Future trends in the development of safer nonsteroidal anti-inflammatory drugs

TMAO Impairs Mouse Aortic Vasodilation by Inhibiting TRPV4 Channels in Endothelial Cells

Trimethylamine oxide (TMAO) is an intestinal flora metabolite associated with risk of cardiovascular diseases. Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable ion channel that is essential for vasodilation and endothelial function. Currently, there are few studies on the effect of TMAO on TRPV4 channels. In the present study, Ca2+ imaging of vascular tissue showed that TMAO inhibited TRPV4-mediated Ca2+ influx into aortic endothelial cells in a dose-dependent manner. Furthermore, a whole-cell patch clamp assay showed that TMAO blocked TRPV4-mediated cation currents. Notably, results of aortic vascular tension measurement showed that TMAO impaired endothelium-dependent vasodilation in mouse aortic vessels through the TRPV4-NO pathway. Our results indicated that TMAO inhibited Ca2+ entry in endothelial cells and impaired vasodilation through the TRPV4-NO pathway in mice. These results provide scientific evidence for novel pathogenic mechanisms underlying the role of TMAO in cardiovascular disease.

Natural products as inhibitors of carcinogenesis

BACKGROUND

Although carcinogenesis and cancer have been studied intensively for > 50 years, the rates of cancer incidence and mortality remain high. The most successful approach for reducing these rates has been primary prevention. For individuals at a high risk of developing cancer owing to certain genetic, environmental and occupational factors, cancer chemoprevention is a logical approach.

OBJECTIVE

This review discusses natural products as inhibitors of carcinogenesis.

CONCLUSION

Natural product chemopreventive agents are inherently biologically active and have been demonstrated to prevent and reverse the carcinogenic process in a pleiotropic manner. Derivatives of compounds discovered by screening natural products for chemopreventive agents have shown efficacy in clinical trials. Despite the obstacles that must be overcome before chemopreventive drugs become an integral component of standard medical practice for cancer prophylaxis, there is vast potential for significant improvement in cancer morbidity and mortality through the use of natural product chemopreventive drugs.

Comparison of analgesic and anti-inflammatory efficacy of selective and non-selective cyclooxygenase-2 inhibitors in dental implant surgery

BACKGROUND

The analgesic and anti-inflammatory efficacy of tenoxicam and meloxicam were evaluated in this double-masked, randomized, prospective study by analyzing pain scores and the need for rescue-analgesic agents following dental implant surgery.

METHODS

One hundred patients, in whom 241 dental implants were placed, were divided into two groups. For 4 days beginning the day before surgery, the first group received meloxicam, 15 mg daily, and the second group received tenoxicam, 20 mg daily, followed by 1 hour preoperatively and for 2 days thereafter. Pain intensity was rated by the subjects based on a visual analog scale on the operation day and on the following 6 days. The patients were recommended to use a rescue analgesic if the pain score was > or =4. Postoperative complications, such as edema, hematoma, infection, severe pain, paresthesia, or gastrointestinal complaints, were also noted.

RESULTS

Statistical analysis revealed that 54% of patients in the tenoxicam group and 66% of patients in the meloxicam group used rescue analgesics on day 1. However, the difference between the groups was not significant (chi(2) = 1.05; P = 0.30). The relationship between the reduction of consumption and time was not significant in either group (Z = 0.84; P = 0.40). The relationship between the use of rescue analgesics and the number of implants placed was not significant. Among patients who reported postoperative complications, there was not a statistically significant difference between the groups (chi(2) = 0.04; P = 0.84).

CONCLUSION

Meloxicam and tenoxicam exhibited a similar analgesic and anti-inflammatory efficacy in the present investigation.

Effects of nonselective cyclooxygenase inhibition with low-dose ibuprofen on tumor growth, angiogenesis, metastasis, and survival in a mouse model of colorectal cancer

PURPOSE

To determine whether the nonselective and relatively inexpensive nonsteroidal anti-inflammatory drug ibuprofen would be effective in inhibiting colorectal cancer and might improve mortality in a mouse model.

EXPERIMENTAL DESIGN

The effects of ibuprofen on tumor growth inhibition and animal survival have been examined in both mouse and human colorectal cancer tumor models. Angiogenesis was measured by in vitro endothelial cell tube formation and immunohistochemistry.

