Observations of alanine aminotransferase and aspartate aminotransferase in THRIVE studies treated orally with ximelagatran

Treatment of acute venous thromboembolism (VTE) and prophylaxis of recurrent events has been investigated in the THRIVE (THRombin Inhibitor in Venous Thrombe Embolism) Treatment and the THRIVE III trial using the oral direct thrombin inhibitor ximelagatran. Alanine aminotransferase (ALAT) increased in 9.6% and 6.4% of patients in the THRIVE Treatment and THRIVE III trials, respectively. The authors analysed the time course of the ALAT and in additionally of aspartate aminotransferase (ASAT) in blood from 52 and 23 patients participating in the THRIVE Treatment and the THRIVE III trials in Germany. Analysis of variance for repeated measures and t test were performed. In the THRIVE Treatment trial, ALAT was significantly higher at week 2 for enoxaparin/warfarin (p => .0039, t test) and at months 3 and 6 for ximelagatran (p = .0453, p = .0014, respectively). ASAT and ASAT/ALAT ratio values did not increase and not differ for both groups. In the THRIVE III trial, ALAT and ASAT did not increase and did not differ compared to the comparator placebo. 2 x 36 mg Ximelagatran, induced higher ALAT values at months 3 and 6 compared to 2 x 24 mg ximelagatran (p = .0105, p = .0063, respectively). ASAT did not differ between the two doses of ximelagatran. The ASAT/ALAT ratios were lower at week 2 for enoxaparin/warfarin (t-test, p = .0032) and at month 3 and 6 for 2 x 36 mg versus warfarin or 2 x 24 mg Ximelagatran (p between .0187 and .0002). The authors conclude that ALAT increases dose dependently during therapy with ximelagatran. The less frequent and lower increase of ASAT values compared to ALAT values indicates a nontoxic effect of ximelagatran on liver cells.     

Isofraxidin, a coumarin component from Acanthopanax senticosus, inhibits matrix metalloproteinase-7 expression and cell invasion of human hepatoma cells

7-Hydroxy-6,8-dimethoxy-2H-1-benzopyran-2-one (isofraxidin) is a major coumarin component isolated from the stem bark of Acanthopanax senticosus, a widely used Chinese medicinal herb. We investigated isofraxidin in its anti-tumor effects on human hepatoma cell lines HuH-7 and HepG2. Isofraxidin significantly inhibited hepatoma cell invasion, without affecting cell attachment or growth. Expression of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced matrix metalloproteinase-7 (MMP-7) in hepatoma cells was inhibited by isofraxidin at the both mRNA and protein levels. This inhibition tended to be greater in cells inoculated at low density than in those at high density. Isofraxidin showed an inhibitory effect on the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in hepatoma cells, whereas activator protein-1 (AP-1) DNA binding activity, nuclear factor-kappa B (NF-κB) nuclear translocation, and inhibitory kappa B (IκB) degradation were affected very little. These results indicate that isofraxidin inhibits expression of MMP-7 and in vitro cell invasion at a non-toxic level through inhibiting ERK1/2 phosphorylation in hepatoma cell lines, which suggest isofraxidin might become an effective agent for suppressing hepatoma cell invasion.     

Absorption, distribution, metabolism, and excretion of ximelagatran, an oral direct thrombin inhibitor, in rats, dogs, and humans.

