Pharmacologic Treatment of Coagulopathies Flashcards
What do Anticoagulants do?
inhibit the action or formation of clotting factors
Name some Oral Anticoagulants
Warfarin (Coumadin, Jantoven)
Dabigatran (Pradaxa)
Apixaban (Eliquis)
Rivaroxaban (Xarelto)
Describe Warfarin (Coumadin)
is the most widely used oral anticoagulant.
Mechanism of action: Inhibition of vitamin K dependent coagulation factors II, VII, IX, X
Also inhibits Protein C and S
How long does it take for Warfarin to reach therapeutic effect
36-72 hours
Normal clotting factors need to clear from the circulation
What is Warfarin used for?
to prevent further clot formation.
Indications for use of Warfarin
Venous and arterial thromboembolism Pulmonary embolus Stroke prevention in atrial fibrillation Thrombus prevention in cardiac valve replacement Stroke Transient ischemic attacks Prevention of clots
Dosing is based on what?
PT/INR
Normal INR is 1.0
Not therapeutic until INR is 2.0
For most indications the INR range is 2.0-3.0
How soon should the INR be checked after each dose change?
3rd day
What level should we start dosing Warfarin?
5 mg nightly
What things can dosing be dependent on?
Chronic dose will vary depending on the patient and their other medications
Chronic dose will also vary depending on the patient’s genotype
Adjust dose as need to achieve desired INR
What drugs can interact with Warfarin?
Just assume that EVERY drug interacts with warfarin - LOOK IT UP JACKASS!!!
Major interactions: cholesterol lowering meds (statins), most antibiotics, NSAIDs, drugs cleared through the liver
Food interactions that can decrease the INR
Vitamin K containing foods (dark leafy greens, green tea) decreases INR
Smoking/tobacco decreases INR
Alcohol increases the INR
Purple Toe Syndrome
Skin/tissue necrosis leading to gangrene
Usually occurs 3-8 days after starting
Purple toe syndrome (3-8 weeks after starting
Treatment of Purple Toe Syndrome
stop the coumadin and switch to another anticoagulant.
Same treatment for skin necrosis.
Management of an elevated INR
No bleeding and INR < 5 -Hold warfarin Bleeding or INR > 5 -Hold warfarin -Oral or IV or subQ vitamin K Life threatening bleeding -Vitamin K -Factor VII -Fresh frozen plasma or Prothrombin concentrate
Dosing patients on Warfarin with vitamin K, How and when is it dosed?
Sub Q variable
IV 1-2 hours later give slowly or they DIE!
Oral 24-48 hours later
Avoid IM
Note:: affects warfarin for up to a week after administration
Patient education needs to include
indication, dosing, monitoring, side effects, drug interactions, diet, alcohol, birth defects if appropriate
How often should the INR be checked after each dose change?
2-3 days
How long should warfarin be held when anticipating a surgical/invasive procedure?
5 days
Name 2 reasons it might be best to take this medication at night.
Not as much food reaction, For adjusting doses
Why is bridging with heparin important for initiation of therapy and for patients that may need procedures?
As a procoagulant state, to avoid necrosis. Patients with abnormal heart rhythm and a clot
Newer oral anticoagulants
Dabigatran (Pradaxa)
Rivaroxaban (Xarelto)
Apixaban (Eliquis)
Dont have to check INR
Major pros of new oral anticoagulants as compared to warfarin
No need for routine lab monitoring
Not affected by foods
Not as many drug interactions
Major cons of new oral anticoagulants as compared to warfarin
No antidote
No way to monitor anticoagulation
Dose adjustments likely needed for renal patients
Not for use in valvular heart disease