Anticoagulant Drugs Flashcards
What is hemostasis?
process of stopping bleeding
What occurs during primary hemostasis?
- vasoconstriction (first response to injury in vessel wall - ↓ blood flow site of injury)
- platelet plug (platelets aggregate and activate secondary hemostasis)
what occurs during secondary hemostasis?
- clotting cascade activation
- fibrin clot
- prevents excessive bleeding (hemorrhages)
What is the extrinsic pathway activated by?
activated by damage of outside of blood vessel → blood to lead out of vessel
**when tissue factor is exposed
what is the intrinsic pathway activated by?
triggered by elements that lie within vessel - surface within vessel
**when collagen is exposed
where is tissue factor (III) found?
subendothelium
How does warfarin work?
- 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
what are the indications of warfarin?
- prophylaxis and treatment of thromboembolic events (DVT, PE)
- ↓ risk of subsequent MI
what are the characteristics of warfarin?
- 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
what are the drug to drug interactions of warfarin?
aspirin, heparin, NSAIDs, anti-platelet drugs = ↑ risk of bleeding
what are the adverse effects of warfarin?
• abnormal bleed
**PT/INR test used to monitor
What is prothrombin time used for
to monitor warfarin effectiveness
what is the normal range of PT?
12 - 15 seconds - how long it take to form a clot
what is a therapeutic range for PT?
1.5 to 2 times baseline
what are the characteristics of PT?
lab testing methods vary
INR used to interpret PT
what is the International Normalized Ratio (INR)?
a standardized system
what are the characteristics of INR?
measured daily
outpatient lab testing - weekly, monthly
what is the normal range for INR?
0.8 - 1.2
what is the therapeutic range for INR?
- 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
why do older adults exhibit greater than expected PT/INR response?
kidney function, liver function, ↓ protein levels = ↓ albumin = more free warfarin
what are the 5 nursing implications of warfarin?
- avoid IM injections
- assess hematocrit (risk for bleeding)
- observe for s/sx of bleeding
- routine time
- high alert medication (2 nurses to give)
what are the 6 concepts for patient teaching?
- 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
what are the herbal and food interaction for warfarin?
• 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
•
what is phytonadione?
vitamin k
koagulation vitamin
hepatic synthesis of factors 2, 7, 9, 10
antidote to warfarin
what forms does phytonadione come in?
PO, SC, IV
Characteristics of PO phytonadione
↑ INR and no serious LT bleeding
Characteristics of IV phytonadione
↑ INR and serious/LT bleeding
