Anticoagulants

Question 0

Vascular injury

Answer 0

Platelets adhere

Tissue factor is released

Question 1

Anticoagulant

Answer 1

Targets clotting factors/cascade

Question 2

Virchows triad for thrombus formation

Answer 2

1) Damaged endothelium
2) Hypercoagulability: smoking, estrogen
3) slow blood flow

Question 3

Arterial thrombi

Answer 3

Prevent/TX: antiplatelet, anticoagulant agents

Due to high blood flow

Question 4

Venous thrombi

Answer 4

Static blood flow
High clotting factors

Prevention/tx: anticoagulants

Question 5

Vitamin K factors

Answer 5

2, 7, 9, 10

Target major sites 2,10 are most important

Question 6

UFH

Answer 6

Inhibit II, X equally, binds ATIII

Nonlinear dose response

Interpatient clearance variability based on weight

Easily reversible with protamine

Question 7

LMWH

Answer 7

Inhibit II and X (more X)

Linear Dose response

Lovenox SC

Dose adjustment in renal impairment

Question 8

Fondaparinux

Answer 8

X inhibitor

Linear dose adjustment

Once daily dosing

Contraindicated in CrCl <30

Question 9

Heparin

Answer 9

Accelerates ATIII activity to neutralize clotting factors (Xa IIa)

Question 10

Warfarin pharmacometrics

Answer 10

Blood levels
Inhibit vit K reductase
Synthesis rate and half-life
INR prothrombin time

Question 11

Warfarin pharmacokinetics

Answer 11

S isomer more active than R

Highly protein bound

S-2C9 metabolism R-3A4

Inhibits vitamin K VKOR (coagulation protein production)

Vitamin K antidote if INR>10

Smoking increases clearance
Chronic alcohol increases metabolism

Overall elimination not a factor

Question 12

Warfarin onset

Answer 12

Based on clotting factor degradation

Protein C, S limit thrombosis but degrade first place causing increased prothrombin time

1-3 weeks to reach stable INR

Question 13

Warfarin inhibition

Answer 13

S:Fluconazole, Amiodarone
R: quinolones (levofloxacin)

Variance explained by VKOR and 2C9 differences

Question 14

Warfarin INR goals

Answer 14

2-3 in normal patient

2.5-3.5 if prosthetic heart valve

Question 15

Acetaminophen

Answer 15

Analgesic of choice for those on warfarin

Question 16

Dabigatran

Answer 16

IIa inhibitor

Affected by Pgp and 3A4

Requires renal function

BID dosing

Question 17

New oral anticoagulants appropriate

Answer 17

CrCl>30
Difficulty with INR a monitoring
Concern with food interactions

NOT for prosthetic valve, renal impairment, GI bleed, noncompliance, cost