Anticoags Flashcards
Anticoagulants
- prevent the formation of clots
- best for DVTs
- reducing formation of fibrin
Anticoagulants MOA
Inhibit synthesis cloting factors (factor x and thrombin)
- inhibits the activity of clotting factors ( Xa, thrombin)
Anticoagulant Uses
- Prevention of venous thrombosis
- DVT, pulmonary embolism, A-Fib
If Clot is life threatening
- IV or SQ admin
- Change to oral drug for long term use
Does it actually thin the blood ?
- It doesn’t make blood less viscous
Prototype for Heparin
Heparin (unfractured)
Heparin MOA
- inactivates several clotting factors
- inhibits thrombin activity
- suppresses formation of fibrin
Heparin measured in…..
units
Must be given what routes?
SQ (prophylaxis) or IV (immediate)
- IV is immediate
- SQ up to 1 hour for effect
Half-Life of Heparin is
90 minutes
Uses of Heparin
- Preferred Rapid anticoagulation (open heart surgery, DVT, renal dialysis)
- Prophylaxis of Venous thrombi
What happens if pt is too anticoagulated
- you can just stop heparin drip due to short half-life
What is the antidote for Heparin?
protamine sulfate (onset 5 mins)
- hardly ever used
- slow IV push
Some things to know lab monitoring
- monitor aPTT
- in the hospitial
- intrinsic factor
- Normal PTT is 40 sec
- Therapeutic level is 1.5-2x baseline (60-80 sec)
-IV heparin: measure aPTT Q 6 hours - gets 4 half lives to get to therapeutic
4 x 1.5 = 6 hours
Heparin SE
SE: bleeding, heparin induced thrombocytopenia (HIT)
After 4 days body creates antibodies causing platelets to drop
- For HIT monitor platelets. IF <100,00 or platelets reduce by 50% then stop heparin
Administration of Heparin
- SQ abdomen
- IV intermittent or continuous
How to know if a patient is bleeding
- pettechaie, lumbar pain, bruising, perotineal bleeding
- never give when somone has epidural
Low Molecular Weight Heparin
- LMWH: same mechanism of action but a little diff, but safer, better bioavailability
- no frequent blood tests
- dosage based on weight
- Can be administered at home
- MOA activates factor Xa, lot less able to activate thrombin
- Half life is 6x a longer
Low Molecular Weight Heparin is DOC for
DVT prevention
Side effects of LMWH
Bleeding, HIT
-check platelets before admin
Antidote for LMWH
Protamine Sulfate
LMWH Admin
Abdomen anterior or post abdominal wall
- 45-90 deg
- SQ
- don’t expel bubble
LMWH Prototype
enoxaparin (Lovenox)
Vitamin K antagonist Warfarin (Coumadin) MOA
MOA: inhibits hepatic synthesis of vitamin K dependent clotting factors (VII, IX,IX, X) and prothrombin
Antidote for Coumadin
Vitamin K (decrease effects in 6 hours)
- given IV risk of anaphylaxis
- can be given oral and SQ
Warfarin uses
-Prevent DVT, PE, prevent clots in patients with Afib, prosthetic heart valves or had TIA or recurrent MI
Problems with Warfarin
- highly protein bound
- lots of drug-drug interactions
- Drug- Food interactions: a lot of green leafy veggies
- Pregnancy category X (not safe)
- Have a consistent amount of green leafy veggies
- Narrow theurapeutic index
WArfarin SE
Hemorrhage
Gentic variants can be tested for WArfarin Response
VKORC1 and CYP2C0
- These variants lead to increase risk of bleeding
Lab monitoring for Warfarin
- Half life of 1.5-2 days
- 4 half lives to get to therapeutic level
- PT or INR (extrinsic pathway) outpatient
- PT normal 12 sec
- Therapeutic : 1-2x baseline (12-24 sec)
- PT varies in diff labs so INR is used
- Internationalized ratio: 2.0- 3.0 therapeutic
- Mechanical heart valve higher
Nursing Consideration for Warfarin
- Take same time everyday
- Balance Vit K foods
- Watch s/s bleeding: check labs
- soft toothbrush
- No staight edge razor
- Pain control drugs dont take asprin or ibuprofen
- Tylenol is better for pain drug
- hold pressure if blood is drawn
- must stop before surgery 1 week
- Medic alert bracelet
- Garlic and Gingko
Direct Thrombin inhibitors ( MOA, route, uses, AE)
MOA: direct, reversible inhibitor of thrombin
Route: IV, SQ, and ORAl
Uses: Afib, hip/knee replacement
AE: bleeding, GI
- take with food or protein pump inhibitor or H2 blocker
Prototype for direct thrombin
dabigatran (Pradaxa)
- Oral
- no lab monitroing
- Lower risk of bleeding
- few drug-drug/ drug-food interactions
- rapid onset
- set dose
Antidote fro direct thrombin
idarucizumab ( Praxbind)
Should direct thrombin be stopped before surgery
YES!
Direct factor Xa inhibitors
ACtion: binds with factor Xa and inhibits thrombin Route: ORal -Rapid onset - No lab monitoring - Rapid onset - fixed dose - lower bleeding risk - Few drug interactions (CYP3A4)
Direct Factor Xa inhibitors prototypes
Rivaroxaban (Xarelto)
Apixaban (Eliquis)
Antidote for direct factor Xa
Andexanant alfa (AndexXa)
Uses for Direct Factor Xa
- Post hip/knee replacement, afib, tx of DVT/ PE
SE for Driect FActor Xa inhibitor
Bleeding; spinal/epeidural hematoma
-contrraindicated; liver dz; pregnancy
What happens when going from IV heparin -> oral agent
- Stop heparin and immediately start oral doses
- Rivaroxaban or apixaban
- May see doubled up doses for a couple of days, then see once a day dosing
IV heparin -> Coumadin
- typically, 2-3 days simultaneous admin
- Takes a couple of days for warfarin to take effect
- No effect on clotting factors already in circulation
- increased risk of bleeding
- monitor both PTT and PT/INR