The absorption, metabolism, and excretion of the oral direct thrombin inhibitor, ximelagatran, and its active form, melagatran, were separately investigated in rats, dogs, and healthy male human subjects after administration of oral and intravenous (i.v.) single doses. Ximelagatran was rapidly absorbed and metabolized following oral administration, with melagatran as the predominant compound in plasma. Two intermediates (ethyl-melagatran and OH-melagatran) that were subsequently metabolized to melagatran were also identified in plasma and were rapidly eliminated. Melagatran given i.v. had relatively low plasma clearance, small volume of distribution, and short elimination half-life. The oral absorption of melagatran was low and highly variable. It was primarily renally cleared, and the renal clearance agreed well with the glomerular filtration rate. Ximelagatran was extensively metabolized, and only trace amounts were renally excreted. Melagatran was the major compound in urine and feces after administration of ximelagatran. Appreciable quantities of ethyl-melagatran were also recovered in rat, dog, and human feces after oral administration, suggesting reduction of the hydroxyamidine group of ximelagatran in the gastrointestinal tract, as demonstrated when ximelagatran was incubated with feces homogenate. Polar metabolites in urine and feces (all species) accounted for a relatively small fraction of the dose. The bioavailability of melagatran following oral administration of ximelagatran was 5 to 10% in rats, 10 to 50% in dogs, and about 20% in humans, with low between-subject variation. The fraction of ximelagatran absorbed was at least 40 to 70% in all species. First-pass metabolism of ximelagatran with subsequent biliary excretion of the formed metabolites account for the lower bioavailability of melagatran.     

Formation of a novel quinone epoxide metabolite of troglitazone with cytotoxicity to HepG2 cells.

Troglitazone, an oral antidiabetic drug, was reported to cause adverse hepatic effects in certain individuals, leading to its withdrawal from the market. After incubation of troglitazone (100 microM) with the human hepatoma cell line, HepG2 cells, and human primary hepatocytes for 48 to 72 h, an unknown peak was detected in the cell culture. The formation of this peak from troglitazone (100 microM) was also catalyzed by expressed CYP3A4, and further HPLC analysis revealed that there were three metabolites (metabolite A, B, and C) in the peak. The major metabolite, metabolite C (M-C) was identified as an epoxide of a quinone metabolite of troglitazone by comparison with a synthetic authentic standard using tandem mass spectrometry, (1)H NMR, and (13)C NMR analyses. The other two metabolites (M-A and M-B) were stereoisomers with the same molecular weight as M-C, probably produced from M-C by intramolecular rearrangement at the epoxide moiety. M-C showed a weak cytotoxicity in HepG2 cells at low concentrations, as assessed by the crystal violet-staining assay. Since epoxides are generally regarded as the chemically reactive species, M-C may play a role in idiosyncrasy of troglitazone hepatotoxicity via individual differences either in the formation or degradation of this metabolite.     

Pro-inflammatory response and adverse drug reactions: Mechanisms of action of ximelagatran on chemokine and cytokine activation in a monocyte in vitro model

There is a lack of suitable human in vitro systems which can predict drug hepatotoxicity that in many cases involves inflammatory responses mediated by macrophages. In the present investigation we used an in vitro model based on human THP-1 cells to evaluate the inflammatory cytokine/chemokine activation properties of ximelagatran, a drug previously shown to cause elevation of liver transferases in a subset of patients. Treatment of the cells with ximelagatran caused an intracellular accumulation of the metabolites hydroxymelagatran and melagatran. A decreased viability and increased release of the pro-inflammatory cytokines and chemokines IL-8, VEGF and MCP-1 was seen. Ximelagatran exposure caused activation of ERK1/2 and JNK as evident from determination of the phosphorylation status. In accordance, the release of IL-8 was attenuated by inhibitors of the ERK- and JNK-pathways. It is concluded that human monocytes might constitute a valuable additional in vitro model for monitoring the basis for cytotoxic action of drugs.     

