Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0034065 (pulmonary embolism)
 14,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ximelagatran is an oral direct thrombin inhibitor (DTI), the active form of which is melagatran. Approximately 20% of an oral ximelagatran dose becomes bioavailable as melagatran, which binds noncovalently and reversibly to both fibrin-bound and freely circulating thrombin. Oral ximelagatran dosing not only inhibits thrombin activity rapidly, competitively, and potently, but also delays and suppresses thrombin generation. In humans, oral ximelagatran exhibits anticoagulant, antiplatelet, and profibrinolytic effects, with only minor prolongation of the capillary bleeding time. Oral ximelagatran exhibits a stable and predictable pharmacokinetic profile during repeated dosing, with low intra- and inter-individual variation, and a low potential for interaction with other medications. It is excreted primarily as melagatran via the kidney, without unexpected bioaccumulation. Dosing requirements do not vary with age, gender, ethnicity, obesity, or food or alcohol intake. Clinical trials (total n>30,000) have evaluated oral ximelagatran in four indications: the prevention of venous thromboembolism (VTE, comprising deep venous thrombosis with or without and pulmonary embolism) after elective hip- or knee-replacement surgery (with approval granted by France, as the Reference Member State for the European Union); treatment and long-term secondary prevention of VTE; the prevention of stroke and other systemic embolic events associated with nonvalvular atrial fibrillation; and the prevention of cardiovascular events after an acute myocardial infarction. The results of these trials suggest that the benefit-risk profile of oral ximelagatran therapy, administered at a fixed-dose without coagulation monitoring, compares favorably with that of currently approved standard therapy.
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PMID:Ximelagatran--a promising new drug in thromboembolic disorders. 1572 69

(1) The reference drug for prophylaxis against venous thromboembolism after hip or knee replacement surgery is a low-molecular-weight heparin (LMWH), given subcutaneously for 1 to 5 weeks. Vitamin K antagonists, including warfarin, have similar risk-benefit balances. (2) Subcutaneous melagatran and its oral metabolic precursor ximelagatran have recently been granted marketing authorisation in France for use as prophylaxis after hip or knee replacement surgery. Melagatran, unlike LMWH, is a specific thrombin inhibitor. (3) There are four randomised double-blind trials in more than 9000 patients comparing these agents with a LMWH (enoxaparin in three trials, dalteparin in one). Melagatran was given subcutaneously for one or two days before being replaced with ximelagatran (as soon as oral feeding was possible) for 6 to 9 days. These trials showed no advantage of melagatran-ximelagatran in terms of clinical endpoints such as symptomatic deep venous thrombosis, pulmonary embolism, and death from all causes. (4) Three randomised double-blind trials have compared ximelagatran with warfarin in more than 5000 patients. Treatment lasted 7 to 12 days. Ximelagatran was no better than warfarin when assessed using clinical endpoints. (5) In these trials melagatran-ximelagatran did not increase the risk of bleeding compared with LMWH or warfarin. (6) Melagatran-ximelagatran can cause an increase in serum transaminase activity, and is contraindicated if pretreatment serum transaminase activity is more than twice the upper limit of normal. (7) Trials versus warfarin showed a higher risk of myocardial infarction in patients taking ximelagatran (0.7% versus 0.16%). (8) There are few data on the patient subgroups most likely to receive melagatran-ximelagatran, namely patients over 75, underweight and overweight patients, and patients with renal failure. (9) There is currently no clotting test that allows the melagatran-ximelagatran dose regimen to be adjusted in patients who have an increased risk of adverse effects due to overdosing. There is no available antidote if overdose occurs. (10) Erythromycin increases melagatran bioavailability, thereby increasing the bleeding risk. Melagatran and ximelagatran must not be combined with other anticoagulants, thrombolytic agents or antiplatelet drugs because of a increased bleeding risk. (11) In practice, low-molecular-weight heparin remains the reference prophylactic treatment for venous thromboembolism after hip or knee replacement surgery.
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PMID:Melagatran and ximelagatran: new drug. No real simplification of anticoagulant therapy. 1610 94

