Assessment of the safety of selective cyclo-oxygenase-2 inhibitors: where are we in 2003?

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs worldwide despite their well-documented adverse gastrointestinal (GI) effects. The risk of developing a severe GI event varies from patient to patient and NSAID to NSAID. Selective cyclo-oxygenase-2 inhibitors (coxibs) have been designed to have similar efficacy but less GI toxicity than traditional NSAIDs, and have been shown to have an improved GI tolerability and less adverse events across a range of different GI safety assessments. In clinical trials, particularly VIGOR and CLASS, rofecoxib and celecoxib, respectively, significantly reduce the risk of ulcers and ulcer complications than nonselective NSAID comparators with ulcer rates comparable to placebo. The real benefit of a coxib comes from the sparing of the thromboxane and hence preservation of normal platelet function. Thus, there is less risk of bleeding with selective inhibition of COX-2, which is the most common and serious complication of non-selective NSAIDs. Moreover, bleeding can occur anywhere in the GI tract. Although some concern has been raised about the cardiovascular safety of coxibs, when used in recommended doses, there is no convincing evidence that patients treated with a coxib have an increased risk of cardiovascular thrombotic events. Different approaches have been advocated to minimize NSAID-related GI toxicity. Choice of less harmful NSAIDs such as coxib has been one of the strategies promoted in guidelines. The introduction of coxibs with a higher benefit-risk ratio has dramatically changed the therapeutic scenario for anti-inflammatory treatment in the clinical practice.     

Renal adverse effects of nonsteroidal anti-inflammatory drugs

NSAIDs depress prostaglandins synthesis through inhibition of COX-1 that is involved in maintaining cell integrity and COX-2 that, although presents particularly in the kidneys, is overexpressed in response to inflammation. Both the beneficial and side effects of NSAIDs are, therefore, through their inhibition of COX enzymes. Introduction of COX-2-selective inhibitors has improved the safety profile of the drugs with regard to their most common side effect which occurs at the gastrointestinal level but has not rendered them less cardio-nephrotoxic. Renal side effects of NSAIDs are rare, sometimes transient and often reversible upon drug withdrawal. The incident rate and the severity of the renal side effect, however, increase in patients with risk factors such as those with diabetes, heart failure, renal dysfunction and in the elderly. The side effects range from electrolyte retention and reduce glomerular filtration to nephritic syndrome and chronic renal failure. These effects are shared among NSAIDs with evidence of dose and exposure dependency. There is no known predictor for the nephrotoxicity. However, a relationship has been found between high plasma concentration and the renal adverse effect of NSAIDs. The usefulness of therapeutic drug monitoring in patients with risk factors needs to be explored.     

Risk:benefit ratio of nonsteroidal anti-inflammatory drugs in systemic lupus erythematosus

Nearly 80% of patients with systemic lupus erythematosus (SLE) are treated with NSAIDs for fever, arthritis, serositis and headaches. This article reviews currently available literature on non-selective and selective inhibitors of cyclooxygenases, with an emphasis on the efficacy and safety profile reported in SLE patients. All NSAIDs, regardless of their cyclooxygenase selectivity, induced renal side effects including sodium retention and reduction in glomerular filtration rate. In addition, lupus nephritis is a risk factor for NSAID-induced acute renal failure. NSAID-induced hepatotoxicity is increased in SLE patients in addition to cutaneous and allergic reactions. Finally, aseptic meningitis has been reported more frequently in NSAID-treated SLE patients. Nevertheless, NSAIDs can safely be prescribed to most lupus patients provided that their administration is re-evaluated on a regular basis and the patient is closely monitored.     