索拉菲尼对肝癌细胞的抑制作用及其对CDK5表达水平的影响

目的探讨索拉菲尼对体外培养的人肝癌HepG2细胞的增殖抑制作用及其对周期素依赖性蛋白激酶5表达的影响。方法体外培养人肝癌HepG2细胞株,采用MTT法检测不同浓度索拉菲尼对HepG2细胞增殖的影响;同时经细胞爬片后,采用免疫细胞化学法检测肝癌细胞内CDK5的表达情况。结果索拉菲尼可使人肝癌细胞增殖率明显下降,且呈明显的时间-剂量依赖效应;药物作用48h后,给药组CDK5的表达较对照组明显减少,其着色程度随药物浓度增高而逐渐变淡。结论索拉菲尼对人肝癌HepG2细胞增殖有抑制作用,并能下调肝癌细胞中CDK5的表达,从而起到抗肿瘤的治疗作用。     

Cucurbitacin E inhibits the proliferation of hepatoma cells in vitro and in vivo through induction of G2/M phase arrest

Objective Cucurbitacins are the highly oxygenated tetracyclic triterpenes,which are predominantly found in the Cucurbitaceae family but are also present in several other families of the plant kingdom.A number of compounds of this group have been investigated for their cytotoxic,hepatoprotective,anti-inflammatory,cardiovascular and anti-diabetic activities.In China,the cucurbitacin preparation,which contains mostly cucurbitacin B and cucurbitacin E,has been clinically used for the treatment of the primary liver carcinoma.It has been previously reported that cucurbitacin E could produce cytotoxicity against a variety of cancer cells,and various mechanisms were implicated in its cytotoxic effect.The present study is to investigate the effect of cucurbitacin E on hepatoma cells in vitro and in vivo and to study their potential mechanisms of action.Methods The MTT assay was used to assess the viability of human HepG2 and BEL7402 hepatoma cells in vitro after treatment with different concentrations of cucurbitacin E.The cell cycle distribution was determined by flowcytometric analysis after propidium iodide(PI)staining.The cell cycle-related proteins were detected using western blotting analysis.Implanted mouse hepatoma H22 model was built to evaluate the growth inhibitory effect of cucurbitacin E in vivo in mice.Results Our studies found that cucurbitacin E(10-300 nM)produced anti-proliferative effect on human HepG2 and BEL7402 hepatoma cells in vitro without cytotoxicity.According to flowcytometric analysis,cucurbitacin E arrested the cell cycle at G2/M phase in both HepG2 and BEL7402 hepatoma cells after 24 h treatment.Cucurbitacin E induced the decrease in the level of CDK1 protein and the increase in the level of p21 protein,but had no effect on the levels of cyclin A,cyclin B1 and Cdc25C protein.In in vivo anti-tumor experiment,cucurbitacin E had significant inhibitory effects on the growth of mouse H22 hepatoma cells.Conclusions Cucurbitacin E inhibited the proliferation of hepatoma cells in vitro and in vivo,at least in part,through induction of cell cycle arrest at G2/M phase,which was mediated by concomitant upregulation of p21 and downregulation of CDK1.We consider that cucurbitacin E may be useful in the treatment of liver cancer.     

Immunotoxins Composed of Monoclonal Antibody to α-Fetoprotein and Gelonin as a Potent Hepatoma-Targeted Drug Delivery System

Abstract

This study was carried out to evaluate our monoclonal antibody (MoAb) to α-fetoprotein (AFP), 80G, as a carrier for targeting AFP-producing hepatoma. Pharmacokinetic analysis showed that the MoAb 80G was actively incorporated into AFP-producing HuH-7N cells (xenograft of human hepatoma cell line, HuH-7) in nude mice. Four conjugates composed of MoAb 80G, and a type 1 ribosome-inactivating protein, gelonin, were prepared. They involve two disulfide-linked and two thioether-linked conjugates. The binding activity of conjugates against AFP remained as high as that of intact 80G according to enzyme-linked immunosorbent assay. The in vitro cytotoxic effects of all the conjugates were specific against AFP-producing HuH-7 cells. Of these conjugates, two containing gelonin modified with 2-iminothiolane were more potent than the others. They showed significant antitumor activity upon AFP-producing HuH-7N cells in nude mice. However, the disulfide conjugate was more toxic to mice than the thioether conjugate judging from the loss in body weight and the liver damage. These results suggest that our MoAb 80G is a suitable carrier for targeting AFP-producing hepatoma cells, and that the noncleavable thioether conjugate is promising as an AFP-producing hepatoma-targeted drug delivery system.     

