Anticoagulants COPIED

Question 1

Key mechanism of Warfarin (coumarin compounds)

Answer 1

Vitamin K antagonist

Vitamin K is used to synthesis coagulation factors II (prothrombin), VII, IX, and X

Question 2

Name three LMWHs

Answer 2

enoxaparin

dalteparin

tinzaparin

Question 3

What’s the management of acute thromboembolic disorders?

Answer 3

LMWH (Low molecular weight heparin) plus warfarin, and then withdraw LMWH when warfarin is effective.

Question 4

Does Warfarin act immediately?

Answer 4

No because pool of circulating clotting factors needs to be depleted first.

Synthesis of new factors is then inhibited.

(takes 3-5 days to reach maximal effect)

Question 5

What’s the advantages of LMWH compared to standard heparin?

Answer 5

can be administered subcutaneously.

more predictable anticoagulation activity (aPTT monitoring not required)

Question 6

What is the INR for recurrent embolization or artificial heart valves?

What is the INR for warfarin (generally)

Answer 6

3 - 4.5

2-3

Question 7

What is HIT?

Answer 7

Heparin-induced-thrombocytopenia

Question 8

Name three LMWH

Answer 8

enoxaparin

dalteparin

tinzaparin

Question 9

Tell me about HIT 2

Answer 9

less common, more serious.

Immunoglobulin mediated platelet inactivation.

High risk of thrombotic complications and mortality.

Question 10

What’s the antidote for warfarin-induced bleeding

Answer 10

Phytonadione (vitamin K1)

Question 11

What are the key adverse effects of Heparin?

Answer 11

Bleeding

thrombocytopenia

(hyperkalemia)

Question 12

Tell me about HIT 1

Answer 12

occurs in 25% of patients. Direct interaction between heparin and platelets, leading to platelet aggregation. Mild and reversible.

Question 13

Clinicial uses for Warfarin

Answer 13

Long term management of DVT, AF, and artificial heart values.

Question 14

What is the principal component of fibrinolysis?

Answer 14

Enzyme plasmin

(generated from inactive precursor plasminogen)2

Question 15

Can Warfarin be used in pregnancy?

Answer 15

No because it crosses the placenta

Question 16

How does Dabigatran work?

Answer 16

Direct thrombin inhibitor

(thrombin is used in the pathway of transforming fibrinogen to fibrin)

Question 17

How does LMWH compare to unfractionated heparin in it’s modus operandi?

Answer 17

Primarily deactive factor X

Question 18

How does Fondaparinux work?

Answer 18

Indirect Factor Xa inhibitor

It selectively binds to antithrombin (an endogenous anticoagulant)

which

inactivates Xa resulting in a strong inhibition of thrombin generation and clot formation.

Question 19

What is antithrombin?

Answer 19

an endogenous anticoagulant (potent inhibitor of coagulation)

Question 20

Key mechanism of heparin

Answer 20

inactivates clotting factors by potentiating the activity of an endogenous anticoagulant (antithrombin III)

Question 21

Can Heparin be given orally?

Answer 21

No because heparin and related anticoagulants are not absorbed from the gut (large molecules) and so much be administered by IV.

Question 22

Patient advise for Warfarin

Answer 22

• Any signs of bleeding, including ecchymoses.
• Contraindicated in pregnancy (fetal warfarin syndrome)
• Avoid physical activities such as kick boxing
• Don’t >>> green vegetables (vit K)
• Avoid grapefruit juice, cranberry juice
• Avoid major weight changes
• Avoid aspirin, NSAIDs

Question 23

Some common uses of Warfarin

Answer 23

Long-term treatment of DVT

Patients with AF

Patients with artificial heart valves.

Question 24

How Warfarin monitored?

Answer 24

Prothrombin Time (PT)

Question 25

What does INR stand for?

Answer 25

International normalized ratio INR = (PT _observed / PT _control) PT = prothrombin time

Question 26

What is the antidote to unfractionated heparin and LMWH?

Answer 26

**Protamine sulfate** (+ve charged protein than combines with -ve charged heparin) \*\* measure **aPTT** to monitor \*\*

Question 27

How do you monitor (a) Heparin (b) Warfarin (c) Dabigatran

Answer 27

(a) Heparin - aPTT **(b) Warfarin - PT - Prothrombin Time (remember the INR equation for warfarin)** (c) Dabigatran - TT (thrombin clotting time)

Question 28

What initiates the formation of platelets along the vascular wall?

