will summarize some of the recent findings that pertain to the nature and regulation of these defense mechanisms in the context of a historical overview. Therapeutic implications of these findings will also be presented in the discussion of novel antiinflammatory compounds designed to upregulate simultaneously several defensive mechanisms, with the expectation that gastroduodenal damage will be minimized.

Pharmacology and potential therapeutic applications of nitric oxide-releasing non-steroidal anti-inflammatory and related nitric oxide-donating drugs

This review examines the biological significance, therapeutic potential and mechanism(s) of action of a range of nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAID) and related nitric oxide-releasing donating drugs (NODD). The slow release of nitric oxide (NO) from these compounds leads to subtle changes in the profile of pharmacological activity of the parent, non-steroidal anti-inflammatory drugs (NSAID). For example, compared with NSAID, NO-NSAID cause markedly diminished gastrointestinal toxicity and improved anti-inflammatory and anti-nociceptive efficacy. In addition, nitroparacetamol exhibits hepatoprotection as opposed to the hepatotoxic activity of paracetamol. The possibility that NO-NSAID or NODD may be of therapeutic benefit in a wide variety of disease states including pain and inflammation, thrombosis and restenosis, neurodegenerative diseases of the central nervous system, colitis, cancer, urinary incontinence, liver disease, impotence, bronchial asthma and osteoporosis is discussed.