Antiplatelet, Anticoagulation and Hemostatic agents Flashcards
(116 cards)
Warfarin MOA
○ Molecule is structurally related to Vitamin K
○ Binds Vitamin K Oxide Reductase, inhibiting it
■ Inhibits ability to activate Vitamin K (factors II, VII, IX, X, Protein S, & C)
Warfarin indications
○ VTE (DVT/PE) prophylaxis
○ VTE treatment
○ Stroke prevention with A-Fib
○ Prevention of mechanical heart valve
thrombosis
Warfarin Contraindications
○ Pregnancy (teratogenic and risk of fetal bleeding)
○ Active bleed or high risk for bleed (like Thrombocytopenia)
○ Blood dyscrasia
○ Recent major surgery
○ Eclampsia or Preeclampsia
○ Frequent falls or high risk for falls
○ Dozens of Drug-Drug interactions! (Use Interaction Checker!)
Warfarin Side effects
○ Easy bruising
○ Bleeding gums
○ Nausea/vomiting/diarrhea
○ Fatigue and malaise
○ Headaches
○ Dizziness
○ Taste changes
Warfarin Major adverse reactions
○ Intracranial hemorrhage (often
fatal)
○ Skin necrosis
○ GI hemorrhage
○ GU hemorrhage
Warfarin BBW
○ Major or fatal bleeding may occur. Monitor high risk patients closely.
INR > 4.0 is very high risk for bleed
Warfarin (Coumadin) administration and surgery
If surgery planned, D/C warfarin 5 days before procedure. Restart 12-24 hours after
procedure. Bridge w/ a Heparin in high VTE risk.
Warfarin follow up/monitoring
○ Considered contraindicated in pregnancy unless Pt has mechanical heart valve, then need
to weigh risks/benefits. Probably safe with lactation.
○ Adjust doses based on PT/INR. Target INR is 2-3 for most; Some high-risk patients may
require target INR 2.5-3.5.
○ Local “coumadin clinics” are extremely helpful with monitoring.
Indirect Thrombin Inhibitors - Heparin
○ AKA - Unfractionated Heparin (UFH)
■ Mixture of proteins with a wide range of
molecular weights
Low Molecular Weight Heparins
(LMWHs)
○ Enzymatically or chemically broken down UFH, about 1⁄3 the size of UFH
■ Enoxaparin (Lovenox)**
■ Dalteparin (Fragmin)
■ Fondaparinux (Arixtra)
Indirect Thrombin Inhibitors MOA
○ Antithrombin III inhibits Factor
X and Thrombin
○ Heparin binds to Antithrombin
III and accelerate its rate of action by about 1000 fold
○ UFH: Thrombin ___ Factor X
○ LMWH: Factor X ___ Thrombin
> ; >
Indications (SC, IV) of UFH and LMWH
■ Prevention of thrombosis with Atrial
Fibrillation and PCI
■ VTE Prophylaxis in high risk patients
■ Treatment of acute VTE
■ Treatment of Acute Myocardial Infarction
and unstable angina in combo with
antiplatelet Rx
○ Enoxaparin (Lovenox) is the drug of choice during pregnancy
Indirect Thrombin Inhibitors contraindications
○ Thrombocytopenia
○ Personal history of Heparin-Induced Thrombocytopenia
○ Hemorrhage or active bleed
○ Not to be given as an IM administration
○ Hypersensitivity to Pork or Corn
Indirect Thrombin Inhibitors Minor Side Effects
○ Urticaria
○ Fever
○ Minor elevation in ALT, AST
Indirect Thrombin Inhibitors Major Adverse Reactions
○ Osteoporosis with long-term use
○ Hemorrhage (reversed by Protamine Sulfate)
○ Heparin-Induced Thrombocytopenia
○ Anaphylaxis
○ Hepatotoxicity
BBW Indirect Thrombin Inhibitors
High risk for Epidural/Spinal hematoma from acute hemorrhage during lumbar puncture or spinal injection. Can cause acute spinal cord or spinal nerve compression
Follow up and monitoring - UFH
○ UFH can be given IV or SC
■ Usually IV bolus for immediate anticoagulation, then continued until PO anticoagulant takes over
– Anticoagulant effect within minutes of IV administration
■ Monitor closely using PTT or Heparin Anti-Xa
Monitor platelets daily if on IV UFH, for at least 10 days
Follow Up and Monitoring - LMWHs
■ Peak effect is reached in 2-4 hours
■ Don’t routinely need to be monitored, but if renal insufficiency or
pregnancy, can check Heparin Anti-Xa
If drop in platelet count by more than ___%
from baseline, D/C medication as now
there is concern for HIT
50
Direct Thrombin Inhibitors
● Bivalirudin (Angiomax)
● Argatroban (Acova)
● Dabigatran (Pradaxa)**
Direct Thrombin Inhibitors
○ Just as the name implies, these
work by directly inhibiting Thrombin
○ Inhibitory effects on the Coagulation Cascade
Direct Thrombin Inhibitors Indications (IV, PO)
Bivalirudin and Argatroban are only IV
– Anticoagulation during HIT
– Prevention of thrombosis during PCI (in presence of Heparin
allergy/HIT)
Dabigatran is a PO capsule
● Stroke prevention in Atrial Fibrillation
● DVT/PE prophylaxis in high risk patients
● DVT/PE treatment
Direct Thrombin Inhibitors contraindications
○ Active bleeding
○ History of a bleeding disorder
○ Peptic ulcer disease
○ Mechanical Heart Valve Anticoagulation