RESULTS

Ibuprofen significantly inhibited cell proliferation in mouse (MC-26) and human (HT-29) colorectal cancer cell lines. In vitro angiogenesis assays also indicated that ibuprofen decreased both cell proliferation and tube formation. The administration of chow containing 1,360 ppm ibuprofen, which achieved an average plasma concentration of ibuprofen lower than the peak level achieved in humans at therapeutic doses, inhibited tumor growth by 40% to 82%. Fewer liver metastases were found in the ibuprofen group compared with the control group. In combination therapy with the standard antineoplastic agents, 5-fluorouracil, or irinotecan (CPT-11), tumor volumes in the groups with ibuprofen +/- CPT-11 or 5-fluorouracil were smaller than in the control group. Ibuprofen was similar to the cyclooxygenase-2 selective inhibitor rofecoxib in its ability to suppress tumor growth and improve overall survival.

CONCLUSIONS

Ibuprofen, in part by modulating tumor angiogenesis, decreases both tumor growth and metastatic potential in mice. The ibuprofen doses were in the low range of therapeutic human plasma concentrations. Ibuprofen potentiates the antitumor properties of CPT-11 and improves survival of mice without increasing gastrointestinal toxicity.

Cyclooxygenase 2, pS2, inducible nitric oxide synthase and transforming growth factor alpha in gastric adaptation to stress

AIM

To determine the role of mucosal gene expression of cyclooxygenase 2 (COX-2), pS2 (belongs to trefoil peptides), inducible nitric oxide synthase (iNOS) and transforming growth factor alpha (TGFalpha) in gastric adaptation to water immersion and restraint stress (WRS) in rats.

METHODS

Wistar rats were exposed to single or repeated WRS for 4 h every other day for up to 6 d. Gastric mucosal blood flow (GMBF) was measured by laser Doppler flowmeter-3. The extent of gastric mucosal lesions were evaluated grossly and histologically and expressions of COX-2, pS2,iNOS and TGFalpha were determined by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot.

RESULTS

The damage to the surface of gastric epithelium with focal areas of deep haemorrhagic necrosis was induced by repeated WRS. The adaptative cytoprotection against stress was developed with activation of cell proliferation in the neck regions of gastric glands. The ulcer index (UI) in groups II, III and IV was markedly reduced as compared with group I (I: 47.23+/-1.20; IV: 10.39+/-1.18,P<0.01). GMBF significantly decreased after first exposure to WRS with an adaptive increasement of GMBF in experimental groups after repetitive challenges with WRS. After the 4th WRS, the value of GMBF almost restored to normal level (I: 321.87+/-8.85; IV: 455.95+/-11.81, P<0.01). First WRS significantly decreased the expression of pS2 and significantly increased the expressions of COX-2, iNOS and TGFalpha. After repeated WRS, pS2 and TGFalpha expressions gradually increased (pS2: I: 0.37+/-0.02; IV: 0.77+/-0.01; TGFalpha: I: 0.86+/-0.01; IV: 0.93+/-0.03, P<0.05) with a decrease in the expressions of COX-2 and iNOS (COX-2: I: 0.45+/-0.02; IV: 0.22+/-0.01; iNOS: I: 0.93+/-0.01; IV: 0.56+/-0.01, P<0.01). Expressions of pS2, COX-2, iNOS and TGFalpha showed regular changes with a good relationship among them.

CONCLUSION

Gastric adaptation to WRS injury involves enhanced cell proliferation, increased expression of pS2 and TGFalpha, and reduced expression of COX-2 and iNOS. These changes play an important role in adaptation of gastric mucosa after repeated WRS.

Cyclooxygenase-2 selective inhibition with NS-398 suppresses proliferation and invasiveness and delays liver metastasis in colorectal cancer

