Coagulants and Anti-Coagulants

Question 1

What are physiological activators of platelets?

Answer 1

Thrombin
ADP
Epinephrine 
Collagen
Arachidonic acid
Thromboxane A2

Question 2

What are platelet inhibitors?

Answer 2

Prostacyclin

Nitric oxide

Question 3

What state does the body prefer?

Answer 3

Vasodilation and anticoagulant state

Question 4

What produces thrombin to stimulate platelets to release arachadonic acid?

Answer 4

Collagen

Question 5

What is arachidonic acid converted to for an inc in platelet aggregation?

Answer 5

Thromboxane

Question 6

What is heparin?

Answer 6

Prevention of venous thrombosis
Treatment of deep venous thromboembolism
Early treatment of pts with unstable angina and acute MI

Question 7

Normal heparin is in a ______ preparation.

Answer 7

Heterogeneous

Question 8

What releases the heparin to bind at more sites?

Answer 8

Antithrombin-protease interaction

Question 9

What does the half-life depend on for heparin?

Answer 9

Dose

Question 10

What is a major complication of heparin?

Answer 10

Bleeding excessively
Thrombocytopenia
Osteoporosis with long time use

Question 11

What is the molecule difference between low molecular weight heparin (LMWH) and regular heparin?

Answer 11

More homogeneous mixture

Question 12

What are the characteristics of LMW heparin?

Answer 12

Reduced interaction with platelets
Half-life is twice and long
Bio-availability at 90%
More predictable anticoagulant response

Question 13

How can heparin toxicity be minimized?

Answer 13

Right pt
Careful control of dose
Close monitoring of aPTT

Question 14

What should be done for all pts receiving heparin?

Answer 14

Platelet count should be performed frequently

New thrombus

Question 15

When should heparin be discontinued?

Answer 15

If thromboembolic disease is due to heparin

Question 16

What are the contraindications for heparin?

Answer 16

Hypersensitivity
Active bleeding
Co-morbidies

Question 17

How must heparin be administered?

Answer 17

IV dose parenterally
Intermitten
NEVER IM

Question 18

What should be done for heparin reversal?

Answer 18

Administer protamine sulfate (negates anticoagulant action)

Question 19

How does warfarin work?

Answer 19

Blocks the carboxylation of glutamate residues in prothrombin, factors VII, IX and X and proteins C and S
Results in biologically inactive molecules - no coagulation
Interferes with vit K

Question 20

What does warfarin prophylax or treat?

Answer 20

Venous thrombosis + extension
Pulmonary embolism
Thrombic complications

Question 21

What are the major adverse effects of warfarin?

Answer 21

Hemorrhage

Crosses the placenta and is teratogenic

Question 22

What is considered the most reliable clinical test for clotting?

Answer 22

Prothrombin time (PT)

Question 23

What is the International Normalized Ratio (INR)?

Answer 23

Mathematical correction of the PT ratio for differences in sensitivity of thromboplastin reagents

Question 24

Should a large loading dose of warfarin be used?

Answer 24

Probably not

Question 25

When switching from heparin to warfarin, how should it be cone?

Answer 25

Can be started along with heparin | Heparin should be continued for at least 4 days

Question 26

What should the dosing monitoring for warfarin be like?

Answer 26

Start with a low dose (5 mg) Stabilize the dose via INR and monitor Adjust if/when necessary Monitor INR regularly

Question 27

What are the signs of warfarin OD?

Answer 27

Unsual bleeding | in stool or urine, excessive menstral bleeding, nose bleeds or gums, bleeding from tumor, ucler or lesions

Question 28

If warfarin falls below INR 2.0 what occurs?

Answer 28

A diminished effect

Question 29

If warfarin falls below INR 1.5 what occurs?

Answer 29

No efficacy

Question 30

If warfarin is above INR 4 what occurs?

Answer 30

Safety is compromised

Question 31

What are the warfarin analogs?

Answer 31

Dicumarol (incomplete absorb, GI issues) | Phenindione (Renal and hepatic effects)

Question 32

What should be for warafin reversal?

Answer 32

Discontinue drug Administer vit K May need plasma, prothrombin complex or VIIa

Question 33

What are the new oral anticoagulants?

Answer 33

Dabigatran Rivaroxaban Apixaban

Question 34

What is the mechanism of action for dabigatran

Answer 34

Factor Iia Inhibitor Prodrug - converted by nonspecific esterases in plasma and liver Reversibly and competitively binds to active site free and clot-bound thrombin (factor IIa)

Question 35

What are the indications for dabigatran?

Answer 35

Prevention of stroke and systemic embolism in pts with atrial fibrillation Primary prevention of venous thromboembolism

Question 36

What are the side effects to dabigatran?

Answer 36

Excessive bleeding | Severe dyspepsia

Question 37

What is the mechanism of action for rivaroxaban?

Answer 37

Factor Xa inhibitor | Binds to active site of factor Xa and affects free and platelet bound factor Xa

Question 38

What are the indications for rivaroxaban?

Answer 38

Primary prevention of venous thromboembolism | Prevention of stroke and systemic embolism in pts with AF

Question 39

What are the side effects of rivaroxaban?

Answer 39

``` Mild hepatic impairment Bleeding Musculoskeletal pain Pruitus Blisters Upper ab pain Syncope ```

Question 40

What is apixaban?

Answer 40

Oral direct inhibitor of factor Xa | Selective and reversible inhibitor of free and clot-bound factor Xa as well as prothrombinase activity

Question 41

What are the indications for apixaban?

Answer 41

Prevent stroke and systemic embolism in AF | Primary prevention of venous thromboembolism

Question 42

What is Ecarin Clotting Time?

Answer 42

Meizothrombin generation test used to measure thrombin inhibitors Added to plasma an time to clot formation is measured

Question 43

How does aspirin work?

Answer 43

Blocks prostoglandin synth by inhibiting cycooxygenase | Thromboxane A2 formation is inhibited

Question 44

When do hemostatic levels return to normal after using aspirin?

Answer 44

36 hours

Question 45

What is the most common side effect of aspirin?

Answer 45

GI irriation

Question 46

How do fibrinolytics create a lytic state?

Answer 46

By breaking down hemostatic thrombi and thromboemboli

Question 47

Streptokinase

Answer 47

Protein synthesized by streptococci | Combines with proactivator plasminogen

Question 48

Urokinase

Answer 48

Human enzyme synthesized by kidney | Converts plasminogen to active plasmin

Question 49

Ticlodipine

Answer 49

Metab by liver Renal impairment inc plasma conc Prevention of recurrence of thrombic stroke

Question 50

What are the adverse events of ticlodipine?

Answer 50

GI issues Leukopenia Thrombic thrombocytopenia purpura Side effects limited when dose below 500 mg/d