Cardiovascular Meds: anticoagulants

Question 1

Specify 3 laboratory tests to monitor the effectiveness of anticoagulants

Answer 1

PT/INR: patients who are taking Warfarin

aPTT: those who are taking Heparin

Heparin Anti-Xa level: those who are on unfractionated (UF) heparin and sometimes with low molecular weight (LMW) heparin

Question 2

Describe the mechanisms of action of

1. anticoagulants
2. antiplatelets
3. thrombolytics

Answer 2

1. anticoagulants: disrupt the coagulation cascade, less fibrin is produced
2. antiplatelets: inhibit platelet aggregation
3. thrombolytics: lyse the clot

Question 3

Recognize 3 major emergencies for patients on anticoagulants, antiplatelets, and thrombolytics

Answer 3

1. shortness of breath or chest pain
2. vital signs–low BP and high HR
3. changes in level of consciousness/mental status

Question 4

What are 4 examples of serious thrombi?

Answer 4

1. pulmonary emboli
2. myocardial infarction (MI)
3. deep vein thrombosis (DVT)
4. embolic stroke

Question 5

Compare arterial blood clots with venous blood clots

Answer 5

Arterial blood clots:
damage to BV or rupture of plaques
–> platelets adhere to the site
–> platelets secrete ADP and TXA2 which attracts more platelets

Venous blood clots:
when venous flow is slow and stagnant, coagulation cascade occurs and fibrin is produced
–> fibrin attracts RBCs and platelets to make a clot

Question 6

Specify whether anticoagulants treat thrombosis in arteries or veins

Answer 6

Anticoagulants treats THROMBOSIS IN VEINS !!!

Question 7

Classify anticoagulants into 3 groups according to their mechanisms of action and give examples of each

Answer 7

1. activates antithrombin: LMW heparin, UF heparin, and Fondaparinux
2. Vitamin K antagonists: Warfarin
3. Direct thrombin inhibitors: Bivalirudin

Question 8

Specify whether antiplatelet drugs treat thrombosis in arteries or veins

Answer 8

Antiplatelets treat THROMBOSIS IN ARTERIES !!!

Question 9

Classify antiplatelet drugs into 3 groups

Answer 9

1. Aspirin
2. P2Y12ADP receptor antagonists
3. GP llb/lla receptor antagonists

Question 10

Describe the mechanism of action of warfarin

Answer 10

Warfarin stops activation of Vitamin K

So there is less VK-dependent clotting factors (VII, IX, X< and prothrombin)

Question 11

Specify the laboratory test to monitor therapeutic warfarin levels

Answer 11

PT/INR

*** monitor the lab work and adjust dosage –> the goal is to reach & maintain therapeutic warfarin level

*** normal INR level for someone not receiving warfarin is 1.0

*** patients with DVT, pulmonary embolism: target INR is 2-3

***patients with prosthetic aortic heart valves: 2.5-3.5

Question 12

Recognize the dietary restrictions for patients on warfarin

Answer 12

Severely limit vitamin K rich foods!

Question 13

List 3 contraindications of warfarin therapy

Answer 13

1. current severe bleeding
2. poor compliance to medication, INR monitoring, or dietary restrictions
3. pregnant women

Question 14

Identify 4 groups of patients who should take warfarin with caution

Answer 14

1. uncontrolled hypertension
2. severe liver disease
3. recent surgery on brain, spinal column, or eye
4. patients who are also taking OTC aspirin and NSAIDs

Question 15

Describe the mechanism of action of “direct thrombin inhibitors”

Answer 15

Direct thrombin inhibitors are oral produrg:

dabigatran etexilate –> converted to dabigatran in the body
–> binds and inhibit prothrombin in the blood

***Fast onset
No lab monitoring, dietary restrictions, dosage is not weight dependent
Lower risk of serious bleeding

Question 16

Name an example of direct thrombin inhibitors and specify the drug approved for its reversal

Answer 16

dabigatran etexilate

antidote for overdose: Idarucizumab

Question 17

3 therapeutic uses of direct thrombin inhibitors

Answer 17

1. atrial fib
2. knee/hip replacement (immobility –> risk of developing clots)
3. DVT/PE

Question 18

Recognize the rationale for giving unfractionated heparin (UFH) subcutaneous or intravenous (IV)

Answer 18

No oral route for UF heparin!

