Coagulopathy Pharmacology Flashcards
Warfarin (Coumadin)
Oral anticoagulant that inhibits the vitamin K factors: II, VII, IX and X. Also inhibits protein C and S.
How long does it take to achieve full effect of warfarin?
36 - 72 hours. Normal clotting factors need to be cleared from circulation.
Which factors does coumadin inhibit?
II, VII, IX and X. Also protein C and S.
Warfarin indications
Venous and arterial thromboembolism. PE Stroke prevention of Afib Thrombus prevention in valve replacement Stroke TIA PREVENTION OF CLOTS
Can warfarin break up a clot that is already there?
No, it can only prevent them.
What is the preferrable INR range?
2.0 - 3.0
How soon should INR be checked after each warfarin dose change?
2nd or 3rd day
Warfarin Dosing
5mg nightly is a safe dose.
Adjust dose as needed for therapeutic INR
Assume that _____ drug interacts with warfarin.
EVERY.
Major interactions with statins, abx, NSAIDS, and DRUGS CLEARED THRU LIVER
Which foods will decrease INR?
Vitamin K containing foods. dark leafy greens, green tea.
Tobacco decreases INR.
Alcohol INCREASES INR.
Warfarin adverse effects
Bleeding, skin necrosis, purple toe syndrome, BLEEDING.
No bleeding and INR < 5
Hold warfarin
Bleeding or INR > 5
Hold warfarin AND administer oral, IV or subQ vitamin K.
What to do in life-threatening bleeding?
Vitamin K, Factor VII, FFP or PCC (prothrombin complex concentrates)
How long does oral and IV vitamin K take for therapeutic effects?
IV: 1-2 hrs
Oral: 24 - 48 hrs
Can affect warfarin for up to a week
How long should warfarin be held before a surgery/invasive procedure?
5 days
Name 2 reasons it might be best to take warfarin at night.
- Fewer food reactions
2. If it is high in the morning, you can adjust their dose that evening more easily (tell them not to take it)
Why is bridging with heparin important for initiation of therapy and for patients that may need procedures?
Warfarin has a pro-coagulation state that heparin can overcome.
Heparin is also faster-acting, and can cover them through the procedure.
What does Dabigatran (pradaxa) target?
IIa
What does Apixaban (Eliquis) target?
Xa
What does Rivaroxaban (Xarelto) target?
Xa
Types of LMW Heparin?
Enoxaparin (Lovenox)
Dalteparin (Fragmin)
Fondaparinux (Arixtra)
Heparin MOA
Potentiates the action of antithrombin III.
Inactivates thrombin, IX, X, XI and XII (9 - 12)
Prevents conversion of fibrinogen to fibrin
What must be monitored in a patient taking heparin?
Frequent monitoring of PTT, because of the narrow therapeutic window.
Which disorders in unfractionated heparin used for?
DVT PE Dialysis machines Afib MI Thrombosis
Heparin CI and SE
CI: anaphylaxis and recent major surgery
SE: bleeding, allergic rxns, transaminitis, heparin induced thrombocytopenia.
What is used to reverse heparin?
Protamine Sulfate rapidle reverses heparin.
SLOW IV push to prevent anaphylaxis.
Can be used for LMWH and UFH
Heparin induced thrombocytopenia (HIT)
Can occur with LMWH and UFH (most likely to happen).
Noted when platelets drop 50% after therapy
Platelet factor 4 (sensitive)
Serotonin release factor (specific AND sensitive)
HIT Tx
Stop the heparin
Give alt. anticoagulant
NO platelet transfusions
do not give warfarin until platelet count increases.
LMWH advantages
Can be given subQ without need for labs.
Lower risk of HIT
Home administration
Safer than UFH for extended admin.
LMWH mechanism
Inhibits antithrombin III and Xa
Indirect thrombin inhibitor
More strongly inhibits Xa than UHF
What is the time to effect for LMWH?
SQ - 2 hrs, with peak at 4 hrs
Aspirin
Irreversible platelet inhibitor
Prevents formation of clots by inhibiting platelet plug.
Rapid absorption w/ peak effects in 1 hr.
Aspirin Dosing
81 mg/day for CVA/MI prevenion
325 mg/day acutely for MI/CVA
325 daily chewed for acute coronary syndrome
Aspirin SE
GI bleeding Administer w/ food. PPI's and H2 blockers may decrease this risk. TInnitus Resistance Allergy
Stop aspirin ___ days before surgery.
4
Clipidoogrel (Plavix) Mechanism
P2Y12 antagonist.
Irreversible inhibition of activation and aggregation of platelets.
Plavix indications
Prevention of thrombotic events and acute coronary syndrome.
Plavix SE
Bleeding
Multiple drug interactions
Stop 7 days prior to surgery
Dipyridamole
Secondary prevention in patients following stroke or TIA.
Used with ASA is single pill (Aggrenox)
Dipyridamole Mechanism
inhibits ADP and phosphodiesterase
Causes vasodilation and prevents aggregation
GPIIb/IIIa antagonists
Reopro, Integrilin
IV, used for ACS
During percutaneous coronary intervetion
GPIIb/IIIa SE
Bleeding
Thrombocytopenia
Allergy
Fibrinolytics
tPA, Streptokinase, Urokinase
Convert plasminogen to plasmin to break down fibrin strands
Fibrinolytic indications
MI
Stroke
Massive PE
Limb-threatening ischemia
Fibrinolytic CI
Long check-list
Major bleeding or risk of major bleeding
Uses for factor VIIa
Hemophilia A and B
Tx of warfarin related intercerebral hemorrhage
Factor VII deficiency
Autoplex T contains
inanactivated II, IX, X and VIIa.
Can be used to reverse bleeding on pradaxa
Aminocaproid acid (ECA)
AKA amicar
Antifibrinolytic agent
Used for acute bleeding
ECA uses
Bleeding post-dental in hemophilia/vWD
Epistaxis
Menorrhagia
Aprotinin
Derived from bovine lung tissue.
Hemostatic agent during CABG surgery
Desmopressin acetate (DDAVP)
Synthetic analogue of vasopressin (ADH)
Increased VIII and vWF release from endothelial storage sites
DDAVP uses
Tx of mild to moderate bleeding in hemophilia.
vWD bleeding tx or prophylaxis
IV, SQ or nasal
DDAVP SE
water retention
hyponatremia (seizures)
limit dose to once daily to avoid tachyphylaxis (development of resistance to medication)