Influence of nonsteroidal anti-inflammatory drugs on the antiplatelet effects of aspirin in rats

Low-dose aspirin acts by irreversibly acetylating internal cyclooxygenase-1 (COX-1) on platelets, thereby suppressing platelet aggregation. Because nonsteroidal anti-inflammatory drugs (NSAIDs) also inhibit COX-1, the antiplatelet effects of aspirin may be suppressed when it is co-administered with NSAIDs. In this study, the influences of ibuprofen, loxoprofen sodium and etodolac on the antiplatelet effects of aspirin were investigated in male Sprague-Dawley (SD) rats. Aspirin and/or NSAIDs were administered orally at single or multiple daily doses. Platelet aggregation (ADP and collagen were added as stimuli) and serum thromboxane B(2) (TXB(2)) concentrations were measured. The maximum inhibitions of aggregation in the aspirin before ibuprofen group were 41.0±7.8% for ADP and 38.7±5.4% for collagen at 6 h after administration; similar values were seen in the aspirin group; however, percent inhibitions in the aspirin before ibuprofen multiple administration group were lower than those in the aspirin group. Thus, the inhibitory effects of daily low-dose aspirin on platelets are competitively inhibited by the prolonged use of multiple daily doses of ibuprofen. In contrast, serum TXB(2) concentrations in all groups were lower than those in the control group (drug-free). This suggests that the relationship between the inhibition of platelet COX-1 and the suppression of platelet aggregation is nonlinear. When aspirin was administered with loxoprofen sodium, similar effects were observed; however, with etodolac, the antiplatelet effects in all groups were equal to those in the aspirin group. Accordingly, if co-administration with NSAIDs is necessary with low-dose aspirin, a selective COX-2 inhibitor, such as etodolac, should be used.     

The effects of some nonsteroidal anti-inflammatory drugs on experimental induced gastric ulcers in rats

Celecoxib is a frequently used nonsteroidal anti-inflammatory drug (NSAID) in the treatment of rheumatoid arthritis and osteoarthritis. It selectively inhibits cyclooxygenase II (COX-2) enzyme which is responsible for the production of proinflammatory prostanoids. It has been proposed that since it does not significantly inhibit COX-1, an isoenzyme responsible for the production of cytoprotective prostanoids, celecoxib has fewer side effects in the stomach. Dipyrone which is a drug with potent analgesic activity has no significant inhibitory effect on COX. In this sudy, the effects of celecoxib and dipyrone on experimentally induced gastric ulcers in rats were compared with respect to different parameters. In the first experiment, in an attempt to identify the best dose for both drugs, a histamin-induced gastric ulcer model was used and each drug was administered at 5, 25 and 100 mg/kg doses, and ulcer index, acidity and mucus secretion were measured in the stomach. The best dose was determined to be 5 mg/kg for both drugs. Celecoxib was found to delay ulcer healing when compared to dipyrone especially when ulcer index was used as measure. In the second experiment, ulcer index, acidity, mucus secretion, and the levels of myeloperoxidase (MPO), lipid peroxide (MDA), non-protein sulfhydryl groups (NP-SH), and prostaglandin E₂ (PGE₂) were investigated in the stomach of rats with gastric ulcers induced by histamine, stresss and diethyldithiocarbamate (DDC). While celecoxib increased the ulcer index in stress-induced ulcer, dipyrone decreased the index in DDC-induced ulcer. Celecoxib also caused a significant increase of gastric mucus secretion in histamine-induced ulcer model. Gastric lipid peroxidation was significantly increased by dipyrone in the control group without gastric ulcer induction, whereas it was significantly increased by celecoxib in the histamine-induced and stress-induced ulcer groups. Dipyrone promoted a decrease in gastric NP-SH levels in the control group with stress-induced ulcer. With respect to gastric MPO activity, dipyrone caused a decrease in the histamine-induced ulcer group but it caused an increase in the stress-induced and DDC-induced ulcer groups. Gastric PGE₂ levels in the control group without gastric ulcer induction were not affected by celecoxib while they were increased by dipyone. In conclusion, celecoxib prompted the formation of experimentally induced gastric ulcers more than did dipyrone. The study was supported by Osmangazi University Research Funds. Received 8 February 2007; revised 6 March 2007; accepted 13 April 2007     

In vitro effects of nonsteroidal anti-inflammatory drugs on oxidative phosphorylation in rats liver mitochondria.

