anticoagulants Flashcards
Either (med class) _____________ or fondaparinux are used instead of heparin in patients that have heparin-induced thrombocytopenia (HIT).
direct thrombin inhibitors
What is the MOA of rivaroxaban?
It is an anticoagulant that functions by binding to and directly inhibiting the activity of Factor Xa. It can be used to prevent pulmonary embolism.
What is the most common adverse effect of Rivaroxaban (factor Xa inhibitors)?
Bleeding, there is no specific antidote
Heparin is the drug of choice for the prevention and acute management of?
DVT
Heparin is an anticoagulant that can be found in the dense granules of ?
basophils
Heparin can enhance the activity of?
antithrombin
What is used to treat for heparin toxicity?
Protamine sulfate
What is the hematological toxicity of heparin?
Thrombocytopenia
What is the bleeding parameter that we use to monitor the effect of heparin?
Partial thromboplastin time
Common adverse effect of heparin is
bleeding
What has low molecular weight that functions similarly to normal heparin, however they act more on factor Xa?
Enoxaparin
What are the two coagulation factors that primarily targeted by heparin?
Thrombin/factor IIa and factor Xa
LMWH or HMWH has better bioavailability and two to four times longer half-life?
LMWH
Which LMWH or HMWH does not require laboratory monitoring?
LMWH
What is the medication of choice to achieve immediate coagulation and what is it route of administration?
Heparin; parental, intravenous or subcutaneous
What deficiency is a hereditary thrombosis syndrome that involves a decreased ability to inactivate factors Va and VIIIa, thereby increasing the risk of thrombotic skin necrosis and hemorrhaging following warfarin administration?
Protein C and S deficiency
What is the type of blood transfusion therapy that is used to treat warfarin overdose?
Fresh frozen plasma
What is preferred and commonly used for long term prevention of DVT reoccurence?
Warfarin
Griseofulvin is an antifungal which typically (increases/decreases) warfarin metabolism.
increases
Fresh frozen plasma as well as ___________ are used for actively bleeding patients on warfarin?
Vitamin K
What is the bleeding parameter that we use to monitor effect of warfarin?
PT or INR
MOA of warfarin
inhibition of vitamin K epoxide reductase
Which drug is an oral anticoagulant that is metabolised by the cytochrome P450 pathway?
warfarin
What is commonly used as an anticoagulant of choice for the prevention of stroke in atrial fibrillation, especially if patients have a metal valve?
Warfarin
Warfarin use in pregnancy is category?
X
The treatment for severe warfarin overdose is ______________ along with vitamin K.
prothrombin complex concentrate
Common adverse effect of warfarin and how to reverse the effects?
Bleeding; vitamin K
Factor _____ is the first clotting factor reduced after initiating warfarin therapy?
VII
Warfarin effect is tracked through the (intrinsic/extrinsic) coagulation pathway?
extrinsic
An international normalised ratio (INR) of ______ is the optimal target range for prevention and treatment of thrombosis with warfarin.
2-3
Warfarin has an (immediate/delayed) onset of action.
delayed
*warfarin has long half-life
What is often co-administered at the start of warfarin therapy to reduce coagulation induced by protein C and protein S inhibition.
Heparin
**When someone starts taking warfarin, it initially has a complex effect on their blood. One of the things it does is interfere with the activity of proteins C and S, which are natural “brakes” that help prevent the blood from clotting too much.
However, in the beginning, warfarin doesn’t reduce the production of these proteins right away. So, for a short period, while warfarin is starting to work, there’s a temporary imbalance in the blood. It becomes more prone to forming blood clots.
To prevent this early period of increased clotting risk, doctors often coadminister heparin. Heparin is a fast-acting anticoagulant that can help keep the blood from getting too “sticky” while warfarin is taking its time to fully work.
Think of it like this: Warfarin is a slow starter, like a car that takes a bit of time to warm up. Heparin is like a temporary safety net. It steps in right away to make sure you’re protected from excessive blood clotting until warfarin gets up to speed and can do the job on its own.
So, heparin and warfarin work together in the beginning to provide a smoother transition, ensuring you’re not at risk of dangerous clots while warfarin is gearing up for its full anticoagulant action.
By which enzyme system of the liver is warfarin metabolised?
CYP-450
What are the tetratogenic effects of warfarin?
Bone deformities, fetal hemorrhage, abortion and ophthalmologic
Why we use PTT to monitor heparin but PT to monitor warfarin?
Heparin and warfarin are both anticoagulant medications, but they work in different ways and affect different aspects of the blood clotting process. As a result, they are monitored using different laboratory tests:
- Heparin primarily works by enhancing the activity of antithrombin III, a natural protein in the body that inhibits blood clot formation. It mainly affects the intrinsic pathway of blood clotting. Therefore, the Partial Thromboplastin Time (PTT) test is used to monitor the effectiveness of heparin. PTT measures the time it takes for blood to clot through the intrinsic pathway. When a patient is on heparin therapy, the PTT is regularly checked to ensure that the blood remains within the desired level of anticoagulation.
- Warfarin interferes with the synthesis of several clotting factors in the liver, particularly factors II (prothrombin), VII, IX, and X. It primarily affects the extrinsic and common pathways of blood clotting. To monitor the effectiveness of warfarin, the Prothrombin Time (PT) test is used. PT measures the time it takes for blood to clot through the extrinsic and common pathways. The results are usually reported as the International Normalized Ratio (INR), which allows for standardization of PT values and comparison across different laboratories. INR is used to assess and adjust warfarin dosage to maintain the desired level of anticoagulation.
In summary, heparin and warfarin are monitored using different tests because they target different aspects of the clotting cascade. Heparin affects the intrinsic pathway, so PTT is used, while warfarin affects the extrinsic and common pathways, so PT/INR is used. These tests help healthcare providers ensure that the patient’s blood remains at an appropriate level of anticoagulation while minimizing the risk of bleeding or clotting complications.
