fondaparinux and Blood-Coagulation-Disorders

Disorders of coagulation are common adverse drug events encountered in critically ill patients and present a serious concern for intensive care unit (ICU) clinicians. Dosing strategies for medications used in the ICU are typically developed for use in noncritically ill patients and, therefore, do not account for the altered pharmacokinetic and pharmacodynamic properties encountered in the critically ill as well as the increased potential for drug-drug interactions, given the far greater number of medications ordered. This substantially increases the risk for coagulation-related adverse reactions, such as a bleeding or prothrombotic events. Although many medications used in the ICU have the potential to cause coagulation disorders, the exact incidence will vary based on the specific medication, dose, concomitant drug therapy, ICU setting, and patient-specific comorbidities. Clinicians must strongly consider these factors when evaluating the risk/benefit ratio for a particular therapy. This review surveys recent literature documenting the risk for adverse drug reactions specific to bleeding and/or clotting with commonly used medications in the ICU.

Topics: Anti-Infective Agents; Anticoagulants; Antifibrinolytic Agents; Blood Coagulation Disorders; Blood Coagulation Factors; Colloids; Critical Care; Deamino Arginine Vasopressin; Drug-Related Side Effects and Adverse Reactions; Erythropoietin; Estrogens, Conjugated (USP); Factor VIIa; Fibrinolytic Agents; Fondaparinux; Hemostatics; Humans; Polysaccharides; Protein C; Recombinant Proteins; Thrombin; Thromboembolism; Vitamin K

Classic anticoagulant drugs, such as heparin and warfarin, are very effective. However, although in use for more than 50 years, they do have some clinical drawbacks. Heparin, now better termed unfractionated heparin, can only be used intravenously and its laboratory control is complicated. Warfarin is orally administered, but its therapeutic window is very narrow and patients need repeated laboratory tests. Moreover, both drugs are non-specific, as they inhibit the coagulation cascade at several steps. Pharmaceutic research has developed new drugs, some of which are already on the market, such as fondaparinux, a pentasaccharide that can interact with antithrombin, thus inhibiting factor Xa. This pentasaccharide is part of the parent heparin molecule and can be chemically synthesized, with the advantage of avoiding extractive compounds. Fondaparinux has a half-life compatible with once-a-day administration; modification of its structure (idraparinux) has led to more stable binding with antithrombin and to an increase in its half-life to allow once-a-week administration. Alternatives to oral anticoagulants have been developed following the study of some compounds like hirudin, which directly binds thrombin and blocks its catalytic site. One of these molecules, ximelagatran, is in advanced clinical development. Ximelagatran is converted into its active form, melagatran, in the circulation, and thrombin activity can be blocked by oral administration twice daily. There is no need for laboratory control and phase II and phase III studies are encouraging. The next few years should bring great changes to the treatment of patients with thromboembolic disorders.

Topics: Anticoagulants; Azetidines; Benzylamines; Blood Coagulation Disorders; Fondaparinux; Half-Life; Humans; Oligosaccharides; Polysaccharides

Eczematous lesions, resulting from type IV sensitizations are well-known and relatively frequent cutaneous adverse effects of s.c. heparin therapy. If anticoagulation is further required intravenous heparin, heparinoids or lepirudin may be used as a substitute. However, these alternatives are not optimal in terms of practicability and/or safety-profiles. As molecular weight of different heparin preparations has repetitively been implied to determine the frequency of sensitization, we hypothesized, that due to its low molecular weight the pentasaccharide fondaparinux may provide a practicable and safe anticoagulant therapy in patients with delayed type hypersensitivity reactions (DTH) to heparin and other oligosaccharides. To test this concept, patients referred for diagnosis of cutaneous reactions after s.c. anticoagulant treatment underwent a series of in vivo skin allergy- and challenge-tests with unfractionated heparin, a series of low molecular weight heparins (nadroparin, dalteparin, tinzaparin, enoxaparin and certoparin), the heparinoid danaparoid and the synthetic pentasaccharide fondaparinux. In total, data from twelve patients was evaluated. In accordance with previously published data, we report a high crossreactivity among heparins and heparinoids. In contrast--and in support of our initial hypothesis--sensitization towards the synthetic pentasaccharide fondaparinux was rarely observed. Plotting the cumulative incidence against the determined molecular weight of the individual anticoagulant preparations, shows that molecular weight generally is a key determinant of sensitization towards heparins and other oligosaccharides (r2 = 0.842, p = 0.009). Hence, fondaparinux may be used as a therapeutic alternative in patients with cutaneous DTH relations towards heparin and other polysaccharides.

Topics: Adult; Aged; Anticoagulants; Blood Coagulation Disorders; Cells, Cultured; Cross Reactions; Female; Fondaparinux; Heparin; Heparin, Low-Molecular-Weight; Heparinoids; Humans; Hypersensitivity, Delayed; Lymphocyte Activation; Male; Middle Aged; Molecular Weight; Oligosaccharides; Polysaccharides; Prevalence; Skin Tests

Fondaparinux sodium is a synthetic pentasaccharide representing the high affinity antithrombin III binding site in heparin. It is the active pharmaceutical ingredient of the anticoagulant drug Arixtra

Topics: Anticoagulants; Antithrombin III; Binding Sites; Blood Coagulation Disorders; Crystallography, X-Ray; Fondaparinux; Heparin; Humans; Magnetic Resonance Spectroscopy; Molecular Conformation; Oligosaccharides; Polysaccharides