Representative potent anti-inflammatory drugs have been studied for their ability to affect energy metabolism in vitro in rat liver mitochondria. Like 2,4-dinitrophenol, flufenamic acid activated ATPase, inhibited the incorporation of ³²Pi into the ATP fraction, stimulated glutamate oxidation and coupled substrate-level phosphorylation, and promoted state-4 respiration. Aspirin and ibuprofen caused similar but lesser effects on these parameters. These three drugs are considered to be uncouplers of oxidative phosphorylation. Indomethacin and phenylbutazone inhibited both oxidative and substrate-level phosphorylations. Based on their abilities to inhibit glutamate oxidation rather directly and to block the electron transport chain, it was concluded that indomethacin and phenylbutazone could inhibit the generation of energy-rich phosphate compounds by suppressing respiration at multiple sites. Thus, these anti-inflammatory drugs could prevent mitochondrial energy metabolism in different manners.     

Quantitative measurement of gastrointestinal bleeding in rats: the effect of nonsteroidal anti-inflammatory drugs

Accurate quantitative estimation of drug-induced gastrointestinal bleeding in rats can be made by means of ⁵¹Cr-labeled erythrocytes. Comparative tests with various antiphlogistic agents (acetylsalicylic acid, diclofenac sodium, indomethacin, oxyphenbutazone, phenylbutazone, sodium salicylate) revealed marked differences between their anti-inflammatory potency and their gastrointestinal irritant activity.     

Comparative studies on the gastrointestinal lesions caused by several nonsteroidal anti-inflammatory agents in rats

The gastrointestinal toxicity of a single oral administration of five nonsteroidal anti-inflammatory agents (NSAIDs) to rats was compared, by a method using 51Cr-labeled red blood cells (RBC), and by macroscopic and microscopic examination. From the profile of gastrointestinal bleeding, the NSAIDs could be divided into a group consisting of aspirin (ASA), oxaprozin (OXP) and 2-[4-(3-methyl-2-butenyl)phenyl]propionic acid (TA), which caused only a transient increase in fecal blood loss based on a gastric lesion, and another group including indomethacin (IM) and ibuprofen (IP), which produced a biphasic increase in the blood loss. The initial phase was caused not only by a gastric lesion but also an intestinal lesion, and the secondary phase originated only in the intestinal lesion. The order of potency causing blood loss was IM much greater than IP greater than ASA much greater than TA greater than OXP. The safety ratio of OXP and TA was shown to be more favorable than that of the other three drugs.     

Effect of nonsteroidal anti-inflammatory drugs on glycogenolysis in isolated hepatocytes.

E-series prostaglandins have previously been demonstrated to inhibit hormone-stimulated glycogenolysis when added to isolated hepatocytes of the rat. In the present study, the effect of nonsteroidal anti-inflammatory drugs, which inhibit cyclo-oxygenase activity, on glycogenolysis was examined in the hepatocyte model. Ibuprofen (80 microM), indomethacin (50 microM) and meclofenamate (60 microM) all increased rates of glycogenolysis when added under basal conditions. In contrast, piroxicam (50 microM) had no effect on glycogenolysis in the hepatocyte system. Concentrations of ibuprofen below 80 microM did not significantly increase rates of glycogenolysis. Ibuprofen (80 microM) had no effect on glycogenolysis in the presence of 10(-5)M adrenaline or 5 X 10(-7)M glucagon, but did increase glycogenolytic rates in the presence of 5 X 10(-8)M glucagon. Ibuprofen-stimulated glycogenolysis was inhibited by addition of prostaglandin E2 (PGE2). Under conditions where glucagon-stimulated glycogenolysis was inhibited by exogenous PGE2, addition of ibuprofen (80 microM) increased the rate of glycogenolysis. Ibuprofen had no effect on basal or glucagon-stimulated hepatocyte adenylate cyclase activity. In conclusion, these results demonstrate that nonsteroidal anti-inflammatory drugs which are carboxylic acids can increase the rate of glycogenolysis in isolated hepatocytes. The high concentrations of drug required to stimulate glycogenolysis, the lack of effect of piroxicam, and the demonstration of stimulation by ibuprofen in the presence of exogenous PGE2 all suggest that the stimulation of glycogenolysis by ibuprofen, indomethacin and meclofenamate is independent of cyclooxygenase inhibition. These observations are consistent with reports that carboxylic acid nonsteroidal anti-inflammatory drugs can interfere with hepatic intracellular calcium handling.     