Investigations into the liver effects of ximelagatran using high content screening of primary human hepatocyte cultures

Background: Ximelagatran, the first oral agent in the new class of direct thrombin inhibitors, was withdrawn from the market due to increased rates of liver enzyme elevations in long-term treatments. Despite intensive pre clinical investigations the cellular mechanisms behind the observed hepatic effects remain unknown. Objective: The aim of this study was to assess drug-induced cytotoxicity in primary human hepatocyte cultures by ximelagatran and other reference pharmaceutical agents with known in vivo hepatotoxic profiles. Methods: Drugs cause liver injury by many distinct mechanisms that result in abnormal cellular functioning and different patterns of injury. To address many potential toxic mechanisms in a human-relevant model, freshly isolated human hepatocytes were used in automated imaging assays. Ximelagatran was used as a test compound to study biochemical and morphological changes in human hepatocytes. In addition, 11 control, reference and comparator compounds with known liver-toxic potential in humans were used. The response to these compounds was assessed across five different hepatocyte donor preparations. Results: Cytotoxicity induced by a number of compounds was quantitatively monitored using an automated imaging technique. A variety of morphological changes in hepatocyte cytoskeleton and mitochondrial function could be identified at sublethal doses of test compounds. Doses of ximelagatran up to 500 μM did not cause a cytotoxic response in the majority of preparations and no subcytotoxic response was observed at doses below 125 μM. Conclusions: The experiments described here demonstrate that primary human hepatocytes may be used in a medium-throughput format for screening using imaging-based assays for the identification of cellular responses. Overall, it is concluded that ximelagatran did not cause a significant decrease in cell viability when incubated for 24 h at considerably higher concentrations than are found in plasma following therapeutic dosing.     

Ximelagatran,an oral direct thrombin inhibitor,has a low potential for cytochrome P450-mediated drug-drug interactions

BACKGROUND: Ximelagatran is an oral direct thrombin inhibitor currently in clinical development for the prevention and treatment of thromboembolic disorders. After oral administration, ximelagatran is rapidly absorbed and extensively bioconverted, via two intermediates (ethyl-melagatran and hydroxy-melagatran), to its active form, melagatran. In vitro studies have shown no evidence for involvement of cytochrome P450 (CYP) enzymes in either the bioactivation or the elimination of melagatran. OBJECTIVE: To investigate the potential of ximelagatran, the intermediates ethyl-melagatran and hydroxy-melagatran, and melagatran to inhibit the CYP system in vitro and in vivo, and the influence of three CYP substrates on the pharmacokinetics of melagatran in vivo. METHODS: The CYP inhibitory properties of ximelagatran, the intermediates and melagatran were tested in vitro by two different methods, using heterologously expressed enzymes or human liver microsomes. Diclofenac (CYP2C9), diazepam (CYP2C19) and nifedipine (CYP3A4) were chosen for coadministration with ximelagatran in healthy volunteers. Subjects received oral ximelagatran 24mg and/or diclofenac 50mg, a 10-minute intravenous infusion of diazepam 0.1 mg/kg, or nifedipine 60mg. The plasma pharmacokinetics of melagatran, diclofenac, diazepam, N-desmethyl-diazepam and nifedipine were determined when administered alone and in combination with ximelagatran. RESULTS: No inhibition, or only minor inhibition, of CYP enzymes by ximelagatran, the intermediates or melagatran was shown in the in vitro studies, suggesting that ximelagatran would not cause CYP-mediated drug-drug interactions in vivo. This result was confirmed in the clinical studies. There were no statistically significant differences in the pharmacokinetics of diclofenac, diazepam and nifedipine on coadministration with ximelagatran. Moreover, there were no statistically significant differences in the pharmacokinetics of melagatran when ximelagatran was administered alone or in combination with diclofenac, diazepam or nifedipine. CONCLUSION: As ximelagatran did not exert a significant effect on the hepatic CYP isoenzymes responsible for the metabolism of diclofenac, diazepam and nifedipine, it is reasonable to expect that it would have no effect on the metabolism of other drugs metabolised by these isoenzymes. Furthermore, the pharmacokinetics of melagatran after oral administration of ximelagatran are not expected to be altered by inhibition or induction of CYP2C9, CYP2C19 or CYP3A4. Together, the in vitro and in vivo studies indicate that metabolic drug-drug interactions involving the major human CYP enzymes should not be expected with ximelagatran.     