Reason: UF heparin is a large polymer with negative charge –> cannot cross membrane!

Question 19

What is MOA of heparin?

Answer 19

Heparin is a helper to antithrombin, which inactivates factor Xa and thrombin)

Question 20

Describe the common laboratory test that is used to monitor UFH therapy and state its normal value and therapeutic target

Answer 20

aPTT monitoring (activated partial thromboplastin time)

Normal values: 40 sec
Therapeutic target: 60-80 sec (1.5-2x times normal)

Question 21

Identify 6 factors that affect the bioavailability of heparin

Answer 21

1. aging
2. obesity
3. changes in heparin binding proteins
4. liver diseases
5. kidney diseases
6. heparin resistance

Question 22

***List 2 conditions that lead to prolonged activated partial thromboplastic (aPTT) without heparin

Answer 22

Lupus (autoimmune disease)
Deficiency in contact factors

Question 23

Specify the patient group at a higher risk of developing HIT

Answer 23

Post-op patients

Question 24

Define heparin-induced thrombocytopenia (HIT) type II and describe its pathophysiology

Answer 24

Type 2 HIT is an immune-mediated disorder (due to abnormal antibodies) that typically occurs 4-10 days after exposure to heparin and has life- and limb-threatening thrombotic complications

Question 25

Identify 5 complications of HIT type II

Answer 25

Complications include clots--not bleeding! 1. DVT 2. PE 3. skin necrosis 4. MI 5. venous gangrene

Question 26

List an example of low-molecular weight heparin (LMWH)

Answer 26

enoxaparin Sub Q administration

Question 27

Recount 3 differences between LMWH and unfractionated heparin (UFH)

Answer 27

LMWH is: 1. broken into smaller pieces 2. more specific to factor Xa inactivation 3. more predictable; they can be given as a weight based dose

Question 28

What is the antidote for heparin overdosing?

Answer 28

Protamine sulfate

Question 29

Describe the mechanism of action of aspirin and list the 2 therapeutic uses of aspirin

Answer 29

Aspirin suppresses platelet aggregation by inhibiting the isoenzyme "cyclooxygenase (COX)" which leads to pain relief and the reduction of inflammation, fever, and clots. Therapeutic uses: 1. MI and angina 2. ischemic stroke and transient ischemic attacks (TIAs)

Question 30

Describe the mechanism of action of clopidogrel and list the 2 therapeutic uses of clopidogrel

Answer 30

Clopidogrel is a prodrug --> metabolized in the liver into its' active form --> suppresses platelet clumping by blocking P2Y12ADP receptors on the platelets Therapeutic uses: - keep coronary stents open - reduce thrombotic events such as MI, stroke, or peripheral arterial disease

Question 31

Name an example of glycoprotein IIB/IIIa (GPIIB/IIIa) receptor blockers

Answer 31

Amociximab Two things to know: 1. Most effective antiplatelet drugs 2. Must be given IV Nice to know: Block the last step of platelet aggregation by blocking the receptor --> prevent fibrinogen & vWf factors from binding on platelets

Question 32

State 2 indications of GPIIB/IIIa receptor blockers (Abciximab)

Answer 32

1. Percutaneous Coronary Intervention (PCI) 2. Acute Coronary Syndromes (unstable angina and non-STEMI)

Question 33

List precautions for GPIIB/IIIa receptor blockers

Answer 33

1. The elderly, patients with renal disease, and women --> higher risk of bleeding 2. No reversal agent

Question 34

What kind of lab work must be drawn for Abciximab administration?

Answer 34

1. Platelet count 2. Hb labs

Question 35

Discuss the MOA of thrombolytic therapy and name 1 drug in this class

Answer 35

Alteplase (tPA) converts plasminogen to plasmin --> dissolve clots! tPA is for emergency use only!