Effects of nonsteroidal anti-inflammatory drugs on prostacyclin and thromboxane in the kidney

Dose-response curves were obtained relating the effects of increasing amounts of aspirin, a nonselective cyclooxygenase (COX) inhibitor, and celecoxib, a selective cyclooxygenase 2 (COX-2) inhibitor, on the concentrations of prostacyclin and thromboxane in renal cortex and medulla of rabbits. The concentrations of the two agonists (aspirin and celecoxib) which elicit a half-maximal response on the prostanoid concentration (EC(50)) were compared. Additionally, controls for prostacyclin and thromboxane were related to values for the experimental groups. The EC(50) values for celecoxib were considerably lower than those for aspirin, indicating that celecoxib was more effective in suppressing prostanoid production. There were also significant differences between the majority of experimental groups and their respective controls, further evidence for the greater inhibitory activity of celecoxib on prostacyclin. Celecoxib lowered the ratio prostacyclin/thromboxane in the renal medulla; mercuric chloride further diminished the concentration of prostacyclin in the renal medulla. The results confirm that in the normal rabbit kidney, both nonselective and specific COX inhibitors interfere with renal prostanoid synthesis, but that a selective COX-2 inhibitor is more effective.     

Ethanesulfohydroxamic acid ester prodrugs of nonsteroidal anti-inflammatory drugs (NSAIDs): synthesis, nitric oxide and nitroxyl release, cyclooxygenase inhibition, anti-inflammatory, and ulcerogenicity index studies

The carboxylic acid group of the anti-inflammatory (AI) drugs indo-methacin, (S)-naproxen and ibuprofen was covalently linked via a two-carbon ethyl spacer to a sulfohydroxamic acid moiety (CH(2)CH(2)SO(2)NHOH) to furnish a group of hybrid ester prodrugs that release nitric oxide (NO) and nitroxyl (HNO). Biological data acquired for this hitherto unknown class of ethanesulfohydroxamic acid ester prodrugs showed (i) all compounds exhibited superior NO, but similar HNO, release properties relative to arylsulfohydroxamic acids, (ii) the (S)-naproxen and ibuprofen prodrug esters are more potent AI agents than their parent NSAID, (iii) the indomethacin prodrug ester, in contrast to indomethacin which is highly ulcerogenic, showed no visible stomach lesions [ulcer index (UI) = 0 for a 80 μmol/kg oral dose] while retaining potent AI activity, and iv) that the indomethacin prodrug ester, unlike indomethacin which is an ulcerogenic selective COX-1 inhibitor, is a selective COX-2 inhibitor (COX-2 selectivity index = 184) devoid of ulcerogenicity that is attributed to its high COX-2 SI and/or ability to release cytoprotective NO.     

不同抗酸药防治非甾体类抗炎药胃粘膜损伤的疗效观察

目的探讨不同抗酸措施在防治服用非甾体类抗炎药患者的胃粘膜损伤中的作用。方法选择2004年1月-2006年11月我院门诊风湿性疾病患者120例,随机分为3组,均维持原来治疗方案,继续服用NSAIDs 3个月。同时,为防治胃粘膜损伤,A组应用奥美拉唑20 mg,口服,1次/d。B组应用雷尼替丁150 mg,2次/d,铝碳酸镁嚼片2 g,2次/d口服。C组应用雷尼替丁150 mg,2次/d。3组观察时间为3个月。观察胃粘膜损伤以及上消化道症状的发生率。结果A、B组较C组胃粘膜损伤的发生率以及上消化道症状发生率明显降低(P<0.05)。结论对服用非甾体类抗炎药患者,服用奥美拉唑或雷尼替丁+铝碳酸镁较服用雷尼替丁有更好的防治胃粘膜损伤的作用。     

Decrease of urinary prostaglandin E2 and prostaglandin F2 alpha excretion by nonsteroidal anti-inflammatory drugs in rats. Relationship to anti-inflammatory activity

