Exam 2: Hemostasis

Question 1

UFH: MOA

Answer 1

binds to Antithrombin III, enhances action:

• inhibits IIa and Xa (significant)
• inhibits IXa, XIa, XIIa, XIIIa

Question 2

Protamine: indications

Answer 2

reverse anticoag effects of heparin

Question 3

Protamine: MOA

Answer 3

+ charge, basic

reverses heparin b/c heparin is - charge, acidic

Question 4

LWMH: examples

Answer 4

enoxaparin*

dalteparin

Question 5

LWMH: monitoring

Answer 5

• minimal effect on clotting lab assays
• antifactor Xa available (used for complicated conditions: CrCl <30, pregnancy, obesity)
• baseline CBC w/ platelets
• SCr

Question 6

Fondaparinux: MOA

Answer 6

factor Xa inhibitor: synthetic pentasaccharide

Question 7

Fondaparinux: indications

Answer 7

safe/effective alternative to LWMH for VTE (longer half life)

Question 8

Fondaparinux: contraindications

Answer 8

CrCl <30 mL/min

Question 9

Warfarin: indications

Answer 9

Afib: (as long as in afib)
DVT or PE:
-provoked: 3 months
-unprovoked: at least 3 months
-recurrent: indefinite (unless high bleed risk)
-DVT w/ cancer: LMWH 3-6 months, then long term warfarin
Prosthetic heart valves: indefinite
Bioprosthetic heart valves: 3 months (up to 1 year if prior embolism)

Question 10

Warfarin: drug interactions causing increased INR

Answer 10

Amiodarone*
acute alcohol use
Cimetidine
Erythromycin
Fluconazole
Metronidazole
TMP-SMX
BS abx

Question 11

Warfarin: drug interactions causing decreased INR

Answer 11

chronic alcohol use
Rifampin
Carbamazepine
Barbituates
Cholesyramine
Vitamin K

Question 12

Warfarin: drug interactions that increase bleeding risk but do NOT affect INR

Answer 12

Aspirin
Clopidogrel
Ticlopidine
NSAIDs
Dipyridamole
Fish oil

Question 13

Vitamin K Phytonadione: indications

Answer 13

• INR > 10.0 even w/o evidence of bleeding

- any minor bleeding regardless of INR

Question 14

Warfarin: monitoring

Answer 14

• ADRs: skin necrosis, purple toe syndrome, bleeding
• INR on day 3-4
• INR on day 7
• once INR is therapeutic for 2 visits 2 weeks apart, follow-ups every 4 weeks

Question 15

Best choice for long term tx of VTE

Answer 15

DOACS OVER warfarin

Question 16

Best choice for tx of VTE in pts w/ cancer

Answer 16

LWMH OVER DOACs and warfarin

Question 17

DOACs

Answer 17

dabigatran
rivaroxaban
apixaban
edoxaban
betrixaban

Question 18

DOAC: MOA (and the one exception)

Answer 18

direct factor Xa inhibitor, EXCEPT

dabigatran: competitive and reversible direct thrombin inhibitor

Question 19

Dabigatran: contraindications

Answer 19

VTE, if CrCl < 30
Afib, if CrCl < 15
*can’t use at all if CrCl < 15 mL/min

Question 20

Dabigatran: special consideration when starting

Answer 20

VTE tx requires 5-10 days of parenteral anticoag (UFH or LMWH) BEFORE initiation

Question 21

Dabigatran: ADRs

Answer 21

• bleeding: increased risk in elderly (>75 y/o)

- indigestion and gastritis like syndromes

Question 22

Apixaban: contraindications

Answer 22

severe renal impairment

Question 23

Edoxaban: special considerations when starting

Answer 23

VTE tx requires 5-10 days of parenteral anticoag (UFH or LMWH) BEFORE initiation

Question 24

DOAC: contraindications

Answer 24

• pregnancy/lactation
• liver impairment
• CrCl requirements

Question 25

DOAC: boxed warnings

Answer 25

- spinal/epidural anesthesia or puncture risk (risk of hematoma) - premature discontinuation

Question 26

DOAC: appropriate INR at which to switch from warfarin to DOAC

Answer 26

``` Apixaban <2.0 Dabigatran <2.0 Edoxaban <2.5 Rivaroxaban <3.0 Betrixaban (no recommendation) ```

Question 27

DOAC: drug interaction

Answer 27

P-gp and strong CYP3A4 inhibitors

Question 28

DOAC: disadvantages

Answer 28

no reliable measurement assay mgmt of severe bleeding? short half life (esp. compared to warfarin) $$$$$

Question 29

Dabigatran: emergent reversal

Answer 29

``` Idarucizumab (Prax-BIND) activated charcoal hemodialysis prohemostatic agents: -4F-PCC (Kcentra) -aPCC ```

Question 30

Oral factor Xa inhibitors: emergent reversal

Answer 30

Adexanet alfa, for: Apixaban Rivaroxaban ``` activated charcoal hemodialysis prohemostatic agents: -4F-PCC (Kcentra) -aPCC ```

Question 31

Thombolytic agents: MOA

Answer 31

- tissue plasminogen activators (t-PAs) | - preferentially activate plasminogen that is bound to fibrin

Question 32

Thombolytic agents

Answer 32

Alteplase (tPA/ rtPA) Reteplase Tenecteplase

Question 33

Thombolytic agents: indications

Answer 33

ACS: STEMI ischemic stroke >18 y/o Sx onset <4.5 hours before tx

Question 34

Thombolytic agents: contraindications

Answer 34

NSTE ACS | anything that increases pt's risk for bleeding (see slides)

Question 35

Thombolytic agents: reversal

Answer 35

d/c thrombolytic agent blood replacement Aminocaproic acid Tranexamic acid

Question 36

Aminocaproic acid and Tranexamic acid: MOA

Answer 36

- inhibit activation of plasminogen and inhibit plasmin binding to fibrin - (tranexamic acid more potent)

Question 37

Aspirin: MOA

Answer 37

irreversibly inhibits COX-1, decreasing platelet aggregation

Question 38

Thineopyridines

Answer 38

- (group of antiplatelet drugs) - clopidrogrel - plasugrel

Question 39

Thienopyridines: MOA

Answer 39

inhibits platelet P2Y12 ADP receptor>>> irreversible inhibition of platelet activation and aggregation