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Flashcards in Oral Anticoagulants Deck (29):
1

What are the oral anticoagulants?

Warfarin (coumadin), Dabigatran (Pradaxa), Rivaroxaban (Xarelto), Apixaban (Eliquis)

2

Warfarin MOA

Reversibly binds and inhibits enzymes which converts inactive vit K to active vit K, decreases production of vit K-dependent clotting factors; decreases production of natural anticoagulants protein C and S

3

Warfarin (Coumadin) facts

racemic mixture, well absorbed (100%) highly protein bound to albumin, average T1/2: 36-42 hours

4

Warfarin (Coumadin) monitoring

Done with INR, responsive to depression of factors II, VII and X; initial prolongation due to factor VII, antithrombotic effect requires 5-7 days of treatment

5

Challenges associated with warfarin

Drug interactions, frequent monitoring, food interactions, genetic variances in metabolism, narrow therapeutic index, disease state interactions, long/variable half-life, stigmas

6

Factors that increase the effects of warfarin

hyperthyroidism, fever, liver disease, acute heart failure, diarrhea/vominting, genetics

7

Factors that decrease the effects of warfarin

hypothyroidism, fat malabsorption, genetics

8

Drug interactions of warfarin that increases effect

ciprofloxacin, bactrim, alcohol, citalopram, fish oil, propranolol etc

9

Drug interactions of warfarin that decrease effect

griseofulvin, ribavirin, rifampin, mesalamine, barbiturates, high vit K foods

10

Clinical uses of warfarin

prevention of stroke in patients with afib, VTE, history of stroke, VTE prophylaxis

11

Exception to goal 2-3 INR in pt taking warfarin

pt with mechanical valves, goal is slightly higher

12

What is bridge therapy

treating patients with concurrent anticoagulants to bridge the gap between when the warfarin is initiated and when it is therapeutic

13

What is most common drug used with bridge therapy

enoxaparin

14

Pros of early therapeutic INR

decreased length hospital stay, decreased cost of and exposure to using injectable anticoagulants

15

Cons of early therapeutic INR

risk of bleeding, increased hospital stay and cost, clouded picture of patient's maintenance dose

16

Risk factors for bleeding

patient older than 75 yo, bleeding history, serious comorbid conditions, HTN, CVD

17

When to obtain INR

after 2-3 doses of warfarin and then daily until therapeutic INR reached, outpatient reduce initial monitoring to every few days until a therapeutic dose

18

Initiating warfarin

start 5-10 mg for first 1-2 days, subsequent dosing based on INR response, do not load doses

19

When to start doses lower than 5 mg

in patients with increased risk of bleeding, elderly, debilitated, malnourished, CHF, liver disease

20

Monitor using

INR, PT, PTT

21

what is used to reverse anticoagulation with decreased vitamin K

phytonadione

22

Vitamin K recommendations

INR9 5 mg PO, INR >20 or serious bleeding 10 mg IVPB, if no signs or symptoms of bleeding do not treat

23

Dabigatran (Pradaxa)

Oral direct thrombin inhibitor, must adjust for renal, very fast onset (6hrs) so no bridge needed, no monitoring required, no antidote for bleeding, some DI

24

Clinical uses of dabigatran (Pradaxa)

prevention of stroke and systemic emboli in nonvalvular Afib, treatment of VTE (requires 5-10 days of parenteral anticoagulation

25

Rivaroxaban (Xarelto)

oral factor Xa inhibitor, very fast onset (4 hrs), once daily, no reliable lab monitoring available, no reversal agent, renal adjustment

26

Rivaroxaban (Xarelto) clinical uses

prevention of VTE after hip or knee surgery, treatment of VTE reduction in risk of recurrent VTE, prevent stroke and systemic in nonvalvular Afib

27

Apixaban (Eliquis)

oral factor Xa inhibitor, BID, very complex dosing, very fast onset (3 hrs), renal adjust, no reliable lab monitoring, no reversal agents

28

Apixaban (Eliquis) clinical uses

prevention of VTE post operatively, prevention of stroke and systemic emboli in nonvalvular Afib

29

All NOAC

new, brand only, $$$, all eliminated via kidney, slight differences with efficacy and bleeding