An analytical method for measuring in vivo inhibition of prostaglandin (PG) synthesis by nonsteroidal anti-inflammatory drugs was developed for estimation of urinary prostaglandin levels in rats. Drugs were administered orally to rats (Wistar, male, 200-250 g), and water (2.5 ml/100 g body weight) was given 1 hr after drug administration to yield a constant volume of urine. Urine was collected for 4 hr after drug administration, and urinary PGE2 and PGF2 alpha were determined by radioimmunoassay. The urine volume in the 4-hr period was 5.0 +/- 0.30 ml per rat, and prostaglandin contents in the 4-hr urine were 4.56 +/- 0.56 ng PGE2 and 1.31 +/- 0.24 ng PGF2 alpha per rat in the no-drug control group. Administration of nonsteroidal anti-inflammatory drugs decreased the urinary PGE2 and PGF2 alpha dose dependently. The activities of ten typical nonsteroidal anti-inflammatory drugs in reducing urinary PGE2 excretion were compared with their anti-inflammatory activities in rats. A close correlation (r = 0.98, P less than 0.001) between the dose required for 50% reduction of urinary PGE2 excretion and the dose required for 50% inhibition of carrageenin edema was found for each drug. These drugs were also tested for their inhibitory effects on PGE2 biosynthesis in a cultured system of mouse 3T6 fibroblast cells and on prostaglandin synthesizing system in bovine seminal vesicle microsomes. No close correlation was observed between anti-inflammatory activities and inhibition of prostaglandin biosynthesis in vitro.     

谷氨酰胺对非甾体抗炎药所致大鼠小肠黏膜损伤预防作用的研究

目的:研究谷氨酰胺对非甾体抗交药(NSAIDs)所致大鼠小肠黏膜损伤的预防作用,为临床安全用药提供依据.方法:清洁级雄性SD大鼠90只,随机分为9组:4个模型组、4个预防组及1个空白对照组,每组10只.4个模型组分别给予吲哚美辛2.5 mg/kg、阿司匹林50 mg/kg、布洛芬30 mg/kg或塞来昔布20 mg/kg每天2次连续14 d;4个预防组大鼠在给予上述不同NSAIDs的同时给予L-谷氨酰胺100 mg/kg,药物均溶于0.5%羧甲基纤维素钠(CMC)2 ml中灌胃;空白对照组大鼠仅给予CMC 2 ml.第15天处死大鼠,采用CMIAS多功能真彩色图像分析系统测量每只大鼠小肠黏膜损伤深度、面积,计算累计损伤深度和累计面积;并应用检测试剂盒测定小肠组织匀浆中髓过氧化物酶(MPO)、丙二醛(MDA)、超氧化物歧化酶(SOD)和一氧化氮(NO)含量.结果:吲哚美辛、阿司匹林、布洛芬及塞来昔布模型组小肠黏膜累计损伤深度分别为5954、511、1361和1447μm,累计损伤面积分别为1 956 592、164 304、339 711和445 611 μm2,除阿司匹林组外,其余各组与空白对照组比较差异均有统计学意义(均P<0.05).吲哚美辛模型组损伤程度重于其他各组(均P<0.05).吲哚美辛、阿司匹林、布洛芬和塞来昔布预防组小肠黏膜损伤累计深度和面积分别为1206.443、616.723 μm和390 450、92 192、209 655、238 827 μm2,损伤程度均明显低于对应模型组.吲哚美辛、阿司匹林、布洛芬和塞来昔布各预防组MPO分别为(1.10±0.35)、(0.53±0.19)、(0.83±0.24)和(0.37±0.17)U/g,各对应模型组MPO分别为(2.37±0.63)、(1.66±0.50)、(1.35±0.35)和(1.14±0.38)U/g.各预防组的MPO明显低于各对应模型组,差异有统计学意义,均P<0.05.吲哚美辛预防组MDA明显低于吲哚美辛模型组[(0.50±0.16)比(1.19±0.77)nmol/mg,P<0.05)].吲哚美辛、阿司匹林、布洛芬和塞来昔布模型组SOD分别为(3.53±0.64)、(4.03±1.28)、(3.44±1.05)和(3.70±1.53)U/mg,均明显低于空白对照组[(5.49±1.09)U/mg,均P<0.05)],各对应预防组SOD分别为(4.03±1.28)、(4.46±1.53)、(4.29±1.10)和(4.00±1.08)U/mg,高于各模型组,但差异无统计学意义.各预防组与各模型组间NO水平差异无统计学意义(P>0.05).结论:谷氨酰胺对4种NSAIDs所致大鼠小肠黏膜损伤具有预防作用.     