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to reduce the risk and mortality of colorectal cancer (CRC) by inhibiting the activity of cyclooxygenase (COX). The present studies were directed to determine whether selective COX-2 inhibition reduces CRC tumour cell proliferation and invasion/migration, and the possible cellular and molecular mechanisms involved. The MC-26 cells are a highly invasive mouse CRC cell line expressing COX-2 protein. NS-398 (100 μM), a highly selective COX-2 inhibitor, decreased cell proliferation by ∼35% of control, as determined using [³H]-thymidine incorporation. This reduction in cell proliferation was associated with decreased expression of cyclin D1 and proliferating cell nuclear antigen (PCNA). Furthermore, NS-398 inhibited cell invasion/migration through Matrigel extracellular matrix components at 24 h by ∼60%. The addition of exogenous prostaglandin E₂ partially attenuated the inhibition of cell invasion by 10 μM NS-398, but failed to reverse the effect of 100 μM NS-398. Matrix metalloproteinases-2 (MMP-2) and -9 (MMP-9) are two enzymes that facilitate cell invasion/migration by degrading the extracellular matrix. In the presence of 100 μM NS-398, Western blot hybridisation analysis and zymography demonstrated that both MMP-2 and MMP-9 protein levels and enzyme activity were decreased by ∼25–30%. In separate studies, NS-398 also inhibited tumour growth in vivo and retarded the formation of liver metastasis. The results of these studies indicate that the expression and activity of COX-2 appear to be associated with both the proliferative and invasive properties of CRC. Cyclooxygenase-2 inhibition suppresses tumour cell growth and invasion/migration, and retards liver metastasis in a mouse colon cancer model, via multiple cellular and molecular mechanisms.

Clinical potential of cyclo-oxygenase-2 inhibitors

On the basis of their reduced potential to cause injury to the gastroduodenal mucosa, cyclo-oxygenase (COX)-2-selective inhibitors were developed and marketed as a safer alternative to traditional nonsteroidal anti-inflammatory drugs (NSAIDs). This manuscript reviews the major steps leading to the introduction of COX-2-selective inhibitors into clinical practice, from the identification of the COX isoenzymes to their various roles in physiological and pathological processes. The available data show that COX-2 inhibitors have a favourable safety profile and are at least as effective as traditional NSAIDs for the treatment of pain and inflammatory conditions with a reduced incidence of gastrointestinal complications. Emerging evidence points to new and unanticipated effects from these agents. COX-2 inhibition appears to play an important role in the modulation of intestinal polyposis and colorectal carcinogenesis. Additionally, COX-2 expression may be associated with inflammatory responses leading to the occurrence of Alzheimer's disease and potentially, COX-2 inhibitors could be used to retard the progression of this condition. However, by decreasing prostacyclin production, COX-2 inhibitors may lead to increased prothrombotic activity and increase the risk of cardiovascular events. Until further large-scale prospective studies are performed, and the magnitude of these potential risks is quantified, COX-2 inhibitors should be used with caution in patients at risk for cardiovascular morbidity.

Selective COX-2 inhibitors: a review of their therapeutic potential and safety in dentistry

Anti-inflammatory analgesics are commonly used medications in dental and medical practice. Their uses in dentistry include use as analgesics and as anti-inflammatory agents. In addition, antipyretic action accompanies the medication. The action of these groups of drugs depends on the dose provided. Analgesic and antipyretic effects occur at low dose, whereas analgesic effects occur at high dose. Among the common side effects of this class of medications are gastrointestinal irritation with potential for ulceration, increased tendency for bleeding due to antiplatelet effects, and long-term chronic dosing effects on renal function may occur. Recent developments in the anti-inflammatory group of medications include the introduction of cyclooxygenase-II inhibitors. These agents offer potentially significant advantages because of their relative lack of gastrointestinal irritation. Because of this, it is likely that these medications will be frequently used in the management of dental and medical conditions. Patients will present while on these medications, and these agents may serve as medications for management of dental pain, postsurgical pain, and for anti-inflammatory effects. The current literature indicates that COX-2 inhibitors offer substantial benefits because of their favorable gastrointestinal profiles and because of their lack of effect on platelet function.

Comparison of once-daily and twice-daily administration of celecoxib for the treatment of osteoarthritis of the knee

OBJECTIVE

The purpose of this study was to compare the efficacy and tolerability of a celecoxib 200 mg QD regimen with a 100 mg BID regimen in patients with osteoarthritis (OA) of the knee.

METHODS

Patients enrolled in this prospective, double-blind, placebo-controlled, parallel-group, multicenter study were randomly assigned to receive celecoxib 100 mg BID, celecoxib 200 mg QD, or placebo for 6 weeks. Assessments of OA severity (Patient's and Physician's Global Assessments of Arthritis, Patient's Assessment of Arthritis Pain-Visual Analog Scale, Lequesne Osteoarthritis Severity Index, and the Western Ontario and McMaster Universities Osteoarthritis Index) were performed at baseline and at week 2 and/or 6. Patients who discontinued treatment underwent assessments at the time of withdrawal from the study.

