Drugs affecting coagulation

Question 1

What component of the clotting pathway is heparin dependent on?

Answer 1

Antithrombin III, acts as a catalyst for it to inhibit clotting Xa and thrombin. Needs A III to work, negative heparin binds to positive AIII and then to a PLASMA SERINE PROTEASE

Question 2

Which is the one drug in the HMW heparin class? What is it indicated for?

Answer 2

Heparin sodium (Liquaemin) used for anticoag in surgery and IV catheters, as prophylaxis for DVT and PE

Question 3

What is the antidote for heparin?

Answer 3

Protamine sulfate (+ charge binds to -heparin instead of AIII)

Question 4

What is a side effect that all anticoagulants share?

Answer 4

possibility for hemorrhage

Question 5

What are the LMW heparins? What are some benefits to using LMW heparins as opposed to HMW?

Answer 5

Enoxaparin (Lovenox)
Fondaparinux (Arixtra-synthetic)
Can be injected SQ so it can be used in PGN to replace warfarin, lower incidence of HIT

Question 6

Is protamine sulfate used to reverse LMW Heparins?

Answer 6

Not completely enoxaparin, has no effect on fondaparinux

Question 7

How does Lepirudin work? Where is it cleared? What should you use instead if this organ is not functioning well?

Answer 7

It is a direct thrombin inhibitor, does not need AIII to work (heparin is considered indirect), cleared by kidney (use argatroban instead)

Question 8

Your patient is experiencing clotting following heparin therapy. What should you give first if this person has okay kidney function?

Answer 8

lepirudin (refludan)

Question 9

Your patient is experiencing HIT. What should you give if this person has okay liver function and poor kidney function?

Answer 9

argatroban (novastan)

Question 10

What sets dabigatran apart from lepirudin and argatroban? What does that imply?

Answer 10

It is an oral direct thrombin inhibitor, which means it is not evaluated by PTT

Question 11

Why is the black box warning of oral anticoagulants so problematic?

Answer 11

because practitioners are used to continuing effect of warfarin and not the immediate cessation of anticoagulation with removal of a drug as exists with dabigatran

Question 12

What are the two oral direct factor Xa inhibitors?

Answer 12

Rivaroxaban (Xarelto) and Apixaban (Equilis)

Question 13

What are the indications for using rivaroxaban?

Answer 13

Treatment and prevention of DVT and PE, prophylaxis of future clots

Question 14

So if Vitamin K reduction is inhibited by warfarin, what is the antidote for it? What does this tell you of its efficacy?

Answer 14

Vitamin K; efficacy takes time and must be started with heparin because Protein C is also inhibited and it is the first to run out due to its short half life

Question 15

Which anticoagulant(s) are contraindicated in PGN?

Answer 15

warfarin

Question 16

How is warfarin monitored?

Answer 16

INR

Question 17

What are the indications for warfarin? How is it administered?

Answer 17

prophylaxis for DVT and VTE (orally)

Question 18

What are the antidotes for warfarin, both immediate and long term?

Answer 18

Immediate: FFP

long term: Vitamin K

Question 19

Which AC can cause cutaneous necrosis and infarction due to inhibition of protein C formation?

Answer 19

Warfarin

Question 20

What are thrombolytic agents (clot selective as opposed to systemic)? How are they given?

Answer 20

Clot selective: t-PA or Alteplase
systemic: streptokinase and urokinase
Tenecteplase, Reteplase
both are given IV or intra-arterial

Question 21

What is the antidote for t-PA?

Answer 21

Aminocaproic acid, whole blood if necessary

Question 22

What are the indications for t-PA use?

Answer 22

Lysis of clots to re-establish tissue perfusion post MI, severe PE, DVT, and arterial thombosis

Question 23

What is becoming the fibrinolytic agent of choice because it is more fibrin specific and resistant to PAI-1 than standard tPA?

Answer 23

Tenecteplase

Question 24

What are the two antifibrinolytics that we talked about and in whom are they CONTRAINDICATED?

Answer 24

Aminocaproic acid and tranexamic acid

Contraindicated in pts with DIC and GU bleeds

Question 25

What are the three drugs that inhibit thrombogenesis (antiplatelet)? Which interaction should you watch with the one that starts with a C? :)

Answer 25

Aspirin (decreases COX and TXA2), CLOPidigrel and TiCLOPidine (blocks ADP receptor to inhibit aggregation); WATCH OMEPRAZOLE AND CLOPIDIGREL (liver function)

Question 26

Which drug acts by irreversibly inhibiting the COX enzyme, thereby decreasing amount of TXA2?

Answer 26

Aspirin

Question 27

Which drug acts by irreversibly binding to ADP receptor on platelet to inhibit aggregation?
What is its special indication?

Answer 27

Clopidigrel; FOR USE IN STENT PLACEMENT SURGERY to prevent thrombosis

Question 28

You have a patient on omeprazole for heartburn. What drug should you monitor the effects of due to possibility of decreasing effectiveness?

Answer 28

Clopidigrel is metabolized by CYP2C19, which is inhibited by omeprazole

Question 29

Which drugs are considered inhibitors of GPIIB/IIIA? How are they different? How are they all administered?

Answer 29

AbcixiMAB, eptiFIBatide, tiroFIBan
Abciximab is an antibody and the other two are analogs of the carboxy end of fibrinogen
IV

Question 30

What drugs will counteract the affects of warfarin?

Answer 30

• Vitamin K – ANTIBIOTICS decrease absorption of vitamin K, increase effectiveness
• Clotting factors – estrogen/pregnancy, decrease effectiveness
• Platelet aggregation/function – ASPIRIN, increases effectiveness
• Displace from binding sites on plasma albumin
• Inhibit microsomal liver enzymes
• Induce liver microsomal enzymes