Patients undergoing major lower-extremity orthopedic surgery such as total hip replacement (THR) and total knee replacement (TKR) are at an increased risk of venous thromboembolism (VTE). Routine prophylaxis is necessary to reduce the risk of deep vein thrombosis (DVT), which may progress to potentially fatal pulmonary embolism and secondary complications such as postthrombotic syndrome, recurrent DVT, and chronic pulmonary hypertension. Prophylaxis in patients undergoing TKR, THR, and hip fracture surgery is now standard practice and generally involves anticoagulant treatment with either low-molecular-weight heparin (LMWH) or warfarin for a period of 7 to 10 days, with extended prophylaxis in those with ongoing risk factors such as obesity, cancer, or previous VTE. Data from clinical practice suggest that there is a general trend toward longer postsurgical prophylaxis and shorter hospital stays, making practicality of treatment an important consideration. LMWH is effective for the prophylaxis of VTE, but the parenteral route of administration is not convenient for use in the outpatient setting. Warfarin, on the other hand, can be administered orally but requires the infrastructure for careful patient monitoring and dose adjustments because of its unpredictable dose-response relationship. The development of new anticoagulants has been pursued with the aim of improving efficacy, predictability, consistency of response, safety, and convenience. A recently approved anticoagulant, fondaparinux, has been proven to provide superior efficacy for the prevention of VTE compared with LMWH, but this agent requires parenteral administration and does not overcome the convenience issue. Ximelagatran is the oral form of the direct thrombin inhibitor melagatran, which is available for subcutaneous administration. Ximelagatran has a consistent anticoagulant response allowing fixed oral dosing without the need for coagulation monitoring. The efficacy and safety profile of melagatran/ximelagatran prophylaxis for VTE following THR and TKR has compared favorably with standard LMWH prophylaxis, as seen in the European METHRO II and III trials and EXPRESS trial, and with warfarin prophylaxis, as seen in the North American EXULT A and B trials. Several prophylactic treatment regimens have been evaluated in the European trials to determine the optimal dosing and timing of first dose of melagatran to achieve the best balance of efficacy and safety. Preoperative initiation of melagatran was more effective than when prophylactic treatment was initiated postoperatively, and the lowest rates of bleeding were associated with a postoperative initiation of prophylaxis. Early administration of the first postoperative melagatran dose (4 to 8 hours) was also associated with better prophylactic efficacy relative to a later postoperative start (8 to 12 hours). The results of the comprehensive international clinical trial program and in particular the optimal balance of efficacy/safety data provided by the METHRO III study have led to approval of melagatran/ximelagatran in 2004 in the European Union for the prevention of VTE in patients undergoing elective hip or knee replacement surgery. Ximelagatran has the potential to maximize the use of anticoagulation in patients discharged following major lower-extremity orthopedic surgery.
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PMID:Ximelagatran for the prevention of venous thromboembolism following elective hip or knee replacement surgery. 1612 14

The oral direct thrombin inhibitor ximelagatran (24 mg twice daily) has been shown to significantly reduce the incidence of recurrent venous thromboembolism (VTE) vs. placebo over 18 months, with no significant influence on bleeding (THRIVE III). The influence of potential prognostic factors on the risk of recurrent VTE or major and/or minor bleeding and their impact on ximelagatran treatment was evaluated in the THRIVE III study population. The effect of sex, age, body weight, renal function, malignancy, type of initial VTE event, and history of previous VTE events was investigated in the intention-to-treat population using Cox proportionate hazard modelling. Ximelagatran was administered to 612 patients and placebo to 611 patients. Within the placebo group, risk of recurrent VTE was higher among men than women (hazard ratio [HR]: 2.50,95% confidence interval [CI] 1.49,4.17), and in patients with one or more than one previous VTE event (HR: 1.73,95% CI 1.00, 2.99). There was a higher risk of bleeding among women than men in both the ximelagatran (HR: 1.49, 95% CI 1.06, 2.09) and placebo (HR: 1.48, 95% CI 1.01, 2.15) groups, and in placebo-treated patients with an initial pulmonary embolism (HR: 1.53, 95% CI 1.06,2.23) compared to those with initial deep vein thrombosis. There were no significant interactions between treatment effect and any of the potential prognostic factors. In conclusion, the superior efficacy of ximelagatran vs. placebo was maintained in all subgroups. Long-term use of oral ximelagatran, without coagulation monitoring or dose adjustment, should be feasible and well tolerated in a wide cross-section of patients for the secondary prevention of VTE.
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PMID:Prognostic factors for recurrence of venous thromboembolism (VTE) or bleeding during long-term secondary prevention of VTE with ximelagatran. 1626 66

