Anticoagulant Drugs

Question 1

What is hemostasis?

Answer 1

process of stopping bleeding

Question 2

What occurs during primary hemostasis?

Answer 2

• vasoconstriction (first response to injury in vessel wall - ↓ blood flow site of injury)
• platelet plug (platelets aggregate and activate secondary hemostasis)

Question 3

what occurs during secondary hemostasis?

Answer 3

• clotting cascade activation
• fibrin clot
• prevents excessive bleeding (hemorrhages)

Question 4

What is the extrinsic pathway activated by?

Answer 4

activated by damage of outside of blood vessel → blood to lead out of vessel
**when tissue factor is exposed

Question 5

what is the intrinsic pathway activated by?

Answer 5

triggered by elements that lie within vessel - surface within vessel
**when collagen is exposed

Question 6

where is tissue factor (III) found?

Answer 6

subendothelium

Question 7

How does warfarin work?

Answer 7

• interferes vitamin K dependent clotting factors (2, 7, 9, 10) - only effects liver before it makes more.
• no effect on a formed clot
• prevents clot enlargement

Question 8

what are the indications of warfarin?

Answer 8

• prophylaxis and treatment of thromboembolic events (DVT, PE)
• ↓ risk of subsequent MI

Question 9

what are the characteristics of warfarin?

Answer 9

• onset of action 36-72 hrs (1-3 days)
• 3 - 5 days to reach therapeutic range
• bridge therapy needed (heparin to bridge gap while warfarin reaches therapeutic range
• highly bound to albumin 99% - immediately unavailable

Question 10

what are the drug to drug interactions of warfarin?

Answer 10

aspirin, heparin, NSAIDs, anti-platelet drugs = ↑ risk of bleeding

Question 11

what are the adverse effects of warfarin?

Answer 11

• abnormal bleed

**PT/INR test used to monitor

Question 12

What is prothrombin time used for

Answer 12

to monitor warfarin effectiveness

Question 13

what is the normal range of PT?

Answer 13

12 - 15 seconds - how long it take to form a clot

Question 14

what is a therapeutic range for PT?

Answer 14

1.5 to 2 times baseline

Question 15

what are the characteristics of PT?

Answer 15

lab testing methods vary

INR used to interpret PT

Question 16

what is the International Normalized Ratio (INR)?

Answer 16

a standardized system

Question 17

what are the characteristics of INR?

Answer 17

measured daily

outpatient lab testing - weekly, monthly

Question 18

what is the normal range for INR?

Answer 18

0.8 - 1.2

Question 19

what is the therapeutic range for INR?

Answer 19

• 2 - 4.5, depending on the patient’s risk for developing clot
• physician or pharmacist based
• variables include cardiac hx, joint surgery, prosthetic ♥ valve, previous clot

Question 20

why do older adults exhibit greater than expected PT/INR response?

Answer 20

kidney function, liver function, ↓ protein levels = ↓ albumin = more free warfarin

Question 21

what are the 5 nursing implications of warfarin?

Answer 21

• avoid IM injections
• assess hematocrit (risk for bleeding)
• observe for s/sx of bleeding
• routine time
• high alert medication (2 nurses to give)

Question 22

what are the 6 concepts for patient teaching?

Answer 22

• soft toothbrush/no flossing
• electric shaver
• avoid contact sports
• assistive devices (risk for falls → bleeding; stool softeners →avoid straining)
• report s/sx of bleeding (blood in stool, bruising, GI bleeding, nose bleeds, gums bleeding)
• routine lab test

Question 23

what are the herbal and food interaction for warfarin?

Answer 23

• avoid ↑ and ↓ in vitamin K rich foods
• vitamin k rich foods - asparagus, broccoli, cabbage, cauliflower, kale
• green tea, gingko, garlic, ginger, cranberry, chamomile, licorice may ↑ risk of bleeding
• avoid vitamin K supplements
•

Question 24

what is phytonadione?

Answer 24

vitamin k
koagulation vitamin
hepatic synthesis of factors 2, 7, 9, 10
antidote to warfarin

Question 25

what forms does phytonadione come in?

Answer 25

PO, SC, IV

Question 26

Characteristics of PO phytonadione

Answer 26

↑ INR and no serious LT bleeding

Question 27

Characteristics of IV phytonadione

Answer 27

↑ INR and serious/LT bleeding