RESULTS

Of the 718 patients enrolled, 243 received celecoxib 100 mg BID, 231 received celecoxib 200 mg QD, and 244 received placebo. For all measures of efficacy, at all assessments, improvements from baseline in both celecoxib groups were superior to that seen in the placebo group (P < 0.05). No significant differences in efficacy between the celecoxib groups were observed. The overall incidence of adverse events was similar in the 2 celecoxib treatment groups.

CONCLUSIONS

Dosing regimens of celecoxib 200 mg QD and 100 mg BID are equally effective and well tolerated in patients with OA of the knee. The availability of 2 effective regimens provides patients and physicians with increased flexibility in the selection of an appropriate dosing regimen for celecoxib therapy.

Nonsteroidal anti-inflammatory drugs

NSAID-associated dyspeptic symptoms are common and can be managed empirically with an H2-receptor antagonist or a proton-pump inhibitor. Treatment of established gastroduodenal ulcers is accomplished best by withholding the offending drugs. Proton-pump inhibitors appear to heal ulcers at the same rate whether or not NSAID therapy is continued. After the ulcer is healed and if NSAID therapy must be continued, prophylaxis is accomplished best by the concomitant use of proton-pump inhibitors, misoprostol (at least 200 micrograms 3 times a day), or a NSAID that preferentially inhibits COX-2. The future development of newer, safer NSAID preparations, including highly selective COX-2 inhibitors and nitric oxide-releasing NSAIDs, should provide better treatment options for the increasing number of individuals requiring anti-inflammatory agents.

Diagnosis and treatment of nonsteroidal anti-inflammatory drug-associated upper gastrointestinal toxicity

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely prescribed in the United States to treat pain and reduce inflammation from chronic inflammatory disorders such as rheumatoid arthritis and osteoarthritis. Approximately 40% of older Americans take NSAIDs. Chronic NSAID use carries a risk of peptic ulcer and other gastrointestinal disturbances. This article reviews the diagnosis of medication-induced ulcers based on clinical presentation, laboratory tests, and endoscopic findings to assist the clinician in early diagnosis and appropriate therapy. Risk factors for NSAID-induced ulcers include old age, poor medical status, prior ulcer, alcoholism, smoking, high NSAID dosage, prolonged NSAID use, and concomitant use of other drugs that are gastric irritants, such as alendronate, a bone resorption inhibitor prescribed for osteoporosis. Appropriate treatment options for patients with medication-induced ulcers include dosage reduction, medication substitution, medication withdrawal, antiulcer therapy, and discontinuation of other gastrotoxic drugs.

The cyclooxygenase-2 inhibitors: safety and effectiveness

OBJECTIVE

To review the development of cyclooxygenase-2 (COX-2) inhibitors and discuss specific agents that are currently under investigation or have been marketed.

DATA SOURCES

Primary literature on selective COX inhibitors was identified from a comprehensive MEDLINE, English-literature search from January 1966 through September 1998, with additional studies selected by review of the references. Abstracts from recent meetings and package insert literature from approved agents were also used as source material. Indexing terms included COX-2 inhibitors, meloxicam, celecoxib, rofecoxib, flosulide, SC-58635, and MK-966.

STUDY SELECTION

Human clinical, pharmacokinetic, and dose-ranging trials performed in Europe and the US and randomized comparative trials were reviewed.

DATA SYNTHESIS

With the discovery of at least two COX isoforms, a better understanding of the mechanism of action and gastrointestinal toxicity of nonsteroidal antiinflammatory drugs (NSAIDs) has been realized. While COX-1 is involved in physiologic maintenance, COX-2 seems to be involved in inflammation, mitogenesis, and specialized signal transductions. Selective COX-2 inhibitors may allow maximum antiinflammatory activity while improving the safety profile associated with NSAID therapy. Celecoxib and rofecoxib have been approved by the Food and Drug Administration for the treatment of osteo- and rheumatoid arthritis; meloxicam is undergoing Phase III clinical trials. Preliminary data indicate that the selective COX-2 inhibitors provide analgesic and antiinflammatory efficacy comparable with older NSAIDs, with fewer adverse gastrointestinal effects.

CONCLUSIONS

Specific COX-2 inhibitors offer promising benefits over older NSAIDs with regard to gastrointestinal safety while maintaining analgesic and antiinflammatory efficacy. Further study is required to determine long-term efficacy and safety in clinical use.