In the randomized, double-blind THRIVE III trial, the oral direct thrombin inhibitor ximelagatran (24 mg twice daily) significantly reduced the incidence of recurrent venous thromboembolism (VTE) versus placebo over 18 months or until premature study drug discontinuation. A complementary follow-up analysis (intention-to-treat) was conducted post-study to evaluate the cumulative risks of locally-confirmed recurrent VTE and death (Kaplan-Meier procedure) over the full 18-month study period, regardless of whether patients discontinued study drug prematurely. Hazard ratios (HRs) between treatments were estimated using Cox proportional hazard modeling. Of 612 and 611 patients receiving ximelagatran and placebo, respectively, 149 and 181 discontinued treatment prematurely. Of these discontinuations, further information could not be collected for 14 and 13 patients in the ximelagatran and placebo groups, respectively; among the remaining patients, four VTE events and four deaths occurred in the ximelagatran group, and one VTE event and five deaths occurred in the placebo group. The resulting cumulative risks of VTE (3.2% vs. 12.7%; HR 0.21; 95% confidence interval [CI], 0.12, 0.36; P < 0.0001) and pulmonary embolism (0.8% vs. 5.2%; HR 0.13; 95% CI 0.04, 0.36; P < 0.0001) were significantly lower in the ximelagatran than in the placebo group over 18 months. Death from any cause over 18 months occurred in 10 and 12 patients, respectively (HR 0.83;95% CI 0.36, 1.93; P = 0.7). This complementary follow-up analysis confirms the benefit of oral ximelagatran 24 mg twice daily, administered without coagulation monitoring or dose adjustment, for the long-term secondary prevention of VTE.
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PMID:Ximelagatran for the secondary prevention of venous thromboembolism: a complementary follow-up analysis of the THRIVE III study. 1627 Jun 37

The initial treatment of patients with acute pulmonary embolism has traditionally involved unfractionated heparin. Given the more predictable pharmacodynamic and pharmacokinetic properties of low molecular weight heparins, their simpler (fixed) dosing regimens, and few or no laboratory monitoring requirements, low molecular weight heparins are gradually replacing heparin for the initial treatment of most patients diagnosed with acute pulmonary embolism, except in very obese patients or patients with renal failure. Only selected patients with massive, life-threatening pulmonary embolism should be managed with intravenously administered thrombolytic drugs, surgical embolectomy, or catheter-based embolectomy. Likewise, inferior vena caval filter should be considered only in patients with an absolute contraindication to, or a documented failure of, anticoagulant therapy. New anticoagulants, such as ximelagatran, an oral direct thrombin inhibitor, or fondaparinux and idraparinux, selective factor X(a) inhibitors with an almost complete bioavailability after subcutaneous injection are promising alternatives, but these drugs have yet to find a place in the initial treatment of pulmonary embolism in standard day-to-day clinical practice. Long-term anticoagulation treatment is still provided by antivitamin K antagonists (eg, warfarin), which unfortunately have a narrow therapeutic window. Consequently, time-consuming monitoring is required to ensure the therapeutic anticoagulant effect. A target International Normalized Ratio (INR) of 2.5 (INR range: 2.0 to 3.0) is recommended for warfarin therapy. This treatment should be continued for at least 3 months for patients with a first episode of pulmonary embolism secondary to a transient (reversible) risk factor, or up to 6 to 12 months for patients with a first episode of idiopathic pulmonary embolism.
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PMID:Pulmonary embolism: current treatment options. 1628 76

Heparin-induced thrombocytopenia (HIT) is an uncommon but potentially serious complication of hemodialysis, and subsequent reexposure to heparin after the disappearance of antiheparin-PF4 complex antibodies (HIT antibody) has been controversial. We report a 60-year-old woman who was sensitized to unfractionated heparin (heparin) as anticoagulant during hemodialysis (HD) and heparin flush on a nonsession day. The patient suddenly developed acute systemic reactions with acute pulmonary embolism a few minutes after manipulation with heparin flush on day 9, a nonsession day. Although there was no evidence of pulmonary embolism on a pulmonary scintigram on the next day, the fifth HD session was discontinued owing to recurrence of acute systemic reactions and massive clots in the dialyzer 30 min into the session. After confirmation of the presence of HIT antibody and maturation of vascular access fistula, a sixth HD session was carried out with argatroban, a synthetic direct thrombin inhibitor, with a bolus of 10 mg and continuous infusion of 0.5 mg/kg/hr as an alternative to heparin. Optimal dose adjustment of argatroban through activated partial thromboplastin time (APTT) monitoring led to a bolus of 5 mg and continuous infusion of 0.15 mg/kg/hr. The patient's HD treatment at the same doses 3 times a week followed an uneventful course over 6 months. HIT antibody was seronegative about 40 days after the cessation of heparin treatment. Reexposure to heparin was attempted with the monitoring of HIT antibody and platelet counts before and after the sessions on day 210. The titers of HIT antibody compared with before the level of reexposure showed a transient insignificantly small peak, and dialysis with heparin has been maintained to date with no recurrence of HIT. The measurement of HIT antibody titer could be useful in assessing not only the effect of argatroban to replace heparin but also in predicting the recurrence of HIT due to reexposure.
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PMID:Heparin-induced thrombocytopenia in a uremic patient requiring hemodialysis: an alternative treatment and reexposure to heparin. 1745 28

