CVS Drugs Flashcards
what is hemostasis?
The physiologic process by which bleeding is stopped.
What are the 2 stages of hemostasis?
a) Formation of a platelet plug
b) Reinforcement of the platelet plug with fibrin.
How is a platelet plug formed?
-Platelets come in contact with collagen then adhere to site of vessel injury.
What is platelet aggregation?
Complex process that ends with formation of fibrinogen bridges between glycoprotein receptors on adjacent platelets. Glycoprotein receptors must be activated for this to happen.
What is coagulation?
Production of fibrin.
How is fibrin formed and what are the 2 pathways can be produced by?
Produced by two pathways- contact activation and tissue factor pathway.
How is the tissue factor pathway triggered?
Trauma to the vascular wall, which triggers release of tissue factor (thromboplastin)
What are the three things thrombin does?
a) Catalyzes the conversion of fibrinogen to fibrin.
b) Catalyzes the conversion of factor V into its active form.
c) Catalyzes the conversion of factor VIII into its active form.
How is the contact activation pathway triggered?
Triggered when blood makes contact with collagen that has been exposed as a result of trauma to a blood vessel wall.
What 4 factors require vitamin K?
Factors 7, 9, 10 and 2.
What enzyme removes blood clots in the body?
Plasmin.
What is arterial thrombosis?
the formation of an arterial thrombus in the arterial wall.
What is venous thrombosis?
Thrombosis in the venous walls. May result in embolus.
What are the 3 categories of drugs used to treat thromboembolic disorders?
a) anticoagulants
b) Antiplatelet drugs
c) Thrombolytic drugs
What do anticoagulants do?
Reduce formation of fibrin.
What are the 2 classes for anticoagulants?
a) Direct factor Xa inhibitors
b) direct thrombin inhibitors
What is the mechanism of action for heparin?
Enhance the activity of antithrombin.
How does antithrombin work?
It inactivates thrombin and factor Xa.
What are the 2 types of heparin?
- Unfractionated heparin
- Low-molecular-weight heparins
What is unfractionated heparin?
Rapid acting anticoagulant administered only by injection.
What is the mechanism of action for heparin?
Supresses coagulation by helping antithrombin inactivate clotting factors (thrombin and factor Xa). Heparin binds with thrombin and antithrombin to inactivate thrombin.
What is it about heparin that makes it hard to cross membranes?
- Fat
- Juicy
- Highly Polar
What are the therapeutic uses of heparin?
-used for pregnant women.
-pulmonary embolism
- massive deep vein thrombosis
- open heart surgery
- renal dialysis
-PE
-stroke evolving
-low dose therapy postoperatively
Also used for thrombolytic therapy for MI.
What are the adverse effects of heparin?
Hemorrhage, spinal hematoma, heparin induced thrombocytopenia, hypersensitivity reactions.
What are the signs of blood loss?
- BP drop
- HR
- bruises
- petechiae
- hematomas
- cloudy urine
- pelvic pain
What is heparin-induced thrombocytopenia?
Reduced platelet counts and increase in thrombotic events.
What are the contraindications of heparin?
Pts with thrombocytopenia, uncontrollable bleeding.
What is the antidote for heparin overdose?
Protamine sulfate.
How is heparin administered?
IV or subcut ONLY.
What is low-molecular weight heparins?
Heparins that are composed of shorter molecules. Equally as effective as unfractionated heparin. Easier to give and dont need aPTT monitoring.
What is the mechanism of action for LMW heparins?
Same as heparin, except it inactivates factor Xa more than thrombin because of its size.
What are the therapeutic uses of LMW heparins?
a) Prevention of DVT
b) Treatment of DVT
c) Prevention of ischemic complications in pts with unstable angina.
What is the MA of warfarin?
Suppresses coagulation by decreasing the production of factors 7,9,10 and prothrombin. Warfarin inhibits the enzyme needed to convert vit K into its active form, which inhibits the creation of the clotting factors.
What are the therapeutic indications for Warfarin?
a) Prevention of venous thrombosis and PE.
2) Prevention of thromboembolism in pts with prosthetic heart valves
3) prevention of thrombosis in pts with afib.
How is warfarin monitored?
Prothrombin time (PT) test. Average is 12 seconds. Warfarin treatment prolongs PT International normalized ratio used to interpret results. INR can be monitored at home.
What are the adverse effects of warfarin?
Hemorrhage. not recommended for pregnant and lactating women.
What are the 3 categories of drugs that interact with warfarin?
a) Drugs that increase anticoagulant effects
b) Drugs that promote bleeding
c) Drugs that decrease anticoagulant effects
What are the mechanisms that increase the effects of warfarin?
a) Displace warfarin from plasma albumin
b) inhibit hepatic enzymes that degrade warfarin
c) decrease synthesis of clotting factors.
What are the mechanisms that decrease the effects of warfarin?
a) Accelerate warfarin degeneration
b) increase clotting factors
c) inhibit warfarin abosprtion.
What drugs produce interactions with warfarin?
a) Heparin
b) Aspirin
c) Nonaspirin Antiplatelet drugs
d) Acetaminophen
What is warfarin contraindicated for?
- Pts with severe thrombocytopenia
- Uncontrollable bleeding
- Pts undergoing lumbar puncture, surgery of eye, brain, spinal cord.
What is the antidote for warfarin overdose?
Vit K b/c it antagonizes warfarin’s actions.
What are the major differences between warfarin and heparin?
- use different mechanisms to decrease fibrin formation
- given different routes.
- different tests used to monitor effects.
- management of overdose is different,
What is the MA for aspirin?
Causes platelet aggregation by causing irreversible inhibition of cyclooxygenase (enzyme used for platelet activation). Suppresses TXA2 vasoconstriction and platelet aggregation, reducing the risk of arterial thrombosis.
How long can a single dose of aspirin last?
7-10 days (b/c the effects are irreversible)
What are the therapeutic indications of aspirin?
- Ischemic stroke
- TIAs
- Chronic Stable Angina
- Unstable Angina
- Coronary Stenting
- Acute MI
- Previous MI
- Primary prevention of MI
What are the adverse effects of aspirin?
- GI bleeds
- Hemorrhagic stroke
What test is heparin monitored with?
aPTT (activated partial thromboplastin time)
What is INR?
international standard clotting time for blood. Measured for warfarin