Answer 28

**injury** and the expose of the blood to extravascular **_collagen_**.

Question 29

What activates the **intrinsic pathway**?

Answer 29

surface contact with a **foreign body** or **extravascular tissue** (i.e. collagen)

Question 30

What activates the **extrinsic pathway** in the coagulation cascade?

Answer 30

a **complex tissue factor** called **thromboplastin**.

Question 31

Where does the intrinsic and extrinsic pathways converge?

Answer 31

**Factor X -** major rate-limiting step

Question 32

What does the activation of **factor X** lead to?

Answer 32

the formation of **Thrombin**

Question 33

What three factors combined often lead to thrombic changes?

Answer 33

* **sluggish blood flow** * inflammation * **abnormalities in vascular endothelium**

Question 34

What's the difference between arterial thrombi and venous thrombi?

Answer 34

**arterial thrombi** (white); more **platelet** aggrevation driven **venous thrombi** (red); more **coagulation** driven

Question 35

**Aspirin**; clinical usages and action as an antiplatelet drug

Answer 35

**Acute coronary syndrome** **Thrombic strokes; acute and _prophylaxis_** **shown to prevent MI with _angina_.** Artificial heart valves, percutaneous coronary angioplasty. ACTION: inhibits the synthesis of **prostaglandins** from **arachidonic acid.**

Question 36

What's the most important **prostaglandin** affecting platelet aggregation?

Answer 36

**prostacyclin** and **TXA₂** (prostaglandin I₂ (PGI₂) Aspirin irreversibly inhibits cyclooxygenase; enzyme that catalyzes TXA₂ synthesis.

Question 37

Adverse effects of **aspirin**

Answer 37

**GI bleeding** **hypoprothrombinaemia**; therefore increased bleeding risks

Question 38

When is clopidogrel indicated?

Answer 38

* px who can't tolerate aspirin * used in **COMBINATION** with aspirin for **_ACS_**

Question 39

When are the representative drugs **steptokinase, alteplase** indicated?

Answer 39

intravenously to degrade thrombi in px with **MI, thromvotic stroke, PE** Primary means of restoring coronary blood flow if angioplasty facilities not available.

Question 40

Adverse reactions with aspirin?

Answer 40

GI irritation, bleeding, hypersensitivity reactions, tinnitus

Question 41

Adverse reactions to **streptokinase**

Answer 41

bleeding, hypersensitivity reactions, and reperfusion arrhymias (of interest) **anaphylactic shock** can occur with streptokinase, therefore cannot be used repeatedly on same patient.

Question 42

what is **t-PA** and give an example drug

Answer 42

**Alteplase** drugs that are 'recombinant forms of human tissue plasminogen activator' **tissue-Plasminogen Activator**

Question 43

How do Rivaro**_xa_**ban, Api**_xa_**ban, Edo**_xa_**ban work?

Answer 43

Direct Factor **_Xa_** inhibitor

Question 44

How does **_D_**agiba**_t_**ran work?

Answer 44

**_D_**irect **_t_**hrombin inhibitor.

Question 45

What's best for arterial thrombosis? Anticoagulants or antiplatelets?

Answer 45

Antiplatelets

Question 46

Some advantages of NOACs/ DOACs

Answer 46

* few interactions with food/ drugs * predictable anticoagulant effect * no need for routine monitoring

Question 47

Which pathway does Warfarin affect?

Answer 47

Both intrinsic and extrinsic

Question 48

MOA of **Heparin**

Answer 48

binds to body's **own anticoagulant (antithrombin III)** This complex inhibits factor **Xa** (and other factors)

Question 49

What is **Dipyridamole**? What is it indicated for?

Answer 49

**Dipyridamole** a coronary vasodilator and a relatively weak antiplatelet drug. **Dipyridamole** is used in **COMBO with aspirin** to prevent ischaemic stroke in px with history of thrombotic stroke, and persons experiencing TIAs.

Question 50

What is Dipyridamole?

Answer 50

Dipyridamole is an **antiplatelet** medication that also has **vasodilating properties** that can make it **unsuitable** for use in those with severe coronary artery disease, unstable angina, recent myocardial infarction. Can be combined with **aspirin** as an option to prevent occlusive vascular events in patients who have had a **TIA**, or **ischaemic stroke**.