Pharm - Anticoagulants Flashcards
(51 cards)
What are the two acronyms to assess for risk of cardio embolic stroke
CHADS2 and CHA2DS2-VASc
What are the components of CHADS2
CHF HTN Age >75 yo Diabetes Stroke/TIA (2 points)
What are the components of CHA2DS2-VASc
CHF HTN Age 65-74 1 point Age >75 2 point Diabetes Stroke/TIA/systemic embolism Vascular disease (MI, PAD, aortic plaque) Gender: Female 1 point
what is the elevated risk associated with a mechanical mitral valve
greater risk for cardioembolism
22% chance/year
what is the elevated risk associated with a bioprostheitc aortic valve
elevated (but not high) risk for cardioembolism
12% chance/year
MoA Heparin
- Heparin binds to antithrombin
- Increases the effect of antithrombin on factors II, IX, X, X,I, and XII by >1000 fold
- Antithrombin inhibits coagulation by lysing thrombin (II) and other factors ultimately hindering formation of fibrin
Contraindications of Heparin for pt with clot medical hx
- Active uncontrollable bleeding
- History of HIT
Routes (2) of admin for UFH
IV
SubQ
When use IV route for UFH
- continuous effusion is best when a rapid and confirmed effect is needed.
- easier to titrate that IV bolus or subq
- use an empiric initial dose followed by titration based on response
UFH - how to use subq route
initial bolus and then maintenance dosing
appropriate monitoring parameter to assess heparin therapy
aPTT
Given a patient’s INR or aPTT result and the target range, identify the result as therapeutic, subtherapeutic, or supratherapeutic
I think we can all do this :)
What are the diagnostic criteria for heparin-induced thrombocytopenia (HIT)
- absolute thrombocytopenia (pat <150,000 OR >50% decrease from baseline)
- Occurs 5-10 days after initiation of heparin (if heparin naive) and can occur within 12 hours after dose if have used heparin in last 3 months.
- initial dx is clinical
- conformational assays drawn for HIT antibodies
Describe pathogenesis of heparin-induced thrombocytopenia
- Heparin forms complex with platelet factor 4 (PF4)
- Body forms antibodies against the heparin-PF4 complex
- Complexes aggregate and are removed from circulation prematurely, resulting in thrombocytopenia
- Venous or arterial thrombosis can occur – likely due to release of procoagulant particles from complex (counterintuitive)
What is the appropriate treatment for heparin-induced thrombocytopenia
- discontinue heparin
- anticoagulant with non-heparin product
- do not start warfarin until thrombocytopenia is resolved
- platelet transfusions are contraindicated, aggravate the problem (add fuel to the fire)
UFH reversal agent
protamine sulfate
MoA LMWH
- Interacts with antithrombin to accelerate inactivation of clotting factor Xa (mostly) and IIa (less so)
- Focus on Xa is major difference from UFH
Indication for LMWH
- Acute treatment of DVT/PE
- Prophylaxis of VTE in acutely ill pts or pts following some ortho procedures
What are the contraindications for LMWH for a pt with DVT
- history of HIT
- hypersensitivity to LMWH, UFH, or pork
- active major bleeding
- spinal puncture (black box!!)
Route for LMWH
subq
Reversal agent LMWH
protamine sulfate
What is the LWMH dosing regimen based on?
weight and renal function
MoA fondaparinux
Synthetic based on structure of heparin. Enhances antithrombin’s effect on Xa but no effect on IIa
MoA Warfarin
Vitamin K antagonist → inhibits the production of clotting factors II, VII, IX, and X (vitamin K dependent factors)
