weber pre-lecture pt 2

Question 1

what is an example of a factor Xa inhibitor (FXa)?

Answer 1

fondaparinux

Question 2

what is the labeled used of fondaparinux?

Answer 2

prophylaxis following THA, TKA, hip placement, or abdominal surgery
treatment of DVT/PE
HIT

Question 3

how is fondaparinux dosed?

Answer 3

based on weight for treatment
if prophylaxis, do not give for anyone under 50kg
do not use if have renal dysfunction

Question 4

what is the monitoring of fonaparinux?

Answer 4

none for therapeutic efficacy
can monitor anti-Xa levels

Question 5

what are example drugs of IV direct thrombin inhibitors?

Answer 5

lepirudin
bivalirudin (angiomax)
argatroban

Question 6

what DTI has a different indication besides HIT?

Answer 6

bivalirudin (angiomax) is used as an UFH alternative during PCI

Question 7

what DTI elevates INR?

Answer 7

argatroban
overlap with warfarin until INR is at least 4 to be weary against falsely high values

Question 8

what DTI has adjusted dosing?

Answer 8

Lepirudin when CrCl is below 60mL/min
Argatroban when hepatic dysfunction is present

Question 9

what are the brand names of warfarin?

Answer 9

coumadin
jantoven

Question 10

what is the MOA of warfarin?

Answer 10

inhibits enzymes responsible for cyclic conversion of VIT K
inhibits synthesis of Vit K dependent clotting factors

Question 11

what are the clotting factors associated with Vit K?

Answer 11

factors II, VII, IX, X
protein C and S

Question 12

what enantiomer causes more drug-drug interactions in warfarin?

Answer 12

S enantiomer –> 5x more potent and interacts with CYP 2C9

Question 13

when is the peak effect of warfarin seen?

Answer 13

72 to 96 hours

Question 14

what is the duration of action from a single dose of warfarin?

Answer 14

2 to 5 days

Question 15

when is anticoag effect seen with warfarin?

Answer 15

within 24 hours

Question 16

what is the clearance of common clotting factors?

Answer 16

prothrombin –> 60 to 100hrs
VII –> 4 to 6 hrs
IX –> 20 to 30 hrs
X –> 24 to 40 hrs

Question 17

what does it mean if a person has more *1 alleles?

Answer 17

more resistant to warfarin

Question 18

what does it mean if a person has more 2/3 alleles?

Answer 18

more sensitive to warfarin (lower dose requirement)

Question 19

what does it mean if a person has more A alleles?

Answer 19

more sensitive to warfarin
(lower dose requirement)
often seen in the asian population

Question 20

what does it mean if a person has more G alleles?

Answer 20

more resistant to warfarin (higher dose requirement)
often seen in african americans

Question 21

when should a person be genetically tested?

Answer 21

warfarin naive
results are available before the sixth dose
pt at a high risk of bleeding if INR is elevated

Question 22

what drugs increase INR?

Answer 22

metronidazole
amiodarone
fluconazole
ciprofloxacin
bactrim
secondary –> erythromycin, anabolic steroids, isoniazid, liver disease, alcohol, and propafenone

Question 23

what drugs decrease INR?

Answer 23

rifampin
secondary –> cholestyramine, carbamazepine, and alcohol

Question 24

how does alcohol both increase and decrease INR?

Answer 24

acute ingestion –> increases INR
chronic ingestion without liver damage –> decreases INR
chronic ingestion with liver damage –> increased anticoag effect

Question 25

what is important when having Vit K in your diet?

Answer 25

having it be consistent across days to not have to adjust warfarni dose

Question 26

how does aspirin and other NSAIDs interact with warfarin?

Answer 26

increases bleeding risk
no increase in INR

Question 27

what anti platelet drugs can be used in VTE?

Answer 27

aspirin
dipyridamole
limited role due to concomitant use causing increased risk of bleeding

Question 28

when should aspirin be considered in VTE?

Answer 28

when CHA2DS2-VASc score is 1

Question 29

when is dipyridamole used in VTE?

Answer 29

consider concomitant use with warfarin with prosthetic heart valves