bivalirudin and ximelagatran

Topics: Angina, Unstable; Anticoagulants; Azetidines; Benzimidazoles; Benzylamines; Brain Ischemia; Clinical Trials as Topic; Coumarins; Dabigatran; Factor Xa Inhibitors; Fibrinolytic Agents; Fondaparinux; Forecasting; Hemorrhage; Heparin; Heparin, Low-Molecular-Weight; Hirudins; Humans; Morpholines; Myocardial Infarction; Peptide Fragments; Polysaccharides; Prothrombin; Pyrazoles; Pyridines; Pyridones; Recombinant Proteins; Rivaroxaban; Thiophenes; Thrombin; Thrombophilia; Thrombosis; Warfarin

The coagulation cascade, and particularly thrombin, plays a very important role in arterial and venous thrombosis. Thereby, it is clear that thrombin inactivation is an optimal strategy for thrombotic disease prevention and treatment. The direct thrombin inhibitors are a new class of anticoagulant drugs directly binding thrombin and blocking its interaction with fibrinogen. The group of direct thrombin inhibitors includes recombinant hirudin (lepirudin and desirudin), bivalirudin, melagatran and its oral precursor, ximelagatran, argotraban and dabigatran. These drugs have several advantages compared to other anticoagulant drugs, and the particular pharmacokinetic properties of some of them could be very important for future management of thromboembolic prophylaxis. The efficacy and safety of these new drugs are evaluated in several clinical trials; however today only few clinical indications are available for the majority of them.

Topics: Anticoagulants; Antithrombins; Azetidines; Benzylamines; Clinical Trials as Topic; Drug Therapy, Combination; Fibrinolytic Agents; Hirudins; Humans; Peptide Fragments; Recombinant Proteins; Thromboembolism; Treatment Outcome

Topics: Anticoagulants; Arginine; Azetidines; Benzylamines; Blood Coagulation; Fondaparinux; Heparin; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Sulfonamides; Thrombin; Thrombosis; Warfarin

Topics: Acute Disease; Angioplasty, Balloon, Coronary; Anticoagulants; Arginine; Atrial Fibrillation; Azetidines; Benzylamines; Clinical Trials as Topic; Coronary Disease; Heparin; Hirudins; Humans; Myocardial Infarction; Peptide Fragments; Pipecolic Acids; Recombinant Proteins; Sulfonamides; Syndrome; Thrombin; Thromboembolism; Thrombosis; Venous Thrombosis

Patients with renal failure have an increased risk of both thrombotic and bleeding complications. A number of antithrombotic drugs undergo renal clearance. Therefore, estimation of renal function is necessary when prescribing these drugs to patients with renal dysfunction. Pharmacokinetic and clinical data in patients with chronic renal impairment are limited for several anticoagulants, and adequate administration information is often absent. Dose adjustment of anticoagulants may be indicated when the creatinine clearance falls below 30 mL/min. Unfractionated heparin, argatroban, and vitamin K antagonists generally do not require dose adjustment with renal dysfunction. However, smaller doses of warfarin may be required to achieve a particular target international normalized ratio. Close monitoring of anticoagulation is recommended when argatroban or high doses of unfractionated heparin are administered in patients with severe chronic renal impairment. Low-molecular weight heparins, danaparoid sodium, hirudins, and bivalirudin all undergo renal clearance. Lower doses and closer anticoagulation monitoring may be advisable when these agents are used in patients with chronic renal failure. We recommend that fondaparinux sodium and ximelagatran (not yet licensed) be avoided in the presence of severe renal impairment and be used with caution in patients with moderate renal dysfunction. While acknowledging the lack of pharmacokinetic data, this review provides specific recommendations for the use of anticoagulants in patients with chronic renal impairment.

