Anticoagulants Flashcards
Direct Thrombin Inhibitors (DTIs)
MOA: Directly inactivates Factor IIa, impeding the activation of Factor I to fibrin
Direct Thrombin Inhibitors
Hirudin
Lepirudin
Bivalirudin
Argatroban
Dabigatran
Used for the Mx of HIT (Heparin Induced Thrombocytopenia)
Hirudin - Derived from Hiruda medicinalis (medicinal leeches)
Lepirudin - Recombinant form of Hirudin; less associated with hypersensitivity reactions
Toxicity of Hirudin/Lepirudin
Bleeding (monitor with aPTT)
Anaphylactic reactions
Management: Idarucizumab + Activated Charcoal + Aminocaproic Acid
Used in the management of acute thrombosis post-angioplasty
Bivalirudin
Parenteral
Prophylaxis and treatment of thrombosis in patients with HIT
Argatroban
First oral direct thrombin inhibitor
Dabigatran
Alternative to Warfarin
Dabigatran
Alternative for
* Stroke prophlaxis, prevention in px with atrial fibrillation
* Management of vascular thromboembolic events
* Deep Vein Thrombosis (DVT)
Advantages of Dabigatran
- No PT-INR monitoring required
- No significant drug interaction (drug-food)
- AE: Hemorrhage
Indirect Thrombin Inhibitors
Heparin
Unfractionated Heparin (UFH) / Regular Heparin
Low Molecular Weight Heparinm(LMWH)
Warfarin
Mixture of sulfated mucopolysaccharides
MW: 5,000 - 30,000
Heparin
ACIDIC, PARENTERAL
Clinical Uses of Heparin
Initiating anticoagulation therapy
Management of acute coronary syndrome
Management of Deep Vein Thrombosis, VTE (venous thromboembolism), pulmonary embolism
Anticoagulant for Pregnant women
Heparin
Monitoring needed for Heparin
Activated Partial Thromboplastin Clotting Time (aPTT)
Adverse Effects of Heparin
Bleeding/Hemorrhage (Tx: Protamine sulfate)
HIT (heparin-induced thrombocytopenia)
Alopecia
Osteoporosis with chronic use
CI: Active Bleeding, Thrombocytopenia
MOA of Unfractionated Heparin (UFH) / Regular Heparin
Forms an active complex with ATIII by 1000-fold; inactivation of IXa, Xa, XIa, XIIIa
Routes of Admin for Unfractionated Heparin
- IV bolus (80M/kgBW) or IV infusion (180 units/kgBW/hr)
For the management of venous thromboembolism, DVT, embolism - IV Bolus (50M/kBW) or IV Infusion (12-15mg)
Management of acute coronary syndome (MI) - Monitoring for IV infusion:
aPPT: activated partial prothrombin time
Goal: 60-85 sec delay!
<40: underdose
>40: overdose
Low Molecular Weight Heparin (LMWH)
Enoxaparin
Dalteparin
Tinzaparin
Fondaparinux
Dalteparin, Enoxaparin
MOA: Inactivates Xa
MW: 2,000 - 9,000
Less affinity to thrombin
Route: SQ
Monitoring: None required
Fondaparinux
Selective inhibitor of Xa
Synthetic LMWH
No aPTT
MOA of Warfarin
- Inhibits vitamin K epoxide reductase (inactive from of Vitamin K)
- Interferes with production of functional vitamin K-dependent clotting and anticlotting factors (II, VII, IX, X)
- Inhibits Protein C & S (endogenous anticoagulants/anticlotting factors)
Effects of Warfarin
Initial: Transient procoagulation Effect
Mx: Add LMW Heparin
Final: ANTICOAGULATION
Doses of Warfarin
Dosing for Caucaseans: 5mg daily
Dosing for Asians: 1-2 mg daily
(lower dose because there is less
expression of VKERC)
Clinical Use of Warfarin
For chronic anticoagulation
* Chronic atrial fibrillation
* Prosthetic heart valve
* Rheumatic heart disease (RHD)
* DVT, VTE
Contraindications for Warfarin
Contraindicated to Pregnants
Fetal Warfarin syndrome
Monitoring of Warfarin
- PT-INR (prothrombin time - international normalized ratio)
- Goal: 2-3 (most patients)
- 2.4-3.5 : patients with prosthetic heart valve
- > 2: underdose (thrombosis)
- > 3.5: overdose (hemorrhage)
Adverse Effects of Warfarin
Bleeding/Hemorrhage (tx: Vit K1, Fresh plasma, F IX)
Cutaneous Necrosis due to procoagulant effect
Purple Toe Syndrome
Drug Interactions of Warfarin
Increased PT-INR (Hemorrhage)
Warfarin + Cimetidine = Decreased metabolism of
Warfarin + Antibiotics
Warfarin + Aspirin
Warfarin + Hyperthyroidism
Decreased PT-INR (Thrombosis)
Warfarin + Phenobarbital
Warfarin + Green Leafy Vegetables
Warfarin + Hypothyroidism
Active Factor X Inhibitors
Newer Oral Anticoagulants (NOACs/NOVEL)
Rivaroxaban, Apixaban, Edoxaban
Antidote: r-Antidote
Anti-Coagulants
Direct Thrombin Inhibitors
* Hirudin
* Lepirudin
* Bivalirudin
* Argatroban
* Dabigatran (Oral)
Indirect Thrombin Inhibitors
* Warfarin
* Heparin
* Unfractionated Heparin
* LMWH (Dalterparin, Enoxaparin, Tinzaparin) - SQ, IV
* Fondaparinux
Newer Oral Anticoagulants
* Apixaban
* Edoxaban
* Rivaroxaban