非甾体抗炎药致老年人消化性溃疡的临床特点分析

目的:分析非甾体抗炎药(NSAIDs)所致的老年人消化性溃疡的临床特点。方法:回顾性调查上海市金山区亭林医院1999年1月至2006年12月间因消化性溃疡和(或)合并出血入院治疗的491例老年病人的临床资料,根据入院前1周内有无服用NSAIDs史将病人分为两组,对两组病人的临床资料进行分析比较。结果:服药组105例,未服药组386例。与未服药组比较,服药组病人的贫血更明显(P<0.05);复合溃疡和多发溃疡在服药组更多见(P<0.05)。服药组幽门螺杆菌的感染率为67.6%(71/105),未服药组为58.3%(225/386),两组间差别无统计学意义(P>0.05)。结论:应加强对老年人使用NSAIDs所致消化性溃疡的临床特点的认识,减少NSAIDs的不良反应。     

Case-control study on the association of upper gastrointestinal bleeding and nonsteroidal anti-inflammatory drugs in Japan

Objective Studies in Western populations have shown the association of nonsteroidal anti-inflammatory drugs (NSAIDs) and upper gastrointestinal bleeding (UGIB). The role of Helicobacter pylori infection in NSAIDs-related UGIB remains to be studied. We conducted a case-control study in Japan to investigate these related topics.Methods Cases of UGIB due to duodenal or gastric ulcer, or gastritis were identified in 14 study hospitals in various areas of Japan. For each case, two controls were identified from population registries in the same district. Information on drugs and other risk factors was obtained from 175 cases and 347 controls by telephone interviews. Anti-H. pylori antibody in the urine was measured in a single laboratory for all the cases and 225 controls.Results The odds ratio (OR) of UGIB was 5.5 for aspirin and 6.1 for other NSAIDs (NANSAIDs) (p<0.01). The OR for regular use was higher than for occasional use both for aspirin (7.7 vs 2.0) and NANSAIDs (7.3 vs 4.1). Loxoprofen (5.9), frequently used in Japan as a safe ‘prodrug’, was significantly associated with UGIB. The odds ratio for H. pylori infection was 4.9 and the relative excess risk due to the interaction between H. pylori and the use of NSAID was 1.2 (95% CI: −5.8–8.1).Conclusion NSAIDs including loxoprofen increase the risk of UGIB in Japan as in Western countries, with a similar magnitude of association. There was no evidence of biological interaction between NSAIDs and H. pylori infection.     

Inhibitory potential of nonsteroidal anti-inflammatory drugs on UDP-glucuronosyltransferase 2B7 in human liver microsomes

Objective A number of nonsteroidal anti-inflammatory drugs (NSAIDs) are subject to glucuronidation in humans, and UDP-glucuronosyltransferase (UGT) 2B7 is involved in the glucuronidation of many NSAIDs. The objective of this study was to identify a NSAID with potent inhibitory potential against UGT2B7 using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Methods A rapid screening method for detecting the inhibitory potential of various drugs against UGT2B7 was established using a LC-MS/MS system. The effects of nine NSAIDs (acetaminophen, diclofenac, diflunisal, indomethacin, ketoprofen, mefenamic acid, naproxen, niflumic acid, and salicylic acid) against UGT2B7-catalyzed 3′-azido-3′-deoxythymidine glucuronidation (AZTG) were investigated in human liver microsomes (HLM) and recombinant human UGT2B7. Results Mefenamic acid inhibited AZTG most potently, with an IC₅₀ value of 0.3 μM, and its inhibition type was not competitive. The IC₅₀ values for diclofenac, diflunisal, indomethacin, ketoprofen, naproxen, and niflumic acid against AZTG were 6.8, 178, 51, 40, 23, and 83 μM, respectively, while those for acetaminophen and salicylic acid were >100 μM. The IC₅₀ values for NSAIDs against AZTG in recombinant human UGT2B7 were similar to those obtained in HLM. Conclusion The method established in this study is useful for identifying drugs with inhibitory potential against human UGT2B7. Among the nine NSAIDs investigated, mefenamic acid had the strongest inhibitory effect on UGT2B7-catalyzed AZTG in HLM. Thus, caution might be exercised when mefenamic acid is coadministered with drugs possessing UGT2B7 as a main elimination pathway.