Ximelagatran increases membrane fluidity and changes membrane lipid composition in primary human hepatocytes

Ximelagatran, the first oral agent in the new class of direct thrombin inhibitors, was withdrawn from the market due to a potential risk of severe liver injury. Increased rates of liver enzyme elevations had been observed during clinical trials of chronic use. Despite intensive preclinical investigations the cellular mechanisms behind the observed hepatic effects remain unknown. The aim of this study was to investigate whether ximelagatran has an effect on the plasma membrane fluidity and the membrane lipid composition which may be important for the cell integrity. After 1 h exposure of primary human hepatocytes with 10 or 100 μM ximelagatran, a significant elevation of membrane fluidity was observed. This elevation was maintained at 24 h, but diminished at 48 h exposure. As changed membrane lipid composition could influence membrane fluidities, changes in membrane lipid profiles were also studied. After 1 h exposure, the phosphatidylcholine/phosphatidylethanolamine molar ratio decreased, whereas the total cholesterol/phospholipid molar ratio decreased after a 48 h exposure. The change in membrane fluidity and lipid composition in human hepatocytes exposed to ximelagatran might indicate changes in plasma membrane properties that in susceptible subjects, could result in loss of membrane integrity and leakage of cellular proteins.     

Protective potential [correction of potencial] of Euphorbia hirta against cytotoxicity induced in hepatocytes and a HepG2 cell line

Medicinal plants play a key role in human health care. Frustration over the side effects of allopathic drugs has driven the medical world to take asylum in the plant kingdom for the treatment of various ailments. Euphorbia hirta belonging to the family of Euphorbiacae has been reported to possess antibacterial, antiviral, and anticancer activity. The aim of the present study was to investigate the protective effect of E. hirta against antitubercular drug-induced cytotoxicity in freshly isolated hepatocytes. The extent of cytotoxicity of the plant extracts was also analyzed using human liver derived HepG2 cell line by estimating the viability of cells (MTT assay). The alcoholic plant extract normalized the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), triacylglycerol (TAG), cholesterol, total protein, albumin, total and direct bilirubin, which were altered due to antitubercular drug intoxication. A dose-dependent increase in percent viability was observed when antitubercular drug exposed HepG2 cells were treated with different concentrations of plant extracts (125, 250, 500 and 1000 microg/mL) which were compared with a standard hepatoprotective drug silymarin. The highest percentage viability of HepG2 was observed at a concentration of 1000 microg/mL. The results suggest that E. hirta exerts protection against antitubercular drug-induced cytotoxicity in this vitro model system.     

沙立度胺单独及联合多柔比星对人肝癌细胞株HepG2中生存素表达的影响

目的：观察沙立度胺单独及联合多柔比星对人肝癌细胞株HepG2中生存素（Survivin）表达的影响。方法：常规培养人肝癌细胞株HepG2随机分成4组：空白对照组；多柔比星组（1．0mg／L）；沙立度胺组（50、100、200、400mg／mL，4个对半稀释质量浓度）；联合用药组：沙立度胺（200mg／mL）＋多柔比星（1．0mg／L）。分别对HepG2细胞作用12、24、48、72h后，应用免疫组织化学法观察对Survivin表达的影响。结果：沙立度胺单独及联合多柔比星作用于HepG2细胞可下调Survivin表达，单药沙立度胺以200mg／L作用48h效果最为明显，联合用药组下调Survivin表达优于其余各组，差异有统计学意义（P〈0．05）。结论：沙立度胺可下调人肝癌细胞株HepG2Survivin的表达，且与多柔比星有协同作用，可能是沙立度胺抗肿瘤机制之一。     

