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Flashcards in Anticoagulants II Deck (40)
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1

coumarin/Coumadin's uses

Prophylactic use: Prevention of thrombotic disorders

Therapeutic use: Treatment of established thrombus

2

Coumadin inhibits which factors

factors II, VII, IX, and X

3

warfarin's structure is similar to

vitamin K

4

warfarin/coumadin's MOA

All agents depress the formation of functional forms of factors II (prothrombin), VII, IX and X by inhibiting the carboxylation of glutamic acid in these proteins which is essential for Ca+2 binding. (blocks vit k synthesis)

factors are still present but not functional

5

onset of warfarin/coumadin

long- takes 8 to 10 hours before the amount of active factors decreases, 3-5 days before a pt is properly anti-coagulated.

due to binding of albumin in the plasma

therefore it is not use when a pt presents to the ER with a thrombus but can be given for them to take afterwards at home

6

bioavailability of warfarin/coumadin

100%

7

metabolism of warfarin/coumadin

hydroxylated to inactive compounds by the hepatic endoplasmic reticulum.

varies greatly between patients therefore pts must be monitored

8

which pathway does warfarin/coumadin affect

extrinsic

9

what do you use to monitor warfarin/coumadins effects

Prothrombin time (PT)/INR

10

what deviation from baseline is needed for warfarin to be in the therapeudic range

a PT of 1.5 times baseline

11

INR

Reagent based variations have been noted in the prothrombin time. To obtain uniform degrees of anticoagulation, the concept of international normalized ratio (INR) has been introduced.

The INR can be used universally to adjust the level of anticoagulant in a given patient. Thus it helps in the optimization of dosage .

ratio of the patients PT divided by the mean normal control

12

what are some factors that affect the dose of warfarin/coumadin that you want to give a patient

Nutrition
Anemia
Liver disease
Biliary obstruction
Drugs

13

how does diet affect warfarin

green leafy vegetables high in vitamin K decrease the affects of warfarin/coumadin

14


 how do Drugs cause warfarin potentiation

by causing vitamin K deficiency.
by displacing warfarin from protein binding sites.
by decreasing clotting-factor synthesis.
by suppressing or competing for microsomal enzymes.
by having antiplatelet aggregating properties.

15

how do drugs cause inhibition of the anticoagulant action of warfarin

by decreasing warfarin absorption.
by enhancing warfarin metabolism.

16

Toxicity of Warfarin

* hypoprothombinemia resulting in ecchymosis, purpura, hematuria, hemorrhage.

*All oral anticoagulants pass the placental barrier and may cause fetal malformation

necrosis (due to non-functionality of protein C)

17

how is protein C affected by warfarin and how does this affect the patient

protein C non-functioning in the presence of warfarin. functional protein C's levels drop before the other factors. Because protein C is an anticoagulant and inhibits factors V and VII, initially there is an increased tendency to clot

18

Treatment of oral anticoagulant overdose

1. Replacement of 4 factors. Infusion of whole fresh blood or frozen plasma.
2. Recombinant Factor VIIa
3. Vitamin K

19

Function of Vitamin K

Essential to the attachment of a calcium binding functional group to prothrombin protein (presence of γ carboxyglutamic acid).

Required for the synthesis of clottable coagulation factors (II, VII, IX and X).

20

Therapeutic use of Vitamin K

Drug induced hypoprothrombinemia antidote.
Intestinal disorders and surgery (gastrectomy).
Hypoprothrombinemias of newborn.

21

toxicity of Vitamin K

Very non-toxic

High doses sometime cause hemolysis in infants (mainly water soluble vitamin K).

Certain individuals who are sensitive to primaquine may develop hemolysis.

22

anti Xa agents

Rivaroxaban (Xarelto)
Apixiban

23

Antithrombin Agent

- Dabigatran

24

characteristics of new oral anticoagulants (anti-Xa and antithrombin)

given orally
mono-therapeudic drugs

25

oral anticoagulants (anti-Xa and antithrombin) uses

stroke prevention in people who previously had a DVT

or treatment of a DVT

26

advantages and disadvantages of oral anticoagulants (anti-Xa and antithrombin)

they do not need to be monitored but also a disadvantage is you cannot monitor them therefore is emergency surgery is needed you do not know how much is present.

27

rivaroxaban target

factor Xa

28

rivaroxaban dosing

fixed once per day

29

rivaroxaban monitoring

no

30

rivaroxaban clearence

65% renal