The direct thrombin inhibitor, ximelagatran, and its active form, melagatran (X/M), have been compared against conventional anticoagulant therapy (CAT) in many clinical settings. Their risk-benefit profile drove large debate until withdrawal by the manufacturer. A systematic review of all published randomized trials has been performed and a meta-analysis of randomised controlled trial (RCT) of X/M versus CAT. Major medical databases were searched for RCTs. Major adverse events (MAE: all cause death, nonfatal myocardial infarction, nonfatal thromboembolic stroke, pulmonary embolism), major bleeds (MB), minor bleeds and the rate of hepatotoxicity (HT) were compared. In terms of efficacy, X/M was at least as effective as, or even superior to, CAT. In terms of safety, the overall risk of MAE, MB, minor bleeds and HT was not significantly different for X/M compared with CAT. According to individual clinical settings, X/M was associated with a lower risk of MB but a prohibitive higher risk of HT in those clinical settings requiring prolonged treatment.
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PMID:The direct thrombin inhibitor ximelagatran/melagatran: a systematic review on clinical applications and an evidence based assessment of risk benefit profile. 1768 83

Hirudin is a specific thrombin inhibitor which acts independent of antithrombin III and is able to bind to fluid phase and clot bound thrombin. It has become available for clinical use by production with recombinant techniques just recently. Hirudin produces a relatively stable level of anticoagulation when compared with heparin. However, hirudin is not as effective as heparin in blocking thrombin generation, but is more effective than heparin in inhibiting thrombin activity. In patients with unstable angina, hirudin was more effective than heparin in preventing ischaemic events in the acute phase. This clinical benefit was no longer significant after 30 days in the Global Use of Strategies to open Occluded coronary arteries in acute coronary syndromes (GUSTO)-IIb study. Recombinant hirudins as adjunct to thrombolysis with alteplase do not significantly improve early patency, but decrease the rate of reocclusions. However, as an adjunct to streptokinase, hirudin improves the speed of reperfusion. The therapeutic range of hirudin in combination with thrombolysis is very narrow, as demonstrated by the increased rate of intracerebral bleedings in 3 clinical thrombolysis trials with higher doses of hirudin. Subsequent trials with markedly lower doses of hirudin did not show any increase in bleeding complications or any significant clinical benefit of hirudin compared to heparin as adjunct to thrombolysis. In a large trial comparing heparin and hirudin, patients with unstable angina scheduled for percutaneous transluminal coronary angioplasty (PTCA) had a similar event-free survival rate at 7 months, but hirudin reduced the incidence of early cardiac events. There is some evidence from large studies that hirudin is more effective than unfractionated and low molecular weight heparin in preventing deep vein thrombosis in patients who have had hip surgery. Furthermore, in a small trial in patients with established vein thrombosis, hirudin compared to heparin reduced the rate of new pulmonary embolism and the extension of venous thrombosis. Hirudin seems to be the treatment of choice for patients with heparin induced thrombocytopenia type II. It reduces the incidence of thromboembolic complications in this high risk patient group. To date, the considerably higher costs of recombinant hirudins compared to heparin does not justify their routine use, and it is appropriate to limit their use to individual cases where conventional thrombin inhibitors are contraindicated or much less effective.
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PMID:Recombinant hirudins: an overview of recent developments. 1802 Jun 12

Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by platelet-activating antibodies that recognize multimolecular complexes of platelet factor 4 (PF4) bound to heparin. HIT is an intense hypercoagulability state (increased thrombin generation in vivo) that is complicated more often by venous thromboembolism (deep vein thrombosis, pulmonary embolism) than by arterial thrombosis. HIT is a risk factor for coumarin-induced microthrombosis, particularly affecting acral regions of limbs with deep vein thrombosis (venous limb gangrene). Coumarins (e.g., warfarin) are therefore contraindicated during the acute (thrombocytopenic) phase of HIT. Venous thromboembolism can occur early during an episode of HIT, sometimes even before HIT-associated platelet count declines become clear. Recognition of HIT may be facilitated through the use of a clinical scoring system, the 4Ts ( Thrombocytopenia, Thrombosis, Timing, and o Ther explanations). Anti-PF4/polyanion enzyme-immunoassays (EIAs) and washed platelet activation assays readily detect HIT antibodies, and thus have high diagnostic sensitivity; however, only the platelet activation assays have high diagnostic specificity, suggesting that HIT is likely to be overdiagnosed in settings where EIAs are used exclusively for diagnosis. Treatment of HIT emphasizes substitution of heparin with an alternative nonheparin anticoagulant, such as a direct thrombin inhibitor (lepirudin, argatroban), or an indirect (antithrombin-mediated) inhibitor of factor Xa (danaparoid, fondaparinux?).
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PMID:The approach to heparin-induced thrombocytopenia. 1830 88


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