广西瑶药鸡爪风提取物抑制4种人肝癌细胞株体外增殖作用的研究

目的探讨广西瑶药鸡爪风(Desmos chinensis Lour.)体积分数85%乙醇提取物在体外对HCC-LM3、BEL-7404、SMMC-7721、HepG2等4种人肝癌细胞株增殖的影响。方法用体积分数85%乙醇渗漉法提取鸡爪风中组分,采用MTT法评价鸡爪风体积分数85%乙醇提取物对体外培养4种人肝癌细胞株生长的影响情况。结果给予不同质量浓度(0.8,0.4,0.2,0.1和0.05mg·mL-1)体积分数85%乙醇提取物培养HCC-LM3、BEL-7404细胞24和48h,不同质量浓度(0.5,0.25,0.125,0.075和0.037 5mg·mL-1)体积分数85%乙醇提取物培养SMMC-7721、HepG2细胞24和48h,均表现出一定的抑制细胞增殖作用,且作用随药物质量浓度增加而增大、随作用时间的延长而升高,最高抑制率达90%以上。结论鸡爪风体积分数85%乙醇提取物对体外培养的4种不同人肝癌细胞株的增殖均有抑制作用,呈剂量与时间依赖性。     

翻白草油对肝癌HepG2细胞CDK4蛋白的影响

目的:检测翻白草油对肝癌HepG2细胞CDK4蛋白表达的影响,探讨翻白草油抗肝癌的机制.方法:翻白草油作用肝癌HepG2细胞后,用噻唑蓝(MTT)比色法检测HepG2细胞增殖活性和IC50;western blot法检测CDK4蛋白的表达.结果:翻白草油能抑制HepG2细胞增殖,且呈剂量依赖性,IC50值为2.03mg...     

Resveratrol glucuronides as the metabolites of resveratrol in humans: characterization, synthesis, and anti-HIV activity

Resveratrol is a natural product with diverse biological activities. We have previously reported that resveratrol possesses potent synergistic inhibitory activity against human immunodeficiency virus (HIV)-1 infection in combination with nucleoside analogs (Heredia et al. 2000. J Acquir Immune Defic Syndr 25:246-255). As a part of our program in developing resveratrol as a component for anti-HIV chemotherapy, we describe in this article the characterization, chemical synthesis, and biological effects of the human metabolites of resveratrol. We found that resveratrol was metabolized in humans into two metabolites, which were characterized as resveratrol-3-O- and 4'-O-glucuronides. For further biological studies, we reported two simple, alternative methods for the synthesis of the metabolites. The cytotoxic and antiviral activities of resveratrol and its metabolites were compared in cell culture experiments using human peripheral blood mononuclear cells. Whereas resveratrol was cytotoxic at > or =30 microM, no cytotoxicity was observed for the metabolites at concentrations as high as 300 microM. However, resveratrol showed strong synergistic anti-HIV activity with didanosine at 10 microM, but no synergistic effects were observed for either of the metabolites at up to 300 microM. Nevertheless, the in vitro activity of the metabolites (resveratrol glucuronides) may not necessarily reflect their in vivo function, given the fact that the ubiquitously existing human beta-glucuronidase could convert the metabolites back to resveratrol locally or systematically in vivo. The present studies have implications for future development of resveratrol and/or its derivatives as a chemotherapeutic agent.     

