Antiplatelets and Anticoagulants Treatments PDF

Antiplatelets and Anticoagulants Drugs that are used to prevent and/or reverse thrombus formation. These drugs are split into 3 groups: 1) Anticoagulants  Factor Xa inhibitors, anti-thrombins, heparin & vitamin-k antagonists 2) Anti-platelet drugs  Aspirin – inhibits COX...

Antiplatelets and Anticoagulants Drugs that are used to prevent and/or reverse thrombus formation. These drugs are split into 3 groups: 1) Anticoagulants  Factor Xa inhibitors, anti-thrombins, heparin & vitamin-k antagonists 2) Anti-platelet drugs  Aspirin – inhibits COX-1 activity to inhibit platelet aggregation 3) Fibrinolytic agents  Alteplase – breaks down fibrin  Classes of 1. anticoagulants Selective factor Xa inhibitors – Apixaban 2. Direct thrombin inhibitors – Dabigatran 3. Heparin and low molecular weight heparins 4. Vitamin-K antagonists – Warfarin -- Anticoagulants target various factors in coagulation cascade preventing formulation of a stable fibrin framework  Venous Thromboembolism  If it is a confirmed proximal DVT or PE  use Apixaban/Rivaroxaban  If the drugs above are contra-indicated: use LMWH’s followed by dabigatran etexilate or edoxaban OR LMWH’s with a Vitamin-K antagonist – Warfarin for at least 5 days until INR is achieved or Vitamin-K antagonist alone  Patients that undergo surgery where there is a risk of thrombosis (thromboprophylaxis – NICE guidelines) Anti-coagulant cascade  Apixaban  inhibits factor Xa  Dabigatran  Factor 2a (Thrombin)  Heparin  Inhibits XIIa, XIa, IXa, Xa & Thrombin  LMWH  inhibits Xa  Warfarin  inhibits VIIa, Xa , Ixa & thrombin (2a)  Direct-acting oral anticoagulants (DOACs)  Mechanism of action: Dabigatran etexilate = It is a reversible inhibitor of thrombin (factor 2a), and Idarucizumab is a reversal agent.  Apixaban, edoxaban and rivaroxaban’s mechanism of action is that they are all reversible inhibitors of activated factor X (Xa)  known as the Andexanet alfa reversal agent. It prevents thrombin generation and thrombus development.  What are the indications that Apixaban, dabigatran etexilate, edoxaban & rivaroxaban are used: It prevents stroke and secondarily prevents DVT or PE. Prevention of venous thromboembolism following surgery  What are the indications rivaroxaban is used? Prevention of atherothrombotic events in patients with coronary or peripheral artery disease, additionally used following an acute myocardial infarction.  Contraindications and side-effects of Apixaban  Side-effects are anaemia and haemorrhage  Contraindications of Apixaban are to avoid in conditions with significant risk of bleeding, gastrointestinal ulceration, malignant neoplasms (cancerous tumour cells) with high risk of bleeding and oesophageal varices  Prescription in ELDERLY PATIENTS is inappropriate – STOPP criteria = As there is significant risk of bleeding (e.g. severe hypertension)  Oesophageal varices – When there is abnormally dilated veins in the oesophagus, develops when the blood to the liver is  What is the pharmacodynamics of Heparin?  They are a family of sulphated mucopolysaccharides (also known as long chains of sugar molecules) that are found in the secretory granules of mast cells  It can be commercial prepared and can range in MW from 3000 to 30,000 Daltons  Mechanism of action: Inhibits the coagulation cascade by activating anti- thrombin 3 (ATIII)  ATIII is a naturally occurring inhibitor of thrombin & clotting factors IX, Xa, XI and XII  In the presence of heparin, AT III becomes ~1000x more active and inhibition of the clotting factors is instantaneous Low Molecular Weight Heparin (LMWH’s)  Dalteparin sodium, Enoxaparin sodium and Tinzaparin sodium  They are fragments of synthetic heparin and have more consistent activity  LMWHs mechanism of action is to inactivate factor Xa, thrombin (IIa) & activation of anti-thrombin III  Heparin and LMWHs have immediate onset of action  They are inactive when given orally (not absorbed by the GI tract), Administered by IV or SC (for LMWH’s SC), Heparin has a short half-life (low doses =