Topics: Anticoagulants; Arginine; Azetidines; Benzylamines; Fondaparinux; Heparin; Hirudins; Humans; Kidney Failure, Chronic; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Sulfonamides; Warfarin

Unfractionated heparin, derived from porcine intestine, is the prototype of a rapidly acting anticoagulant. It has been used for over 60 years to arrest or prevent thrombus growth. Low-molecular-weight heparins, available in the last 20 years, are manufactured from unfractionated heparin and have superior dose-response relationships because of fewer nonspecific reactions with plasma proteins and cells. Fondaparinux is a recently approved five-saccharide synthetic molecule that carries the evolution of heparin further. It is a pure Xa inhibitor, with minimal nonspecific interactions. It does not appear to elicit the antibody that leads to heparin-induced thrombocytopenia (HIT). All of these agents are given either intravenously or subcutaneously. They act indirectly by activating the natural plasma inhibitor, antithrombin III. Direct thrombin inhibitors bind directly to thrombin's active site without interaction with the cofactor, antithrombin III. Lepirudin (Refludan; Berlex, Wayne, NJ) and argatroban (Argatroban; GlaxoSmithKline, Research Triangle Park, NC) are given intravenously and are usually used in HIT and thrombosis associated with HIT. Bivalirudin (Angiomax; The Medicines Company, Parsippany, NJ) is a parenteral direct thrombin used in place of heparin in percutaneous coronary interventions. Ximelagatran (Exanta; AstraZeneca, Wilmington, DE) is an oral direct thrombin inhibitor under development for both acute and chronic anticoagulation.

Topics: Anticoagulants; Arginine; Azetidines; Benzylamines; Embolism; Enzyme Inhibitors; Fondaparinux; Heparin; Heparin, Low-Molecular-Weight; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Sulfonamides; Thrombin; Thrombocytopenia; Venous Thrombosis

Classic anticoagulant drugs are very effective, save lives and have been used for more than 50 years. Nevertheless, some drawbacks are encountered in their routine clinical use. Recently, pharmaceutical research has developed new drugs, some of which are already on the market. This is the case of fondaparinux, a pentasaccharide which can interact with antithrombin, thus inhibiting factor Xa. Modification of its structure (idraparinux) has led to more stable binding with antithrombin and to an increase in its half-life allowing for once-a-week administration. Another important oral compound is ximelagatran which directly binds thrombin and blocks its catalytic site. There is no need for laboratory control, and phase II and phase III studies are encouraging. Thus, in the next few years, we may witness great changes in the treatment of patients with thromboembolic disorders.

Topics: Anticoagulants; Arginine; Azetidines; Benzylamines; Drug Design; Fibrinolytic Agents; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Platelet Aggregation Inhibitors; Prodrugs; Recombinant Proteins; Sulfonamides; Thrombosis

Ximelagatran and bivalirudin are direct thrombin inhibitors that have been studied for the prevention and treatment of thrombosis and have potential advantages over the traditional indirect thrombin inhibitors (i.e., warfarin, unfractionated heparin and low molecular-weight heparin). They are both reversible inhibitors of thrombin and block both circulating and fibrin-bound thrombin. Ximelagatran and bivalirudin possess favourable pharmacokinetic and pharmacodynamic profiles including wider therapeutic indices, faster onsets of action and less interpatient variability compared to indirect thrombin inhibitors. Ximelagatran has shown favourable clinical trial results in venous thromboembolism prophylaxis and atrial fibrillation. Similarly, bivalirudin has shown positive results in patients with acute coronary syndromes, however, further investigation is needed. Ximelagatran and bivalirudin have shown promising results in the management of thrombosis and the results of future studies confirming their use for the aforementioned indications are anticipated.

Topics: Acute Disease; Administration, Oral; Antithrombins; Azetidines; Benzylamines; Clinical Trials, Phase III as Topic; Coronary Disease; Double-Blind Method; Hirudins; Humans; Peptide Fragments; Randomized Controlled Trials as Topic; Recombinant Proteins; Syndrome; Thrombosis