Rubratoxin B induced the secretion of hepatic injury-related colony stimulating factors in human hepatoma cells

The induction of cytokine secretion by rubratoxin B was investigated using human hepatoma cell lines HepG2 and HuH-7. Interleukin (IL)-8, macrophage colony stimulating factor (M-CSF) and granulocyte-macrophage (GM)-CSF were detected in the media of rubratoxin B-treated both cell lines, and their levels peaked at about 40 microg/ml. Rubratoxin B-induced cytokine secretion was enhanced by tumor necrosis factor (TNF)-alpha in HepG2 cells. While emodin increased GM-CSF secretion, the secretion of the others was decreased, indicating that they are regulated differently in rubratoxin B-treated HepG2 cells. To our knowledge, this is the first report that an exogenous stimulus induced the secretion of M-CSF and GM-CSF in hepatocyte-derived hepatoma cells, suggesting that rubratoxin B is an excellent model compound to study the mechanisms of M-CSF and GM-CSF secretion. Our results showed that hepatotoxin rubratoxin B has a potential to induce the secretion of these two CSFs, implying that these factors play roles in rubratoxin B-caused hepatic injury.     

Ximelagatran: an orally active direct thrombin inhibitor.

PURPOSE: The chemistry, pharmacology, pharmacokinetics, clinical efficacy, dosage and administration, contraindications, and adverse effects of ximelagatran are reviewed. SUMMARY: Ximelagatran is the first orally active direct thrombin inhibitor to be tested in Phase III clinical trials. After oral administration, ximelagatran is rapidly converted to its active metabolite, melagatran. Melagatran (after oral ximelagatran administration) predictably inhibits thrombin function without need for routine anticoagulation monitoring. Melagatran effectively inhibits both free and clot-bound thrombin-a potential pharmacodynamic advantage over heparin products. Melagatran has a half-life of 2.4-4.6 hours, necessitating twice-daily administration. Melagatran is primarily eliminated by the kidneys and has not been studied clinically in patients with severe renal failure. Ximelagatran has undergone 10 Phase III trials (6 for prophylaxis of venous thromboembolism [VTE] due to orthopedic surgery, 1 for initial treatment of VTE, 1 for long-term prevention of VTE recurrence, and 2 for stroke prophylaxis due to atrial fibrillation). Results were generally positive. AstraZeneca applied in December 2003 for marketing approval of ximelagatran for prevention of VTE after total knee replacement surgery, long-term prevention of VTE recurrence after standard therapy, and stroke prevention due to atrial fibrillation. FDA denied approval of ximelagatran for all indications, mainly because of increased rates of coronary artery disease events in ximelagatran recipients in some studies and the possibility of hepatic failure when the medication is used for long-term therapy. CONCLUSION: Ximelagatran has shown promise as a possible alternative to warfarin and other anticoagulants but will require further study to ensure its safety.     

Ximelagatran, the new oral anticoagulant: would warfarin survive the challenge?

The last decade witnessed major advances in the prevention and treatment of venous as well as of arterial thrombosis. Limitations of existing anticoagulants led to the development of novel therapeutic approaches. Ximelagatran is a new direct thrombin inhibitor (DTI) that is given orally, without the need for close monitoring. This compound was tried in the treatment of active venous thromboembolism, and the results were encouraging. Randomized trials suggest that ximelagatran is not inferior to warfarin in the prevention of stroke in patients with nonvalvular atrial fibrillation. Multiple controlled, prospective trials compared ximelagatran with low molecular weight heparin or warfarin in prevention of venous thromboembolism in patients undergoing major orthopedic procedures. The results of these clinical trials are reviewed in this article. Because of certain safety concerns (increased liver enzymes, potential hepatonecrosis, and increased coronary events) ximelagatran has not yet been approved by the FDA. Additional studies may be required to address these concerns. Ximelagatran has been approved, however, by the European regulatory authorities for short-term thromboprophylaxis. The success of ximelagatran or other oral antithrombin agents would provide significant proof of the concept for the long-term use of oral antithrombins in the prevention and treatment of both arterial and venous thrombosis.