Antidote of heparin
Short half-life means anticoagulant effect quickly ceases once stopped.Monitoring of anti-factor Xa is only necessary in patients with decreased kidney function (and significant over- or underweight) anti- factor Xa activity is measured 4 hrs after administration.Effect of LMWH lasts for about 12 hours.Protamine (the antidote) antagonizes effect of UFH.Adequate anticoagulation is achieved sooner due to direct effect on thrombin.Dosage depends on specific drug used, indication, body weight, and kidney function adjust to body weight and decreased kidney function.High dose: intravenous administration with bolus and continuous application via infusion pump.Low dose: subcutaneous administration every 8–12 hrs.Therapeutic administration requires infusion pump.Subcutaneous or intravenous administration.Overview of advantages and disadvantages In patients with antithrombin III deficiency (e.g., due to nephrotic syndrome), this effect is reduced. The effect of most parenteral anticoagulants (except for direct thrombin inhibitors) depends on native antithrombin. Directly inhibit thrombin (free ly circulating and in association with clots).Long half-life: 2–4 times longer than unfractionated heparin.Higher bioavailability than unfractionated heparin.Synthetic heparin: only binds to antithrombin III → selective inhibition of factor Xa.LMWH: binds to antithrombin III → inhibition of factor Xa → decreased conversion of prothrombin → ↓ thrombin.Low molecular weight heparin ( LMWH) and synthetic heparin ( fondaparinux) Short half-life : anticoagulant effect quickly ceases once administration is stopped.Thrombin ( factor IIa ) : UFH binds antithrombin III and thrombin simultaneously at two distinct binding sites → antithrombin III and thrombin held by heparin in close proximity (complex formation) → ↑ thrombin inhibition → ↓ fibrinogen activation → ↓ fibrin.Factor Xa : antithrombin III potentiation → inhibition of factor X a → decreased activation of prothrombin → ↓ thrombin → ↓ fibrinogen activation → ↓ fibrin.Dabigatran: idarucizumab( monoclonal antibody).Possibly aPCC and/or antifibrinolytics (e.g., tranexamic acid).Monitoring during therapy: not generally recommended.Oral: dabigatran (see direct oral thrombin inhibitors).Intravenous: argatroban, bivalirudin, desirudin.Drugs: argatroban, bivalirudin, desirudin, dabigatran.Antidote : protamine sulfate (partial reversal).Monitoring during therapy: anti-factor Xa activity.Antidote : : possibly activated prothrombin complex concentrates ( aPCC).Anti-factor Xa activity can be assessed in specific cases.Antidote : : protamine sulfate (partial reversal).Clearance: renal (contraindicated for patients with renal insufficiency).Monitoring during therapy: anti-factor Xa activity can be assessed in specific cases not generally recommended.Drugs: enoxaparin, dalteparin, tinzaparin, nadroparin, certoparin.In order to detect heparin-induced thrombocytopenia, platelets must be continuously monitored during heparin therapy and a baseline should be established before commencing treatment. Antidote : : protamine sulfate (a positively-charged protein that can neutralize negatively-charged heparin by forming inactive complexes).Clearance: hepatic (preferred agent for patients with renal insufficiency ).Monitoring during therapy : : activated partial thromboplastin time ( aPTT ), platelet count (including baseline before treatment is started).Therapeutic: continuous intravenous infusion.