Hem-Onc - Anticoagulants

Question 1

Heparin: Mechanism

Answer 1

Cofactor for the activation of antithrombin, decreases thrombin, and decreases factor Xa.
Short half life

Question 2

Heparin: uses

Answer 2

Immediate anticoagulant for PE, acute coronary syndrome, MI, DVT. Used during pregnancy (does not cross placenta). Follow PTT

Question 3

Heparin: tox

Answer 3

Bleeding, thrombocytopenia (HIT), osteoporosis, drug-drug interactions.
Antidote: protamine sulfate - get rapid reversal (positively charged molecule that binds negatively charged heparin)

Question 4

Enoxaparin: mech

Answer 4

low-molecular-weight heparin
Acts more on factor Xa
Better bioavailability and 2-4 times longer half-life
Can be administered subQ without lab monitoring.
Not easily reversible

Question 5

Dalteparin: mech

Answer 5

low-molecular-weight heparin
Acts more on factor Xa
Better bioavailability and 2-4 times longer half-life
Can be administered subQ without lab monitoring
Not easily reversible

Question 6

Heparin-induced thrombocytopenia (HIT):

Answer 6

Development of IgG Abs against heparin bound to platelet factor 4 (PF4). Ab-heparin-PF4 complex activates platelets –> thrombosis and thrombocytopenia

Question 7

Argatroban:

Answer 7

Derivatives of hirudin, the anticoagulant used by leeches
Inhibit thrombin directly
Used instead of heparin for anticoagulating patients with HIT

Question 8

Bivalirudin:

Answer 8

Derivative of hirudin, the anticoagulant used by leeches
Inhibit thrombin directly
Used instead of heparin for anticoagulating patients with HIT

Question 9

Bivalirudin:

Answer 9

Derivative of hirudin, the anticoagulant used by leeches
Inhibit thrombin directly
Used instead of heparin for anticoagulating patients with HIT

Question 10

Warfarin (coumadin): mech

Answer 10

Interferes with normal synthesis and gamma-carboxylation of Vitamin K-dependent clotting factors II, VII, IX, and X and proteins C and S. Metabolized by the cytochrome P-450 pathway.
In lab assay, has effect on EXtrinsic pathway in increases PT.
Long half-life

Question 11

Warfarin (coumadin): uses

Answer 11

Chronic anticoagulation (after STEMI, venous thromboembolism prophylaxis, and prevention of stroke in atrial fibrillation). Not used in pregnant women (because warfarin, unlike heparin, can cross placenta).
Follow PT/INR values.

Question 12

Warfarin (coumadin): tox

Answer 12

Bleeding, teratogenic, skin/tissue necrosis, drug-drug interactions.

Question 13

Warfarin (coumadin): antidote

Answer 13

For reversal of warfarin overdose, give Vitamin K

For rapid reversal of severe warfarin overdose, give Fresh Frozen Plasma

Question 14

Direct Factor Xa Inhibitors:

Answer 14

Apixaban, Rivaroxaban

Question 15

Apixaban: mech

Answer 15

Bind and directly inhibit activity of Factor Xa

Question 16

Apixaban: uses

Answer 16

Stroke prophylaxis in patients with A-Fib

Oral agents do not usually require coagulation monitoring

Question 17

Apixaban: tox

Answer 17

Bleeding (no specific reversal agent available)

Question 18

Rivaroxaban: mech

Answer 18

Bind and directly inhibit the activity of Factor Xa.

Question 19

Rivaroxaban: uses

Answer 19

Tx and prophylaxis of DVT and PE, stroke prophylaxis in patients with A-Fib
Oral agents do not usually require coagulation monitoring

Question 20

Rivaroxaban: tox

Answer 20

bleeding (no specific reversal agent availble)