Drugs 1
Which enzyme does warfarin inhibit? (whole name)
VKORC1 - Vitamin K epoxide reductase complex 1
Which of the following is a contraindication to the use of DOACs, except Apixaban?
a. History of VTE
b. Hypertension
c. A fib
d. Severe renal impairment
d. Severe renal impairment
Apixaban is approved for use even in ESRD
A 57 year old woman receives anticoagulation therapy with warfarin for A fib management. Which laboratory test should be monitored regularly to ensure efficacy?
a. Prothrombin time (PT)/International normalized ratio (INR)
b. Activated partial thromboplastin (aPTT)
c. Platelets
d. D-dimer
a. PT/INR
Used to ensure proper therapeutic levels
Which of the following lab findings is most likely to appear in a patient on heparin therapy who develops HIT?
a. Platelet count >150,000
b. Decreased platelet count and presence of anti-platelet factor 4 antibodies
c. Increased aPTT and normal platelet count
d. Increased INR
b. Decreased platelet count and presence of anti-platelet factor 4 antibodies
HIT is characterized by a significant drop in platelets, and antibodies forming against PF4
Both intrinsic and extrinsic pathways meet at a shared point to continue coagulation, the common pathway. At which factor do they meet?
Factor X
Both pathways can independently activate X --> Xa
A 69 year old female presents with A fib. PMH includes hypertension and diabetes. What factor should determine whether the medical team starts anticoagulation therapy for this patient?
a. Age
b. Presenting with A fib
c. CHADS-VASc score
d. Presence of diabetes
c. CHADS-VASc score
Assesses the risk of stroke risk in patients with a fib to guide initiation of anticoagulation therapy or not
A 70 year old male with PMH of HTN, diabetes, presents with his second unprovoked DVT. After being started on rivaroxaban, how long should his anticoagulation be continued? Choose the best answer.
a. 1 month
b. 3 months
c. 5 months
d. Indefinitely
d. Indefinitely
For unprovoked DVT, especially when reoccurring, indefinite anticoagulation treatment is usually indicated.
Which of the following would increase the effect of warfarin?
a. Rifampin
b. Phenytoin
c. Amiodarone
d. St. John’s wort
c. Amiodarone
As an inhibitor, this decreases warfarin metabolism and increases its anticoagulant effect
A 68 year old male with PMH of A fib, CKD4, is started on dabigatran. His CrCl is 14 ml/min. What is an appropriate next step in management?
a. Continue dabigatran dosing
b. Reduce dabigatran dosing by 50%
c. Switch to Apixaban
d. He does not need anticoagulation therapy
C. Switch to Apixaban
Dabigatran should be avoided in CrCl < 15 ml/min
A patient with non-valvular a fib on warfarin presents to the ER with an intracranial hemorrhage. His INR is 3.8. What is an appropriate intervention to reverse warfarin for this patient?
a. IV vitamin K only
b. Fresh frozen plasma (FFP) only
c. Four factor prothrombin complex concentrate (PCC) and IV vitamin K
d. Discontinue warfarin and observe
c. Four factor prothrombin complex concentrate (PCC) and IV vitamin K
The patient requires rapid reversal of warfarin. Four factor prothrombin complex provides rapid restoration of clotting factors, and IV K will provide long term clotting factor synthesis.
A 50 year old patient is started on rivaroxaban for VTE treatment. What is the advantage of this drug choice over warfarin?
a. Longer half life
b. Less risk of bleeding
c. Fewer drug interactions
d. More frequent monitoring required
c. Fewer drug interactions
List the components of the HAS-BLED score and their associated points
Hypertension - 1 point
Abnormal liver or renal function -1 point each
Stroke - 1 point
Bleeding - 1 point
Labile - 1 point
Elderly (age > 65) - 1 point
Drugs or alcohol use - 1 point each
BONUS ROUND
A patient on long-term warfarin therapy for A fib is switched to dabigatran. How should this transition be managed?
a. Start dabigatran while continuing warfarin for one week
b. Start dabigatran when INR < 2
c. Start dabigatran when INR < 2.5
d. Discontinue warfarin and initiate dabigatran immediately
b. Start dabigatran when INR < 2
BONUS ROUND
A patient is started on Fondaparinux for DVT. What is an advantage of this drug over LMWH?
a. Lower bleed risk
b. Lower HIT risk
c. Shorter half-life
d. No monitoring required
b. Lower HIT risk
Fondaparinux has lower risk of HIT compared to UFH and LMWH.
What is the generic for the drug Mephyton?
Phytonadione (Vitamin K)
BONUS ROUND
Correctly spell out the reversal agent used for dabigatran
Idarucizumab
BONUS ROUND
A 70 year old patient requires anticoagulation therapy for his non-valvular A fib. He has a history of GI bleeding. Which anticoagulant would be the best choice to minimize his risk of recurrent GI bleeding?
a. Rivaroxaban
b. Apixaban
c. Dabigatran
d. Warfarin
b. Apixaban
Among the DOACs, Apixaban is associated with lower risk of gastrointestinal bleeding compared to its counterparts.
What are the “5 Gs” that can increase bleeding when given concomitantly with warfarin?
Ginseng, garlic, gingko, ginger, glucosamine
A patient on warfarin presents with purple toe syndrome. What is the mechanism of this condition?
a. Vitamin K deficiency leading to necrosis of skin
b. Small emboli in the blood vessels from plaque rupture
c. Warfarin toxicity which causes small vessel thrombosis
d. Heparin-induced thrombocytopenia
b. Small emboli in the blood vessels from plaque rupture
The result of cholesterol embolization from plaques, purple toe syndrome is rare, but can be noticed 3-8 weeks after starting warfarin therapy
What are the components of Virchow's Triad for thrombus formation?
Vessel injury, hypercoagulability, venous stasis
Brand name of Idarucizumab
Praxbind
List the 4 T's in the assessment score used for HIT risk
Timing, Thrombosis, Thrombocytopenia, oTher causes
What is the gold standard for HIT confirmation?
Serotonin Release Assay
SRA should be used to confirm HIT diagnosis after positive PF4 ELISA test.
A patient on warfarin therapy for recurrent DVT develops skin necrosis. This condition is most likely caused by a deficiency in which of the following?
a. Protein C
b. Antithrombin III
c. Factor V Leiden
d. Vitamin K
a. Protein C
Warfarin-induced skin necrosis is associated with a deficiency in Protein C, which is an anticoagulant protein. Warfarin initially reduces levels of Protein C faster than other factors, leading to a temporary hypercoagulable state and potential for skin necrosis.
BONUS ROUND
What is the precursor to thromboxane A2 production
Arachidonic acid